GULF RESEARCH
REPORTS

Volume 4, Number 3

Tlie R. L. Caylor Memorial Number

Published by the

GULF COAST RESEARCH LABORATORY
Ocean Springs, Mississippi

December 1974

Gulf Research Reports

Volume 4 Issue 3

January 1974

An Address Made at the Dedication of the Richard L. Caylor Building at the Gulf Coast
Research Laboratory Ocean Springs^ Mississippi March 17 , 1973

J. Fred Walker

University of Southern Mississippi

DOI; 10.18785/grr.0403.01

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Recommended Citation

Walker, J. 1974. An Address Made at the Dedication of the Richard L. Caylor Building at the Gulf Coast Research Laboratory Ocean
Springs, Mississippi, March 17, 1973. Gulf Research Reports 4 (3): 323-327.

Retrieved from http;// aquila.usm.edu/gcr/vol4/iss3/ 1

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In recognition of his 19 years of service as head of the Department of
Science at Delta State Teachers College and having served as the first Director
of the Gulf Coast Research Laboratory, the above portrait of Dr. R. L.
Caylor was commissioned by science alumni all of whom studied under him
between 1931 and 1950.

The oil portrait was painted between January and July 1950 by
Artist Karl Wolfe of Jackson, Mississippi. Dr. Jesse S. Wliite, a professor of
biology at E>elta State at the time and a former student, colleague and
friend of Doctor Caylor, drove him to Jackson for the series of sittings
required for the portrait.

At Doctor Caylot’s death, Doctor White succeeded him as head of
the Division of Science which Doctor Caylor organized embracing the De-
partments of Biology, Chemistry and Physics.

The oil painting of Doctor Caylor currently hangs in the R. L. Caylor
Science Hall at Delta State University, A photograph of the portrait repro-
duced here was made in June 1974 by Photographer John R. Dakin of
Qeveland, Mississippi, and supplied for Gulf Research Reports through the
courtesy and interest of Doctor White.

321

AN ADDRESS MADE AT THE DEDICATION OF THE
RICHARD L. CAYLOR BUILDING
AT THE GULF COAST RESEARCH LABORATORY
OCEAN SPRINGS, MISSISSIPPI, MARCH 17, 1973

by

DR. J. FRED WALKER
Professor of Biology
University of Southern Mississippi
Hattiesburg, Mississippi

In keeping with the high and laudable traditions of respect and appreciation
established here, we are this 17th day of March, 1973, dedicating this superb
marine research and teaching facility, this imposing building, to the honor and
memory of Richard L. Caylor. Doctor Caylor was not only the first director of the
Gulf Coast Research Laboratory but the outstanding and peerless leader in the
founding or establishing of this Laboratory.

Dr. Richard Lee Caylor was born on January 1 1, 1894, in Bullock County,
Alabama. He first came to Mississippi as a student at Mississippi College where he
received the Bachelor of Arts degree in 1922. In 1931 he received the Master of
Arts degree from George Peabody College and the Ph.D. degree from LS.U. in
1944. Doctor Caylor did additional graduate studies at George Washington Univer*
sity and at the Marine Biology Laboratory at Woods Hole, Mass. During World
War I he served his country as a member of the U.S. Navy. Doctor Caylor began his
career as a college teacher at Clarke Memorial College. He shortly thereafter accept-
ed a position at Mountain Home College in Arkansas. From 1931 until his untimely
death in 1958, he taught in the Science Department at Delta State College and serv-
ed as head of the department for the last twenty-one years of his life. He was an
active layman in his church and served as a deacon of First Baptist Church of Cleve-
land, Miss, But Dr. Lee Caylor was more than an educator and .scientist; he was also
an outstanding promoter, executive and man of vision.

It was largely due to his exceptional abilities as promoter, executive and man
of vision that this great center for marine research and education was brought into
existence. In keeping with his faith in what it could and has become he initially
designated it “The Gulf Coast Research Laboratory” when there was little visible
evidence, indeed, of a research center. I do not mean to imply that he alone was
responsible for the founding of this marine research center, for the leaders of the
Mississippi Academy of Sciences and many dedicated science professors of the state
played a big part in its establishment. However, it was Richard Lee Caylor who
took the lead in mobilizing the forces of the Mississippi Academy of Sciences, tlie
Gulf Coast political and business leaders and many self-sacrificing and dedicated
university and college professors to work together to obtain the approval and sup-
port of the Board of Trustees of the Institutions of Higher Learning for the estab-
lishment of a marine research and teaching facility under the direct control of the
Board of Trustees as an independent institution rather than operating as a branch

Gulf Research Reports
Vol. 4, No. 3, 323-321 , 1974

323

324

Walker

Figure 1, The Richard L. Caylor Building, completed in May 1971, was constructed with
$466,000 appropriated in 1966 by the Mississippi Lcgi^ature. The facility contains a total of
17,000 gross square feet. Usable space is occupied by The Gunter Library, that houses the
Laboratory's extensive collection of literature in the marine sciences, by dassroom and research
laboratories and by large lecture rooms.

of any one state college. Great leaders with visions and worthwhile goals must face
the practical problems and difficulties involved in achieving their objectives, for not
many can accomplish a major task by ourselves. We must have support from others.
It is quite apparent from what Doctor Cayloi did that he recognized this fact. But
worthwhile projects, such as this one, do iiul launch themselves. A person with
something oul of the ordinary is required to attract the support of others to make
a project succeed. This something “out of the ordinary’’ Doctor Caylor had to a
large degree. He knew the leaders, the individuals, whose support was practically in-
dispensable to get the project off of the ground and he knew how to gain their
enthusiastic support. He located critically needed materials and facilities and learn-
ed how to obtain them for this project at little or no expenditure of funds, which
were extremely limited at that time. He apparently sensed the fact that there were
many otlier influential and well meaning people whose aid would greatly strengthen
the cause, but who had to be convinced of the benefits of the Gulf Coast Research
Laboratory in a very practical way before they would give their full support to the
building of a first class marine laboratory. The best way to convince this group was
to get a marine program under way, even on a very small scale, thus demonstrating
its value by results achieved. This quite evidently was the course he chose to follow.

Wc cannot fully appreciate the present without knowing something of the
past. We most certainly cannot appreciate this historic occasion and period without
being cognizant of the tremendous and almost ovenvhelming problems and dif-
ficulties Doctor Caylor had to face and overcome to gel this Institution organized
and operating. There was no money available for salaries, buildings, equipment and
materials, other than student fees, I think this fact would have stopped most

Dedication of Caylor Building

325

people, but not Doctor Caylor. The impossible was just somewhat more difficult.
Shortly after World War II Doctor Caylor learned that there were several wooden
barrack buildings including a cafeteria building at Magnolia State Park, which had
been used by the British during the war, that were not then in use. They were in
fairly good repair. He recognized that these facilities could be utilized at almost no
cost to initiate a marine summer program of training and research. He proceeded to
call a meeting on the Coast of representative members of the Mississippi Academy
of Sciences and faculties of our state and church colleges to consider the possibility
and feasibility of utilizing the Magnolia Park facilities that very summer for a mar-
ine center. The group agreed for him to proceed with the plan. In the summer of
1947 the first classes of the Gulf Coast Research Laboratory were held in the Mag-
nolia State Park facilities. The program was scheduled to fit primarily into the short
period between the end of the colleges’ summer schools and the beginning of the
new academic year in September. As mentioned above, there was no money for
equipment^ boats, microscopes, illuminators, teachers’ salaries, glassware, etc. It was
under such apparently hopeless conditions that Doctor Caylor demonstrated his
amazing abilities as an executive and promoter. All sorts of surplus commodities
were obtained from government agencies; microscopes were borrowed from various
colleges. Tlie enthusiastic support of local political and business leaders was
obtained during the summers of 1949 and 1950. The old Seafoods Commission
made boats available for field trips to the islands. Even the local children were en-
couraged to collect mayonnaise jars and other glass containers for laboratory use,
and they responded. Doctor Caylor was able to persuade several college and univer-
sity professors of the State to come down to the Laboratory to direct a course or to
give a lecture or two to one of the classes. The financial inducements were for all
practical purposes nil. As an example of faculty compensations I am quite familiar
with one such case, it was room and board for the three weeks plus a financial re-
muneration of $25.00!! Visiting scientists from oilier states were utilized to the
maximum advantage* A member of the L.S.U. zoology staff, the long time director
of the L.S.D. Grande Isle Marine Laboratory, gave yeoman’s service to the cause.
These early instructors and the pioneer students labored under very primitive condi-
tions. There was no air conditioning, no fans, no refrigeration of any sort except in
tlie cafeteria. Much of the class work in botany and parasitology was done on large
wooden tables under the oak tiees. The gnats, hornets, bees and deer flies took a
great interest in students and instructors alike. The hornets seemed especially
curious about the specimens the parasitologists were investigating, and with it all
was the humid, breezeless, summer heat. But the work progressed, large numbers of
students from many colleges and states came to learn; a real marine institution be-
gan to take shape. For several summers toward the end of each summer term, Doc-
tor Caylor would have the instruciors and students prepare a display of specimens
and materials collected during the summer for the local citizens, visiting scientists
and political dignitaries to see and thus learn first hand of what was going on here.
The day of the display was culminated by a banquet attended by the visiting digni-
taries, students and instructors. Doctor Caylor recognized the value and desirability
of events of this type as occasions to demonstrate what this institution could mean,
even in its early days, to the Gulf Coast and to the State of Mississippi. This was
just one technique he used to gain more enthusiastic supporters for the program
and for his larger and more extensive plans for the future.

326

Walker

As your speaker recalls it was during the summer of 1947, that Doctor Caylor
learned that the site now occupied by the Laboratory could probably be purchased
for a very reasonable price. The property was owned by the editor of “Esquire”
magazine and consisted of almost forty acres, a very large two story residence with
a long pier extending out into the bay, plus a fairly large greenhouse. It was clearly
an ideal location for a marine laboratory. Not many months thereafter Doctor Cay-
lor requested that several of us meet with him on the Coast with Ex-Governor
White, who was then chairman of the State Building Commission, in an attempt to
persuade him to purchase this property for the Gulf Coast Research Laboratory, We
were successful in this effort and the property was purchased. During the Summer
Session of 1949, most of the Laboratory’s operations were still carried out in the
Magnolia State Park facilities, the cafeteria and the student dormitories of the park
continued to be utilized as were some two of the classrooms. But with the purchase
of this property Doctor Caylor’s dream of a permanent Gulf Coast Research Lab-
oratory was almost guaranteed.

For the first four summers Doctor Caylor had no State funds to support the
operations of the Laboraloiy, As far as your speaker has been able to learn, the
only money available, as mentioned above, for operating expenses came from stu-
dent fees. At last in 1950, the Board of Trustees did make available $35,000 to ob-
tain and move the present cafeteria building from the federal work’s agency at Pas-
cagoula to its present site. The Magnolia State Park cafeteria building burned to the
ground toward the close of the 1950 Summer Session. It was not until 1951 that
the Board of Trustees approved the granting of SI, 000 to each of the four major
stale colleges (University of Mississippi, Mississippi State, Mississippi Southern and
Delta State) for the specific purpose of supporting instruction and research at tlie
Gulf Coast Research Laboratory. During these first five years of the Laboratory-’s
existence Doctor Caylor gave an enormous amount of his time and energy to pro-
moting and strengthening the Gulf Coast Research Laboratory. Wherever he
traveled he talked about the Laboratory and the things going on down here and
thus helped to attract more and more people from an ever widening area to come
and see and participate in its activities. Doctor Caylor instituted the holding of an-
nual meetings of representatives of the faculties of the senior colleges with the chief
officers of the Mississippi Academy of Sciences at Jackson in the Board of Trustees
Room of the State Office Building with the executive secretary of the Board to
plan each summer’s program. This practice emphasized in a very impressive manner
that the summer programs here were for all the colleges, an opportunity and place
for students and faculty members of all the colleges to carry on marine studies and
research. I think this practice also emphasized and underscored one of the original,
fundamental and basic objectives and intents of those responsible for the founding
of the Gulf Coast Research Laboratory; namely, that this marine laboratory was
never to be a branch of any one of the state colleges or universities, but rather it
was to always be an independent cchter of marine research and training for use by
all the universities and colleges of the State.

By the summer of 1950, the Gulf Coast Research Laboratory had become
quite well known in several states as a good and convenient center for marine
studies and research. During the 1950 Summer Session the New Orleans Times Pica-
yune sent one of its gifted feature writers and a photographer to make a rather de-

Dedication of Caylor building

327

tailed study of what was going on here in marine work. The visit resulted in a pro-
fusely illustrated four page article in the September 10, 1950, Titnes Picayune wto
magazine ‘^‘Dixie;’’ The front cover of this issue carrier! a color picture of a large
number of marine forms, especially various types of fish> collected in the surround-
ing waters, with a caption beneath calling attention to the feature article inside.
This was excellent advertisement for the dien very young marine laboratory over a
multistate area. Toward die close of this article by Miss Dianne Parrel, she quotes a
statement made to her by the captain of the Seafoods Commission boat the
Laboratory was using that summer. The captain was quoted as saying*. “They
tell me that these folks are going to do a real job helping shrimpers get better hauls,
and I think thaCs a fine thing.” The article ended with an answering statement from
Etoctor Caylor as follows: “When this fine thing happens, when they get better
hauls, when the big things happen, Doctor Caylor says it will be the victory for the
guys who slept out in blankets on the beach, and the little girls who collected all
those mayonnaise jars.” This statement, it seems to me, reveals or reflects the spirit
of the man Caylor. It is indicative of the faith of the man in his greater vision of
what this Laboratory would mean to the people of our State. But isn’t it also a very
fine expression of his appreciation for all the little things done by the pioneer stu-
dents, instructors and volunteer helpers under primitive and trying conditions, to-
ward the establishment and progress of this marine center? And some of “The Big
Things” have already happened here, but to fully realize his dreams for this Labora-
tory demands the rededication of the members of the Laboratory staff, present re-
search students and those to come in subsequent yearSi and the citizens of Missis-
sippi to the greater practical objectives of his dream. We still look forward to that
day when our fishermen “get the better hauls” and repeated better hauls because of
the research done here.

By 1951 it was becoming very evident that the Laboratory needed a full time
director. Again it was Richard L. Caylor who located an outstanding and widely ex-
perienced marine scientist, a world authority on the oyster, who miglit be obtained
to fill this position, the late Dr. A. E. Hopkins. Doctor Caylor recommended him
for the position to the Board of Trustees and his recommendation was acted upon
favorably. In 1952, Dr. A. E. Hopkins, a well known and able marine scientist, be-
came Ihe first full time director of the Gulf Coast Research Laboratory. He served
with distinction in this position until his untimely death in 1955. With the employ-
ment of a full time director for the Laboratory, Doctor Caylor’s dream was
realized, his vision had become substance. The so apparent near impossible objec-
tive had been attained within a remarkably short period of time. And now lest some
who come after us should forget what this man has done for this marine facility and
for the State of Mississippi, a plaque bearing his name is placed upon this magnifi-
cent building designating it as the “Richard L. Caylor Building” which will serve to
keep his name and memory alive for years to come on these grounds which he loved
so dearly and to which he gave so much of himself. It |s tlien most appropriate that
with a deep sense of gratitude for what he has done for higher education in Missis-
sippi and for marine research and training in this part of the fabulous “Golden
Crescent” of the Gulf that we honor him today in this manner. The good he has
done will live on and we have good cause to believe that the fruits of his labors here
will bless generations to come.

Gulf Research Reports

Volume 4 Issue 3

January 1974

An Estuarine Low- Temperature Fish- Kill in Mississippi^ with Remarks on Restricted
Necropsies

Robin M. Overstreet

Gulf Coast Research Laboratory

DOI: 10.18785/grr.0403.02

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Part of the Marine Biology Commons

Recommended Citation

Overstreet, R. M. 1974. An Estuarine Low-Temperature Fish-Kill in Mississippi, with Remarks on Restricted Necropsies. Gulf
Research Reports 4 (3): 328-350.

Retrieved from http://aquila.usm.edu/gcr/vol4/iss3/2

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AN ESTUARINE LOW-TEMPERATURE FISH-KILL IN MISSISSIPPI,
WITH REMARKS ON RESTRICTED NECROPSIES^

by

ROBIN M. OVERSTREET
Gulf Coast Research Laboratory
Ocean Springs, Mississippi

ABSTRACT

In January 1973, large numbers of Mugil cephalus (striped mullet), weighing approxi-
mately 250 gm each, died in two freshwater localities in tidewater bayous of Jackson County,
Mississippi. Fish identified Mugil curema. M. cephalus. Megalops a Hantica, Dor mitator macu-
laius, and Fundulus grandis were found dead in other low saline estuarirw areas. Fish-kills
during cold periods are less commonly encountered in Mississippi than in Texas or Florida. Tliis
particular incident is attributed to conditions of stress for fishes iitcomplctcly acclimated to the
encountered low temperatures. The most deleterious stress was the low saline water which prob-
ably allowed a breakdown in the fishes’ ion-osmoregulatoxy mechanisms. Striped mullet and
other euryhaline fishes in salinities greater than 6 ppt survived, as did freshwater centrarchids
and ictalurids in areas with dying mullet- Other stresses thought to contribute to the weak-
ening of striped mullet in Paige Bayou during the period of rapidly decreasing temperatures in-
clude starvation and high levels of pesticide residues. In examined fish, the alimentary tracts
were devoid of food, the gall bladders were distended and leaking bile, the livers contained
excess lipid material and were often stained throughout with bile pigments, and the levels of
DDl metabolites and endrin residues in the liver were higher than in control fish. Stress
caused by low levels of dissolved oxygen, toxic substances in the water, or disease was dis-
counted as a cause of death.

INTRODUCTION

On 16 January 1973, following a short period of freezing temperatures, sev-
eral hundred thousand dead and dying striped mullet, Mugil cephalus Linnaeus,
were observed floating in and lining the banks of Paige and Cooper Bayous near
Vancleave, Mississippi. Many times that number of fish, according to local residents,
had sunk or bee.n swept out of the area earlier that day or the previous day by the
tide. Such mass mortaJixy prompted an immediate search of other areas for dead
fishes and possible causes for the deaths.

Large fish-kills occurring during cold weather, such as the one mentioned, and
apparently not associated with fishing mishaps, toxic substances in the water, or
low concentrations of dissolved oxygen have been documented regularly from

^This study was conducted in cooperation with the U.S. Department of Commerce,
NOAA, National Marine Fisheries Service, under PL 88-309, Project No. 2-174-R and NOAA,
Office of Sea Grant, under Giant No. 04-3-158-53. The U.S. Government is authorized to pro-
duce and distribute reprints for governmental purposes notwithstanding any copyright notation
that may appear hereon.

328

Gulf Research Reports
Vol.4, No. 3, 328-350, 1974

Rsh Cold-Kill in Mississippi

329

Florida (Willcox 1887; Bangs 1895; Finch 1917; Storey and Gudger 1936; Storey
1937; Miller 1940; Galloway 1941 ; Tabb and Manning 1961 ; and Tabb el al. 1962)
and Texas (Gunter 1941, 1945, and 1952; and Gunter and Hildebrand 1951), but
not from Mississippi and Alabama. Near Corpus Christ!, Texas, many people take
advantage of (he first cold spell by collecting stunned foodfish before the fishes
move offshore* Christmas (1973:39) noted that extensive cold-kills have not been
reported from the Mississippi estuaries, but that less extensive cold-kills do occur.
Such deaths happen in Georgia (Dahlberg and Smith 1970) and North Carolina
(Wells et al, 1961), but are rare.

I assume that the mortalities in Mississippi were caused by the combination of
low temperature and other, possibly synergistic, stress-causing factors. Some of
these factors will be discussed.

MATERIALS AND METHODS

Witnessing the extensive fish-kill in Paige and Cooper Bayous, tributaries of
Bluff Creek in Jackson County, at Township 6 South, Range 7 West, Sections 25,
26, 27, and 35, led the writer to the inspection of other areas in the county. These
included another tributary of Bluff Creek farther north in Section 16; the entrance
of a canal situated parallel to Bellefontaine Beach' at T8W, R8S, Section 13 and its
eastern end at T8W, R7S, Section 17; Graveline Lake; a canal at T8S, R8W, Section
1 1, as well as Sinunons Bayou in Section 2, both in Gulf Park Estates; Davis and
Heron Bayous below and near the bridges of old U.S. Highway 90: Davis Bayou at
the Gulf Coast Research Laboratory; the Ocean Springs Small Craft Harbor at both
Shearwater and Pine Drive bridges; and Bayou Porteaux and a nearby bayou, both
off Old Fort Bayou immediately north of Ocean Springs.

When dead fishes were found, as they were in some of the Bluff Creek tribu-
taries; Simmons Bayou, a tributary of Davis Bayou; upper Davis Bayou; and a tribu-
tary of the Ocean Springs Small Craft Harbor at Pine Drive, the standard length was
measured and the gills, alimentaty tract, liver, and gall bladder carefully examined.
Representative samples of liver and gill tissues from fish which were comatose and
in a terminal state were fixed in phosphate-buffered 10% formalin for sectioning.
For comparative purposes, additional material was collected alive from Davis Bayou
on January 19 and 22 and August 3, 7, 24, and 29, 1973 and immediately fixed.
Liver tissue was obtained both from near the base and tip of the left lobe with sec-
tions cut at or S iJL and stained using hematoxylin and eosin, Masson’s trichrome
method, Hall’s method for bilirubin, and the periodic acid-Schiff technique with
and without diastase-hydrolysis. A Sudan black B solution was used to test for
lipids in frozen tissue sectioned at 10— 14^^ with a cryostat. The techniques fol-
lowed those edited by Luna (1960).

Livers from a sample of six striped mullet from the Paige Bayou kill were
immediately frozen for pesticide analysis. Samples for comparison were obtained
from striped mullet caught for human consumption from Davis Bayou on 14 May
1973, Six were frozen immediately upon death and six others left at 25®C for 6

330

Overstreet

hours to reflect any differences attributable to rapid deterioration of residues of
pesticide after death. Each of the three samples consisted of livers from six pooled
mullet. Aliquots of 6.0 to 16.0 gm liver were added to double the amount of anhy-
drous sodium sulfate, 100 ml nanograde isopropanol, and 100 ml nanograde hexane,
and were completely macerated in a stainless steel blender. The blended tissue was
quantitatively transferred to a Buchner funnel to remove solid material. After the
liquid filtrate was transferred to a separatory funnel and washed three times with
distilled water to remove isopropanol, it was filtered througli anhydrous sodium sul-
fate to remove final traces of water, and then concentrated to 5 ml in a Kuderna-
Danisli concentrating apparatus. Pesticide residues were then determined by gas-
liquid chromatography, using a Ni®^ electron-capture detector and calibrating with
standard solutions. Analyses were performed using two different columns as a check
on retention times.

Samples of water from the sites visited at the time of the fish-kill were col-
lected and analyzed for content of salt, chlorine, and calcium. Salinity was deter-
mined with an AO Goldberg temperature-compensated refractometer; chlorosity by
the low-precision, silver nitrate, titration method of Strickland and Parsons (1968);
and calcium with a Perkin-Elmer atomic absorption spectrophotometer Model 305.
Climatological data were obtained from monthly summaries of the U.S. Depart-
ment of Commerce, Environment-.! Data Service, for Biloxi, Mississippi; Corpus
Christi, Texas; and St. Petersburg, Florida.

OBSERVATIONS AND RESULTS

A thin sheet of ice covered the surface of Paige and Cooper Bayous during the
evenings of January 13 and 14. These are sites roughly 1 to 5 m deep and com-
pletely fresh during that time of year. On the following day, vast numbers of striped
mullet surfaced and died. By the next day, January 16, the tide, about 0.6 m in
amplitude, removed the majority of fish, but a minimal estimation of a few hundred
thousand carcasses still remained. Many had sunk and a few fish continued to sur-
face and die, Other than mullet, the only dead fish observed were four specimens of
the emerald shiner, Notropis atherinoides Rafinesque, 16 to 76 mm SL (averaging
7L0 mm) which had apparently been killed by the propeller of an outboard motor.
"‘Shellcracker,’* ^‘bream,” ^‘bass,’" and “catfish” actively fed when local residents,
who frequently fed them, placed food in the water. Because of the presence of ap-
parently healthy centrarchid and ictalurid fishes which would have also been affect-
ed by toxic materials, analysis of the water for such substances was not performed.

Additional areas nearer the coast were then inspected for dead fishes. These
areas, with corresponding observed dead and living fishes, and with values for salin-
ity, chlorosity, and calcium in the water, are listed in Table 1. Only the low-saline
areas of Davis Bayou, the Small Craft Harbor, and Simmons Bayou contained dead
fish. Davis Bayou was visited after most of the dead fish apparently had been swept
away: the tidal flow was strong, and the remaining fish, all striped mullet, were lin-
ing the banks. Signs of raccoon and birds surrounded many partially-eaten fish. The
Pine Drive area of the harbor, mostly less than 2 m in depth, had much less water
movement, and the majority of dead fish had sunk. In contrast to the presence of

TaWe 1.

Some Chaiacteristics of Water and Fauna on the Morning of 16 January 1973 at Several Localities

in Jackson County, Mississippi

Locality

Relative amount
of dead fish

Living estuarine
fishes observed

Salinity

ppt

Chlorosity
gra chloride/liter

Calcium

ppm

Paige Bayou

Very numerous

None

0.0

0.30

6.5

Upper Davis Bayou

Several

5.0

3.48

77

Simmons Bayou

Many

Low

Small Craft Harbor

Rne Drive

Several

None

6.0

4.45

94

Unnamed tributary of

Old Fort Bayou

None

7.5

5.48

175

Bayou Porteaux

None

Striped mullet,
spotted seatrout,
and others

8.0

5.86

138

Heron Bayou

None

Cyprinodontidae

8.5

5.16

122

Graveline Lake

None

Striped mullet
and others

9,0

5.45

128

Canal entrance at

Bellefontaine Beach

None

Cyprinodontidae
and PoecDiidae

10.0

6.68

145

Gulf Coast Research
Laboratory Pier

None

Many species

10.5

6.47

141

Small Craft Harbor

Shearwater Bridge

None

White mullet
and others

11.0

6.99

126

Canal in Gulf Park

Estates

None

Cyprinodontidae
and others

14.0

8.44

165

East end of Canal at
Bellefontaine Beach

None

Cyprinodontidae
and others

14.0

8.99

185

Fish Cold-Kill in Mississippi

332

Overstreet

exclusively dead M. cephalus in the mentioned areas, the harbor contained dead
individuals of the white mullet, A/, curema Valenciennes; tarpon, iVfega/ops atlantica
Valenciennes; and fat sleeper , Do rmiia tor maci^ktus (Bloch); and no observed living
fishes. A.n estimated 500 fisit had died , possibly all that had been present, and other
animals had been feeding on the carcasses. A few hundred meters southwest of this
area, where the salinity was higher, white mullet and cyprinodontids swam near the
piers. Mullet from the latter area appeared partially dazed the previous day. A few
dead M. cephalus and one Gulf killifish, FunduJus grandis Baird and Girard, were
collected from Simmons Bayou in low-salinity water, but, according to fishermen,
many dead fish were tliere earlier. Numbers and measurements of the collected fish
appear in Table 2. An average-sized M. cephalus weighed about 255 gm (0.56 lb).

Table 2.

Fishes^ Dead in Conjunction with Low Temperature on
16 January 1973 in Jackson County, Mississippi

Area

Species

No. fish
aitically
examined

Standard length in mm
Range Average

Paige Bayou

Mugit cephalus

25

170-278

231.0

Upper Davis Bayou

Mugil cephalus

5

219-253

230.4

Simmons Bayou

Mugil cephalus

13

203-261

232.5

Fund ulus grandis

1

83

Ocean Springs

Mugil curema

22

86-154

113.4

Small Craft Harbor

Megalops atlantica

6

226-289

251.5

Pine Drive Bridge

Dormitator macubtus

21

40-102

67.0

t-The largest and smallest observed specimens of all species were included in each sample.

There were mullet and other fishes in some of the areas that were not associ-
ated with mortalities. Fishermen caught striped mullet during and after the cold
weekend of January 13-14 in Graveline Bay and Bayou Porteaux. Table I lists
other observed fishes.

During the cold weather, striped mullet in the relatively high salinity of Missis-
sippi Sound congregated nocturnally about the mouths of bayous and spread out on
the mud-fiats during the day. According to a commercial fisherman, few, if any, of
the mullet present in Davis Bayou on the night of January 14 fed. He said he cut
more gall bladders ihan usual while cleaning these fisli, suggesting enlarged bladders.
By the following night, he reported, normal feeding behavior resumed. An examina-
tion of 13 of those fish refrigerated for 2 days confirmed an adequate intake of
food: a full alimentary tract, normal-appearing gall bladder and liver, and several dif-
ferent parasites, all features which contrast greatly with the condition of mullet
from the more freshwater habitats on the following day.

Numerous representatives of dead and dying fish from all areas were exam-
ined. The gills of dying fish looked healthy; they were filled with well-oxygenated
blood and were not coated with excessive mucus. The viscera had several aspects in

Fish Cold-Kill in Mississippi

333

coniiTion: in specimehs of each species, all stomachs and intestines were empty, gall
bladders were greatly distended, portions of livers and often other organs were
stained with leaked bile, liver parenchyma was pale, and mesenteric and other vis-
ceral depot fat was extensive. It should be emphasized that the liver’s parenchyma
was often stained throughout in the comatose mullet. All of the tarpon, an infre-
quent inhabitant of modern-day Mississippi bayous, appeared thin. Figure 1 illus-
trates viscera from a striped mullet that had recently died. Mullet examined
3 October 1973 also had empty alimentary tracts, enlarged gall bladders, and small
pale areas in the livers (Fig, 2). Mullet, all ripe and nearly ready to spawn, a condi-
tion also apparently associated with a lack of feeding, remained void of all but a
minimal amount of food throughout October and the first part of November.
Figure 3 shows the viscera of a fish from December 4 that had been feeding.

l-Iistological sections of gills and livers from striped mullet involved in the kill
were compared with tissues collected 6 days and then again 7 months later. The gill
tissue of the former was not diseased, had little mucus, and had far fewer ciliate pro-
tozoans and no monogeneaiis and copepods, all of which were common parasites in
material from Davis Bayou where there were no mortalities. Sections of liver stained
with hematoxylin and eosin and with Hall’s method for bilirubin revealed no con-
spicuous bile pigments nor pathological changes in the hepatic ducts that differed
greatly among dying mullet and others collected in January and August, even
though bile pigments discolored the parenchyma throughout much of the livers of
the dying fish. Extensive cytoplasmic vacuolation, however, did occur in the hepato-
cytes of the dying fish (Fig. 4). Vacuolation, to a lesser extent, appeared in all livers
with the least amount found in a fish caught 24 August (Fig. 5). Using routine stain-
ing procedures, the extraction of either lipids or glycogen can cause vacuolation.
Frozen sections retain lipids and some glycogen usually remains in standard sections.

Lipid material, but not glycogen, was exhibited in hepatocytes of the fish
from the mass mortality, Preparations positive for Sudan black also occurred for
two of three livers of fish collected August 3 and 7 that were originally suspected as
being excessively fatty by gross examination. Negative stains for fat resulted for
livers of the remaining fish collected January 19 and 22 and August 3, 7, 24, and
29, The Sudan black stained material throughout the entire liver, but more abun-
dantly in the subcapsular parenchyma, in the dying fish (Fig. 6) and appeared only
on distinct portions of the other two. Figure 7 shows vacuolated tissue without
lipids and Fig. 8 shows less extensive lipid accumulation in a mullet during the
summer.

Preparations positive for PAS, hydrolyzed by diastase and thus indicative of
the presence of glycogen, were demonstrated for all of the livers not collected from
the fish'kill except two in August. One of those had the least amount of vacuolation
of all livers. Figure 9 sliows the absence of glycogen in liver from a dying fish and
Figs. 10 and J I show moderate and considerable deposits of glycogen, respectively.

In addition to vacuolation, the livers from the dying fish occasionally revealed
foci of centralobular hepatic necrosis (Fig. 12). Such a finding was not unusual,
since all livers possessed this possibly typical characteristic. Figure 13 reveals some
inflammatory response associated with an hepatic duct even from fish exhibiting no

334

Overstreet

Figure 1. Viscera of recently
collected dying Mugil cephalus
from mass mortality on 1 6 Jan-
uary 1973. Note the empty ap-
pearing intestinal tract, pale
fatty liver, enlarged gall blad-
der, and leaked bile.

Figure 2. Viscera of Mugil
cephalus ready to spawn on
30 October 1973. Note that
this fish also has an empty in-
testinal tract and an enlarged
gall bladder.

Figure 3. Viscera of typical
feeding Mugil cephalus on 4
December 1973. Note that the
intestine contains material, the
gall bladder is not enlarged, and
the fat adjacent to the intestine
is more abundant than on the
above fish. The livers of some
individuals at other periods
may be more reddish in color.

FISH Cold-Kill in Mississippi

335

Figures 4-5. 4. Extensive vacuolation in Iiepatocytes of Mugil cephalus dying on 16 January
1973, high power view, Masson’s (richrome method. 5. Minimal vacuolation in hepatocytes of
Mugil cephalus on 24 August 1973, higlj power view, Masson’s txichrome metliod.

other pathological lesions. More pronounced was tlie Inflaninialion of specific ves-
sels in fish caught in August and containing excessive amounts of fat (Figs., 14-16).
In a few sections of livers, but not those from the dying fish, a pigment, apparently
a fixation artifact, surrounded some portal veins and occasionally other vessels
(Fig. 17). Hepatic parenchyma of striped mullet, not in distinct lobules, were
arranged in dual-plaied niuralia, especially notable in Fig, 8, separated by sinusoids.
These sinusoids typically appeared more conspicuous peripherally.

Residue levels of some chlorinated hydrocarbon insecticides appear in Tabic 3.
Livers from M. cephalus dying during the kill possessed higher concentrations of
endrin, p,p’-DDE, and p.p’-DDL) than livers collected later from apparently
healthy individuals. Allowing for individual variation, little difference exi'sted
between pooled livers of freslily caught and decomposing mullet.

Table 3.

Pesticides in Parts per Million (milligrams per kilogram) Recovered from Livers of Striped Mullet
Collected 16 January and 14 May 1973 in Jackson County, Mississippi

Insecticide

Fish-kill

Paige Bayou

Source of mullet

Fresh

Davis Bayou

Aged 6 hours
Davis Bayou

Chlord ane ,Ct-iso mer

0.44

0.73

0.38

Endrin

1.02

0.52

0.39

p,p’-DDT

0.38

0.29

0.33

o,p’-DDT

0.51

0.60

0.35

p.p’-DDE

0.64

0.33

0.32

p,p’-DDD

• 1.58

0.53

0.73

Examination for internal and exiernal parasites revealed few organisms. The
fishes from the Small Craft Harbor, somewhat decomposed, had no obvious
parasites. Dying striped mullet from Paige Bayou could be examined much more

336

Overstreet

Figures 6-8. Frozen liver tissue from Mitgil
cephalus stained in Sudan black B solution to
test for lipids. 6. Extensive lipid deposition
in fish from 16 January 1973 kill, high power
view. 7- Vacuolated tissue not containing
lipids in fish from brackish water on 22 Jan-
uary 1973, high power view. 8. Fatty tissue
from fish on 7 August 1973, medium power
view. Note dual-plated mur alia radiating from
central vein.

Figures 9-11. Peripheral areas of liver tissue
from Mugil cephatus stained using periodic
acid-Schiff technique. 9. Liver of fish from
kill on 16 January 1973 revealing no glycogen
deposits, medium-high power view. 10. Liver
from 7 August 1973 revealing moderate glyco-
gen deposits, medium-high power view. Dark-
ly stained areas representing glycogen were
hydrolyzed witli diastase. I 1. Fish of 22 Jan-
uary 1 973 revealing extensive glycogen depos-
its, medium-high power view.

Fish Cold-Kill in Mississippi

337

Figures 12-17. Signs suggestive of patliological changes in liver tissue of Mugil cephalus.
12. Necrosis around central vein of fisli from 16 January 1973 kill, medium-high power view,
hematoxylin and eosin. 13. Minimal white blood cell involvement around hepatic duct of
least pathologically altered liver examined, from fish on 24 August 1973, medium-high power
view, hematoxylin and cosin. 14. More severe degeneration and inflammation within portal
area of liver from 3 August 1973, low power view, Masson’s trichrome method. IS. A less in-
flamed area of same tissue as Fig. 14 with moderate lymphocytic infiltration, medium-high
power view. 16. High power view of still another area in the liver illustrating extensive involve-
ment by eosinophils, the large cells surrounding Ute vein which contains smaller lymphocytes
and eryUirocytes, hematoxylin and cosin. 1 7. Substance, apparently a fixation artifact, sur-
rounding vessel of fish from 29 August 1973, medium-high power view, hematoxylin and eosin.
Similar pigment surrounded occasional veins, arteries, and hepatic ducts of a few other mullet.

338

Overstreet

critically, but harbored few parasites. Externally, the mobiline peritrich Trichodina
sp. lightly infested the gills of most, and the piscicolid leech Myzobdella lugnbris
Leidy, 1851 occurred feeding on about 5% of several hundred superficially examined
fish. One such fish had a light infection of Trypanosoma sp., a protomonad flagel-
late infecting the blood, but blood samples of the other mullet were not collected.
The neoechinorhynchid acanthocephalan, Floridosentis elongatus Ward, 1953, in-
fected one of ten fish examined for intestinal parasites.

On January 25, residents along Cooper and Paige Bayous reported that several
dead mullet were again present on the surface. By the time the area was visited, a
few thousand mullet floated on the surface, and others could be seen dead on the
bottom. Examination revealed them to be bloated and well decomposed. The adi-
pose eyelids of the fish had become translucent with hemorrhaging at the base, and
filamentous algae, up to 4 cm long, covered the external surface of many fish. I be-
lieve all the floating fish had been sunken fish on January 15 and had filled with gas
from decomposition and then surfaced. Healthy mullet had by this time partially
repopulated the bayou. That same day, assistants examined sites of other kills, as
well as additional sites, without finding any trace of dead fish.

Earlier, on January 22, a resident living on a canal off Mary Walker Bayou in
Gautier, Mississippi, reported that about 3000 dead mullet had floated into his
canal, but not adjacent ones, during the previous three days. These mullet were also
bloated and contained considerable filamentous algal growth. They probably died
earlier in the low-saline western region of Mary Walker Bayou. Personnel at nearby
fishing camps northwest of the U.S. Higliway 90 bridge over the West Pascagoula
River staled on January 22 that they had observed no unusual number of dead fish
recently, except on the two days following the freeze on January 13 when they saw
large numbers of dead mullet in the upper West Pascagoula River. Since Bluff Creek
joins that river, those mullet probably constituted the same ones under study.

In order for the reader to understand relative temperature values, two figures
are presented. Figure 18 reveals that the air temperature reached its lowest level,
-4.4T, on January 13, after declining steadily for 8 days. Fora comparative exam-
ination of temperatures in areas producing extensive mortalities, montlily values for
average and lowest air temperature in Corpus Christi, Texas; St. Petersburg, Florida;
and Biloxi, Mississippi were obtained. During winter months, temperature values
from Texas were usually lower than those from Florida, and therefore closer to
those in Mississippi and better to compare for critical differences with those from
Mississippi where fish are not as prone to mortality during cold spells. This com-
parison, indicated by Fig. 19, shows that both the average and the lowest tempera-
tures during cold months were lower in Mississippi than in Texas. Air temperatures
replace those for water temperatures because of unavailability of the latter data.
Althougli sligluly higlier in value, air temperatures reflect the general condition of
the water rather well. The winter temperature of shallow water and small bodies of
water surrounded by land is slightly lower than that in deep and open waters.

On 17 December 1973, the temperature once again fell below freezing, and a
thin sheet of ice covered some of the coastal bayous. All the areas where dead fish
were found earlier in January were examined. The salinity of the water in those
areas along the coast ranged from 9.0 to 19.0 ppt, and numerous different fishes

Fish Cold-Kill in Mississippi

339

Figure 18. Values for the lowest daily air temperature during December 1972 and January
1973 in Biloxi, Mississippi.

Average
Mississippi
.... Texas

Lowest
_ Mississippi
Texas

Figure 19. MontliJy values for average and lowest air temperatures in Corpus Christi, Texas,
and Biloxi, Mississippi, between January 1968 and February 1973.

340

Overstreet

were present. Paige and Cooper Bayous were completely fresh, but, according to
operators of fishing camps, all the mullet had moved out about 2 weeks earlier dur-
ing some less severe cold weather. In any event, no dead fish were observed on or
following December 1 7.

DISCUSSION

The death of fishes reported here most certainly resulted from the low tem-
peratures, but the cause appears to be more complicated than temperature alone.
Why did the estuarine striped mullet die in Paige Bayou, wliile, in the same area,
centrarchids and ictalurids fed eagerly, and while mullet survived in Mississippi
Sound and bayous of relatively liigJi salinity? Stress on the fish in different amounts
and in addition to that caused by low temperature probably can be attributed to
factors involved in osmoregulation, lemperature-rate-change, acclimation, nutrition,
pesticides, as well as other possibilities. Many will be discussed.

Salinity -Osmoregulation

A marine fish, such as any of the dead fishes, wiiich is capable of entering
brackish water normally counteracts osmotic and ionic changes in low saline water
by regulating blood and other body fluids. Its ability to regulate osmolarity also
depends on temperature. I'he present results suggest that at the encountered tem-
perature or its rate of change, mullet and the other observed euryhaline fishes could
not tolerate concentrations of or less than about 6.0 ppt salinity with 4.5 gm
chloride per liter and 94 ppm calcium. E.xact values of concentrations are probably
meaningless, and presumably, if the level of calcium ions or, perhaps, other ions
were higlier, llien salinity per se would have even less meaning. Calcium ions affect
permeability of membranes, but their exact function remain.s poorly understood.

Cameron (1970) studied blood of striped mullet from the natural environ-
ment in Texas and found lowered hematocrit values, hemoglobin concentrations,
and red blood cell concentrations during winter. In opposition to his finding for the
pin fish, Lagodon rhomboides (Linnaeus), Cameron did not find a decrease in hemo-
globin and hematocrit value in mullet when salinity was decreased.

Striped mullet can be transferred from seawater to freshwater, if dilution is
gradual (e.g. Cummings 1955). McFarland (1965) showed that the fish regulated
serum ion concentration, muscle ion concentration, and osmolarity about as well
when living in freshwater as when in a hypersaline solution. Although aware of a
possible influence by temperature, McFarland did not study that relationship. Also
not studied in relation to temperature was the prolactin concentration of the mul-
let's pituitary gland (Sage 1973). Sage found that this hormone, one that apparently
acts by reducing surface permeability [see review by Johnson (1973)] , was involved
both with initial and long-term adaptation of A/, cephalus from seawater to fresli-
water. Suppression and alteration of ion-osmoregulatory mechanisms in fishes at
low temperatures has been discussed (Morris I960; Houston 1973). An alteration in
acid-base balance can also accompany cold-shock (Boucher-Firley 1935). Possibly,
in the kill reported here, at least a breakdown of the ion-osmoregulatory mechanism
took place. 1 do not know how long individiud mullet inhabited the freshwater bay-

FISH Cold-Kill in Mississippi

341

ous off Bluff Creek before the fish-kill, but the fish were devoid of many ectopara-
sites common in brackish areas, and a large group resided there continuously for
several weeks. Immigration takes place, since a few mullet reinhabited the area by
January 24.

There was no reason to suspect low concentrations of dissolved oxygen during
the cold period, especially with the rich supply of oxygen in the gills of dying fish
and the presence of live freshwater fishes. Results from striped mullet in Texas sug-
gest that even if the oxygen concentration decreased, the fish could readily make
appropriate physiologic^ and behavioral adjustments to the hypoxic environments
(Cech and Wohlschlag 1973). On the other hand, dissociation of any linked systems,
such as ventilation and circulation, and the shut-down of any one of them, will lead
to death (Roberts 1973).

Acclimation

Lack of thermal acclimation would seem to be more responsible for the re-
ported deaths than low salinity ► Both, however, are interrelated as has been suggested
earlier and will be explained later. Acclimation, or the conditioning of an aquatic
poikilolherm to a particular state by its previous thermal history, allows the animal
to survive almost any low temperature. Brett (1960) stated '‘AH species to date,
endemic to the United States and Canada, given adequate acclimation, have shown
the ability to tolerate temperatures in the region of the freezing point of fresh
water. Rapidly onsetting low temperature, however, can constitute one of the great-
est threats to survival when fish are accustomed to relatively warm water because of
the inherent slow rate of acclimation to low temperature.” The lowest temperature
encountered in this study apparently preceded proper acclimation.

In addition to gradual reduction in temperature allowing for proper acclima-
tion, it probably also allows estuarine fishes to leave unfavorable areas such as low-
saline habitats. The rate of temperature decrease illustrated in Fig. 18 for the period
preceding the kill had been surpassed during the previous month, but the lowest
temperature had not. Fish, however, remained in near-freezing water longer in
December.

Lack of proper acclimation probably determines why mass mortalities occur
more frequently in Texas and Florida than in Mississippi. Figure 19 illustrates the
difference in temperatures between Biloxi, Mississippi, and Corpus Christi, Texas.
Fishes in Mississippi living in water normally cooler than in Texas are necessarily ac-
climated to lower temperatures. Consequently, a sudden drop to near-freezing levels
would affect those fishes less.

The inability of tropical marine animals not accustomed to low temperatures
to survive or function during such periods was discussed as long ago as 1914 (Mayer
1914). Doudoioff (1942) studied the effects of acclimation and low temperatures
on marine fishes and defined two stages referred to as primary and secondary chill-
comas. At low temperatures, fishes almost immediately ceased all movements and
died from primary chill-coma, but could recover from the initial shock at less ex-
treme temperatures. After some hours or days, these shocked fish again showed dis-
tress and died from secondary chill-coma. Doudoroff (1945) could delay the lethal

342

Overstreet

effect at the secondary coma point by placing the fish in an isosmotic solution,
apparently relieving a malfunctioning ion-osmoregulatory mechanism, Brett (1956)
suggested a combination of three causes of death for young salmon in cold saline
solutions slightly hypertonic to their blood: disturbance of the central nervous sys-
tem, an upset osmotic balance, and a delayed unknown cause. Upset osmotic bal-
ance, as mentioned earlier, would seem to be involved in the die-off, or “secondary
chill-coma,” of the fishes in this study which died 1 to 3 days following the onset of
ice formation on the water’s surface.

Much of the mystery of acclimation and the effect of temperature on it is
answered by an understanding of biochemical adaptations. Ilochachka and Somero
(1971) review this topic. In brief, for any given enzyme, the stabilization of its
activity resulting from increases in the enzyme-substrate affinity with dropping
tem^perature occurs only over a certain range of temperatures. Two or more variants
of a given enzyme, if acting together, can then promote thermally independent
enzymic functions over a wider range of temperatures. Apparently, the crucial pro-
cess in cold-acclimation is the bios>'nlhesis of enzyme variants, either poly-
morphisms or isozymes, better adapted for catalysis at low temperatures than the
primary enzyme in the same individual. The ability for the organism’s complex
adaptive responses to function may also depend on the rate and extent of fluctua-
tions of environmental parameters in addition to temperature, such as dissolved
gases and salinity.

Sidell ct al. (1973) measured the time course of acclimation from 15°C to
5°C and to 25®C for two compensating enzymes, and found those enzymes in short
goldfish reached a steady state quicker than in large ones. In a study on metabolic
rates, Morris (1965) found body-size had a significant effect on respiration rate of
acclimated yellow bullhead ^ but that there were no differences by size in the ability
to acclimate. To my knowledge, all members of every euryhaline species in the
present study died. With marginal temperature-stress, however, mortalities differen-
tiate by length. Gunter (1947) observed large individuaMne/joa m/7c/n7// (Valenci-
ennes) and Menidia beryllina (Cope) having more difficulty surviving a natural cold-
shock in Texas than small fish. Morris (1962) clarified this problem by measuring
oxygen consumption of Aeqiiidem portalegrensis, a native Brazilian cichlid. Stimu-
lation with a cold-shock following cold-acclimation caused depressed respiration in
fish larger than 6.0 gm only.

Nutrition

All fish examined during the period of the kill, both living and dead, possessed
empty stomachs and intestines. Because of this and since their gall bladders were
greatly distended with bile which leaked throughout much of the liver tissue and
often on adjacent visceral tissues, I assume the fish were under some stress. Whether
such stress affects the lethal thermal threshold is unknown. Under average tempera-
ture conditions, however, fish beyond postlarval stages can withstand long periods
of starvation. As illustrated by Fig. 2, se.xually ripe mullet occasionally stop feeding
during non-winter months long enough to cause distended gall bladders and partially
discolored livers. Even though I have often observed carnivorous fishes with empty
digestive tracts, adult mullet, which feed mostly on plant material and sediments,
typically have material in the intestine. This observation is based on examination of

Fish Cold-Kill in Mississippi

343

several hundred specimens for the presence of parasites and on comments by com-
mercial fishermen.

Frozen sections of livers from the dying mullet revealed considerable amounts
of lipid, a finding not limited to fish encountering low temperatures. The amount
of permanent damage, if any, to the hepatocytes is unknown. Other than possessing
relatively large vacuoles, they seemed normal.

Lipid accumulation m hepatocytes often follows periods of starvation, poison-
ing. or extreme stress (Hinton et al. 1973). Experimentally, it can be caused by
feeding animals diets high in fat, low in protein, and deficient in lipotropic sub-
stances such as choline and lecithin. Deficiencies in vitamins A, B^, Bg, C, E, and
nicotinic acid have all been implicated in the condition. Dixon (1973) reviewed the
literature concerning solubilization and cellular fatly change, including a brief dis-
cussion on the relationsliip between the change and temperature. Since mullet killed
in the winter were starved, were osmotically stressed, and contained high quantities
of insecticides, excessive fatly globulation in hepatocytes could be expected.

Using lipid stains, one can be reasonably sure vacuolation in histological sec-
tions signifies lipids rather than glycogen. Fish tl\at had lipid-positive livers were
either dying or suspected upon capture of containing copious fal from the abnor-
mally greasy texture of their flesh and viscera. Vacuolation in livers of other fish
was probably caused by glycogen that had been extracted during preparation of the
sections as reported by Leske and Mayersbach (1969). Hinton et al. (1972), who
positively identified glycogen as the primary cause of vacuoles in livers of large-
mouth bass, and others pointed out the need to critically differentiate causes of
vacuolation.

Newell (1970:437) summarized the biochemical changes in liver of cold-
adapted fish as extremely complex with increases in glycolysis, glyconeogenesis,
glycogen synthesis, lipogenesis, and hexose monophosphate shunt participation.
Both lipid and glycogen storage products may vaiy' according to temperature, sea-
son, composition and amount of food consumed, reproductive cycle, sex, and age.

The liver and skeletal muscle serve as the main sites of lipid storage in fish, in
contrast to adipose tissues in mammals (Bilinski 1969). Bilinski generalized that the
liver acts as the storage site for such reserves in sluggish, bottom-dwelling fishes,
whereas skeletal muscle plays this role in more active species. The striped mullet,
however, from this study and additional observations appears to utilize adipose tis-
sue as well as liver and muscle for storage. Such storage appears seasonal and
seasonal variation in the amount of oil present in many fishes from the northern
Gulf of Mexico is marked (Thompson 1966).

The concentration of glycogen in liver also varies seasonally and with respect
to nutritional state. Swift (1955) investigated seasonal variation in food reserves of
brown trout. In livers of rats, at least, the concentration of glycogen fluctuates
cyclically on a daily basis and this rhythm varies throughout the year (Leske and
Mayersbach 1969). Black et al. (1966) reported a 38% reduction in liver-glycogen
for rainbow trout starved 84 hours when compared to controls. In hatchery -I rout
deprived of food for 2 weeks, glycogen and vacuolation disappeared (Simon et al.

344

Overstreet

1967). The apparent absence of glycogen in the dying mullet could be because of a
starved condition.

Growth of adult striped mullet practically ceases during midwinter where
studied in northwestern Florida (Broadhead 1953:23) and along the southern North
American Atlantic coast (Anderson 1958). Growth may also decrease during the
mullet’s spawning period. Presumably during these periods, mullet utilize their re-
serves, suggesting that the presence or absence of vacuolation in hepatocytes
represents a normal seasonal phenomenon.

Mullet also use their reserves during other periods. Cummings (1955) main-
tained striped mullet in a freshwater pool for 3 to 4 months after transfer from
seawater. He then divided them into groups of “healthy” and “feeble” specimens
and for each individual measured its blood for concentration of chloride. Those
“feeble” fish had considerably less chloride and also had smaller livers with corres-
pondingly distended gall bladders. They appeared nutritionally deprived.

A need to study seasonally large numbers of livers from male and female
striped mullet, in addition to understanding the storage of lipid and glycogen, is
apparent to determine the reason for the presence of the inflammation associated
with many hepatic vessels. Are the various white blood cells associated with a patho-
logical condition, caused by a natural state preceding or immediately following
death, or related to haematopoicsis? Eosinophils indicate the presence of foreign
proteins and lymphocytes indicate a chronic condition. Necrosis of liver cells adja-
cent to vessels are known to be caused by aquatic pollutants (Hinton et al. 1973).

Pesticides

Levels of pesticide residues, especially that of endrin, appear rather high in the
mullet tested; these insecticides probably decreased the mullet’s resistance to the
effects of low temperatures. The values for both endrin and combined metabolites
of DDT in livers of fish from the kill did surpass those of apparently healthy fish in
May. Those for aged and fresh tissue in May agreed fairly well.

Little meaningful data exist for levels of pesticides in estuarine fishes includ-
ing mullet. Hansen and Wilson (1970) reported DDT residues for homogenized
whole estuarine fishes, other than mullet, near Pensacola, Florida, as rarely exceed-
ing 0.1 ppm, except in fishes from the lower estuary in summer and fall when tlie
amount of DDT and its metabolites reached 1.3 ppm. At least part of that residue
was acquired during a spraying program. Other pesticides, including endrin, did not
exceed 0.02 ppm. Alfred J. Wilson, Jr. (personal communication) analyzed several
apparently healthy striped mullet from Jolly Bay near Panama City, Florida, for
DDT and its metabolites. He obtained the following values recorded in ppm from
pooled liver, the organ tested in this study: DDF=0.30, DDD=0.34, and DDT=0.28.
All registered lower than for mullet in Mississippi. Corresponding values for residues
in muscle were less, 0.14, 0.07, and 0.03 ppm. Tissues of storage such as liver paren-
chyma and fat typically incorporate hi^er levels of pesticides than other tissues,
excepting possibly nervous tissues, gut, gills, and blood (e.g. Lane and Livingston
1970).

FISH Cold-Kill in Mississippi

345

Croker and Wilson (1965) studied the effects of 0.2 pounds of DDT applied
per acre of a tidal marsh near Pensacola. Small mullet, 25 to 50 mm long died first.
Some pooled homogenated mullet in this length-group not killed by the pesticide
accumulated 12.33 ppm DDT, and others 100 to 175 mm long possessed up to
39.24 ppm. Other mullet died after accumulating far less pesticide. When 1 pound
per acre of dieldrin was applied to a salt marsh in St. Lucie County, Florida, all indi-
viduals of several species died. The striped mullet, by far the most common fish
present with the possible exception of the smaller Gulf killifish, responded first to
the toxic stimulus (Harrington and Bidlingmayer 1958). Endrin, found in high con-
centration in my study, was found to be the most toxic of 10 chlorinated hydro-
carbon insecticides studied by Henderson et al. (1959). Butler (1963) listed the
concentration of numerous pesticides in seawater necessary to kill 50% of tested
white mullet in 24- and 48-hour periods.

The amount of pesticide that a fish can tolerate depends on numerous vari-
ables. These include genetic tolerance and environmental history, Genetically
resistant stocks of several fishes are known. Some populations of mosquitofish,
Gambusia affinis (Baird and Girard), resist over 100 times the level of endrin killing
susceptible individuals (Ferguson et al. 1966). Environmental and biological pa-
rameters affect the rate, amount, and means which pesticides are presented to,
accumulated by, and released from the individual. Pesticides can be acquired from
food or water either quickly or slowly. Influenced by individual and species-specific
biochemistry, physiology, and behavior, as well as stage of maturity and age,
accumulation in the fish varies. Different organs respond differently to pesticides,
and the presence of additional pesticides or chemicals may cause synergistic effects.
Temperature, salinity, and, perhaps, dissolved gas may influence uptake and deposi-
tion of pesticides. A fish with a high level of pesticide in its fat and a low level in its
muscle may be a healthy fish until it is starved, at which time large quantities of
pesticide are released into the blood stream, killing or severely stressing the fish.
The levels reported here from mullet consequently have little significance other than
that considerable endrin and DDT persisted in the liver. If the deaths had been
caused entirely from pesticides, residue levels probably would have been higher,
behavior of dying fish would have differed, and other fishes, either in the same or
adjacent areas, would have also been affected.

Governmental agencies need to perfect values for maximal permissible con-
centrations of residues in fish considered fit for human consumption. Mount (1967)
points out that levels, unacceptable by health standards, in edible portions of fishes
may result from exposure by fishes to concentrations in water that do not directly
harm them. Butler (1969) presents a good review of the significance of DDT residues
in estuarine faunas.

Pomsites

Parasites of many kinds infect internally or infest externally the striped mul-
let in Mississippi. Both mullet and other species, however, examined during the kill
were depauperate of parasites. On many of the mullet from Paige Bayou, a leech
occurred and, althougli it removes blood from the fish, too few had fed to cause
much stress. In addition, noninfested fish died as readily as infested ones. A

346

Overstreet

trypanosome, possibly transmitted by the leech, occurred in low numbers in the
blood. Even heavy infections of trypanosomes in fishes seldom severely harm their
hosts. Trichodina sp., the ciliate, occurred on the gills in small numbers. This and
related species often infest local mullet in enormous numbers, both on the gills and
skin. Related species cause mortalities in fishes, but usually confined larval or young
fishes such as cultured channel and blue caifishes are most seriously diseased. Post-
metamorphosed flatfish in hatcheries have died from ciliate infestations (Purdom
and Howard 1971); however, when mortalities occur there is usually an association
of the ciliate with a monogenetic trematode (Pearse 1972). The spiny-headed worm
Floridosentis elongatus infected too few mullet to be involved with mortalities.

The impoverished parasitic fauna suggests that it in no way affected the hosts’
health. Amlachcr (1961:257), however, pointed out that fishes suffering from fatty
degeneration are more sensitive than are healthy ones to infectious diseases. The
lack of parasites is presumably because the fish had been in freshwater long enough
to cause osmotic or reproductive stress in the ectoparasites with resulting sloughing.
Also, there would be no introduction of additional ecio- and endoparasites acquired
from brackish intermediate hosts. Common, but conspicuously absent parasites of
local mullet, include hemiurid, monorchiid, haploporid, haplosplanchnid, hetero-
phyid, and monogenetic trematodes, an ascaridoid nematode, ergasilid copepods, an
argulid, myxosporideans, and ciliates. Other parasites infect this host, but are less
commonly observed in Mississippi.

Hypotheses by Local Residents

All interviewed long-time residents of the Bluff Creek area separated mortali-
ties happening during cold periods from those caused by depletion of dissolved oxy-
gen during warm periods. Several, however, still considered limited oxygen as the
reason for the reported deaths. Residents remembered mass-mortalities in the past,
but considered the present kill as one of the worst. According to a few individuals,
the last two occurred in 1966 and 1969.

Since mullet died exclusively while other fishes lived, most residents attributed
deaths to specific behavioral traits of the mullet. Some ascribed the cause as
ruptured or frozen gill filaments from their characteristic behavior of jumping out
of the water. Others suggested that the fish fed on something disagreeable such as
an algae or other matter available only during cold periods or that parasites killed
them.

I discount all the hypotheses. Fish had enough oxygen and their gills appeared
healthy. Because the mullet had not fed, they probably did not feed on toxic sub-
stances. Toxins in the water should also kill or affect other fishes. Parasites infected
fewer hosts in smaller numbers than expected and no unusual species were present.
I observed no lesions or signs indicative of bacterial or viral diseases.

ACKNOWLEDGMENTS

I would like to acknowledge the help of many people who gave useful infor-
mation for this study: residents near the mass-mortality, James Mailette of the
Mississippi Game and Fish Commission, sports fishermen, and commercial fisher-
men, especially David Boothe, who all showed an interest in the problem. Technical

Fish Cold-Kill in Mississippi

347

assistance was provided by Edward C. Whatley, Jr., Ronnie G. Palmer, and Theresa
Ann St. Andrie of the Gulf Coast Research Laboratory. In addition, others at the
Laboratory helped: Harold D. Howse^ William E. Hawkins, and Rosemary Cheek
stained histological sections; William W. Walker analyzed material for chlorinated
hydrocarbon insecticides; Mary Marshall determined values for chlorosity and cal-
cium; and Richard Waller identified the shiner. Roy T. Sawyer of the College of
Charleston verified my identification of the leech and Alfred J. Wilson, Jr. of the
Environmental Protection Agency, Gulf Breeze, Florida, provided values for
pesticides in mullet from Florida.

LITERATURE CITED

AMLACHER, ERWIN

1961. Textbook of Fish Diseases, T. F. H. Publications, Jersey City. Translated from the
German by D, A. Conroy and R. L. Herman. 302 p.

ANDERSON, WILLIAM W.

1958. Larval development, growth, and spawning of striped mullet iMugil cephalus)
along the south Atlantic coast of the United States. Fishery Bull. Fish Wildl. Serv.
U. S. 1441501-519.

BANGS, OUTRAM

1895. The present standing of the Florida manatee, Trichecus latirosrris (Harlan), in
Indian River waters. Am. Nat. 29:783-787.

BILINSKI, E.

1969. Lipid catabolism in fish muscle. In Fish in Research, (editors, O. W. Heuhaus and
J. E. Halver), Academic Press, New York. pp. 135-152,

BLACK, EDGAR C., N. J. BOSOMWORTH and GEORGINA E. DOCHERTY

1 966. Combined effect of starvation and severe exercise on glycogen metabolism of rain-
bow trout, Salmo gairdneri, J. Fish. Res. Bd Can. 23(9):1461 -1463.
BOUCHER-FIRLEY, S.

1935. Rcchcrchcs biochimiques sur les (eleostcens apodes (anguilla, congre, murene).
Annls lust. Oceanogr., Monaco 15:217-327.

BRETT, J. R.

1956. Some principles in the thermal requirements of fishes. Q. Rev. Biol. 31(2):75-87.
1960. Thermal requirements of fish-three decades of study, 1940— 1970. /n Biological
Problems in Water Pollution, Transactions of the 1959 Seminar (editor, C. M.
Tarzwell), Public Health Service, Robert A. Taft Sanitary Engineering Center
Tech. Rept. W60-3. pp. 1 10-1 17.

BROADHEAD, GORDON C.

1953. Investigations of the black mullet, Mugil cephalus L., in northwest Florida. Florida
Bd. Cons. Tech. Ser. 7:1-34.

BUTLER, PHILIP A.

1963. Commercial fisheries investigations. In Pesticide-Wildlife Studies: A Review of
Fish and Wildlife Service investigations During 1961-62. Fish WUdl. Serv. U. S.,
Cir. 167:11-25.

1969. The significance of DDT residues in estuarine fauna. /n Chemical Fallout, (editors,
M. W. MDler and G. G. Berg), Charles C. Thomas, Springfield, pp. 205-220.

CAMERON, JAMES N.

1970. Tlic influence of environmental variables on the hematology ofpinfish {Lagodon
rhomboides) and striped mullet iMugil cephalus). Comp. Biochem. Physiol. 32:
175-192.

CECH, JOSEPH J., JR. and DONALD £. WOHLSCHLAG

1973. Respiratory responses of the striped mullet, Mugil cephalus (L.) to hypoxic con-
ditions. J. Fish Biol. 5(4):421-428.

CHRISTMAS, J. Y.

1973. Cooperative Gulf of Mexico Estuarine Inventory and Study, Mississippi. Phase 1.
Area Description. Gulf Coast Research Laboratory, Ocean Springs, Miss. pp. 1 -71,

348

Overstreet

CROKER, ROBERT A. and ALFRED J. WILSON

1965. Kinetics and effects of DDT in a tidal marsh ditch. Trans. Am. Fish. Soc. 94(2):
152-159.

CUMMINGS, E.G.

1955. The relation of the mullet {Mugil cephalus) to the water and salts of its environ-
ment: structural and physiological aspects. Ph.D. dissertation, North Carolina
State College, Raleigh, 103 p.

DAHLBERG, MICHAEL D. and FREDERICK G. SMITH

1970. Mortality of estuarine animals due to cold on the Georgia coast. Ecology 51(5):
931-933,

DIXON, KENDAL C-

1973. Solubilization and cellular fatty change. Histochem. J. 5(4): 363-387,
DOUDOROFF, PETER

1942. The resistance and acclimatization of marine fishes to temperature changes. I.

Experiments with Girella nigricans (Ayres). Biol. Bull. 83(2):21 9-244,

1945. The resistance and acclimatization of marine fishes to temperature changes. 11.
Experiments with flindulus and AtheHnops. Biol. Bull. 88(2):194-206.
FERGUSON, DENZEL E., J. LARRY LUDKE and GEORGE G. MURPHY

1966. Dynamics of endrin uptake and release by resistant and susceptible strains of
mosquitofish. Trans. Ajn- Fish. Soc. 95(4):335-344.

FINCH, RUY H.

1917. Fish killed by the cold wave of February 2-4, 1917, in Florida, Mon. Weath. Rev.
April, 1917:171-173.

GALLOWAY, J. C.

1941. Lethal effect of the cold winter of 1939-40 on marine fishes at Key West,
Florida. Copeia 1941(2):118-119.

GUNTER, GORDON

1941. Death of fishes due to cold on the Texas coast, January, 1940. Ecology 22(2):
203-208.

1945. Studies of the marine fishes of Texas. Pubis Inst. Mar. Sci. Univ. Tex. 1(1):1— 190.
1947. Differential rate of death for large and small fishes caused by hard cold waves.
Science I06(2759):472.

1952. Tlie import of catastrophic mortalities for marine fisheries along the Texas coast.
J. Wildl. Mgml 16(l):63-69.

GUNTER, GORDON and H. H. HILDEBRAND

1951. Destruction of fishes and other organisms on the south Texas coast by the cold
wave of January 28-February 3, 1951. Ecology 32(4):731-736.

HANSEN, DAVID J. and ALFRED J. WILSON, JR.

1970. Residues in fish, wildlife and estuaries. Pestic. Monit. J. 4(2):51-56.
HARRINGTON, ROBERT W., JR. and WILLIAM L. BIDLINGMAYER

1958. Effects of dieldrin on fishes and invertebrates of a salt marsh. J. WUdl. Mgmt
22(l):76-82.

HENDERSON, CROSWELL,Q, H. PICKERING and C, M. TARZWELL

1959. Relative toxicity of ten chlorinated hydrocarbon insecticides to four species of
fish. Trans, Am. Fish. Soc. 88(l);23-32.

HINTON, D. E., M. W. KENDALL and B. B. SILVER

1973. Use of histologic and histochemical assessments in the prognosis of the effects of
aquatic pollutants. Biological Methods for the Assessment of Water Quality, A. S.
T.M. STP 528:1 94-208.

HINTON, D. E., ROBERT L. SNIPES and MICHAEL W. KENDALL

1972. Morphology and enzyme histochemistry in the liver of laigemouth bass
(Micropterus salmoides). J. Fish. Res. Bd Can. 29(5):53l— 534.

HOCHACHKA, P. W. and G. N. SOMERO

1971. Biochemical adaptation to the environment. In Fish Physiology, (editors, W. S.
Hoar and D. J, Randall), Academic Press, New York. pp. 99-156.

HOUSTON, ARTHUR H.

1973. Environmental temperature and the body fluid system of the teleost. In Responses
of Fish to Environmental Changes (editor, W. CJhavin), Charles C. Thomas, Spring-
field, pp. 87-162.

Fish Cold-Kill in Mississippi

349

JOHNSON, DONALD W.

1973, Endocrine control of hydromineral balance in teleosts. Amer. Zool. 13(3):799-
818.

LANE, CHARLES E. and ROBERT J. LIVINGSTON

1970. Some acute and chronic effects of dieldrin on the sailfin molly, Poecilia
latipinna. Trans. Am. Fi.sh. Soc. 99(3):489-495.

LESKE,R. and H. V.MAYERSBACH

1969. Tlie role of histochemical and biochemical preparation methods for the detection
of glycogen. J. Histochem. Cytochem. 1 7(8); 527— 538.

LUNA, LEEG. (editor)

1960. Manual of Histologic Staining Methods of the Armed Forces Institute of Pathol-
ogy. 3rd Ed. McGraw-Hill Book Comp., New York. 258 p.

MAYER, ALFRED G.

1914, The effect of temperature upon tropical marine animals. Publ. Carnegie Inst.
Wash., Pap. Tortugas Lab. 6:3-24,

MC FARLAND,W. N.

1965. The effect of hypersalinity on serum and muscle ion concentrations in the striped
mullet, l\fugii cephalus L. Pubis Inst. Mar. Sci. Univ. Tex. 10:179-186.

MILLER, E. MORTON

1940. Mortality of fishes due to cold on the southeast Florida coast. Ecology 21(3):
420-421.

MORRIS, R.

1960. General problems of osmoregulation with special reference to cyclostomes. Symp.
Zool. Soc. Lond. 1:1-16.

MORRIS, ROBERT W.

1 962. Body size and temperature sensitivity in the cichlid fish, Aequidens portakgrensis
(Henscl), Am. Nat. 96(886):35-50.

1965. Thermal acclimation of metabolism of the yellb)v bullhead, Ictaluris natalis
(LeSueur). Physiol. Zool. 38(3):219-227.

MOUNT, DONALD I.

1967. Considerations for acceptable concentrations of pesticides for fish production.
Am. Fish. Soc. Spec. Publ. No. 4:3-6.

NEWELL, R. C.

1970. Biology of Intertidal Animals, American Elsevier Publishing Comp., Inc., New
York. 555 p.

PEARSE, L.

1972. A note on a marine trichodinid cUiate parasitic on the skin of captive flatfish.
Aquaculture 1:261-266.

PURDOM, C. E. and A. E. HOWARD

1971. Ciliate infestations: a problem in marine fish farming. J. Cons. Int. Explor. Mer
33(3):S11-514.

ROBERTS, JOHN L,

1973. Effects of thermal stress on gill ventilation and heart rate in fishes. /n Responses
of Fish to Environmental Changes (editor, W. Chavin), Charles C. Thomas, Spring-
field, pp 64—86.

SAGE, MARTIN

1973. Tlie relationship between the pituitary content of prolactin and blood sodium
levels in mullet {Mugil cephalus) transferred from sea water to fresh water. Contr.
Mar. Sci. Univ, Te.x, 17:163-167.

SIDELL, BRUCE D., F. RAY WILSON, JEFFREY HAZEL and C. L. PROSSER

1973. Time course of thermal acclimation in goldfish. J. Comp. Physiol. 84(2): 1 19-127.
SIMON, RAYMOND C, ALEXANDER M, DOLLAR and EDWARD A. SMUCKLER

1967. Descriptive classification on normal and altered histology of trout livers. /n Trout
Hepatoma Research Conference Papers. U. S. Dep. Health Educ. Welfare; U. S.
Dep. Inter. Res. Rep. 70. pp. 18-28.

STOREY, MARGARET

1937. The relation between normal range and mortality of fishes due to cold at Sanibel
Island, Florida. Ecology 18(1); 10-26.

350

Overstreet

STOREY, MARGARET and E. W. GUDGER

1936. Mortality of fishes due to cold at Sanibel Island, Florida, 1886-1936. Ecology
17 (4): 640- 648.

STRICKLAND, J. D. H. and T. R. PARSONS

1968. A practical handbook Of seawater analysis. Bull. Fish. Res. Bd Can. 167:1-311.
SWIFT, D. R.

1955. Seasonal variations in the growth rate, thyroid gland activity, and food reserves of
brown trout (Salnio trutta Linn.). J. Exp. Biol. 32:751-764.

TABB, D. C, D. L. BUBROW and R. B. MANNING

1962. The ecology of northern Florida Bay and adjacent estuaries. Florida Bd. Cons.
Tech. Sei. 39: 1-81-
TABB, D. C. and R. B. MANNING

1961. A checklist of the flora and fauna of northern Florida Bay and adjacent brackish
waters of the Florida mainland collected during the period July, 1957 through
September, 1960. Bull. Mar. Sci. Gulf Caribb. 1 1(4):552-649.

THOMPSON, MARY H.

1966. Proximate composition of Gulf of Mexico industrial fish. Fishery Indust. Res.
3(2):29-67.

WELLS, HARRY W., MARY JANE WELLS and I. E. GRAY

1961. Winter fish mortality in Pamlico Sound, Nortli Carolina. Ecology 42(1):217-219.
WILLCOX, JOSEPH

1 887. Fish killed by cold along the Gulf of Mexico and coast of Florida. Bull. U.S. Fish
Commn 6:1 23.

Gulf Research Reports

Volume 4 Issue 3

January 1974

Primary Productivity of Coastal Marshes in Mississippi

Armando A. De La Cruz

Mississippi State University

DOI: 10.18785/grr.0403.03

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Recommended Citation

De La Cruz, A. A. 1974. Primary Productivity of Coastal Marshes in Mississippi. Gulf Research Reports 4 (3): 351-356.
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PRIMARY PRODUCTIVITY OF COASTAL
MARSHES IN MISSISSIPPI'

by

ARMANDO A. DE LA CRUZ
Department of Zoology, Mississippi State University
P. 0. Drawer Z, Mississippi State, Mississippi

ABSTRACT

The annual net primary production of nine types of marsh communities common in Mis-
sissippi Gulf Coast estuaries were studied by means of the Harvest Method. Production values
ranged from 600 g m“^ yr~^ for a Sagittaria lancifolia marsh to 2330 g m“^ yr“^ for a
Phragmitex communis marsh. Primary productivity values for the other marsh types are Juncus
roemerianus - 1 697 g m“^ yr~' , Scirpus robustus - 1 056 g yr“' , Spartina cynosuroides -

2190 g m~^ yr~', Spartina patens — 1922 gm“^ ^Spartina alterniflora tall form — 1964
g yr“', 5. alterniflora short form - 1089 g m~^ yr“V, and Distichlis spicata - 1484 g m~^
yr“' . Annual net productivity in Mississippi marshes are generally slightly higher than those
reported for the Atlantic marshes.

INTRODUCTION

Coastal marshes are commonly characterized as sites of extremely high primary
production. Available data, however, are insufficient to support or refute such a
generalization. It is more likely that marshes differ considerably in their produc-
tivity. The diverse nature of marshlands along the Gulf Coast of Mississippi offers
an ideal opportunity to test differences in the primary productivity of different
species of marsh plants. The marsh types described by Uhler and Hotchkiss (1968)
as irregularly flooded marsh dominated by J. roemerianus, waterlogged salt flats of
D, spicata, and salt meadows of S. patens are found in Mississippi coastal estuaries.
Mixed stands of several marsh plant species are common. As many as 34 species
may be found in one locality although only a few of these are of major importance
(Gabriel and de la Cruz 1 974).

Primary production studies in the northern Gulf of Mexico marshes are few.
Kirby (1971) reported an annual net production of 1006-1410 g m-^ for an S,
alterniflora marsh in Louisiana. Eleutenus (1972) estimated production value of
about 2000 g m“^ yr“' for a J. roemerianus marsh in Mississippi. More recently an
initial study on a vegetationally mixed marsh at St. Louis Bay estuary in Mississippi
showed production value of 1 100 g m”^ yr“' (Gabriel and de la Cruz 1974), In all
these studies, only the annual net primary productivity of above ground materials
was measured.

ACKNOWLEDGEMENTS

I thank Syed Naqvi, Johnny Bufkin and Rick Kergosien who assisted in the
field work, and Raina Mukhopadyay for the caloric analysis of samples. I am

Supported by a National Science Foundation Giant No. GA-35715.

Gulf Research Reports
Vol. 4, No. 3, 351-356, 1974

351

352

DELA Cruz

indebted also to Lionel Eleuterius of the Gulf Coast Research Laboratory and
Sidney McDaniel of Mississippi State University Department of Botany for their
assistance in the identification of marsh plants.

MATERIALS AND METHODS

Monolypic stands of nine species of marsh plants were selected in the Gulf
Coast of Mississippi (Fig. 1). S. lancifolia Pursh. (arrowhead) and P. communis
Trinius. (common reed) were sampled along the terminal tributaries of Jourdan
River about 3 km inland west of St. Louis Bay in Hancock County. This habitat is
ba.sically freshwater with salinities rarely exceeding 5 7°° during flood tides. /.
roemerianus Scheele (needlerush), 5. robustus Pursh. (salt marsh bulrush), 5.
cynosuroides (L.) Roth, (giant cordgrass), and S, patens (Aiton) Muhl. (salt meadow
cordgrass) were collected from St. Louis Bay estuary on a marsh island on the
western side of the bay. The bay is a brackish water system with salinities ranging
2 %o to 12 ‘’/oo. D. spicata (L.) Greene (salt grass) and S, altemiflora Loisel
(smooth cordgrass) were harvested from Bayou Casotte on the eastern section of
the Mississippi coast in Jackson County a few kilometers from the Alabama state
line. The D. spicata community is a waterlogged salt flat which was flooded during
the entire period of the study; both short and tall forms of S. altemiflora are
located along the eastern shore of the mouth of Bayou Casotte. This habitat is
exposed to the inundation of saline water (>20 °loo) from Mississippi Sound.

Figure 1. The Mississippi Gulf Coast showing the location of (1) Jourdan River, (2) St Louis
Bay, and (3) Bayou Ca^tte marshes.

Productivity of Marshes

353

Three 1 -square-meter plots were harvested monthly from each of the nine
communities during the growing season (May to August 1973). The plants were
clipped at the base about 2 cm above ground. Each m^-plot sample was routinely
examined for the presence of other species. Alive (i.e., green) plant parts were
separated from the dead or brown biomass. Partially decaying plant tissues on the
ground were gathered from each plot and thoroughly washed of mud. The decaying
material was placed in a wire basket (5 mm mesh), washed by shaking the basket in
the bay water, and rinsed in tap water in the laboratory. All plant materials were
dried at 103°C for 24-48 hr. Annual net primary production of the above ground
material (i.e., aerial parts) was estimated from the monthly increases during the
growing season according to the procedure described by Milner and Hughes (1968)
using the formula:

Total annual primary aerial production (g/m^) = Sj (Bn-Bn-i)

where Bn = biomass of nth sampling period (time tn)

Bn-i = biomass of a previous sampling period (time

Calorific values of samples of above ground plant material collected during
the growing season were determined in an automatic Paar Adiabatic Bomb Cal-
orimeter Model 1241 and production estimates were converted to ash-free kilo-
calories per square meter. Ash-free weiglit was determined by combustion at 550°C
for 5 hr.

RESULTS AND DISCUSSION

Only two of the nine marsh communities studied were found in pure mono-
typic stands (Table 1). The seven species that appeared to be mono ty pic had a
mixture of 1-22% of one or two other species. Compared to salt marshes in the
south Atlantic coast, I observed that the Mississippi marshes are more dense and
diverse; and are, in general sliglitly more productive.

The net aerial primary productivity of the marsh vegetations studied ranged
from 600 g m~* yr"'* for S. lancifolia to 2330 g m~^ yr~* for P. communis
(Table 2). Production value of 1697 g m”^ yr“^ for/, roemerianus is higher than
previously reported in the literature (Williams and Murdoch 1972, Heald 1969,
Stroud and Cooper 1968, Foster 1968, Waits 1967).

Net primary productivity of S. altemiflora short form (1089 g m""^ yr“*)
is higher than previously reported; the tall form productivity (1964 g yr“*) is
comparable to the values reported for Georgia and Louisiana (de la Cruz 1973,
Keefe 1972). The values obtained for the other species are comparatively higher
than the production values observed for similar and related species from other
estuaries.

Caloric content of the plant species ranged from 4.46-4.75 Kcal/ash>free g
(Table 3) and kilocalorie production of the marshes, ranges from 2468 Kcal M“^
yr""^ for .S', lancifolia to 9841 Kcal m~^ yr“^ forP. communis (Table 2).

354

DE LA Cruz

Table 1.

Vegetational Association of the Tidal Marsh Communities
Studied on the Gulf Coast of Mississippi

Marsh

Dominant Species

Sagittaria

lancifolia

Percentage Composition of Minor Species

Scirpus Juncus Spartina Distichlis

robustus roemerianus patens spicata

Cladium

famaicense

Sagittaria lancifolia

2

22

« • f

Phragmites communis

9

- . • ...

. • .

. . «

0.5

Scirpus robustus

14

...

...

, .

Juncus roemerianus

10

. . .

. .

Spartina cynosuroides

4

. . .

1

. -

Spartina patens
Disiichlis spicata

Spartina aherniflora
(tall)

5

Monotypic Stand
Monolypic Stand

5

Spartina alterniflora
(riiort)

...

...

...

1

...

Table 2.

Annual Net Primary Productivity of Above Ground Materials of Various Marsh
Communities in Mississippi Gulf Coast Estuaries

Marsh Community

Habitat

Type

Geographic

Location

Annual Net Primary Production
dry g/m^ Kcal/m^*

Sagittaria lancifolia

Fresh

Jourdan River

600

2468

Phragmites communis

Fresh

Jourdan River

2330

9841

Scirpus robustus

Brackish

St. Louis Bay

1056

4576

Juncus roemerianus

Brackish

St. Louis Bay

1697

7558

Spartina cynosuroides

Brackish

St. Louis Bay

2190

9347

Spartina patens

Brackish

St- Louis Bay

1922

8464

Distichlis spicata

Brackish

Bayou Casotte

1484

6020

Spartina alterniflora
(short form)

Saline

Bayou Casotte

1089

4028

Spartina alterniflora
(tall form)

Saline

Bayou Casotte

1964

8088

*Ash>£ree basis.

The Mississippi tidal marshes are definitely more diverse (Gabriel and de la
Cruz 1974) and are generally more productive than the marshes found in the
Atlantic seaboard. The factors (e.g., soil types, tidal amplitude, and salinity regimes)
that may influence the higher production values observed in the Mississippi marshes

PRODUCTIVITY OF MARSHES

355

Table 3.

Ash-free Weight and Caloric Content of Marsh Plants

Marsh Plants

No.

Samples

Ash-free Dry Wt.

(Per Cent)

Mean Value Coef. Var.

Caloric Content
(Kcal/ash-free g)
Mean Value Coef. Var.

Sagittaria land folia

6

90.01

0.004

4.57

0.005

Phragmites communis

6

92.02

0.001

4.59

0.021

Scirpus robust us

6

93.40

0.003

4.64

0.011

Juncus roemerianus*

16

94.96

0.007

4.69

0.009

Span ina cynosuroides *

16

92.78

0.033

4.60

0.041

Spartina patens

6

92.71

0.009

4.75

0.008

Distichlis spicata*

19

90.96

0.052

0.47

0.024

Spartina alterniflora
(short)

6

82.01

0.007

4.51

0.003

Spartina alterniflora
(tall)

6

88.18

0.005

4.67

0.017

*Oata from Gabriel and de la Cruz 1974 (Literature Cited)

studied are currently under investigation. Kirby (1971) suggested that the greater
productivity in the Gulf marshes may be partly due to the longer growing season in
this geographic region. The significance of the high productivity of marshes in
general has already been reviewed elsewhere (de la Cruz 1973).

LITERATURE CITED

DE LA CRUZ, A. A.

1973. The role of tidal marshes in the productivity of coastal waters. Association South-
eastern Biologists Bulletin, 20: 147-156.

ELEUTERIUS, L. N.

1972, TTie marshes of Mississippi. Castanea, 37:153-168.

FOSTER, W. A.

1968. Studies on the distribution and growth of Junct4s roemerianus in southeastern
Brunswick County, North Carolina, M.S. Thesis, Univ. of Michigan. 72 p,

GABRIEL, B. C. and DE LA CRUZ, A. A.

1974. Species composition, standing stock, and net primary production of a salt marsh
community in Mississippi. (Hresapeake Science, 15:72-77.

HEALD, E. J.

1969. The production of organic detritus in a South Florida estuary. Pli.D. Dissertation,
Univ. of Miami, 1 10 p.

KEEFE, C S.

1972. Marsh production: A summary of the literature. Contrib. in Marine Sci., 16:
163-181.

KIRBY, C, J., JR.

1971. The annual net primary production and decomposition of the salt marsh grass
Spartim alterniflora Loisel in the Barataria Bay Estuary, Louisiana. Ph.D. Disser-
tation, Louisiana State Univ. 73 p.

356

DE LA Cruz

MILNER, C. and R. E. HUGHES

1968. Methods for the measurement of the primary production of grassland. Inter-
national Biological Program Handbook No. 6, Blackwell Sci. Publ., Oxford. 70 p.

STROUD, L. M. and A. W. COOPER

1968. Color-infrared aerial photographic interpretation and net primary productivity of
regularly flooded North Carolina salt marsh. Univ. of North Carolina Water Re-
sources Research Inst., Report No. 14. 86 p.

UHLER, F. M. and N. HOTCHKISS

1968. Vegetation and its succession in marshes and estuaries along South Atlantic and
Gulf coasts. Proc. Marsh and Estuary Management Symp., Louisiana State Univ.,
p. 26-32.

WAITS, E. D.

1967. Net primary productivity of an irregularly flooded North Carolina salt marsh.
Ph.D. Dissertation, North Carolina State Univ., 1 1 3 p.

WILLIAMS. R. B. and M. B. MURDOCH

1972. Compartmental analysis of the production of Juncus roemerianus in a North
Carolina salt marsh. Chesapeake Science, 13:69-79.

Gulf Research Reports

Volume 4 Issue 3

January 1974

Mississippi Flora. 1. Monocotyledon Families with Aquatic or Wetland Species

Samuel B. Jones Jr.

University of Georgia

DOI: 10.18785/grr.0403.04

Follow this and additional works at: http:// aquila.usm.edu/ gcr

Part of the Botany Commons, and the Marine Biology Commons

Recommended Citation

Jones, S. B. Jr. 1974. Mississippi Flora. I. Monocotyledon Families with Aquatic or Wetland Species. Gulf Research Reports 4 (3) :
357-379.

Retrieved from http:/ / aquila.usm.edu/ gcr/vol4/iss3/ 4

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MISSISSIPPI FLORA. 1. MONOCOTYLEDON
FAMILIES WITH AQUATIC OR
WETLAND SPECIES:

by

SAMUEL B. JONES, JR.

Department of Botany
The University of Georgia
Athens, Georgia

ABSTRACT

Keys, distribution maps, habitats, references, nomenclature, and notes are given for
some 16 families of monocotyledons occurring naturally or naturalized in Mississippi. These
families all contain one or more species tvhich are found in aquatic or wetland liabitats. They
are: Alismataceae, Araoeae, Cannaceae, Haeniodoraceae, Hydrocharitaceae, Juncaginaceae,
Lemnaceae, Marantaceae, Mayacaceae, Najadaceae, Pontederiaceae, Potamogetonaceae, Rup-
piaceae, Sparganiaceae, Typhaceae, Zannichelliaceae.

INTRODUCTION

The primary aim of this paper is to improve our knowledge of the aquatic and
wetland plants of Mississippi. In studying a number of families for the Mississippi
Flora project, I became aware of the limited collections available for study of many
aquatic and wetland species. Hopefully, this paper will be reviewed and criticized
by many, and corrected before the proposed Guide to the Flora of Mississippi is
published. Any overlooked species, additional collections, needed modifications, or
suggestions should be sent to me as soon as possible so that corrections can be
made. I should point out that my concept of a species is rather conservative and
allows for much ecological as well as genetical variation; therefore, few infraspecific
taxa are recognized.

In this day of increasing concern for aquatic and wetland habitats, our knowl-
edge of the plants found in such habitats, especially in the mid-South, is rather
limited. There are several reasons for this lack of knowledge. First of all, it is
difficult to collect and to prepare specimens of many aquatic species. Until recently
there had been little botanical activity within the state of Mississippi. Aquatic and
wetland habitats arc not continuous over wide geographical areas, so that the col-
lections produce spotty distribution maps.

Support for the field work, begun in 1964, was provided by two National

Gulf Research Reports
Vol. 4, No. 3, 357-379, 1974

357

358

Jones

Science Foundation research grants to the Mississippi Flora project. Later support
was also provided to me by the University of Georgia. I am indeed grateful for the
support of (his research. I am indebted to many individuals who have provided help
and cooperation. Foremost among these are Tom Pullen and Ray Watson, my co-
investigators on the Mississippi Flora project. Bob Mills and Bob Noble accompanied
me on field trips as did my wife Carlecn Jones and many of my Students. Lionel
Eleuterius of the Gulf Coast Research l.aboratory helped in many ways, especially
with the coastal plants. F. H. Sargent and Ken Rogers, both of whom have a keen
eye for plants, turned up many good collections. The first draft of the manuscript
was read and criticized by A1 Radford and Jirn Massey. Wilbur Duncan provided the
facilities of the University of Georgia Herbarium. E. C, Ogden made suggestions on
Potamogeton and Jean Wooten read the Alismaiaceae. Without their assistance
these studies would not have been possible. I am especially fortunate to be able to
publish these families in Gulf Research Reports, and the assistance of Dr. Gordon
Gunter is gratefully acknowledged. Mrs, Mary Ann Keller has patiently prepared the
typescript for all of my studies on the Mississippi Flora project.

In undertaking any floristic work one must use information from the
published work of many others. Included here are the various manuals that cover
some of the species that are found in Mississippi: Small (1933), cited as S in the
synonymy; Fernald (1950), cited as F; Gleason and Cronquist (1963) cited as G;
Radford, Allies, and Bell (1968), cited as R. Other frequently used manuals included
Steyermark (1963) and Correll and Johnston (1970). Noteworthy is the recent
illustrated manual of aquatic and wetland plants by Correll and Correll (1972). It
is highly recommended to all aquatic biologists. Many revisionary treatments were
used and they are cited in the text.

The keys to the genera and species, while they definitely include the plants of
our area, in many instances have been written so as to include plants that might
eventually be found in Mississippi. Unless otherwise noted, I have examined one or
more specimens of each species from the state. Specimens were examined at the
following herbaria: University of Mississippi; Mississippi State University; University
of Georgia, University of North Carolina; Duke University; and North Carolina
State University. The taxonomic format follows that of the contributors guide to
the Mississippi Flora project. The abbreviations of authors’ names in this paper
follows that of Correll and Johnston. It should be noted that a few species are
included which do not grow in aquatic or wetland habitats. This was necessary in
order to test the generic keys for the proposed guide. Family keys were not included
since all monocotyledon families are not covered in this paper. 1 would suggest to
the reader the family keys in Correll and Johnston, Correll and Correll, or Gleason
and Cronquist.

The physiographic regions of Mississippi are outlined in Figure 1 . The ab-
breviations used in the text are; 1, Tennessee River Hills, TRH; 2, Northeastern
Prairie Belt, NPB; 3, Pontotoc Ridge, PR; 4, Flalwoods, FW; 5, North Centra!
Plateau, NCP; 6, Jackson Prairie, JP; 7, Loess Bluff Hills, LBH; 8, Yazoo-Mississippi
Delta, YMD; 9, Longleaf Pine Region, LPR; 10, Coastal Pine Meadows, CPM. The
regions are based on those of Lowe (1921).

Mississippi Monocotyledons

359

p

Figure 1. Physiographic regions (see explanation in text) and distribution in Mississippi of
Echinodorus parvulus. Echinodorus rostratus, Echinodorus cordifolius, Sagitiaria montevidensis,
Sagittaria subulata, Sagittarw lancifolia, Sagitiaria gmminea, and Sagitiaria papillosa.

360

JONES

ALISMATACEAE

1. Achenes in a single whorl; receptacle small, flat;

stamens 6

1. Achenes in several series, densely crowded; receptacle
large, globose; stamens more than 6.

2. Achenes ribbed or ridged, not winged; flowers all

perfect

2. Achenes distinctly winged not ribbed or ridged;

flowers perfect or unisexual, the upper ones
mostly staminate

1. Alisma.

2. Echinodorus.

3. Sagittaria,

Beal (1960a) is a useful reference for this family.

1. ALISMA L. Water Plantain, Mud Plantain

1. Alisma subcordatum Raf., May-Sept. Shallow water, marshes, ponds,
streams; though reported from Mississippi by G, R, F, and S, I have seen no material
from the state, Hendricks (1957), in his revision of the genus, did not cite a
specimen from Mississippi.

2. ECfflNODORUS Rich. BURHEAD

1 . Achenes 20 or fewer in a loose head, beakless \. E. parvulus.

1. Achenes 30-40 or more in a dense tight head, dis-
tinctly beaked.

2. Scape erect; sepals with smooth ridges 2. E. rostratus.

2. Scape repent or prostrate at maturity; sepals with

papillose ridges 3. E. cordifolius.

1. E. parvulus Engelm., Apr.— Sept. Mud or shallow water, ponds; I have
not seen a specimen; reported by Fassett (1955) from Pike Co., LPR. E. tenellus
(Mart.) Buch. — F. Fig. 1.

2. E. rostratus (Nutt.) Engelm,, June-Sept. Mud or sliallow water of streams,
ditches, ponds; YMD. E. cordifolius (L.) Griseb. — S. Fig. 1,

3. E. cordifolius (L.) Griseb., CREEPING Water PLANTAIN. Apr.-Sept. Mud
or shallow water, ditches, streams, ponds; througliout. E. radicam (Nutt.)
Engelm. — S. Fig. 1.

3. SAGITTARIA L. ARROWHEAD

1. Pistillate flowers with sepals appressed or spreading;
pedicels recurved and thickened in fruit.

2. Sepals closely appressed to the pistillate flowers; leaves

typically sagittate; plants emergent S. montevidensis.

2. Sepals only loosely appressed to or spreading on the
pistillate flowers; leaves filiform; plants usually
submerged 2, S. subulata.

MISSISSIPPI MONOCOTYLEDONS

361

I. Rstillate flowers with reflexed sepals; pedicels typically

ascending, usually not thickened in fruit.

3. Filaments pubescent or minutely scaly.

4. Bracts papillose or ridged, thickened, nearly free;

filaments linear , 3. S. lancifolia.

4, Bracts not papillose nor with definite ridges, mem-

branous, more or less connate; filaments

dilated 4. 5. graminea.

3. Filaments glabrous.

5. Bracts papillose; leaves never sagittate 5. S, papillosa.

5. Bracts not papillose; leaves typically sagittate.

6. Achene-beak laterally inserted; bracts small, up to

1 cm in length, obtuse to acute 6. S. lati folia.

6. Achene-beak apically inserted; bracts long, 0.8 to

3 cm in length, linear-lanceolate 1. S. engelmanniana.

1. S, montevidensis Cham. & Schlecht, June— Sept, Sloughs, lakes, ponds,
ditches; nw Mississippi. Lophoiocarpus calycinus (Engelrn.) J. G. Sm. — S, F; S.
calycina Engelrn. — R. Our plants have been segregated as ssp. calycina (Engelrn.)
Bogin.

2. S. subuiata (L.) Buch., June— Sept. Submerged in tidal streams along the
coast. S, filiformis J. G. Sm., S. stagnorum Small, S, lorata (Chapm.) Small — S. See
Adams and Godfrey (1961). Fig. 1.

3. S. lancifolia L., May-Sept. Brackish tidal marshes, fresh waler marshes;
mainly along the coast but scattered inland. S. falcata Pursh — R, F, S; S.
angustifolia — S. Our plants have been segregated as ssp. media (Mich.) Bogin.
Often confused with S. graminea but differing in the thickish, ribbed or papillose
bracts, and large stamens with linear, pubescent filaments. Sagittaria papillosa does
not have pubescent filaments. Fig. 1.

4. S. graminea Michx., June-Sept. Shallow, fresh or brackish water of
marshes; abundant along the coast, scattered throughout the interior. S. eatoni

J, G. Sm., S. weatherbiaria Fern. — F; S. teres, Wats., S. isoetiformis J. G. Sm.,

S. cycloptera (J. G. Sm.) Mohr — S; S. graminea var platyphylla Engelrn. — R;
S. platyphylla (Engelrn) — F, S. Ours have been segregated by Bogin (1955) as var.
plalphylla Engelrn. and var. chapmani J. G. Sm. Bogin concludes his treatment of
this species by noting that in a genus characterized by variable species, S. graminea
probably represents the high tide of that variability and that every characteristic
is extremely plastic and many intermediate individuals occur. In a guide to the
plants of an area, 1 do not feel that poorly marked and highly variable infraspecific
taxa should be recognized. Fig. 1 .

5. S. papillosa Buch., June— Sept. Ditches, marshes, swamps, ponds; LPR.
Often confused with S. lancifolia and probably overlooked as both occur together.
Both have papillose bracts but S. papillosa has glabrous filaments whereas S.
lancifolia has pubescent filaments. Fig, 1.

6. S. latifolia Willd., ARROWLEAF, DUCK-POTATO, WAPATO. June - Sept.
Marshes, ditches, stream or pond margins; throughout. S. omithorhyncha Sm^l,
S. pubescens Muhl. — S; S. latifolia var. obtusa (Muhl. ex Willd.) Wieg., var.
pubescens (Muhl.) J. G. Sm. — R, F, G. Bogin said that this species assumes a

362

JONES

bewildering number of ecological variations which in turn have given rise to wide
synonymy. He recognized only var. latifolia and var. pubescens, S. latifoUa is dis-
tinguished by tire boat-shaped bracts and the large achenes with laterally inserted
beaks of various lengths. Fig. 2.

7. S. engelmanniana J, G. Sm., June-Sept. Margins of swamps, ponds,
streams, ditches; througliout. S. australis (J. G. Sm.) Small — S, F;S'. engelmanniana
ssp. longirostra (Mich.) Bogin — S; S, longirostra (Mich.) J. G. Sm. — S, R. Our
plants have been segregated as ssp. longirostra (Mich.) Bogin. Fig. 2.

Adapted from the treatment of Sagittaria by Bogin, the work of Wooten
(1973) is a valuable addition to our knowledge of this highly variable genus.

ARACEAE

1 . Plants floating 5 . Pistia.

1. Plants rooted in soil.

2, Spathe well-developed, fleshy or petaloid, enclosing
the inflorescence.

3. Leaves compound Arisaema.

3. Leaves simple 2. Peltandra.

2. Spathe absent^ or obscure or like the foliage leaves,

not enclosing the inflorescence.

4. Spadix naked, terminating the terete scape; leaf

blades oblong 3. Orontium.

4. Spadix much-overtopped by the swordlike spathe
that re.sembles the foliage leaves; leaf blades
linear 4. Acorus.

Wilson (1960) is an excellent general reference for this family in the south-
eastern United States.

1. ARISAEMA Mart.

1. Primary leaf pedately divided into 5-15 very unequal

leaflets A. dracontium.

1. Primary leaf palmately divided into 3—5 segments.

2. Primary leaf with 5 segments, the lateral segments

sometimes partly united 2. A. quipatum.

2. Primary leaf with 3 segments, the lateral segments

rarely bilobed 3. A. triphyllum.

1. A. dracontium (L.) Schott, GREEN DragON-ROOT. Apr.-May.l-ow rich
woodlands; throughout, except YMD, Muricauda dracontium (L.) Small — S. Fig. 2.

2. A.quinatum (Nutt.) Schott, JaCK-IN-THE-PULPIT, INDIAN-TURNIP. Apr.-
May. Moist wooded areas, loess bluffs; scattered throughout except CPM and YMD.
Fig. 2.

3. A. triphyllum (L.) Schott, JACK-IN-THE-PULPIT, INDIAN-TURNIP. Apr.-
May, Moist wooded areas; throughout. A. pusillum (Peck) Nash, A. acuminatum

MISSISSIPPI MONOCOTYLEDONS

363

Figure 2. Distribution in Mississippi of Sagittarta Uitifolla> Sogittarta engelntanniam, Arisaema
dmcontium, Arisaema quinatum, Arisaema triphyttum, Peltandra virginica, Peltandra sagit-
tae folia, aquaticum, and Acorus calamus.

364

Jones

Small — S; A. atrorubens (Ait.) Bl., A stewardsonii Britt.— F;v4. triphyllum var.
stewardsonii (Britt.) Stevens, A. triphyllum var. pusillum Peck — G. Fig. 2.

2. PELTANDRA Raf. ArroW-ardm

1. Spa the green; berries greenish or blackish 1. P. virginica.

1. Spathe white; berries red 2. P.sagittaefolia.

1. P. virginica (L.) Kunth, May— July. Wooded swamps, edge of ponds;
mostly se scattered in ne. Fig. 2.

2. P. sagittaefolia (Michx.) Morong, May— July. Low moist woods, swamps;
along coast. P. glauca (Ell.) Feay ex Wood — S. Fig. 2.

3. ORONTIUM L. Golden Club

1. Orontium aquaticum L., Mar.— Apr. Swamps, streams, shallow water of
ponds; CPM, LPR, TRH, abundant near the coast. For additional information on
this colorful species see Grear (1966). Fig. 2.

4. ACORUS L. Calamus, Sweetflag, Calomel

1. Acorus calamus L., May-Aug. Wet places; scattered throughout. Harper
(1936) noted that “calomel root” was cultivated by black families who used it
medicinally. Fig. 2.

5. PISTIA L, Water-lettuce

1. P. stratiotes L., May— June. Streams, lakes, and ponds; reported by Correll
& Correll to occur along the Gulf Coast. 1 have seen specimens from La. but none
from our state. It should be watched for in the coastal counties.

CANNACEAE
1. CANNA L. C ANNAS

1. Corolla tube longer than or equaling the lobes; fruit

twice or more as long as broad 1 . C flaccida.

1. Corolla tube shorter than lobes; fruit as long as broad

or nearly so 2, C. generalis.

1. C. flaccida Salisb., GOLDEN CANNA. June- Aug. Marshes; along the coast.
It was collected in the late 1800’s in Jackson Co. but no recent specimens have
been seen and it may be extinct. There is one recent collection from Attalla Co.
which undoubtedly represents an escape. I have seen it on Dauphin Island in nearby
Ala. Fig. 3.

2. C. generalis Bailey, COMMON GARDEN CANNA. June-Oct. Commonly
cultivated and escaping to disturbed habitats and ditches. This taxon represents
horticultural hybrids and is highly variable with many named cultivars. Fig. 3.

Mississippi Monocotyledons

365

Figure 3. Distribution in Mississippi of Canna flacdda, Canna generalis, Lachnanthes caroli-
niana, Lophiola americana, Limnobium spongia, Vallisneria americana, Elodea nuttailii,
Thalassia testudinum and Halophila engelmannii.

366

Jones

HAEMODORACEAE

1. Stamens 3, exserted; style deciduous; petals exceeding

sepals by more than 2 mm , * 1 . Lachnanthes.

1. Stamens 6, included; style persistent; petals and sepals

about equal in length 2. Lophiola.

1. LACHNANTHES Ell. REDROOT

1. L. caroliniana (Lam.) Dandy, June— Sept. Wet savannahs, ditches, wet
pinelands, bogs; CPM and se LPR. Gyrotheca tinctoria (Walt.) Salisb. — S; L
tinctona (Walt.) Ell.— ^F, G. Fig. 3.

2. LOPHIOLA Ker. GOLDCREST

1. L. americana (Pursh) Wood, May-June. Savannahs, wet pinelands; CPM
and se LPR. L. aurea Ker. — S. Fig. 3.

HYDROCHARITACEAE

1. Freshwater plants.

2. Leaves broadly ovate to reniform, with a differentiated

petiole 1. Limnobium.

2. Leaves linear or ribbon-like, without a differentiated
petiole.

3. Leaves ribbon-like, basal 2. Vallisneria.

3. Leaves not ribbon-like, cauline.

4. Leaves In whorls of 4 or 5 3. Egeria.

4. Leaves in whorls of 3 4. Elodea.

1 . Marine plants.

5. Leaves alternate on a short stout concealed stem,

ribbon-like, 1 dm long or longer 5. Thalassia.

5, Leaves opposite at tip of stem, oblong-elliptic, 5 cm

or less long 6. Halophila.

1. UMNOBIUM Rich. FrOG’S-BIT

1. L. spongia (Bose) Steud., June-Oct. Floating on shallow quiet ponds,
swamps, ditches; scattered throughout, uncommon. Fig. 3.

2. VALLISNERIA L. TAP^GRASS, EELGRASS, WATER-CELERY

1. V. americana Michx., June-Oct. Submerged in fresh water streams near
the coast, which may be brackish at high tides. Fig. 3.

3. EGERIA Planch. WATERWEED

1. E.densa Planch., May— Nov. Ponds; reported by R based upon a cultivated

MISSISSIPPI Monocotyledons

367

specimen from Grenada in the Univ. of N. C. Herbarium. St. John (1961), in his
monograph of Egeria, does not cite a specimen from Mississippi. Philotria densa
(Planch.) Small — S; Elodea densa (Planch.) Casp. — F; /inacharis densa (Planch.)
Viet.— G.

4. ELODEA Michx. Waterweed

1. E. nuttallii (Planch.) St. John, June-Oct. Ponds; reported by St. John
(1965) from Holmes Co., YMD. Anacharis nuttallii Planch. — G. Fig. 3.

5. THALASSIA Soland. TURTLEGRASS

1. T. testudinum Konig., Aug.-Nov. Submerged in shallow salt water of
Mississippi Sound where it forms dense grass beds on sandy bottoms, common.
Fig. 3.

6. HALOPHILA Thou SEAGRASS

1. H, engelmaiinii Asch., June— Dec. Submerged in shallow salt water of
Mississippi Sound where it forms part of the flora of the grass beds; uncommon.
Fig. 3.

JUNCAGINACEAE

1. TRIGLOCHIN L. ARROWGRASS

1. T. striata R. & P., Apr.— Sept. Wet, sandy or mucky soil, salt marshes.
Fig. 4.

LEMNACEAE

1. Roots present on plants, arising from the lower side

of the flattened thallus.

2. Each thallus with usually two or more roots 1. Spirodela.

2. Each thallus with one root 2. Lemna.

1. Roots absent.

3. Thallus globular or ellipsoidal 2). 'Wolffia.

3. Thallus sickle-shaped, elongate and linear 4. Wolffiella.

Two useful references on this family are Harrison and Beal (1964) and
Daubs (1965).

1. SPIRODELA Schleid. DUCKWEED, DUCKMEAT

1. Thallus conspicuously several-nerved with the nerves
radiating from the stipe base, each thallus with

368

Jones

THALASSIA TESTUDIMUM

LACHNANTHES CAROLINIANA

Figure 4. Distribution in Mississippi of Trtglochin striata, Spirodela poiyrhiza, Spirodeia
oligorhiza, Lemm trinervis, Lemna gibba, Lemna perpusUla, Lemna valdiviam, Lemna minor,
and Woiffia columblana.

Mississippi Monocotyledons

369

5 to many roots; thallus orbicular-obovate, not

punctate \. S, polyrhiza.

1. Thallus faintly nerved, each thallus with 2—4 roots;

thallus oblong-obovate to slightly elliptic,

punctate 2. S. oligorhiza.

1. S. polyrhiza (L.) Schleid. Present at all seasons but especially abundant in
the late summer and fall, Quiet waters, ponds, lake margins, bayous; scattered
throughout. Fig. 4.

2. S. oligorhiza (Kurtz) Hegelm. Abundant in late summer and fall. Margins
of pools, ponds, bayous; scattered in sw Mississippi. This is a Far Eastern species
which has been introduced into the United States and is now rather widespread.
Fig. 4.

2. LEMNA L. DUCKWEED

1 . Thallus indistinctly to prominently 3-nerved.

2. Thallus distinctly 3*nerved \. L. trinervis.

2. Thallus usually not prominently nerved.

3. Thallus orbicular-obovate, inflated beneath; root

sheath without wings or appendages 2. L. gibba.

3. Thallus obovate to elliptical, not inflated beneath,

root sheath with definite wings or appendages . . 3. L perpusilla.

1 . Thallus nerveless or very obscurely 1 -nerved.

4. Thallus elliptic-oblong to crescent shaped 4. L.valdiviana,

4, Thallus orbicular-obovate or elliptic-obovate.

5. Thallus orbicular-obovate, inflated and noticeably

convex beneath; thallus yellow-green above ... 2. L. gibba.

5. Thallus elliptic-obovate, not inflated but flat or
slightly convex beneath; thallus dark green
above 5. L. minor.

1. L. trinervis (Aust.) Small, Abundant in late summer and fall. Margins of
lakes, streams, ponds; YMD. L. perpusilla var. trinervis — F, Fig, 4.

2. L. gibba L., INFLATED DUCKWEED, WINDBAGS, Abundant late in the
season. Ponds, sloughs; YMD. Fig. 4.

3. L. perpusilla Torr., Summer. Margins of ponds, lakes; LPR. Fig. 4.

4. L. valdiviana Phil., Summer. Ponds, lakes and ditches; abundant and com-
mon, producing large vegetative masses, throughout. L. cydostasa (EIL) Chev. — S.
Fig. 4.

5. L. minor L., WATER LENTIL, Most abundant in summer. Quiet waters
of sloughs, lakes, ditches; YMD. Fig. 4.

3. WOLFFIA Horkel WATER-MEAL

1. Thallus mostly globular, the dorsal surface strongly

convex, without a papilla, not punctate .... 1. W. Columbiana.

1. Thallus ellipsoidal or broadly ovoid, with a prominent

conical papilla, punctate 2. W. papulifera.

370

JONES

1. W. Columbiana Karst., Ponds, sloughs; YMD, LPR. Fig. 4.

2. W. papulifera Thomps., Ponds, sloughs; Ken Rogers (personal communica-
tion) collected this species in Forrest Co., LPR. I have not seen the specimen.
Fig. 5.

4. WOLFFIELLA Hegelm. MUD-MiDGET, BOG MAT

1. W. floridana (J. D. Sm.) Thomps., Ponds, ditches, sloughs; reported by R
to be in Mississippi, Ken Rogers (personal communication) collected this species in
Forrest Co., LPR; however, I have not seen this or any other specimen. Fig. 5.

MARANTACEAE

1. THALIA L. POWDERY THALIA

1. T. dealbata Roscoe, June-Oct. Wet ditches, edge of ponds, margins of
swamp forests; one location in Leflore Co,, YMD, rare. Fig. 5.

MAYACACEAE

1, MAYACA Aubl. BOGMOSS
1. Pedicels longer than the leaves; capsules globular or

ovoid; stems 2-20 cm long . . . l.M.aubletii.

1 . Pedicels shorter than the leaves; capsules ellipsoid; stems

often 40 cm long 2. Af. fJuviatilis,

1 . M. aubletii Michx., July-Aug. Springy places, margins of pools or streams;
CPM & se LPR, common. Fig. 5.

2. M. fluviatilis Aubl., July-Aug. Submerged in streams, pools; CPM and se
LPR, local. Fig. 5.

NAJADACEAE

1. NAJAS L. Bushy Pondweed, Water Nymph

1 . Leaf-bases broadly and auriculately lobed 1. N. gracillima.

1. Leaf-bases not broadly and auriculately lobed but

sloping 2. N. guadalupensis.

1. N. gracillima Magnus, June-Oct. Ponds and lakes; LPR. Fig. 5.

2. N. guadalupensis (Spreng.) Magnus, June-Oct. Ponds, lakes, estuaries;
LPR, CPM. Fig. 5.

Mississippi Monocotyledons

371

Figure 5. Distribution in Mississippi of Wolffia papuUfem, Wolfflelia flaridam, Thalia dealbata,
Mayaca aubletii, Mayaca fluvlatUis, Najas gmcildma, Nafos gu^lupensis, Pontederut cordata,
and Eichomia crassipes.

372

Jones

As is often the case with aquatics, these two species are more common than
indicated by the distribution maps. This is adapted from the treatment of Clausen
(1936).

PONTEDERIACEAE

1. Flower 2-lipped; stamens 6, 3 exserted and 3 included.

2. Corolla lobes 1 cm long or less; ovary 1 -celled; plants

attached to the soil; petioles not inflated .... 1 . Pontederia.

2. Corolla lobes 3—4 cm long; ovary 3‘Celled; plants

usually free floating; petioles inflated. ...... 2. Eichhomia,

1. Flower regular or nearly so; stamens 3, exserted .... 2. Heteranthera.

1. PONTEDERIA L. PICKERELWEED

1. P. cordata L., Apr.-Sept. Shallow water, marshes, ditches; CPM and e
LPR. Includes P. lanceolata Nutt, — S, F, G. Fig. 5,

2. EICHHORNIA Kunth WaTER-HYACINTH

1. E.crassipes(Mart.) Solms., June-Sept. Ponds, lakes, sloughs; s Mississippi.
Piaropus crassipes (Mart.) Britt. — S. Fig. 5.

3. HETERANTHERA R. & P. Mud-PLANTAIN

1. Leaves sessile, blades linear, grasslike; spathe sessile in
axils of leaves; stamens all alike, anthers coiled
with age,

2. Perianth tube much less than twice as long as the
spathe; seeds ellipsoid, yellow-brown, the 10—

12 membranaceous wings soon disappearing . . \. H. dubia.

2. Perianth tube twice as long as the spathe or longer;

seeds nearly globose, black-brown, the 14-16

wings persistent . 2. H. liebmannii.

1. Leaves petioled, blades expanded; spathe peduncled;
stamens of two forms, anthers not coiled.

3. Leaf blades ovate to elliptic or elliptic-lanceolate;

spathe 1 -flowered 3. H, limosa.

3. Leaf blades round-reniform; spathe 3-10 flowered . . 4. H, reniformis.

1. H. dubia (Jacq.) MacM., WATER STAR GRASS. Streams, quiet waters;
reported by R to occur in the state, I have seen no specimens. Zosteralla dubia
(Jacq.) Small — S, G.

2. H. liebmannii (Buch.) Shinners, Apr.-July. On mud or floating in ponds,
ditches; distribution reported by Correll and Johnston includes Mississippi, no speci-
mens have been seen.

3. H. limosa (Sw,) Willd., June— Oct. Wet soil, lakes, ponds; scattered in w-
central Mississippi. Fig. 6.

MISSISSIPPI MONOCOTYLEDONS

373

KETERANTHERA RENIFORMIS

POTAMOGETON BERCHTOLOH

P0TAM06ET0N NOOOSUS

TYPHA LATIFOLIA

Figure 6. Distribution in Mississippi oi He teranthera lim^sa, Heterantheru reniformls, Potamo-
geton berchtoldii, Potamogeton diversifolius, Potamogeton pulcher, Potamogeton nodosus,
Ruppia maritima, Sparganium americanum, and Typha latifolia.

374

Jones

4. H. reniformis R. & P., July— Aug. Creeping on mud or in shallow water,
ponds, streams; Claiborne Co. Fig. 6.

This treatment is adapted from Correll and Johnston. Additional collections
oi Heteranthera are badly needed.

POTAMOGETONACEAE

1. POTAMOGETON L. PONDWEED, FiSHWEED

1. Submerged leaves linear, most more than 10 times as
long as wide.

2. Stipules united with the base of the leaf for a distance

of at least 10 mm; floating leaves absent .... \. P. pectinatus.

2. Stipules not united with the base of the leaf or if
united then for a distance of less than 10 mm.

3. Floating leaves absent; stipules completely free from
the base of the leaf; seed not coiled more than
1 revolution, the coil not evident through the
thick pericarp.

4. Fruits with a thin wing-like undulate dorsal keel;

nodal glands usually absent 2. P. foliosus.

4. Fruits with a rounded or obscure dorsal keel; nodal
glands usually present.

5. Leaves with 3-5 veins; stipules connate when

young; peduncles 1.5—8 cm long; spikes 6—12

mm long, of 3-5 separate whorls 3. P. pusillus.

5. Leaves with 1-3 veins; stipules not connate;
peduncles rarely more than 3 cm long; spikes
2—8 mm long, of 1—3 contiguous whorls ... 4. P. berchtoldii.

3. Floating leaves usually but not always present; stipules
free or united with the base of the leaf for a
distance of less than 7 mm; the coil evident
through the thin pericarp 5. P. diversifolius.

1. Submerged leaves lanceolate to ovate, mostly less than
10 times as long as broad.

6. Leaves sessile, all submerged, cordate and clasping the

stem 6. P. perfoliatus.

6. Leaves sessile or petioled, submerged leaves not cordate
nor clasping the stem.

7. Tips of submerged, leaves acute to sharp pointed

sometimes mucTonate; stipules firm 7 . P. illinoensis.

7. Tips of submerged leaves acute but not sharp pointed;
stipules delicate.

8. Floating leaves with 21-29 + veins, bases usually

cordate, rarely rounded 8. P. pulcher,

8. Floating leaves with 9—21 veins, bases cuneate or

rounded 9. P. nodosus.

Mississippi monocotyledons

375

1. P. pectinatus L., June-Oct. Brackish or calcareous ponds, lakes, estuaries;
reported by R to be in Mississippi but no specimens have been seen, although it has
been collected in La.

2. P. foliosus Raf., June-Oct. Brackish or calcareous ponds, lakes, streams;
reported by R to be in Mississippi but no specimens have been seen. Eugene Ogden
(personal communication) indicates it is in La., Ark., and Tenn.

3. P. pusillus L., May-Oct. Neutral or slightly alkaline or brackish water of
ponds; reported by Ogden (1966) to be over most of eastern U. S. but no specimens
have been seen from Mississippi. It has been collected in La. and Ark. (Ogden,
personal communication).

4. P. berchtoldii Fieb., May-Oct. Ponds, slow-moving streams; one collec-
tion by Ken Rogers from Forrest Co., LPR, not seen by writer but it was det. by
Ogden. Fig. 6.

5. P. diversifolius L, June -Oct. Ponds, lakes; throughout, common. Includes
P, capillaceus Poir, — F. Sensu Klekowski and Beal (1965), Fig. 6.

6. P. perfoliatus L., June-Oct. Neutral to calcareous or brackish water,
ponds, streams, estuaries. R reported it in Mississippi but no specimens have been
seen. It has been collected in Alabama.

7. P. illinoensis Morong, June-Oct. Quiet or flowing water, streams, ponds;
reported by R to be in the state but no specimens have been seen. Ogden has seen it
from Ark. P. lucens L,,P. angustifolius Bercht. & Presl. — S.

8. P. pulcher Tuckerm., June— Oct. Ponds, lakes; scattered throughout, com-
mon. Fig. 6. ,

9. P. nodosus Poir., June-Oct. Ponds, lakes, slow moving streams; central
Mississippi./^, fluitam Roth — S. Fig. 6.

Adapted from the treatments of Ogden, and K 2 i<^ioi<Xet al Potamogeton has
been poorly collected in Mississippi. We need some field botanists who do not
object to getting their feet wet! A useful reference is Hotchkiss (1964).

RUPPIACEAE

1. RUPPIA L. Ditchgrass, Widgeongrass

1. R. maritima L., July— Oct. Submerged in shallow, brackish rivers, ponds,
estuaries; along the coast and in lagoons and ponds on the barrier islands, it grows
on soil with high organic matter content. Fig. 6.

SPARGANIACEAE

1. SPARGANIUM L. BUR-REED

1. S. americanum Nutt., June-Sept. Shallow ponds, streams; scattered
throughout except in CPM, YMD and LBH. S. eurycarpum Engelm, — S, misapplied.
Concept of this species sensu Beal (1960b). Sparganium provides an excellent
example of the former paucity of collections prior to our field work on the Mis-

376

Jones

sissippi Flora Project. Beal borrowed specimens from all of the proper herbaria but
found none from Mississippi. Fig. 6.

TYPHACEAE

1. TYPHA L. Cat-tail

1. Stigmas lanceolate to ligulate; staminate and pistillate

portion of spike usually contiguous 1 . 7, latifolia.

1. Stigmas filiform to linear; staminate and pistillate por-
tions of the spike usually separated.

2. Abortive pistil with a truncate-flattened apex 2. T. angnstifoUa.

2. Abortive pistil with a rounded apex 3. 7. domingemis.

1. T. latifolia. L., COMMON Cat-TAIL. Apr.— May. Marshes, shallow water,
ditches; throughout. Typha latifolia hybridizes with 7. angustifolia to form 7. x
glauca Godr. The hybrids have linear-lanceolate stigmas. Fig. 6.

2. T. angustifolia L., NARROW-LEAVED Cat-TAIL. Apr.-May, Coastal and in-
land marshes; s Mississippi. Fig. 7.

3. T. domingensis Pers., Apr.— May. Marshes; this species has been reported
from along the coast and Ken Rogers (personal communication) has it from Forrest
Co., but no specimens have been seen by this writer. Leaf measurements overlap
with 7. angustifolia. The best character appears to be the abortive ovary apex as
used in this key. Fig. 7.

Treatment adapted from Hotchkiss and Dozier (1949) and Fassett and
Calhoun (1952).

ZANNICHELLIACEAE

1. Leaves from simple or much branched, floating, sub-
merged stems, which are rooted to bottom ... 1. Zannichellia.

1. Leaves from submerged stems which are sometimes
covered by sediments.

2. Leaves flat 2. Halodule.

2. Leaves terete or nearly so 3. Cymodocea.

1. ZANNICHELLIA L. HORNED PONDWEED, POOLMAT

1. Z. palustris L., Fresh or brackish water of ditches, ponds; Hancock and
Oktibbeha Counties. Fig. 7.

2. HALODULE Endl.

1, H. beaudettei (Den Hartog) Den Hartog, Submerged in Mississippi Sound,
on sandy bottoms, one of the species that forms the grass beds, common. Halodule

MISSISSIPPI Monocotyledons

377

Figure 7. Distribution in Mississippi of Typha angustifoiia, Typha domingemis, Zannichellia
palustris, Halodule beaudettet, and Cymodoceae flllformis.

wrightii Asch* — S; Diplanthera beaudettet Den Hartog of authors. D. wrightii
(Asch.) Asch., of authors. Treatment follows that of Den Hartog (1964) who
indicates that Diplanthera is illegitimate because it had been applied earlier to
another genus. Fig. 7.

3. CYMODOCEA Konig. Manatee-GRASS

1. C. fUiformis (Kutz.) Correll, Submerged in deeper water of Mississippi
Sound, bottom has some organic matter present, one of the members of the “sea
grass” community. C.^^manatorum Asch. — S. Syringodium fdiforme Kutz., of
authors; 5. filiformh Kutz., of authors. Fig. 7.

Manatee-grass usually appears in the marine literature as Cymodocea man-
atorum or Syringodium jiliforme. It is indeed unfortunate when well known names
such as Halodule or in this case for Manatee-grass must be changed but it is necessary

378

Jones

for nomenclatural stability. Correll (1968 and personal communication) pointed
out that S, filiforme published in 1860 is an earlier name than C manatorum
published in 1868. Therefore, it was necessary for him to make the combination
C filiforme (Kutz.) Correll. Detailed infonnation on the nomenclature oitialodule
and Cymodocea can be found in Den Hartog and in Correll.

Another confusing point concerns the spelling and abbreviation of the author’s
name. Correll and Johnston (1970, cf. p. 1780) list Kutz. for F. T. (Kuetzing)
Kutzing.

LITERATURE CITED

ADAMS, P, and R. K. GODFREY

1961. Observations on the Sagittaria subulata complex. Rhodora 63:247-266.

BEAL, E. O.

1960a. Tlte Alismataceae of the Carolinas, J, Elisha Mitchell Soc. 76i68-79.

1960b. Sparganium (Spaiganiaceae) in the southeastern United States. Brittonia 12:
176-181.

BOGIN, C.

1955. Revision of the genus Sagittaria (Alismataceae). Mem, N. Y- Botan. Card.
9:179-233.

CLAUSEN, R. T,

1936. Studies in the genus Najas in the northern United States. Rhodora 38:332-
346.

CORRELL, D. S.

1968. Some additions and corrections to the flora of Texas VI. Wrightia 4:74-78.
CORRELL, D. S. and H. B, CORRELL

1972. Aquatic and wetland plants of southwestern United States. E. P. A. U. S. Gov,
Printing Office, Washington, D. C. 1 777 pp.

CORRELL, D. S. and M. C. JOHNSTON

1970. Manual of the vascular plants of Texas. Texas Res. Foundation, Renner, Texas.

1881 pp.

DAUBS, E. H.

1965, A monogiaph of Lemnaceae, 111. Biol. Monog. number 34,

DEN HARTOG, C.

1 964. An approach to the taxonomy of the seagrass genus Halodule Endl. (Potamo-
getonaceae). Blumca 12:289-312.

FASSETT, N. C.

1955. Jb'chinodorus in the American Tropics. Rhodora 57: 187.

FASSETT, N. C. and B. CALHOUN

1952. Introgression between Typha latifolia and T. angustifolia. Evolution. 6:367-
379.

FERNALD, M. L.

1950. Gray’s Manual of Botany, 8th ed. American Book Co., N. Y. 1632 pp,
GLEASON, H. A. and A. CRONQUiST

1963. Manual of Vascular Plants of Northeastern United Slates and Adjacent Canada.
Van Nosirand-Reinhold Co., N. Y. 810 pp.

GREAR,J. W.

1966. C^togeography of Oronlium aquaticum (Araceae). Rhodora 68:25—34.
HARPER, R. M.

1936. Is Acorus caismus native in the United States? Torreya 36.143-147.
HARRISON. D. E. and E. O. BEAL

1964. The Lemnaceae (Duckweeds) of North Carolina. J. Elisha Mitchell Soc. 80:
12-18.

Mississippi Monocotyledons

379

HENDRICKS, A. J.

1957. A revision of the genus (Dill.) L. Am. Mid. Nat. 54:470-493.
HOTCHKISS, N.

1964. Pondweeds and pondweedlike plants of eastern North America. U. S. Fish and
Wildlife Cir. 187. 30 pp.

HOTCHKISS, N. and H. L. DOZIER

1949. Taxonomy and distribution of N. American Cat-tails. Am. Midi. Nat. 41:
237-254.

KLEKOWSKl, E. J. and E. O. BEAL

1965. A study of variation in the Potamogeton capillaceus - diversifolius complex
(Potamogetonaceae). Brittonia 17:175-181.

LOWE. E. N.

1921. Plants of Mississippi. Miss. State Geol. Survey Bull. 17. 293 pp.

OGDEN. E. C.

1966. Potamogetonaceae. (in) C. L. Lundell, Flora of Texas l(3):369-382, plates
48-56.

RADFORD, A. E., H. E. AHLES, and C. R. BELL

1968. Manual of the vascular flora of the Carolinas. Univ. N. C. Press, Chapel Hill.
1183 pp.

ST. JOHN. H.

1961. Monograph oiEgeria Planchon. Darwiniana 12:293-307.

1965. Monograph of the genus Elodea: part 4 and summary. Rhodora 67:1-35.
SMALL, J. K.

1933. Manual of the southeastern Flora, (reprint) Univ. N. C. Press. Chapel Hill.
1554 pp.

STEYERMARK, J. A.

1963. Flora of Missouri. Iowa State Univ. Press, Ames. 1725 pp.

WILSON, K. A.

1960. The genera of the Arales in the southeastern United States. J. Arnold Arbor.
41:47-72.

WOOTEN, J. W.

1973. Taxonomy of seven species of Sagittaria from eastern North America. Brittonia

25:64-74.

Gulf Research Reports

Volume 4 Issue 3

January 1974

A Review of Salinity Problems of Organisms in United States Coastal Areas Subject to the
Effects of Engineering Works

Gordon Gunter

Gulf Coast Research Laboratory

Buena S. Ballard

Gulf Coast Research Laboratory

A. Venkataramiah

Gulf Coast Research Laboratory

DOI: 10.18785/grr.0403.05

Follow this and additional works at: http:/ / aquila.usm.edu/ gcr

Part of the Marine Biology Commons

Recommended Citation

Gunter^ G., B. S. Ballard and A. Venkataramiah. 1974. A Review of Salinity Problems of Organisms in United States Coastal Areas
Subject to the Effects of Engineering Works. Gulf Research Reports 4 (3): 380-475.

Retrieved from http:// aquila.usm.edu/gcr/vol4/iss3/5

This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean
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A REVIEW OF SALINITY PROBLEMS OF ORGANISMS IN
UNITED STATES COASTAL AREAS SUBJECT TO
THE EFFECTS OF ENGINEERING WORKS'

by

GORDON GUNTER, BUENA S. BALLARD and A. VENKATARAMIAH
Gulf Coast Research Laboratory
Ocean Springs, Mississippi

ABSTRACT

The nongaseous substances that normally move in and out of cells are metabolites,
water and salts. The common salts in water determine its salinity, and the definition of sea
water salinity and its composition are discussed. The relationships of salinity to all phyla of
animals living in the coastal waters axe reviewed, with emphasis on the estuaries of the Gulf and
Atlantic coasts of the United States, which are particularly influenced by coastal engineering
works and changes of salinity caused hereby.

The fauna of estuaries is made up of a few brackish water species which complete their
life cycles there, marine species which spend only a part of their life cycles there and which
have definite low-salinity limits, a few anadron>ous species passing through, and a few fresh
water species with high salinity limits. Organisms of marine origin are dominant. Floods and
drought periods, resulting in severe osmotic changes, may kill organisms or result in drastic
changes of the biota, which may take extended time to reestablish itself, if the conditions re-
turn to normal.

Many invertebrate animals have few mechanisms for controlling the movement of waters
and salts across their external membranes and thus are osmotic conformers. Species that cannot
withstand wide salinity change are said to be sienohaline, but many species can tolerate rather
wide changes; they have broad tolerance at a cellular level. Osmoregulators exhibit considerable
control of their internal salinity by excretory mechanisms and permeability control of the body
surface to water arid salts. In general, the wonn-s and molluscs are more often osmocon formers
than the crustaceans, the latter having greater control over their internal osmotic environment
than other invertebrate groups. Effects upon different stages of life history are different, but
in general the limiting effects of salinity and other environmental factors bear upon the repro-
ductive stages or the young- The limits of salinities are nearly always on the lower side with
regard to estuarine organisms. Aside from osmotic adjustments, animals react to salinity changes
by closing their shells, closing their burrows, burying in the bottom where interstitial water has
liighcr salinity, or motile forms simply move out. In spite of these adjustments, none may be
successful during large floods.

The salinity relationships of all phyla are reviewed, even though some of them are
unimportant paits of the marine populations. Dinoflagellate Protozoa which cause red tides

' This paper is modified from a report that was prepared by the Gulf Coast Research
Laboratory under Contract No. DACW39-72-C-0003 with the U- S. Army Engineer Waterways
Experiment Station (WES) and Contract No. DACW73-7CFC-0004 with the Department of the
Army, Office of the Chief of Engineers (OCE) (Gunter, Ballard and Venkataramiah 1973).
Preparation of that state-of-knowledge summary was initiated on the recommendation of the
OCE Estuarine Ecological Consultants Board in an Interim Report entitled “Effects of Engineer-
ing Activities on Coastal Ecology” (Cronin, Gunter and Hopkins 1971). The report was pub-
lished by the Waterways Experiment Station,

380

Gulf Research Reports
Vol. 4, No. 3, 380-475, 1974

Salinity Problems

381

have precise salinity requirements and their outbreaks would be subject to control if reservoirs
of fresh water were available. Sponges are generally high salinity organisms and not often
damaged by low salinity. All the worms, including several phyla and the rather advanced
Annelida, and the Mollusca are weakly motile at best and are thus subject to extermination by
heavy floods in estuaries. However, most of these animals have short life cycles and their
populations are quickly reestablished when the salinity regime returns to normal.

The dominant invertebrates in estuaries are crustaceans. The larger species arc generally
motile and not subject to catastrophic damage. Nevertheless, the lower limits of toleration of
most species are quite limited and even a change of half part per thousand salinity will cause
changes in the range in many species. If the salinity gradient falls, species drop out of the com-
plex because their lower limits are reached, with the numbers of species becoming less in lower
salinities.

There is an estuarine life history among the higher crustaceans such as shrimp and crabs
which is also applicable to the fishes, and which is closely related to salinity. The adults spawn
in high salinities of the open ocean and the young come back into the estuaries to raise. The
young apparently prefer the lower salinities that the species will tolerate; and they move back
out to sea as they grow, thus bringing about a correlation with rising* salinity and increase in
size, w^hich may be quite precise as in the case of the commercial .shrimp of the Gulf coast.

Although catastrophic changes in salinity are quite important to populations, the day-to-
day generally normal salinity regimes also play a great part in determining the population
picture of an estuary. Nineiy-eight per cent of all the commercial fishery production in the Gulf
of Mexico is from species connected with the estuary sometime in their life history.

The fishes of bays and sounds are made up of a relatively few species which spend their
lives there, of semi-anadromous and anadromous fishes going from and coming to fresh water,
of a few strays from fresh water, a few strays from the open ocean and a host of semi-
catadromous species that undergo the marine-estuarine type of life history. Large specimens
are found in higher salinity water for most species. Being strongly motile, few species are
damaged by floods. The weakly motile amphioxus is the only chordate known to be destroyed
in vast numbers by fresh water. The fishes are strong osmoregulators and in the changing
salinity of the bays they regulate as freslr water fishes or marine fishes, depending upon whether
or not the ambient salinity is higher or lower than that of the blood.

The salinity relations of salt water plants are less well known than those of the animals;
however, a summary is given on what information we have concerning the flowering plants of
the marshes and the totally submerged marine grasses along the Gulf coast.

Each separate bay, sound or estuary is an individual case with regard to salinity, but
they can be appraised by biologists acquainted with the local fauna and flora so as to minimize
and possibly even enhance their biotic potential in connection with salinity changes caused by
engineering works.

GENERAL CONSIDERATIONS

The unitary or individualistic character of life has not been stated any clearer
than it was by Claude Bernard when he said that organisms have enclosed them-
selves in a kind of hothouse, where the perpetual changes of external conditions
cannot reach, and to this extent they are free and independent. He went on to say
that all vital mechanisms have only one objective, that of preserving constant con-
ditions of life in the internal environment. His succinct statement was, “Constancy
of the internal medium is the condition of free life” (Bernard 1878).

The things which must be conserved for the maintenance of life are certain

382

Gunter, Ballard and Venkataramiah

physical and chemical limits and certain materials. Physical characteristics such as
temperature and specific gravity are, of course, influenced and changed by the
material exchange between the organism and the external environment, but we are
concerned with the materials themselves which may be divided into water, electro-
lytes and non-electrolytes. Non-electrolytes, the metabolites, are used for the main-
tenance of structure or oxidized for the production of energy and their end products
are cast out. A flux-equilibrium of these materials must be maintained. Here we are
limited in attention to those materials, water and the electrolytes, which change
within the organism when the external medium is changed in salinity. These changes
involve the problems of osmotic regulations.

SALINITY

Salinity is the distinguishing characteristic of sea water, both physically and
chemically. Pearse and Gunter (1957) have stated that “the most significant prop-
erty of sea water in relation to the ecology and physiology of organisms depends on
the fact that it is a complex solution of salts.”

The salinity of the natural waters at the margins of the seas of this country
and its cycles and natural fluctuations are changed or modified by large public works
constructed there by the Corps of Engineers or by various agencies to which the
Corps issues permits. The ecology of these areas is coming in for ever-closer .scrutiny
and it has become a matter of great importance to consider the salinity factor and
its relation to marine organisms as influenced by large engineering works near the
seas. The approach here is to review the biological information. The facts are some-
times technical but withal relatively simple.

The following account of the salinity of sea water is modified from Pearse
and Gunter (1957) and other sources.

The oceans are primarily solutions of metallic salts, chiefly of sodium, mag-
nesium, calcium, potassium and strontium. Organic materials are present in small
amounts and atmospheric gases are held in the solution in varying amounts. Dis-
solved nitrate, phosphates and silicates are present in relatively minute and variable
concentrations and are excluded from salinity determinations. The five chief metallic
salts are in such constant proportions that a simple analysis of one component,
the chloride, is theoretically sufficient in any ocean for determination of total
salinity, specific gravity and proportions of the salts. Salinity has been officially
defined by an International Commission as “the total amount of solid material in
grams obtained in one kilogram of sea water, when all the carbonate has been con-
verted to oxide, the bromine and iodine replaced by chlorine, and all the organic
matter completely oxidized” (Sverdrup, Johnson and Fleming 1942). It is expressed
in parts per thousand by the symbol / qo . Tables for determination of the chloride
by titration and specific gravity by hydrometer have been prepared by Knudsen
(1901) and they are standard tools of the oceanographer. Modern workers with
more precise techniques are modifying the salinity tables, especially at the extremes
of concentrations and dilutions, but generally this is only in the fourth decimal
place of a part per thousand or less and is not of particular importance to this account.

Salinity Problems

383

Near the mouths of large rivers and their estuaries, where salinities are low,
proportions of salts are slightly different from those of sea water. Some hard fresh
waters are almost one part per thousand saline because of the carbonates and sul-
fates contained. On the other hand, the very low salt content of rivers along the
State of Mississippi and Louisiana coasts cause coastal waters to have salinities
lower than ordinary fresh water, but with salts still in the proportion of sea water
(Price and Gunter 1964). Presumably, the Amazon River presents a similar case in
its offshore waters.

The average salinity of ocean water is about 35 parts per thousand, but it is
slightly different in the various oceans. The mid-Pacific surface salinity is 35.5 and
the mid-Atlantic and the mid-GuIf is 37 and in the Red Sea it is about 40. Readings
above 80 are quite common in the Sivash of Crimea and in the Laguna Madre of
Texasandin the latter, during past years when there was less circulation than today,
readings up to 112 were observed. In tropical shore ponds, which are only inter-
mittently connected with the sea, readings equivalent to 155 parts per thousand
have been observed; but certain salts settle out before these concentrations are
attained and the saline proportions are not those of sea water. Higlier than normal
sea water salinities are not common in the world oceans or their margins, but they
are found in certain restricted areas (Gunter 1967a).

Tables 1, 2 and 3 showing the salt content of sea water and some continental
waters were taken from the various sources shown. Table 4 gives the major sea

Table 1.

Common Constituents of Sea Water and Typical Freshwaters, °/oo

Ions

Normal Sea Water

( 1 )

(pH 8.17) (2)

Hard Fresh Water
(3)

Soft Fresh Water
(3)

cr

19.630

18.9799

0.041

0.019

S 04 “

2.701

2.6486

0.025

0.007

Br“

0.066

0.0646

F"

0.001

0.0013

CO 2

0.001

H 2 CO 3

HC03~

0.116

0.1397

CO 3 '

0.012

0.119

0.012

H 3 BO 3

0.022

0.0260

H2B03“

0.005

Na+

10.770

10.5561

0.021

0.016

Mg++

1.298

1.2720

0.014

0.00053

Ca++

0.408

0.4001

0.065

0.010

K+

0.387

0.3800

0.016

. • .

Sr++

0.014

0.0133

Salinity

35.161

34.3159

0.301

0.065

(1) From Rubey (195 1); (2) From Sverdrup el al. (1 942); (3) From Baldwin (1937).

384

Gunter, Ballard and Venkataramiah

Table 2.

Percentage of Dissolved Salts in Various Waters

After Rankama and Sahama (1950) and Garke (1924)

Constituent

Sea

Water

Lake and
River Water
(Average)

Jordan River
Near Jericho

Dead Sea
North End

Bear River
Near Mouth

Great Salt
Lake

CO 3

0.41*

35.15

13.11

Trace

21.53

0.09

SO 4

7.68

12.14

7.22

0.31

8.16

6.68

G

55.04

5.68

41.47

65.81

32.36

55.48

NO 3

. . .

0.90

Trace

. . .

. . -

Ca

1.15

20.39

10.67

4.73

10.12

0.16

Mg

3.69

3.41

4.88

13.28

4.76

2.76

Na

30.62

5.79

18.11

11.65

20.54

33.17

K

1.10

2.12

1.14

1.85

1.66

Fe 203 , AI 2 O 3

- * ,

2.75

1.45

. . .

2.53

. . .

Si02

• i ■

11.67

1.95

Trace

* . .

* . .

Sr, Br, H 3 BO 3

0.31

Br

2.37

100

100

100

100

100

100

Salinity, °/oo

35.0

.146

.770

192.15

.637

203.49

*AsHC03“

Table 3.

Percentage of Dissolved Salts in Various Semi-enclosed and Inland Seas

Data from Garke (1 924); for the sea water, from Rankama and Sahama (1950)

Constituent

Sea Water

Baltic Sea

Eastern

Mediterranean

Black Sea

Caspian Sea

Aral Sea

G

55.04

55.01

55.30

55.12

42.04

35.40

Br

0.13

0.16

0.18

0.05

0.03

SO 4

7.68

8.00

7.72

7.47

23.99

30.98

CO 3

0.41*

0.14

0.19

0.46

0.37

0.85

Na

30.62

30.47

30.51

30.46

24.70

22.62

K

1.10

0.96

1.12

1.16

0.54

0.54

Rb

» • •

0.04

. • .

0.02

0.02

Ca

1.15

1.67

1.19

1.41

2.29

4.02

Mg

3.69

3.53

3.81

3.74

5.97

5.50

Fe, Si02) PO 4

0.05

0.03

0.04

Sr, Br, H 3 BO 3

0.31

. . .

. . .

, . .

100

100

100

100

100

100

Salinity, %©

35

7.21

38.36/41.15

18.2/22.2

12.94

10.84

♦AsHCOj-

Salinity Problems

385

Table 4.

Major Seawater Constituents (Home 1969)

Ions

Concentration, gm/kg
of 35 °/oo seawater

Ions

Concentration, gm/kg
of 35 ®/oo seawater

a-

19.353

0.387

Na+

10.76

HCO 3 "

0.142

S04^~

2.712

Br“

0.067

Mg2+

1.294

Sr 2 +

0.008

Ca 2 +

0.413

Table 5.

Main (Components of Sea Water in the Form of Salts (Per m^ of Sea Water
of 35 %o Salinity and 20°C) (Neumann and Pierson 1966)

NaCl

28,014 kg

MgCl 2

3.812

MgS04

1.752

CaS 04

1.283

K 2 SO 4

0.816

CaCOs

0.122

KBr

0.101

SrS 04

0.028

H 2 BO 3

0.028

water components according to Horne (1969). Sea water is higltly ionized and
therefore the characteristics of the individual salts are somewhat masked in the
regular solution. However, if the water is all evaporated the remaining salts are
those shown in Table 5 according to Neumann and Pierson (1966). These are very
close to the figures given by Dittmar (1 884) in his reports of chemical studies of the
ocean as determined by the Challenger expedition.

The salt content of sea water modifies its physical properties, some of which
are of considerable ecological significance. The temperature of maximum density of
pure water is 4“C, while at 35.5 parts per thousand it is lowered to minus 3.8°C.
The freezing temperature of water declines with increased salinity and at 35.5 parts
per thousand this value is about minus 1.96®C, the initial freezing point at which a
fewicc crystals appear^ Because of these facts earlier workers used the determination
of freezing point lowering to measure the amounts of salts in the fluids of organisms.
This method is still used where total osmotic pressure alone is to be detennined,

WATER

Water is essential to all life because its physical and chemical attributes make
it absolutely necessary to protoplasm and indeed it is incorporated in all living

386

Gunter, Ballard, and Venkataramiah

substance. It is the chief road or avenue by which chemical and physical processes
travel in living material. It serves as a solvent necessary for the chemical reactions
involved in cellular metabolism and it acts as an ionizing agent. The properties of
water are too extensive to be discussed here and understanding must of necessity be
assumed, along with knowledge of osmosis.

Water must be present in the proper amount so that there is neither excessive
swelling nor shrinking of the cell or other effects connected with its solvent func-
tion, specific heat properties, etc. Salts are also necessary to living cells and must be
maintained in proper proportions for normal functioning of the cells. The relative
amounts of salts and water determine the osmotic pressure of biological fluids and
all living organisms face the problem of maintaining a proper water-salt balance.

Terrestrial animals must retain water; that is, they must have some mechanism
for counteracting a tendency toward water loss through evaporation. All fresh water
and salt water organisms have a problem, too, because even though immersed in
water they are not usually in osmotic balance. Many marine and parasitic species
are isosmotic with their media, but others face an osmotic problem due to dif-
ferences in concentration of their body fluids and the surrounding medium. Fresh
water animals must exclude water that tends to move into their bodies or remove it.
They must also have some means of counteracting the loss of salts to the dilute
medium. All animals that live in sea water of a salinity higher than their blood tend
to lose water. In the relatively few animals that live in hypersaline waters, above sea
water salinity, the tendency to lose water is greatest. Between these two extremes a
variety of animals live in the waters of bays and sounds, where they are affected by
salinity changes.

THE ESTUARINE ENVIRONMENT AND SALINITY

Salinity and its effects on living things are especially noticeable and important
along the mar^ns of the seas, where it sometimes varies greatly in both space and
time. This area includes the coastal marshes, bays and estuaries, the importance of
which has been much emphasized in recent years.

Estuaries form a large portion of the sea immediately adjacent to land. They
are areas where sea water is measurably diluted with fresh water from land drainage.
Salinity conditions are unstable because of variations in the relative amounts of
fresh and salt water present, dependent on variable drainage and tidal effects.
Salinity varies horizontally as the tide moves back and forth and as varying amounts
of fresh water flow into the estuary. There is a general pattern of increasing salinity
from the mainland shore seaward but the gradient is not always the same, not only
because of the relative amounts of fresh and sea water present at any one time, but
also because of the effects of winds and currents.

There are also vertical variations in salinity as the lighter fresher water generally
overrides the denser salt water. In some estuaries there is distinct layering, but this
type of gradient can also be affected by the mixing action of tides and currents and
even by the shape of the basin. Estuaries, being relatively shallow and next to land,

Salinity Problems

387

are subject to atmospheric temperature changes which interact with salinity to
influence distribution of animal life.

A large part of the coastline of the United States is bordered by estuaries and
lagoons where fresh and sail water mix in varying proportions. Estuaries and lagoons
are generally enclosed or semi-enclosed by peninsulas or barrier islands. Emery
(1967) estimates that 80-90% of the Atlantic and the Gulf of Mexico coasts of the
United States and 10— 20% of the Pacific coast are bordered by lagoons and estuaries.
They are generally called bays or sounds and sometimes “rivers^^ in North America
and seldom estuaries. There is no sharp distinction between estuaries and lagoons
but the latter is generally low in fresh-water influx and is considered to be more
stable and saline and to support a more indigenous fauna (Caspers 1967). There is
one hypersaline lagoon in south Texas and northern Mexico representing a relatively
small area (see Gunter 1967a).

The fauna of an estuary is made up of three general categories of animals:
(1) a relatively few typically brackish water species that can withstand wide changes
in salinity and which complete their life cycles in the estuary, (2) many marine
species that are able to live in unstable conditions but with low-salinity limits,
including species that spend only a part of their life cycles in (he estuary, (3) and
a very few fresh water species but with high-salinity limits (Potts and Parry 1964a,
Gunter 1967a). The senior author has emphasized in several publications that organ-
isms of marine origin dominate the estuarine fauna even at very low salinities (see
Gunter and Shell 1958).

Ordinary day-to-day variations in salinity do not normally disturb the com-
position of the fauna, since the characteristic animals of an estuary are adapted to
such variations. Motile forms may move about somewhat and sessile species may
withdraw temporarily into shells and tubes. Seasonal changes in salinity, interacting
with temperature, however, can cause widespread and characteristic fluctuations of
the fauna as certain specie.s move In and out with advance and retreat of high-salinity
waters caused by seasonal variations in rainfall. Gunter et al. (1964) pointed out,
for example, that there is maximum invasion of the bays of the northern Gulf of
Mexico by marine species in the dry fall season. Non-periodic and unpredictable
severe conditions resulting in unusual osmotic conditions such as severe floods or
prolonged drought can produce major catastrophes, killing off many species and
causing others to move out of the estuary, hi such cases it may take an extended
period of time for the fauna to reestablish itself (Hoese 1960).

Degree of motility and method of osmoregulation can be important for sur-
vival in severe or sudden salinity changes. The influx of large amounts of fresh water
on nonmotile or feebly motile species can be fatal. Large increases in salinity can
also result in changes in the composition of the fauna. Estuarine motile animals can
often withstand full sea water but preferentially choose lower salinities and so move
at times of higher salinities.

Gunter (1961) has shown that on the northern Gulf of Mexico coast, the most
important fishery region of North America, 98% of the fishery animals are con-
nected at some stage of their life history with the estuaries. McHugh (1966) has
shown that the American Atlantic fisheries are 63% estuarine dependent.

388

GUNTER, BALLARD, AND VENKATARAMIAH

The famous New England and Canadian fisheries north of Cape Cod are based
on the cod and its relatives from tJie offshore, liigh salinity banks. This fishery and
that for the tuna are the only ones of consequence in North America which depend
upon non-estuarine species. In northern Canada, the Pacific Northwest of the United
States, western Canada and Alaska the fisheries are dominated by the trouts and
salmons (Family .Salinonidae) many if not most of which are anadromous or semi-
anadromous and thus euryhaiine. This same dominance of the salmonids formerly
extended south to the Sacramento River and San Francisco Bay, but with the
damming of the Columbia and the Sacramento tributaries the salmonids are fading
in the southern part of their former realm.

It is clear from these remarks that the fisheries of North America are domi-
nated by species with estuarine connections. This holds true for both sports and
commercial fisheries, which overlap in species in many cases.

For a modern and recent summary account of the physical and chemical
characteristics of estuaries the reader is referred to Abbott, Dawson and Oppen-
heimer (1971). Except for some questionable salinity limits given for the oyster,
this is an excellent account.

Estuaries have been termed mixing bowls and even depositories for the ma-
terials that are brought down from the land. Even so, it should be held in mind that
most of the material transported from land passes on through an estuary. For
instance, the amount of sediment passing throu^ an estuary during its lifetime may
be over a hundred times the amount of sediment it would take to fill it completely
(see Gunter, Mackin and Ingle 1964).

Pritchard (1951) has shown that salt water in bays in the northern hemisphere
penetrates farther to the right, flowing in, due to rotation of the Earth. The cause
is known as Coriolis force. This leads to a differential distribution of marine organ-
isms on the opposite shores of the bays but the situation is not well documented as
Emery and Stevenson ( 1 957) have pointed out. Cowles ( 1 930) recorded stomalopods
farther in on the east side of Chesapeake Bay than on the western shore. Similarly
Loesch (1965) found penaeid shrimp larvae differentially distributed in Mobile Bay.
Sergerstrale (1957) has given similar information on the Baltic Sea.

A SUMMARY OF THE INFLUENCE OF SALINITY ON MARINE INVERTEBRATES

Many invertebrate animals have very little mechanism for controlling or coun-
teracting osmotic movement of water, and the blood is nearly isosmoiic with the
surrounding water over the entire range tolerated. When such an animal is in a
medium more dilute than its body fluids, water moves in through the body mem-
branes and changes the concentration of body fluids until equilibration is reached.
Conversely, when an animal is placed in a medium having a higher concentration
than its body fluids, water will move out through the body membranes, thereby
concentrating the body fluids, until an equilibrium is reached. Salts may also move
in and out, but the end result is a change of the body fluids to a concentration
approximately equal to that of the surrounding water. Such animals are termed

Salinity Problems

389

con formers or osmoconformers. Osmoregulation in such cases would seem to be
largely a matter of tolerance at cellular levels.

Conformers vary greatly in their tolerance to dilution. If they have a very low
tolerance they are, of necessity, confined to a very narrow salinity range. Such
animals are said to be stenohaline. Most strictly marine animals are stenohaline. If
conformers can withstand some dilution of their body fluids they can have a more
e.xtended range into regions of lower salinities. There are wide variations among
species in the degree of dilution tolerated but there is always a limit, and the
environmental range of such animals is limited by the degree of toleration. Animals
with a wide salinity range are termed euryhaline. The mussel Mytilus edulis is an
example of a euryhaline conformer. It occurs in salinities ranging from 30 ®/oo to
1 0 %o and even down to 4 ®/oo in some areas (Conklin and Krogh 1938, Segerstrale
1957). The American oyster, Crossostrea virginica, is an even better example. It will
live for weeks at salinities just above fresh water (Gunter 1953) and lives indefinitely
in full sea water (Gunter and Geyer 1955). According to Kelley and Burbanck
(1972) the estuarine ho^QdCyathumpolitaii normally tolerant of salinities between
0.5 and 32 per mille.

Most estuarine organisms are of marine origin (Gunter 1956b, 1961a, Pearse
and Gunter 1957) and almost all of them can live in full sea water, but the lower
limits of salinity are limiting or lethal.

In addition to dilution of body fluids, change in body volume is a problem
that must be faced by osmoconformers and is a factor involved in determining the
salinity range tolerated. Animals vary in their permeability to salts and water. If
they are permeable to both salts and water they may be able to withstand lower
salinities than if they are permeable to water but fairly impermeable to salts. In the
former case, althougli there may be an initial swelling on exposure to dilute media,
equilibration will soon be reached as osmotic intake of water is accompanied by
outward diffusion of salts. If salts do not move out fast enough and if there is no
mechanism for excreting excess water, then the animal has no means of volume con>
trol and its salinity range is determined not only by its tolerance to internal dilution
but also by the rate of salt loss. Two closely related species of polychaete worms
illustrate the effect of differences in salt loss very well, Nereis diversicolor is
placed in 20% sea water it swells at first but begins to lose weiglit slowly until it
regains nearly its original volume. On the other hmd.Perinereis cuhrif era becomes
swollen and inert in 20% sea water and remains swollen. W. diversicolor regulates its
volume by loss of salt from its body, but salt is not lost to any extent from P.
cultrifera {headle 1931, Ellis l937,Scheer 1948).

A number of animals are osmoconformers but almost none are ionic con-
formers. The concentrations of specific ions differ in the internal and external fluids
even in those forms whose total blood osinoconcentration is equivalent to that of
the external medium (see Table 6). The coelomic fluid of echinoderms closely
approximates sea water in composition but it contains a slightly higher concentra-
tion of potassium. Various examples are cited by Pearse and Gunter (1957, p. 136).
In some groups such as the cephalopods and decapod crustaceans ionic regulation
extends to most ions in the blood (Robertson 1949, 1953, 1960, Nicol 1967). Ionic

390 Gunter, Ballard, and Venkataramiah

Table 6.

Composition of the Body Fluids of Some Invertebrate Marine Animals.
Values Are Expressed as a Percentage of the Corresponding Values
in Sea Water or in the'Body Fluid Dialyzed Against Sea Water

Taken from Shaw (1960) from Various Sources.

Animal

Freezing-

point

Depression

Na

K

Ca

Mg

Cl

SO 4

Echinodervm

Echinus esculentus

100

100

102

101

100

100

101

Holothuria tubulosa

100

101

103

102

104

100

100

Annelid

Arenicola marina

100

100

103

100

100

98

92

Mollusks

Mytilus edulis

100

100

135

100

100

101

98

Eledone cirrosa

100

97

152

107

103

102

77

Arthropods

Homarus vulgaris

100

110

85

131

14

101

32

Carcinus maenas

98-103

no

118

108

34

104

61

Pachygrapsus marmoratus

91

94

95

92

24

87

46

Palaemon serratus

74

79

70

115

22

74

9

exchanges take place by active transport across permeable body surfaces by mech-
anisms not fully understood, and the excretory organs, when present, may also be
involved.

Some invertebrate animals have the ability to maintain their blood at some
concentration different from that of the environment. Such animals are termed
osmoregulators. The most successful regulators among the invertebrates are the
arthropods, especially the crustaceans, but some annelid worms and a few other
forms can maintain hyperosmoticity in dilute media.

Tliere is great variation among species in the degree of regulation exhibited.
Some regulators live in a rather constant environment and so maintain a rather con-
stant blood concentration either hyperosmotic to the medium, as for example the
freshwater crayfish Astacus, or hyposmotic to the medium, as for example the brine
shrimp Anemia.

Other species are subjected to fluctuating osmotic conditions and so must
constantly face changing gradients between their internal fluids and the external
medium. Apparently no animal is able to maintain an absolutely constant internal
concentration under such conditions. All show some degree of variation in blood
concentration with changes in salinity and so must exhibit some degree of tolerance.
In fact, some regulators tolerate as great a change in internal concentration as do
many con formers (Lockwood 1962). Even so, the internal change can be held with-
in narrower limits than that of the external medium or, in other words, the environ-
mental range of osmoregulators can be greater than their internal tolerance range.

Salinity Problems

391

Tolerance to dilution of the body fluids does not imply equal tolerance to
intracellular dilution. The cells must be protected to some extent against fluctu-
ations in blood concentration in both conformers and in regulators. The concept of
intracellular regulation or regulation at the cell-blood boundary has become recog-
nized. In this connection Fingerman and Fairbanks (1956) have shown that the
very internal or central internal media of the oyster, around the heart, change salin-
ities more slowly than the peripheral areas when the external medium changes.

Cellular isosmoticity appears to be accomplislied by or at least accompanied
by regulation of the intracellular concentration of organic substances, principally
amino acids. It has been demonstrated that a direct relationship exists between
concentration of free amino acids in the tissues, blood osmoconcent ration, and
salinity of the medium, but the exact mechanisms responsible for variations in
amino acids have not yet been determined (Duchkeau and Florkin 1955, Potts
1958, Allen 1961, Lynch and Wood 1966, Lockwood 1967).

Most marine invertebrates are in osmotic equilibrium with their environment,
although much recent work shows that most of them are not in ionic equilibrium
(see Shaw 1960). In most animals, both water and salts penetrate the membranes
and semipermeability is never approached closely. Possibly the most important
finding of recent work is the fact that most materials are actively transported by
some means or another against a concentration gradient in osmoregulation. This
process was originally referred to as electroendosmose. As Shaw (1960) has pointed
out, a steady state between an organism and its environment may be far from an
equilibrium and thus energy must be supplied to maintain it. For this reason the
osmoregulatory powers of most marine organisms break down quickly when they
are deprived of oxygen, even thougli recent work (see Kinne 1971) has shown that
thermodynamic work done in osmoregulation is a very small percentage of the
metabolism.

Schlieper (1930) first showed that most marine invertebrates are isosmotic
with sea water, but he and other workers have shown that this applies more to the
worms and molluscs, and the crustaceans have better osmoregulatory powers and
are not so prone to be so isosmotic.

Some invertebrates protect themselves from unfavorable changes in salinity
by behavior resulting in minimum exposure to the medium. Oysters and barnacles
may make themselves relatively impermeable by closing their shells. Worms may
bury themselves in the mud or seek crevices near the bottom where salinities are
higher than in the overriding fresh water. Certain tube worms have been observed to
cease irrigation movements and thus reduce to a minimum the mixing of water of
the immediate environment with fresher water (Mangum 1964), Some hydrozoan
coelenteratcs show structural changes that reduce the surface area exposed to the
medium (Kinne 1964). Motile invertebrates may actively move to more favorable
environments and some bury in the mud, but many are too small to escape sudden
changes. Others may retreat to the bottom of deep burrows. Occasionally heavy
freshets or floods will kill bottom burrowing organisms and large mortalities will
take place (see Dawson 1 965).

A consideration of salinity effects must be concerned with life cycles since

392

Gunter, Ballard, and Venkataramiah

the requirements at different life stages may differ. Embryos and larvae may be
more sensitive to unusual stresses than adults are (see Robertson 1957) and it is a
general law (Shelford 1915) that the effects of environmental limils or extremes act
on particular phases of life histories, often the reproductive stages or young. The
early larvae of some estuarine species will not develop normally in low salinities and
so the adults must migrate to higli salinities to spawn (Sandoz and Rogers 1944,
Costlow and Bookhout 1959). Adult white shrimp live in higli salinities, but the
young, postlarval shrimp apparently must reach low-salinity estuarine waters or
most of them die (Viosca 1920, Weymouth et ah, 1933).

Although various factors such as temperature, age, sex, and stage of molt may
influence osmotic response (Baumburger and Olmsted 1928, Kinne 1963, Robert-
son 1960^ Ballard and Abbott 1969), salinity, or concentration of the environment,
is the basic factor determining blood salt concentration. Since invertebrates inhabit
widely varying salinities, they have a variety of mechanisms for handling osmotic
problems. Perhaps no environment is so demanding as the estuarine environment
where there are seasonal and even daily fluctuations in salinity due to such factors
as river discharge and tides, as well as seasonal and short-term changes in tempera-
ture which affect osmotic response. Animals living in such an environment must
adjust to fluctuating osmotic conditions either by efficient osmoregulation or, per-
haps, by a combination in which, althougli there is change in blood concentration
with change in salinity, the internal variation is less than that of the external
environment.

Life in an estuary appears to be rigorous, but the very variability is a constant
feature, and estuarine species must be labile and euryhaline. Nonetheless, salinity
can be a limiting factor, particularly on the lower side, and does affect the distribu-
tion of species (Gunter 1961a, Pearse and Gunter 1957, Potts and Parry 1964b and
many previous papers). The upper salinity distribution limit may be ecological and
behavioral rather than physiological. A number of brackish water species such as
the polychaete worm, Nereis diversicolor, the shrimp, Palaemonetes varians, and
the oyster, Crassostrea virgintca, can survive well in full sea water but they do not
usually occur in the sea.

Tlie lower salinity limit, on the other hand, is largely physiological. As the
water in estuaries becomes more dilute, the number of species declines in the order
of their decreasing ability to tolerate or regulate (Gunter 1961a, Prosser and Brown
1961). Enemy species and diseases similarly decline with lowering salinity, which is
probably one reason the estuaries are primarily nursery grounds for so many impor-
tant species. Similarly the increase of enemies and diseases with increasing salinity
is one reason many organisms are not commonly found in higli salinities which they
can tolerate physiologically.

The present summary of the influence of salinity changes on invertebrates
could be divided as follows: (1) the worm.s and lower organisms (2) the molluscs
(3) the crustaceans (4) lophophorates and (5) deuterostomes, but the phyietic array
is followed. Osmoregulating species have received the most attention, but studies
have been made of degree of tolerance, ionic regulation, and cellular regulation in
conformers as well. Since most strictly marine (offshore) species are isosmotic in a
relatively constanl environment, and since the present analysis is related to engi-
neering changes in coastal areas, emphasis is placed on effects of varying salinity on

Salinity Problems

393

estuarine and coastal invertebrates which could be affected by such works. How-
ever, some genera! remarks will be made concerning the physiology of marine and
freshwater species,

INFLUENCE OF SALINITY ON SPECIFIC INVERTEBRATE AND VERTEBRATE GROUPS

The Invertebrata include all animals without a notochord or backbone and
are larger in numbers, species and biomass than the chordate animals which all
people, including zoologists, are inclined to overrate in the Animal Kingdom.

These organisms are generally small and many of them are parasites or com-
mensals of other animals. They are also extremely diverse and their natural history
and physiology are not as well known as that of vertebrates in general. In this arti-
cle we shall take up the larger groups of invertebrates roughly in a hierarchy pro-
ceeding from the simple to the complex as recognized by zoologists. Parasites are
not considered here because the effect of salinity on the host species is always
paramount.

A. PROTOZOA. These organisms may be defined as one-celled individuals
which cannot manufacture their own food and must take it from the outside.
Many species are parasitic and virtually nonmotile at most stages of their life
history.

In spite of the purely animal character of a number of protozoans, some of
them, especially the Flagellala, are so closely related to single-celled, purely plant-
like organisms in their nutrition that separation of groups by clear-cut definitions
are quite difficult. This presents no real problem), however, and is merely an indica-
tion of the close kinship of lower organisms.

The purely animal flagellates are sometimes of interest because of their ability
to produce light, such as Noctiluca^ when they bloom or swarm in large quantities,
but they are not abundant in estuarine habitats and are osmotic conformers in high-
salinity waters (see C, C. Davis 1953 and papers cited). There are certain shelled or
naked amoebae living in low-salinity waters which are very much like freshwater
forms except that they may lack a contractile vacuole. These organisms are crawlers
and creepers and they are not numerous, at least in swarm numbers, and they are
difficult to demonstrate.

Various members of the Ciliate, Folliculina and relatives, build little clear
houses of chitinous material and attach themselves to hard substrata such as oyster
shells, bryozoans, or hydroids and may be numerous seasonally in low-salinity estu-
arine areas (see Andrews 1915). They are known as bottle animalcules. Some
cilia tes devour larvae of valuable mollusks (Loosanoff 1959) and their ecological
importance may be underestimated.

Tlie radiolarian ooze of the deep sea and the foraminiferal ooze of the shal-
low sea and the chalk beds have been of considerable interest not only to the
modern oceanographer but to the geologists who want to relate various geological
strata to one another. But again we receive the impression that these organisms
are abundant only in high-salinity waters and in fact there are few papers on living

394

Gunter, Ballard, and Venkataramiah

Foraminifera in the bays. Those of the Gulf coast are listed by Waldron (1963). His
work concerned Timbalier Bay in Louisiana and he concluded that upper bay (low-
salinity waters) included mostly arenaceous species, while lower bay species includ-
ed chiefly calcareous or marine species. Ayala-Castanares and Segura (1968) record-
ed the Foraminifera from the Laguna Madre of Tamaulipas, a dying lagoon only
containing water following hurricane breaches of the barrier island, which rapidly
becomes hypersaline or dies completely.

Tire Radiolaria arc uncommon in estuarine waters and the Foraminifera are
not abundant. Nevertheless, we must say that we do not know what part the Pro-
tozoa play in the living energy systems of bays and estuarine areas, but it may be
assumed that large floods of fresh water will kill them out in untold millions.
However, the rapidity of the life cycle is such that they probably replenisli barren
areas with great rapidity when salinities return to normal. Waldron (1963) said
there were three or four population peaks per species in Timbalier Bay in ten
months.

Some things are known about the osmotic relationship of the Protozoa. In
general, their osmotic problems are the same as those of larger organisms, as it
makes little difference if a living membrane is composed of one or many cells. Most
protozoans maintain an internal concentration slightly hyperosmotic to the medium
in brackish water. Some show an initial swelling when placed at lower salinities but
will generally return to normal after a period of time. Papers cited by Davis (1953)
give the salinity of the cell sap.

In freshwater Protozoa the contractile vacuole is considered to be an organelle
of excretion of the waste products of metabolism, as well as a way of getting rid of
excess water taken in by osmosis or in feeding. The latter idea is supported by the
fact that certain marine amoebae have vacuoles only during times of active feeding
(Nicol 1967). Rudzinska and Chambers (1951) found that the vacuolar output of a
freshwater suctorian increased six times during feeding. Frequency of contraction is
always greater in freshwater forms but may increase in marine forms placed in
fresher water (Kaimus 1929). Many marine fomis have no contractile vacuoles
under normal conditions, but others do.

According to Shaw (1960) the cell sap of the freshwater Protozoa is much
lower in salt content than that of some of the fishes or Crustacea. He shows in a
table, p. 478, that some crustacean liquids may be 35 limes as salty as the cell sap
of Spirostomumy a ciliale. There are some indications that the cell membranes of
the Protozoa are much more permeable to water than to salts. This fact, the low
cell sap salinity, and the contractile vacuoles set the Protozoa off osmotically
from all but some of the lowest Invertebrata.

Kinne (1971) has pointed out that resting stages, spores, and cysts of proto-
zoans, hydrozoans and sponges have higher salinity tolerances than active stages
and this is of great importance in enabling populations to survive periods of stress.

Kinne (1971, p. 832) cites papers showing that certain young stages of Proto-
zoa and other invertebrates may tolerate abrupt salinity changes more easily than
adults. But this work needs further investigation and is possibly connected some-
how with the fact that adults are often in higher salinities than juveniles and young.

Salinity Problems

395

Very little is known of ionic regulations in the Protozoa, although they must
have high capabilities in this regard to maintain cell sap at such different salinities
from the blood of other invertebrates in the same water (Shaw 1960).

Some euryhaline Protozoa are good volume regulators at wide ranges of
salinity, and although the contractile vacuole rate increases or decreases clearly with
salinity changes (see Kanoshiro et al. 1969) some good volume regulators have no
vacuoles. Krogli (1939) demonstrated quite a number of protozoan osmoconformers.

Harder (1968) has shown that certain Protozoa, Gymnodinium

and Tinntinnopsis, accumulate at discontinuity layers of sea water, which means
that they can avoid certain densities to some extent.

The naked dinoflagella tes which cause the so-called Red Tide are purely
phytoplankton, called by the botanists Dinophyceae. Nevertheless, they are more
often treated by zoologists* probably because these plankton blooms are lethal to
many organisms. Small blooms in fresh water and on north temperate coasts have
been known for a long time. These are mostly localized in bays and along our own
northwest Pacific coast are generally caused by Gonyaulax (see Martin and Nelson
1929 and papers cited).

Gessner (1959) found that in Baltic and North Sea waters dinoflagellate
species were about twice as common in salinities above 30 %o as at 0.25 to 6.0 %o.

Some flagellates seem to have ver>^ wide ranges of salinity optima. Goyacheva
(1969) said that the optimal salinity range was 20 to 40 ppt \ot Bodo marina, and
Hand, Collard and Davenport (1965) stated that Gonyaulax swam at high speed
from 20 to 36 ppt salinity, while Gyrodinium swam at above 225 microns per
second from 8 to 41 ppt. The first species is littoral and Gyrodinium is lagoonal or
estuarine in distribution. Certain flagellate species have been recommended for
mass culture because of their tolerance in wide environmental conditions, including
salinity (see Spektorova 1970).

The vast fish kills of the lower two-thirds of west Florida and occasionally a
similar region of south Texas and northwest Mexico are caused by Gymnodinium
breve Davis (Davis 1948) as was first shown by Gunter, Williams, Davis and Smith
(1948). Much work has been done on this organism and it was reviewed by
Rounsefell and Nelson (1966).

Tlie above-cited papers summarize information on the Red Tide. It follows
heavy drainage from land, which probably brings in some component as yet un-
known, and a long spell of warm weather where the water temperatures approach
30“C, and a period of calm weather. The organisms may attain densities of
60,000,000 to the liter — enough to change the. physical properties of the water
and everything dies, including G, breve, either frorn lack of oxygen or autointoxica-
tion. It is one of the major catastrophic mortalities of the sea, rivaling the Peruvian
die-off, El Nino, which may well involve a Red Tide organism as the senior author
has suggested before.

The salinities found at times of Florida blooms are between 31-35 %o. At
times following heavy rains a wide belt of such salinity may extend all along the

396

GUNTER, Ballard, and venkataramiah

Florida coast. This may lead to extensive spread of the Red Tide. Small patches
first begin in the lower bays and possibly they could be destroyed there by releases
of fresh water in storage basins above. At present the Lake Okeechobee outlet
through the Caloosahatchee River is the only one appropriate to the situation in
west Florida and there is none in south Texas or Mexico,

The Florida Red Tide can be killed by low concentrations of copper sulphate,
but so is everything else and the only feasible control method remaining is fresh
water, if the water supply can be obtained.

B. PORIFERA or PARAZOA, This phylum of animals, the sponges, is one
that most people have heard of and two verbs in English have been derived from it.
It is generally considered to be the lowest group of the multicellular organisms and
has no nervous, muscular oi vascular systems, although there are single cells which
carry on some muscle and nerve functions. Chiefly because the embryonic develop-
ment of the germ layers does not correspond to that of the other multicellular
organisms, the Metazoa, these animals are considered to be a branch aside from all
others and are called Parazoa. Their flagella cells have collars around them and
show a great similarity to the choanoflagellate Protozoa. There is nothing else in
the Animal Kingdom like their internal interlacing skeleton of calcite or silicate
spicules and sometimes horny fibers, from which comes the commercial sponge.
Their organization is also quite different from the other invertebrates. There arc
various layers of tissues and essentially a sponge is a body of cells which draws
water in through numerous pores by the action of flagellate cells, and casts the
water into a central chamber and out through a single opening, the osculum.

There are about 3,000 species of sponges, with a few hundred in the fresh
waters of the world and the remainder in the ocean from the surface to great depths.

Insofar as sponges have no vascular system or body cavities holding their own
liquids and live with sea water both inside and out, osmotic studies can be only of a
cellular nature, and apparently these are uncommon. Thus known salinity relation-
ships derive almost solely from field observations, and few observers have taken
salinities along with collections of sponges. Here we have gathered the few data
from a wide literature.

Sponges are found chiefly in high salinity and clear waters; thus they are un-
common in estuarine waters, except for the boring sponge, Cliona, which is common
on oyster beds and calcareous rocks which they perforate in moderate to high
salinity waters. A few other genera of encrusting sponges, such as Microciom and
Haliclona are found in the bays where there is a hard substratum and fairly high
salinities.

The shallow offshore waters of the west Florida Peninsula to 350 feet in
depth, southward through the Keys, during the first half of this century was one of
the more prolific commercial sponge producing areas on Earth. These waters arc
clear, possibly because there is small land drainage, combined with the effect of
high calcium content of this drainage- The industry was centered at Tarpon Springs
and was devastated . by a sponge disease in 1938—39 and the Red Tide in 1946-47.
It has never recovered, due in part to the competition from synthetic sponges.

SALINITY PROBLEMS

397

Nevertheless, large amounts of sponges still inhabit the dear warm waters of
the west coast of Florida. In contrast, no sponges were reported by Gunter and Hall
(1965) in the Caloosahatchee Estuary where the salinity ranges from 0.13 to 32.2
ppt. On the other hand, the offshore areas of Pine Island Sound and San Carlos Bay
outside the Caloosahatchee, where the salinities were always around 30 ppt and
above, sponges of several species formed the greater bulk of trawl catches, and this
area was described as a “sponge reef.”

Dawson and Smith (1953) reported commercial Florida sponges at salinities
ranging from 28.5 to 36.6 ppt and averaging 34.6 at 35 stations. Storr (1964) stated
that when the salinity dropped to 26.0 ppt following storms and heavy rains it was
lethal to the Florida commercial sponges.

Sponges are relatively uncommon on the northern Gulf coast, probably due
to the higlr turbidity of these waters as well as low salinities. Haliclona has been
reported by Hopkins (1956) at 20.0 ppt in Texas and Louisiana. The most common
habitat for these sponges seems to be the jetties of the passes, but Microciona has
been reported on oysters in Aransas Bay, Te.\as, at salinities as low as 19.0 by
Gunter (1955), The boring sponge CUona sometimes damages living oysters and it
is killed out by floods and freshets (see Gunter 1953). .Salinity records are scarce for
this species, but Hopkins (1956) says absence of C. celata on Louisiana oyster shells
indicates salinities below 10.0 one-fourth of the time, while the absence of C truitti
indicates salinities below 10.0 half the time. Mrs. Harriet Perry has several collec-
tions of Craniella sp. from Dog Keys Pass, Mississippi, at salinities of 25,0 to
32.0 ppt.

Hopkins (1962) refined the salinity observations on four species oiCliom in
Virginia and found that in waters ranging from 3 to 36 ppt the mean at the sample
areas was 22.1 but the mean of salinities where species were caught were: celata
26.1 , vastifera 22.8, lobata 19.1 and truitti 18,9.

Sponges feed upon minute organisms, bacteria or flagellates, or possibly dead
organic materials, and they have some effect upon the environment in that way.
They also shelter large numbers of crustaceans, worms and other organisms that live
in cavities of the sponge. Otherwise they are not of great importance. Marine
sponges are generally high salinity organisms and are easily killed out by freshets,
but in general, tliey are not harmed often because they live mostly outside and
beyond the lower bays or the low salinity effects. Nevertheless, heavy rainfall some-
times affects sponges in the ocean, if they are close to shore (Storr 1964).

C. MESOZOA. This peculiar group of organisms may be as aberrant and
different from all other animals as the sponges are. They consist of a definite num-
ber of cells with no germ layers and no organ systems. They have the appearance of
degenerate, ciliated flatworms and have a solid blastuia; this and some life history
features have led some workers to believe that they are degenerate trematodes,
while others look upon them as inherently primitive. One group, the Dicymia, live
only in kidney tubes of octopuses and the other, the Orthonecta, are parasitic in
the tissues and spaces of other marine invertebrates. As parasites or commensals
their relations to salinity follow that of their hosts.

398

Gunter, Ballard, and Venkataramiah

D. COELENTERATA or CNIDARIA, There are two phyla of Uiploblastic
or two-layered animals, the coelenterales and ctenophores, commonly called
jellyfish.

The Coelenterata all have stinging cells and live from fresh water to the deep
seas. Their symmetry is generally radial. A number of species are simple hydroids,
like Hydra, and some are fairly complicated medusae^ with a nerve ring around the
bell and with statocysts. There is also alternation of generations between hydroid
and inedusoid generations in many species. This group also includes the sea
anejiiones, the sofl corals (sea pens, sea fans and the like) and the hard corals or
coral reefs. There are no blood or tissue spaces and all osmoregulation is cellular.

HYDROZOA AND SCYPHOZOA

Macallum (1903) reduced the large medusae, Aurelia and Cyanea, to a liquid
and found a much higher potassium and much lower sulphate content than in the
surrounding sea water. Robertson (1949) found low sulphate in the mesoglea of
Aurelia, the jellylike substance between the cell layers of the jellyfish, but no higher
potassium. Bethe(1908) showed that when the Mediterranean medusae, Rhizostotna
and Carmarina, w'crc subjected to 80% sea water for 48 hours there was no slowing
of movements but in 75% sea water slowing took place in 30 minutes, and slopped
entirely in one hour in 50% sea water.

Webb, Schimpe and Olmon (1972) found higher concentrations of free amino
acids in the tissues of three common scyphozoans of Virginia waters at higher
salinities.

The abundant scyphozoan jellyfishes of the bays of the South Atlantic and
the Gulf coasts are Aurelia aurita, Stomolophus rneleagris and Chrysaora quin-
quecirrha. The last species stings rather virulently and is considered to be quite a
pest in Chesapeake Bay. In Texas waters along the Gulf Pelagia noctiluca is
abundant in dry years (Sanders and Sanders 1963), and the dangerous cubomedusan>
Chiropsalmus quadrurnanun, become abundant in the bays (Guest 1959). Most of
the iimeOirysaora is most abundant in bay waters although Aurelia is the dominant
medusa in some years (Gunter 1955). This species has been observed in Texas waters
at 16.0 ppt saline (Gunter 1950) which is lower than recorded elsew'here, see
Table 7. Franks et al. (1972) noted this discrepancy and reported Anre/ffl as taken
only in Mississippi waters at high salinities.

The generally smaller hydrozoan medusa Liriope tetraphylla and Bougain-
villea spp. are also abundant in Mississippi waters.

The siphonophore Physalia physalis is abundant in the open ocean, especially
in the western Gulf and is quite evidently a higli salinity organism.

Table 7 gives salinity ranges of common jellyfish taken at the Gulf Coast
Research Laboratory during 1968—71 inclusive. This table and the information was
furnished by Mr. David Burke.

In Mississippi Sound the greatest incidence of hydromedusae occurs at

salinities of 25.1-30.0 ^joo as demonstrated in Table 7. There is a gradual

Salinity Problems

399

Table 7.

Some Salinity Ranges and Averages of Jellyfish on the
Mississippi Coast from 1968 to 1971.

Salinity

Salinity

Number of

Range /oo

Average °/oo

Specimens

Scyphozoa

Aurelia aurita

29.2-31.0

29.3

343

Cyanea capUlaia

23.2-29.6

26.4

50

Stomolophus meleagris

19.4-25.7

24.8

285

Pelagia noctiluca

32.0-33.9

25.9

134

Chrysaora quinquecirrha

10.6-31.3

27.0

2,306

Chiropsalmus quadrumanus

18.2-34.0

27.0

329

Hydro'zoan medusae

. . .

. . .

Liriope tetraphylla

27.5-32.5

28.4

46,971

Persa incolorata

25.0 35.0

Nernopsis bachei

7.5-32.5

16.4

1,003

Bougainvillea sp.

10.0-25.0

26.2

6,364

Euphysora gracilis

17.0-35.5

Siphonophora

Physalia physalis

28.2-37.6

decline with decreasing salinities, and a marked decline with increasing
salinities. Under true marine conditions hydromedusae are apparently dis-
placed ecologically by siphonophores, no species of which occur below
25 °/oo in Mississippi Sound.

Among the entire array of hydromedusae present in Mississippi Sound
(54 species), only one species, Liriope tetraphylla. is apparently rigidly
stenohaline, and is to be found between the limits of 27,5 and 32.5 °/oo. A
distribution more typical of hydromedusae is demonstrated by Nernopsis
bachei, which occurs throughout a salinity range of 7.5-32.5 ^/oo.

Most Scyphozoa in Mississippi Sound are higli salinity organisms. Excep-
tions to the above trend are exemplified by Chrysaora quinquecirrha which
occurred throughout a range of 10.6 to 31.3 %o, and Chiropsalmus which
occurred throughout a range of 18.2—34.0 ®/oo. One specimen of the
coronates, Nausithoe punctata, was collected at a salinity of 35.3 %o.

The importance of the jellyfish to the living community is as predators. They
live on the microplankton and animals ranging up to the size of small fishes.
Stomolophus has no mouth and only hundreds of minute openings. On the other
hand, the Portuguese man-of-war can capture fishes several inches long. Fraser
(1969) made brief reference to reports on food studies of medusa, most of which
are European, and presented results of his laboratory studies. He noted that larval
fish are important f^ood sources and presented evidence that medusae may consume
from 50 to 15,000 larval fish during a lifetime, which he took to be about six weeks

400

Gunter, Ballard, and Venkataramiah

in Newfoundland waters; the number consumed varied with species and size of the
jellyfish.

There is no doubt that medusans of inshore waters consume vast numbers of
Small invertebrates and larvae and larval fishes, especially at times of their peak
abundance, when some of the hydrozoan medusae, such as Nemopsis bachei, can be
collected in Mississippi Sound by the jarful! by dipping overboard. Phillips, Burke
and Keener (1969) have presented observations on the trophic importance of jelly-
fishes in Mississippi Sound, which are generally applicable to much of the east coast
of the United States.

anthozoa

The chief studies of the anemones of the south Atlantic and Gulf coasts,
(Field 1949) and Carlgren and Hedgpeth (1952), make no mention of salinity dis-
tributions of those organisms but it is obvious that they are found near or in the
passes to the ocean or the outside beaches. Christmas and Langley (1973) noted
thirty-one Calliactis polypus, a species associated with hermit crabs, at salinities of
approximately 22.5 to 33.5 ppt in Mississippi waters.

Dregol’Skaya (1961) determined how long celia of Actinia equiti were main-
tained at temperatures of 38-42^C arid different salinities. Anemones from the
Black Sea (17.5 °/oo) were acclimated to 35 ^/oo. This led to a 70% increase in heat
resistance at all temperatures. This was higlier than Actinia from the Barents Sea
where the salinity is 35 ppt. 'Flius the difference in heat resistance of the two
populations is not caused by salinity of the anemone’s habitat.

Shoup (1932) found that Metridium marginatum in sea water at 30 ppt con-
sumed less oxygen when the water was changed to 10, 15,45 and 60 ppt sea water
of M/2 or M/4 NaCl, KCl or CaCij. The greatest decreases were at 60 ppt. At 10 ppt
the tentacles contracted about a third. Contraction also occurred in hypertonic sea
water. At 60 ppt tentacles were completely withdrawn, mucous was secreted and
the namatocysts were discharged. The anemones returned to normal after four
hours in normal sea water.

Tlic soft coral, Leptogorgia setacea and Reriilla mulleri, are found in the
shallow Gulf, sometimes in large quantities. The latlei is more offshore, but L,
setacea often washes up in windrows on Texas beaches. Gunter (1950) reported
salinities ranging from 26.7 to 36.7 for Renilla in Texas. Less common species there
are L. hebes and Eugorgia virgulata. In Mississippi waters Christmas and Langley
(1973) reported taking 472 Renilla at salinities from about 19.0 to 35.5 ppt within
the bay waters. In the open Gulf of Mississippi Franks et al. (1972) reported 16,808
specimens taken at a salinity range of 24.9 — 37,8. Bayer (1954) says a few species
of the Alcyonaria can live where salinities are occasionally reduced but “are never
found where appreciable dilution regularly occurs,” p. 281.

Two hard corals, Astrangia astreifortnes and Oculina sp., are sometimes found
in the lower bays and shallow offshore waters in very small patches. Christmas and
Langley (1973) have lepoiied Astrangia in Mississippi Sound at a salinity of 24.4 ppt.

Salinity Problems

401

Coral reefs are not present on the northern Gulf coast and the closest one is
Blanquilla Reef near Tampico (Moore 1958). Vaughan (1915) showed that Florida
reef corals lived well in 80% sea water but died at 50% within 24 hours. These
animals live in full sea water and it is generally assumed that they are never damaged
by freshets or rain.

It is obvious from the above remarks that changes in salinities in coastal
waters will have greatest influence on the coelenterate fauna through effects on the
Hydrozoa and Scyphozoa, which are important as predators and sometimes annoy-
ances to swimmers. The anemones, and especially the soft and hard corals, are
rather poorly represented in estuarine or inshore waters and so are not generally
exposed to salinity changes.

E. CTENOPHORA. Tliese animals are all marine and they are biradially
symmetrical. They come under the common name jellyfish, but are quite different
from the Coelenterata in several ways. Tliey do not have stinging cells but instead
they have adhesive cells called colloblasts or “lasso” cells. There is some evidence
that Beroe ovata does produce a toxin at the colloblasts. They swim by cilia in eight
meridional bands. In spite of the fact that they seem to be among the most fragile
organisms in the world, tearing under their own weiglit when removed from the
water and being almost impossible to preserve, they are nevertheless very important
predators upon small fishes and invertebrates and some workers have stated that the
abundance of invertebrate plankton^ including oyster larvae in the bays, is low when
large numbers of ctenophores are present (Nelson 1925, Phillips et al. 1969). This
predatory relationship to the plankton is the chief importance of these organisms to
other animals in the coastal areas. Gudger (1943) has summarized some of the older
literature on the fish-eating habits of ctenophores.

Ctenophores are also of considerable interest zoologically because certain
genera are much like the flatworms in general appearance and anatomy, thus con-
stituting something of a connecting link between the two phyla. One of these
Coeloplana has lost all cilia and crawls on the substrate. It has been recorded in
south Florida (Smith 1945).

Tlrere are no body spaces or lacunae in the Ctenophora and there is little
literature on their adjustment to salinity changes. Lazareva (1961) found that
changes between 10—20 %o salinity did not affect oxygen consumption of Pleurob-
ranchia pileuSy but variations outside this range lowered O 2 consumption. Wells,
Ledingham and Gregory (1940) showed that cilia of the same animals were in-
hibited, followed by accommodation, after sudden changes of salinity either up or
down.

The two species, Mnemiopsis mccradyi and Beroe ovata, are found from New
England to the southern limits of the country and beyond, and practically always in
the bays and sounds. They are both plankton consumers and the first is a prey of
the latter. Sometimes they are so numerous in the bays that trawl catches are largely
masses of ctenophore jelly in which individuals cannot be distinguished and other
animals are difficult to pick out. Gunter (1950) reported these two ctenophores as
being most abundant in Texas waters from October to December at salinities of

402

Gunter, Ballard, and Venkataramiah

1 1.5 to 13.7 per mille Wliitten, Rosene and Hedgpeth (1950) noted large numbers
of Mnemiopsis washed in among jetty rocks along ship channels. Christmas and
Langley (1973) reported Mnemiopsis sometimes so abundant in Mississippi Sound
that they made trawls and seines inoperable. Perry and Christmas (1973) noted
ctenophore swarms from April through November in the Sound and they slated
that by far the largest component of plankton volume was ctenophores. They found
the greatest numbers between 5 and 20 parts per thousand saline, with no swarms
at higher or lower salinities. The minimum salinity at which the species were taken
was 5.6 ppt and the maximum was 33.3. The average salinity was 16.8.

Very small tentaculate ctenophores, sometimes called cydipped larvae, have
been taken even in tributaries of Mississippi Sound, and so it seems that the whole
development may be completed in estuarine waters (David Burke, personal com-
munication). This is contrary to previous ideas that early development and breeding
in the Ctenophora is always in the oceanic environment.

F. PLATYHELMINTHES. This phylum consists of the free-living turbel-
larians, and two parasitic groups, the trematodes and cestodes. It is the lowest
phylum with a definitive mesoderm, although claims have been made for the
ctenophores, and is thus iriploblastic. It has no coelom. Most species possess
protonephridial tubules and flame cells and some have excretory bladders. The
available evidence indicates that these organs are osmoregulatory rather than involved
in nitrogen excretion.

A protonephridial system is the characteristic osmoregulatory mechanism of
flat worms, nemertine worms and some of the rather heterogeneous group designated
as Aschelminthes, as well as the entoprocts, the next four phyla to be discussed.
This system consists of varying numbers of tubules closed at one end by specialized
cells equipped with long cilia or flagella which keep the fluid contained in the
tubules in motion. The cells are called flame cells or solenocytes, depending on
criteria which may not be valid but they function in the same way. If the system
is fully developed the tubules empty by way of dilated ampullae into a contractile
bladder which opens to the outside through an excretory pore.

Although the protonephridial system is more complex than a contractile
vacuole and may in some instances have an excretory function, its major function
appears to be to get rid of excess water. Water moves into the system of tubules by
an active uptake mechanism, is kept in motion by the action of the flame cells, and
is expelled to the outside by contraction of the bladder. An osmoregulatory function
is indicated by the fact that the system is poorly developed in marine fla (worms but
is highly developed in freshwater species. On the other hand some marine Turbellaria
have flame cells as do the free-living larval stages, the cercariae, of trematode
parasites of marine fishes.

Webb, Johannes and Coward (1971) found that both a freshwater and marine
starved turbellarian species lost free amino acids from the tissues at a higher rate
at higher salinities.

The English turbellarian, Procerodes ulvae, lives under stones where streams
enter the sea and undergoes changes from sea water to one-tenth sea water during

Salinity Problems

403

one tidal cycle. The fresh water of the streams is rich in Ca and CO 3 (Panlin 1931a).
In Plymouth tap water the worms swell to double their size, then decrease slightly
and in 48 hours they die. In the high calcium waters of their home stream they swell
little and calcium added to the tap water protects them (Weil and Pantin 1931).
Apparently calcium lowers permeability of the worms to water. In this connection
Pan tin (1931b) has shown that the worms lose 25% of their salts in dilute solutions
while taking in water, and Ca reduces the rate of salt loss.

Beadle (1934) has analyzed the case further and showed that the worms live
indefinitely in salinities ranging from full sea water down to 5% sea water. Wlien
placed in diluted sea water the worm swells and activity decreases; then the excess
water in the swollen parenchyma is taken up by the gut cells, which become vacuo-
lated, and equilibrium is reached with a return of activity. This situation is main-
tained in the presence of Ca so long as the animal remains in diluted sea water above
5%. At lower dilutions cytolysis occurs.

In Procerodcs the role of the flame-cell system is in question. Protection
against dilution during the two daily tidal cycles is accomplished by a special
mechanism involving temporary storage of water in endodermal cells lining the gut,
as mentioned above. The vacuoles have not been observed to empty into the gut as
miglrt be expected. It is possible that the tlamc-cell system is involved in some
manner as yet unknown.

Rees (1941) observed a European tide pool species, Monocelis fusca, that
lived at salinities from 26 to 64 ppt. Experimentally it could survive transfer to
salinities from 5.6 to 76.8 ppt. If the salinity was gradually raised the worms could
survive salinities up to 120.3. They could also secrete mucous cysts in which they
withstood sea water evaporated to about 275 ppt.

Kromhout(l 943) studied a species, Gyratrix hetmaphroditus, which has fresh,
brackish and sea water populations. He found progressive loss of components of the
protonephridial system from fresh water to sea water. In the latter medium the
tubules, ampullae and paranephrocytes were all absent.

Various flatworms are enemies of oysters over widely spaced areas of the
earth. Stead (1907) observed Leptoplana australis killing oysters during dry periods
in Australia. Danglade (1919) reported the oyster leech from five areas in Florida.
Roughley (1922) observed that freshets killed the ‘‘wafers and borers” and were
thus beneficial to oysters. Villadolid and Villaluz (1938) repotied Psudoceros sp. as
attacking oysters in the Philippines when the salinity was higli.

Pearse and Wharton (1938) found that the predatory oyster “leech” of Florida,
Stylochus frontalis, laid eggs which developed normally at salinities from 17.8 to sea
water and would live experimentally as low as 1 5.5 ppt when transferred directly. It
would not lay eggs at salinities below 15 ppt. The worm died at 6 ppt sea water.

Landers and Toner (1962) transferred 5. ellipticus from Milford Harbor,
Connecticut, to various salinities. They all survived down to 7.5 ppt, but at that
salinity they lost color, secreted an abnormal amount of mucous and became
sluggish. Worms transferred directly to 5 ppt sea water suffered a 20% mortality and

404

Gunter, Ballard, and Venkataramiah

all died when placed in 2.5 sea water. Activity and response slowed as salinity
decreased below 7.5 °/oo sea water, but worms acclimated to 5 °/oo sea water survived
when placed in 2.5 %<> sea water. Landers and Rhodes (1970) found that lowering
the temperatures below 10°C progressively reduced predation but lowering the
salinity did not. They also reported that worms from high salinities preferred
barnacles as food, but low-salinity worms preferred oysters.

The flatworm phylum is of vast importance biologically because of Its parasitic
component. However, the free-living species are not numerous in fresh water, sea
water or damp earth and thus are not trophically important to the life web. Probably
the oyster enemies, Stylochus frontalis and S. ellipticus, of the eastern and south-
ern seaboard are the most important of all. Presumably they would be killed by
sudden influxes of fresh water.

The swimming larval stages of the fluke and tapeworm parasites of the Phylum
Platyhelminthes are as exposed to the salinity of the environment as the free-living
species, but very little is known of their salinity limitations. Stunkard and Shaw
(1931) placed larval trematodcs (cercariae) in six mixtures ranging from tap water
to pure sea water. The conclusion was that these marine parasites could complete
life histories in salinities as low as 4 to 8.5 ppt.

Kawashima and his associates have shown that miracidia of the lung fluke
Paragonimus ohirai will easily infect three shore snails of the g^ms Assiminea in the
laboratory, but in the field are found only in A. parasitalogica which is found at the
high tide line. The snail and miracidia both seem to prefer the low salinities at this
tide level rather than the higher salinities at the lower tide levels preferred by the
other two snail species (taken from Schwabe and Kilejian 1968).

StyczynskaJiirewick (1971) worked with three marine trematodes from tidal
waters and a freshwater species. Cercariae from brackish waters survived over a wide
salinity range and the freshwater .species survived salinities up to 18 per mille.

Lame of the liver flukes of cattle and sheep ency.st on grasses and plant
stems that are sometimes submerged in water. In the marshes of western Louisiana,
cattlemen have noticed that their cattle do not get liver flukes when grazing on
marshes that have been flooded witli brackish waters. Presumably the trematode
cysts are killed by the brackish water salinities.

Schwabe and Kilejian (1968) have given a brief review of ‘'osmochemicals”
and platyhelminth parasites and the readers who are interested in further details are
referred to that account.

G. NEMERTEA. The nemertines are smooth, unsegmented, ribbon-like
worms. They are ciliated and have no coelom and some zoologists are impressed
with their similarity to the Platyhelminthes. But they have an anus, a circulatory
system and a very distinctive evertible proboscis for capturing prey, quite unlike
any flatworm. Some of them (Cerehra talus) are classical material for embryological
work and morphological studies because of their penchant for fragmentation. They
are notable as voracious feeders on any organism they can capture with their
proboscis which may be covered with an adhesive substance or armed with stylets.

Salinity Problems

405

Some of’ them, Lineus, may be 20 meters in length and some are found to depths of
over a thousand fathoms in the ocean. A few live in freshwater lakes and streams
and even under damp logs, but predominantly they are creatures of the ocean shore
and shallows down to about 10 fathoms (see Coe 1954), Some nemerteans have no
larva; others have a helmet-like larva called a pilidium or a crawling “larva of Desor.”

Coe stated that there were 53 known species on the Atlantic continental coast,
95 on the Pacific and 17 in the Gulf of Mexico, The group is not great in biomass
and it is not of great trophic importance. Salinity relationships have not been
recorded, to our knowledge, except that all workers have noted that the marine
species are mostly found in the lower bays and the outside higher salinity waters.

H. ASCHELMINTHES. This is a grouping of what was formerly considered
to be five phyla. The common characteristics are a pseudocoel, lack of segmentation,
a covering of cuticle, a straight nonmuscular intestine and a posterior anus. Many
members of these groups are given to cell constancy, that is, a given species has a
given number of cells. The pseudocoel is the body cavity surrounding the gut, and
is the first seen as we go up the scale of increasing complexity of animal organiza-
tion; but it has no epethelial lining and it derives from the blastocoel of the embryo.
Thus it is not a coelom.

The lumping of such different animals into one phylum appears to be a
strained classification and it will probably dissolve as more facts are brought to
bear. In any case four rather inconsequential types of organisms, the Nemalomorpha,
Rotifera, Gastrotricha and Kinorhyncha are cast together with the numerous and
important Nematoda.

Tlie Nematomorpha superficially resemble long nematodes, but they all
possess a cloaca, lack an excretory system and are all parasitic in arthropods. Only
one genus Necionema is marine and the group merits no further consideration here.

The Rotifera are denizens of fresh water and the shallow sea. The body has a
flat bell-shape with a stemlike foot. There is a trochal disk of cilia around the
mouth which has caused the name “wheel animalcule” to be given to these little
animals. Females are small and males are minute or absent in many species. Breeding
entails a violent piercing of the female body wall to the inner cavity. Most marine
species are epizoio, that is, they are creepers on the bodies of larger animals. They
are of little ecological importance. Bayly (1967) reported one species, Brachionus
plicatelB, in a salt lake in New Zealand at 15 ppt with NaCl predominating. The
authors know of no other salinity data on the rotifers.

The Gastrotricha are about 1 mm long. They are covered with scales and
bristles. An excretory system witli two flame ceils is sometimes present. Cilia are
present on areas of the body. They have a typical constricted area behind the head
called the neck. There is a sort of vacuolated series of body spaces called pseudo-
coels.One order is exclusively marine, but distribution is very spotty and it is known
mostly from Europe.

The Kinorhyncha are minute cylindrical animals living usually in shallow
marine and brackish water sediments. The body is superficially divided into 13
segments. The head may be retracted into the trunk region leaving the spines

406

GUNTER, Ballard, and Venkataramiah

protruding. The sexes are separate. Kinorhynchs are exclusively marine and are
widely distributed on muddy bottoms, sometimes in low-salinity water. The salinity
relationships of these organisms are otherwise unknown.

Nernatoda are elongated round worms^ covered with a cuticle and generally
rather pointed at each end. They have nerve cords and an excretory system. Muscles
within the body only permit a lashing type of movement back and forth and this is
the only type of movement these animals have. Some organ systems, especially the
nerves, exhibit constancy of cell number.

These worms are enormously abundant, widespread and variable in their ways
of life. They vary in length from a millimeter or less to several meters long in some
parasites. They are freediving as scavengers or predators or suckers of plant juices
and they are parasites in thousands of species of animals and plants. Public health
authorities have pointed out that thousands of tons of nematodes exist as parasites
inside human beings in backward parts of the Earth. They cause elephantiasis,
hookworm and several other diseases in man and domestic animals. One authority
staled that if the whole earth except for the nematodes disappeared, its general
outline.s and features, including buildings, and larger plants and animals would be
signified by the remaining nematodes alone.

Nematodes have been around so long and are so numerous in the ground
that certain soil fungi have become adapted to very quickly growing a net of fila-
ments around living nematodes and secreting juices which digest them. It has been
estimated that the top three inches of sea beach sand contain five billion nematodes
per acre and there are more thousands of millions per acre on the ocean bottom
(Sprent 1972).

In spile of these well-recognized generalities, the impact of nematodes upon
the life web of the sea in terms of trophic and ecological relationships is not known
andean only be dimly perceived. The soil forms certainly serve as food for the mud-
eaters and the parasites have large elYects upon billions of marine organisms, but
the details are lacking. Similarly the relationships of nematodes to salinity are al-
most completely unknown. It may be surmised from the broad distribution of
nematodes that they are adaptive or tolerant to wide ranges of salinity, especially
the shallow- water or nearshore species.

The cuticle which covers the body is permeable to water entering but not
leaving (Meglitsch 1967) so there must be some mechanism for getting rid of excess
water in those species which live in fresh and low-salinity waters. They do not have
a protonephridial system but rather have a special gland cell, the renette cell, and
sometimes tubes derived from it. Neither excretion nor osmoregulation is under-
stood in nemalodes but there is evidence that the intestine is the major site of
nitrogen excretion. Evidence of changing activity of the excretory system with
osmotic stress indicates an osmoregulatory function, but there is uncertainty about
the mechanism involved (Meglitsch 1967).

In the middle reaches of the Blyth Estuary at stable marine salinities, it was
found by Capstick (1959) that the populations were 3,000 per 100 square ems in
sand and 28,800 in thick black mud. The latter figure is equivalent to about 11

Salinity Problems

407

billion to the acre. Three transects were made across the intertidal zone from the
channel to shore in the lower, middle and upper reaches. Even though the dif-
ferences of interstitial salinities were small, 21-32 ppt upper and 26-34 ppt lower,
there was a considerable salinity effect. Populations decreased upstream and among
the 37 species taken the population was primarily of marine origin.

Chitwood (1951) says that true brackish water nematodes are not known and
that the transition from fresh water to marine species is a “quick change.”

Timm (1952) reported 78 species from the Maryland (upper) portion of
Chesapeake Bay at salinities ranging from 8 to 16.9, Some species were known be-
fore from fresh water, but most were marine,

Tietjen and Lee (1972) found the generation time Monohystera denticulata
was 10—12 days at 25°C and a salinity of 26 ppt, which appears to be the worm’s
optimum for both factors. The variation of salinity in either direction increases the
generation time.

Attempts to acclimate marine nematodes to fresh water and vice versa have
failed (Chitwood and Timm 1954), but a Massachusetts species found in decaying
seaweed, which has been cultured on agar made up from tap water or sea water,
later could be transferred directly to either medium. Those authors also noted that
the excretory system is much better developed in freshwater nematodes than in
marine species. They suggest that a study of estuarine forms would be interesting,
because there is practically no overlapping of freshwater and marine species.

I. ACANTHOCEPHALA. This is a small phylum of spiny-headed parasitic
worms. It has no digestive tract and usually no excretory system. The proboscis is
armed with hooks and it invaginates. Sexes are separate. All species are found in the
vertebrate digestive tract and there are no free-living stages. Thus they are limited
to salinities their hosts can tolerate. Several species are found in marine birds and
fishes. Their salinity problems are essentially those of their hosts, but parasites are
in a sense buffered by their hosts, and in a sense the Acanthocephala have no osmo-
regulatory problems, or if they do they are not known.

J. ENTOPROCTA. This is a small phylum of small, sessile animals formerly
included with the Bryozoa. Except for one fresh water genus, Umatella, all of them
live in the sea. They have a pseudocoel and all of them have flame-cell protonephridia.
To what degree these function in excretion or in osmoregulation has not been
determined. The organisms consist essentially of a goblet-shaped calyx, containing
the viscera, on a supporting stalk. The calyx is mounted by a ring of ciliated
tentacles. The mouth and anus open within this ring. In most species the stalks
produce stolons which branch and produce other stalks and calices and thus a
colony. A second group is solitary and lives commensally with sponges, tubeworms,
and bryozoan colonies and other invertebrates.

The Entoprocta are not of much trophic consequence and their salinity rela-
tionships are unknown.

K. ANNELIDA. The segmented worms comprise a very important phylum
with a true coelom, a linear grouping of segments separated by septa and very much

408

Gunter, Ballard, and venkataramiah

alike with regard to nerve and blood vessel branching and the replicated nephridial
system. The animals are dioecious or bisexual but cross-fertilization occurs in the
latter. There are three large classes and a small one.

Annelids have successfully populated fresh, brackish, and salt water as well as
damp terrestrial environments. The characteristic excretory structures of this group
are the metanephridia which are involved not only in excretion of nitrogenous
wastes but also in water and electrolyte balance. Metanephridia differ from
prolonephridia chiefly in that instead of ending blindly in closed cells, they open
by way of ciliated funnels called nephrostornes into the coelom. The nephrostonies
continue as tubules or canals of varying complexities which eventually open to the
outside throu^ nephridiopores. In some of the more primitive worms protonephridia
may still be present, and in some cases the tubules may be reduced to simple sacs.
Coelomic fluid can pass into the nephrostome and as it passes througfi the nephridial
canal various components including water and sails may be reabsorbed. Thus the
excretory system may be involved in osmoregulation and in ionic regulation.

The Afchiannelida is made up of a small number of marine, brackish or fresh-
water species, most of which are to be found in the interstitial water of sand. They
are heterogeneous and are united for convenience only. Simplification of anatomy
is mostly due to small size and the group is not primitive. The trophic importance
of the group is small and its salinity relationships are unknown.

The Oligochaeta is a group of largely freshwater or terrestrial worms of which
about half are earthworms. They have setae on each segment, but no parapodia.
They have no eyes. Some freshwater species are sometimes secondarily littoral-
marine. Very few are to be found in sea water and salinity relationships are not well
known.

Jansson {196'2) showed that an interstitial oligochaete,y4fcfeflfnVi/s, from 6 ppt
tolerated 1.25—20.0 ppt, but preferred 2.5—5 ppt and preferred 5 ppt even after
8 days at 20 ppt. Another species, Marionina, from 2 ppt tolerated 2.5—10 ppt for
6 days. The same species from zero salinity preferred 0.2— 0.3 ppt.

Kahler (1970) showed that acclimation of the oXigoch'AQie, Enchytraeus, to
high salinity increased its resistance to temperature extremes. The effect decreases
with rising adaptation temperature.

Lassere (1970) has shown that two euryhaline oligochaetes take up salt at
3-25 and 3-30 ppt. Outside these limits the variation in oxygen intake indicated a
metabolic disturbance.

Zoology texts generally state that earthworms are terrestrial. However, marine
earthworms are found on the island of Bermuda and in Redfish Bay in South Texas.
The senior author has taken the latter in lenses of water, with a salinity of 34.0 ppt,
over coarse sand and always under piles of rotting seaweed. Apparently the worms
do not dig into the sand and do not ingest it.

Studies of the earthworms Lumbricus terrestris (Ramsay 1949) and Pheretima
posthuma (Bahl 1947) which live in contact with soil water and can live in aerated
fresh water indicate that, in fresh and brackish water, salts are absorbed by the

SALINITY Problems

409

nephridia resulting in production of a hypotonic urine. Krogh’s work (1939) showed
a similar mechanism for leeches.

The Hirudinea are predaceous worms or blood-sucking ectoparasites. A num-
ber of species are marine but the greatest number are found in fresh water. They
have many features in common with the oligochaetes, but all species known have
33 segments, a constancy not found in any other annelid group. Salinity relation-
ships are virtually unknown.

Ramamurtlii (1968) has shown that an Indian cattle leech can be acclimated
to 38% sea water and some survival was obtained at 75% sea water. The leeches had
minimum oxygen consumption at 25% sea water and a maximum at 50%. They
were isotonic at 25%. The fact that these essentially freshwater animals can be
acclimated to low percentages of sea water is not surprising when we consider that
their food, vertebrate blood, ranges from about 12 to 14 ppt saline.

Most of the studies of osmoregulation in annelids have been done with mem-
bers of the class Polychacta, particularly with the nereids, which include both
brackish and marine species as well as a few that can tolerate fresh water. Some
work has been done with the lugworm Amiicola marina (Sclilicpcr 1929, Wells and
Ledingham 1940) and with a few other polychaetes.

Dice (1969) took specimens of California species, Cirriformia spirabrancha,
from sea water and placed them in a series from zero to 300% sea water; at 150%
shrinking occurred; at higher salinities movement decreased and swelling took place.
Duchateau-Bosson, Florkin and Jeuniaux (1961) found that loss of amino acids in
Arenicola transferred from sea water to half sea water accounted for 41% of the
osmotic pressure change. Ebbs and Staiger (1965) reported Onuphis magna as a
hyperosmotic regulator at less than 15 g/1 chloride. Under hyposaline conditions
there is swelling followed by volume regulation. The first 10 to 15 segments, which
have no nephridia, swelled most. Ellis (1939) found Nereis diverucolor \% able
to regulate in brackish water, while Perinereis cultxifera, a stenohaline species, can-
not. The first species lost salt and swelled least. Fretter (1955) found that the
integument of the latter species is much more permeable to ions than TVere/s, which
takes up sodium, nevertheless, over a wide salinity range. Jeuniaux, Duchateau-
Bosson and Florkin (1961) report that both in N. diversicolor and P. cultrifera
osmoregulatory mechanisms involve amino acids. The first species is more euryhaline
than the latter. Losovskaya (1961) studied three Black Sea species. He reported that
N zonata withstood a salinity fluctuation from 10—30 ppt. There was a 3%
mortality at 40-45 ppt. The optimum for Platymreh dumerilii was 1 5-30 ppt at
20-24*^^. Melinna palmata had an optimum of 9-30 ppt salinity at 9— 2l'^C.
Pearse (1928) worked on four American Atlantic species; Nereis virens, Scoleco-
lepides viridis, Arabella opalina, and Glyceria dibranchiata. The first showed con-
siderable tolerance for one-fourth sea water and the second two did well for several
days at half sea water and all tolerated three-fourths sea water. At low salinities all
of them showed a tendency to swell, become turgid and extended. Robertson
(1949) studied several marine invertebrates in Scotland, including the polychaetes,
Arenicola and Aphrodite. He found that they regulate potassium and sulphate, and
in ionic ratios were similar to the jellyfish and echinoderms in contrast to the higher

410

Gunter, Ballard, and Venkataramiau

crustaceans. Smith (1953) found that the Pacific species, Nereis lighti, lived at 2—3%
sea water in (he upper Salinas Estuary and near the river mouth at 40 to 100% sea
water, both locales being more favorable than the lower estuary which has full tidal
exchange part of the year. Smith (1964a) found that succinea in 50% sea

water loses salt at a much higher rate than N. limnicola. Both worms show equal
water intakes at given wet weiglits. No increase of water intake with increased
osmotic gradient was shown.

The class Polychacta includes osmoconformers and osmoregulators of varying
efficiencies. N, pelagica (Schlieper 1929) and N vexillosa (Smith 1963, Oglesby
1965) and Perinereis cultrifera (Beadle 1931, Ellis 1939, Wells and Ledingham
1940) are stenohalinc conformers. Cirriformia spirabranchia (Dice 1969) can hyper-
regulate to some degree but its lowest salinity tolerance is higher than that of the
nonregulating Arenicola marina which is able to tolerate wide ranges in internal
concentration.

Laeonereis culveri (Oglesby 1965), succinea, N. limnicola (Smith 1963,
1964a:, Oglesby 1966), N. virens (Potts and Parry 1964a), and N. diversicolor
(Schlieper 1929, Beadle 1937, Ellis 1937) conform at higli salinities and hyper-
regulate at low salinities, but they vary in their lower salinity limits. According to
Beadle the worms use more 0^ at lower concentrations not because of osmotic
work but because muscles contract to counteract swelling.

The euryhaline species N. diversicolor has received considerable attention.
Wlien it is first subjected to a dilute medium it swells due to osmotic intake of
water at a faster rate than can be handled by the excretory system. However, as the
body fluids become more dilute and there is less gradient between internal and
external concentrations, water intake is reduced. Calcium in the dilute environ-
mental water aids in this reduction by reducing permeability. When water intake
is sufficiently reduced it is exceeded by water excretion and by actual expression
through the nephridia and swelling subsides (Beadle 1937, Ellis 1937).

Initial rapid loss of salts also contributes to reduction of the internal con-
centration and restriction of swelling. Although the body fluids are diluted, they
remain more concentrated than the environmental water and hyperosmoticily is
maintained. In spite of an initial rapid salt loss, in the latter stages of adaptation
salt is actively absorbed, possibly under stimulation of a lowered blood concentra-
tion. Maintenance of hyperosmoticity has been ihouglit also to require reabsorp-
tion of salts by the nephridia and excretion of a hypotonic urine (Ellis 1937). The
complexity of the nephridium as compared with other species suggests such a func-
tion, It IS long and coiled and could provide a large surface area for reabsorplion.
The nephridium of the con forme r cultrifera is a simple sac (Brown and

Stein 1960). Potts and Parry (1964a) believe, however, that active uptake is suf-
ficient to balance loss of salts by diffusion and in the urine except at ver>' low
salinities. There is little doubt that N. diversicolor actively osmoregulates since the
ability to mainiain hyperosmoticity is lost in the presence of cyanide or in the
absence of oxygen.

Other factors may also be involved in adaptation of this species to low
salinities. Comparative studies have shown that in dilute media A. diversicolor is less

Salinity Problems

411

permeable to water and ions than other nereids tested. pelagica andA^. virens are
about three times as permeable to water as N. diversicolor (Jijirgensen and Dales
1957). A^. virens can hyperregulate but because of more rapid water uptake it must
exert more energy to do so and it cannot tolerate as low salinities asM diversicolor
(Potts and Parry 1964a). P. cultrifera is about three times as permeable to sodium
(Fretter 1955) and A^. virens h about three times as permeable to chloride (Jorgensen
and Dales 1957) asA^. diversicolor.

N. diversicolor may also live successfully in dilute media because of tolerance
of its tissues to dilution. In spite of low permeability as compared with other
species and some osmoregulatory ability, dilution of its body fluids does occur at
low salinities. Wells and Ledingham (1940) showed that isolated muscles of N.
diversicolor function normally in salinities as low as 5% and 10% sea water, whereas
those of the stenohalrne N. pelagica do not function in salinities lower than 20% sea
water.

There are some differences in the various populations of N. diversicolor.
Smith (1955b) found the lower limit to be 4 ppt in Finland, and 1.25 in Denmark.
Smith (1955c) compared the blood and media of worms from four European
regions ranging from an upper limit of 2 ppt to stable high salinities. The womi was
found to be a typical adjustor above about 10 ppt salinity and was a regulator in
lower salinities. Smith (1955a) found, that in sand^lowered salinities of 9-29 ppt
persisted even at high tide, N. diversicolor was found there in greatest abundance.
Smith (1956a) found no significant differences in chloride regulation of populations
of N. diversicolor from widely distributed and different habitats and salinities.
Smith (1956b) found this species regularly endures salinities of 0.5 in the Tamar
River Estuary and is not found in true marine situations. Smith (1964b) found that
larval development ofA^. diversicolor In Finnish waters at salinity from 5,4-6.3 ppt
took place at 3 to lOg Cl/1, with an optimum of 7.5; .Swedish worms from a
salinity of 20 ppt developed at 5 -I5g Cl/1 with slower rates near the extremes.

In summary, N. diversicolor exhibits at least four characteristics that con-
tribute to its euryhalinity: (1) relatively low permeability to water and ions, (2) vol-
ume regulation, 0) active uptake and possible rcabsorption of salts by the nephridia
and (4) tolerance of tissues to dilution of the body fluids.

Tolerance to changes in internal concentration is a characteristic of estuarine
species. Other than certain behavioral patterns, it is essentially the only way that
conforniers can cope with changing osmotic conditions, and many regulators also
tolerate considerable variation in body fluids. Tissue tolerance involves osmoregula-
tion on a cellular level, yet intracellular water and salt composition must be held
relatively constant. Experimental evidence indicates that cellular osmoregulation is
accomplished largely by changes in concentration of free amino acids in the cells.
The kinds of amino acids involved vary with the species, but in a number of animals
tested the total concentration varies directly with variations in concentration of the
body fluids.

Studies have been made of variations in tissue composition of some annelids
as related to salinity changes. At high salinities the muscles of the conformer
Arenicola marina contain higher levels of amino acids than at low salinities, with

412

Gunter, Ballard, and venkataramaiaii

glycine and alanine showing the greatest change (Duchateau-Bosson, Florkin and
Jeuniaux 1961). Perinereis cultrifera, which cannot regulate blood concentration,
shows changes in amino acids with changes in salinity that are larger than those
exhibited by N. diverskolor which exhibits some degree of osmoregulation (Jeuniaux,
Duchateau-Bosson and Florkin 1961).

Some studies have been made purely of distributions. Amos (1957) found
N, siiccinea at 8.8 to 30.7 ppt in Delaware Bay and most abundant at 20-21 ppt.
Estcourt (1967) gave the distribution of 15 species over a salinity gradient in
Heathcote Estuary, New Zealand. Only two species were found where salinities
dropped down to fresh water. Hempel (1957) compared Polydora ligni, wliich is
found at up to 80 ppt in the Laguna Madre, with Py’gospio elegans found at 2.1 ppt
in the Baltic-North Sea Canal. Hill (1967) found Plcopomatus in Nigeria only above
33 ppt, while a scrpulid Hydroides imcimta only lived between 20 to 30 ppt;
another serpulid lived from 0.5 to 18 ppt, but not at 21. Loosanoff and Engle
(1943) reported that Polydora websteri, a commensal of oysters which sometimes
riddles their shells with its tubular excavations, does not grow well at salinities
above 25 ppt. Muus (1967) reports a morphological dine of rV. diversicolor from
Finland (low salinity) to the North Sea (high .salinity).

A few workers have studied the effects of salinity on the development of
annelids. Berger and Lebskii (1969) found if fertilized eggs of Evlalia viridis were
transferred from 25 ppt to 14 ppt and below they died immediately. At 16 ppt
tlrree divisions took place and at 18 division went on to 64—128 blastomeres,
Trochophores were formed only at the normal salinity 20-24 ppt. Similarly they
found that the life cycle of spermatozoids increased from 16 ppt and reached a
maximum at 20-25 ppt. KJesch (1970) found L. culveri at salinity variations of 2-
64 ppt. Spawning took place at 44 ppt. The highest density of worms, 203 m^, was
at 28 ppt. Lyster (1955) 'pwX Phyllodoce maculata larvae in a vertical salinity gradient
and found that the larvae congregated at about 12 ppt because they could not .swim
higher in the fresher water of lower specific gravity. It was said that this prevented
the worms from being carried out of the estuary as the low-salinity water flowed
out at the surface. Mohammad (1966) found that 16 ppt was fatal to the eggs of
Axiothella nuicosa. Larvae and juveniles raised at optimum salinities, 32—40 ppt,
showed swelling at 16 ppt but readjusted after one week. Low temperature and low
salinity acted independently in slowing growth.

A recent study by Oglesby (1973) has shown the lugworm Abarenicola pacifica
is an osmotic conformer within the limits of its tolerance, which is as low as 23%
sea water in the laboratory, but the coelornic fluid is slightly hyperosmotic to the
medium. A literature review shows (his to be characteristic of other members of the
family. In conliasl, the coelornic fluids are slightly hypo-ionic to the medium in
cliloride and sodium. The animal has very little ability to control its volume and
water content at different salinities. It is concluded that this lugworm will not form
permanent populations where the interstitial salinities fall below 50% sea water.

Many polychaete worms live quite successfully in an estuarine environment.
Like otlier species they have developed more than one method of coping with
fluctuating osmotic conditions. Some, like Arenicola, conform, regulating only at
the cellular level, while others, like N. diversicolor, maintain hyperosmoticity by

Salinity Problems

413

active transport mechanisms. Some swim away and some withdraw into tubes or
holes.

It is clear that the various marine worms are considerably affected by salinity
and have developed several ways of coping with it. As the salinity changes in an
estuary large changes in the marine worm population will take place, but the details
are not well known.

L. ECHIURIDA. This is a small group of worms that mostly burrow in the
sand and mud of shallow waters, but have been taken from 4500 fathoms. These
worms seem to have affinities with both the annelids and the next group, the
Sipunculida, which are unsegmented. They have a trochophore larvae like the
annelids, but metamerism is only transitory in development stages. The group is not
ecologically important and there are only scattered records from the Gulf of Mexico
(Hedgpelh 1954a).

M. SIPUNCULIDA. This is a group of unsegmented worms with a trocho-
phore larvae. There is no circulatory system. They are found in sand or mud to
3000 fathoms. They are small and not numerous and, for instance, there are only
1 1 species from the Gulf of Mexico, with only one known from the northern Gulf
and 10 from South Florida (Hedgpeth 1954a). They are detritus feeders chiefly.
The group is of little ecological importance and there is little information on its
salinity relationships. Hogue and Oglesby (1972) studied the osmotic and ionic con-
centrations of Themiste dyscritum, a large Pacific coast species acclimated to 41-
101% sea water. Oglesby (1969) reviewed the literature. He concludes that all
.sipunculids studied are osmocon formers at all tolerable salinities, with weak powers
ofionic regulation at any salinity.

N. PRIAPUUDA. This is a small group of worms living in the mud of
temperate seas down to 44 fathoms. This group has recently been found to be
coelomate. The surface is superficially segmented. The mouth and pharynx are
eversible. There is a peculiar larva within a case or lorica. The animals are predaceous
and feed in part on annelid worms. They are sublittoral and not often subjected to
salinity changes.

O. MOLLUSCA. It is customary in most zoological classifications to follow
the Annelida with the Arthropoda, to which they are thought to be so similar,
cliiefly because of metamerism. But they seem to be a much higher group than the
molluscs in diversity as a whole and in complexity of parts, in spite of the fact that
the octopus is said to have the finest brain outside of the vertebrates. Furthermore,
the artluopod larvae have no resemblance at all to the annelid trochophore and the
Arthropoda have no cilia at any stage. The molluscs are replete with cilia and their
early veliger larva is a sort of prototroch. Lastly, the Mollusca arose as early as the
Arthropoda in the geological time scale. Fossil gastropods and bivalves are known
from the lower Cambrian along with tlie trilobites.

The Mollusca rank next to the arthropods in numbers, but except for one
group of gastropods, they have not invaded the land.

The Monoplacophora is a primitive group recently found in bottom trenches

414

Gunter, Ballard, and Venkataramaiah

off western America and in the Gulf of Aden. It shows indubitable seriation of
parts or metamerism, indicating kinship to the Annelida. Fossils are known from
the early Cambrian. This remnant group comes from high-salinity and generally
deep waters and is not subject to salinity modification.

The Amphineura include the shelless, wormlike solenogastres and the chitons
with eiglit hinged shells on the back. They are combined chiefiy because of the
primitive nervous system. The chitons live mostly in the littoral and sublittoral of
rocky shores. The solenogastres burrow in mud, sometimes at great depths, or crawl
over soft sessile animals on which they feed. This class of molluscans is not numerous
or well-studied and salinity relationships have not been recorded.

The class Scaphopoda is an elongated tooth-shaped group of molluscs that
burrow in sand and mud and are reported to feed mostly on Foraminifera. They are
a small group and salinity relations are unknown. They are not estuarine.

The Cephalopoda are the squids, cuttlefish and octopuses. They are considered
to be purely marine. Out of 276 short squids, Lolliguncula brevis, taken over a two-
year period, Gunter (1950) collected 97 in Aransas Bay, Texas, and the remainder in
the Gulf. The salinity range was 17.7-37.2 per mille. Forty-eight squid were caught
at less than 25 ppt and nine were taken below 20. The size of the squid in saltier
water was greater than at lower salinities. Gunter (1950) also took 45 Luligo pealeii
in offshore waters at salinities from 30.7 to 35.8 per mille. He reported small
octopus, Octopus vulgaris, from bay waters but had no salinity data. Cephalopoda
of some species do venture rarely into waters of median salinities in estuaries.

The Gastropoda are predominantly marine snails and there are about 40,000
known species. A characteristic twisting and coiling has been superimposed on
bilateral symmetry resulting in a single coiled shell. The Prosobranchia have a head
and tentacles and sometimes eyes, and a shell closed by an operculum. They are
scavengers or predators and sometimes bore holes in their prey with a radula or kill
them with poisons. Many small species scrape unicellular organisms from rocks for a
living. This is the main group of gastropods in the bays and estuaries. The
Opisthobranchia are species with shells reduced or absent such as the sea hares and
pteropods. Tliey are fully marine and many are planktonic on the high seas. Rela-
tively few come into low-salinity waters. The Pulmonata are similarly found in small
numbers in estuaries, being mostly land snails.

The Pelecypoda or Bivalvia have a poorly developed head, consisting of a
mouth at the end of the visceral mass. They have close-fitting bivalves for protec-
tion. This is the only class of the Mollusca without a radula. They are plankton or
detritus feeders and are sometimes dominant organisms in bays and sounds.

In the following account all groups are treated together:

The mechanisms involved in osmotic and ionic regulation in mollusc.s are the
same as already described for other invertebrates. In general they do not hyper-
regulate as well as crustaceans, possibly due to the greater permeability of their soft
bodies, but many have the advantage of being able to close their shells lightly and
maintain an immediate environment quite different in concentration from the outside
water. Milne (1940) showed that the euryhaline mussel Mytilus edulis can maintain

Salinity Problems

415

a salinity of 24 7°° within the mantle cavity when the outside water has a salinity
as low as 7 7oo. Pearse and Gunter (1957) noted that oysters very often taste salty
when the surrounding water may be practically fresh. Shelled molluscs can remain
closed for relatively long periods but must eventually open to feed. Therefore, all
euryhaline, bracklsli, and fresh water species must make adjustments to low salinities.

Species subjected to varying salinities appear to rely almost altogether on
cellular regulation. They exhibit little ability to regulate blood concentration hut
can tolerate wide internal variation. Mytilus edulis occurs in salinities ranging from
30 °loo to as low as 4 7°® (Segerstrale 1957) and is isosmotic to all salinities at least
above 10 °loo, Conklin and Krogli (1938) reported that specimens from 5.5 7®°
were isosmotic, but Beliaev and Tschugunova (1952) reported slight hyperosmoticity
at 4 7°®. Beudant (1816. vide Robertson 1964) claimed to have acclimatized this
species to fresh water by gradual dilution of sea water over a period of 5 to 8
months. In any case, measurements of blood concentration have shown that it can
vary from a freezing point depression of 0.58, or about 10 7 ®®t to 2.2, or about
38 7oo (Potts 1954b). Isolated tissues function normally in 40^ to \ S0% sea water
(Pilgrim 1953).

On the coasts of the United States the mussel Brachidontes exustus is found
ill high-salinity areas of estuaries and B. recurvus is found in low salinities. However,
this speeies is more susceptible than oysters to being killed by freshets because the
closed shell leaks through the byssus opening.

Castagna and Chanley (1973) studied salinity tolerance of 36 species of com-
mon bivalves from Virginia estuarine waters by distribution and tolerance studies in
the laboratory. Most of them were tolerant of wide variations, but one-third of the
species were not found in nature over the whole range of salinity they were known
to tolerate, because temperature or other environmental factors were overriding.

Most brackish water molluscs are conformers, but a few hyperregulate at
salinities below 50%. Hyperosmoticity has been demonstrated in the smil Littorina
littorea at salinities below 17 7°®, but this species is isosmotic at higher salinities
(Todd 1964a). The gastropods Hydrobia ulvae and Fotamopyrgus jenkinsi, which
have invaded fresh water in recent times, also hyperregulate to some degree (Todd
1964b).

All fresh water molluscs are hyperosmotic, but their body fluids may be more
dilute than that of most conformers. The fresh water clam, Anodonta cygnea^ has a
blood concentration equivalent to about 3 7®® sea water, tlie lowest of any known
an\inal (Potts 1954a). Its lack of ability to maintain a hi^ier blood concentration
may be related to its large gill area and low metabolic rate. Fresh water molluscs
maintain hyperosmoticity by the usual method of taking up salts to offset their loss
by diffusion and in the urine. The excretory organs, which in the molluscs open
from the reduced coelom represented by the pericardial cavity, are involved in
osmoregulation and ionic regulation. A large volume of hypotonic urine is excreted.
Comparison of the kidneys of certain fresh and brackish water populations of the
same species shows correlation with habitat. The kidneys of fresh water populations
of Lymnaea peregra are larger than those of brackish water populations (Hubendick
1948). This species has the highest known blood concentration of any mollusc

416

Gunter. Ballard, and Vankataramaiah

occurring in fresh water. It excretes a hypotonic urine only 70% of the concentra-
tion of the blood (Potts and Parry 1964a).

Marine molluscs are isosmotic but can regulate ions. Gastropods and pelecypods
regulate mostly potassium and calcium, but cephalopods regulate almost every ion
in the blood. Ionic regulation is accomplished by active uptake of salts and, in the
cephalopods at least, by differential excretion of ions by the kidneys (Robertson
1949, 19.S3). Some soft*bodied molluscs can withstand slight dilutions of the
medium by means of volume control. The sea \\'dtt,Aplysia, swells when first placed
in dilute water but, like the poiychaete Nereis diversicolor, is permeable to salts as
well as water and so regains volume and a new steady state with lowered blood con-
centration (Bethe 1930).

Much recent work has been directed toward elucidating the role of free amino
acids and other intracellular organic substances in cellular regulation. There is much
indirect evidence of their function. Their concentration is greater in marine inverte-
brates than in fresh water or terrestrial species, Included among molluscs in which
free amino acids have been demonstrated to decrease with decreasing salinities and
increase with increasing salinities are Af. edulis (Potts 1958, Lange 1963, Bricteaux-
Gregoire et al. 1964), RangUt cuneata (Allen 1961), Hydrobia ulvae (Negus 1968),
and Crassostrea virginica (Lynch and Wood 1966). Knight (1966) demonstrated
similar increase in n inhydrin-reactive substances with increased salinities in C.
virginica. The principal amino acids involved appear to be glycine, alanine, aspartic
acid and glutamic acid (Allen 1961). Taurine occurs in relatively high concentrations
in many marine and brackish water species, including molluscs, but is absent from
fresh water species (Simpson et al. 1959). Its function is not known, but its distri-
bution according to species habitat suggests an osmoregulatory role.

Although Mytilus edulis has a very wide salinity range, individuals are small in
both hi^ and very low salinities indicating that salinities which approach the upper
and lower tolerance limits may represent stress conditions. The same relationship of
salinity and size was noted by Andrews (1940) for the snail Neritim virginea and
may be general. The effect varies with the optimum salinity of the particular species.
Although Mytilus and Neritina are smaller at low salinities, R. cuneata is larger
(Ladd 1951 ). Presumably low salinity represents optimum conditions for R. cuneata,
whereas the optimum for Mytilus and Neritina is at some intermediate salinity.

Prosser (1964) has staled that there are commonly three periods to be
recognized in physiological adaptation as measured by rate functions. First there is
shock reaction, second, a stabilized rate for minutes or hours and third, acclimation
or compensation over days or weeks, Van Winkle (1972) says these periods are quite
evident in ciliary activity and oxygen consumption of gill tissue of four common
bivalves {Crassostrea, Mercenaria, Modiolus and Mytilus) when subjected to salinity
change. He found a shift of recovery time response towards lower salinities for all
low salinity acclimated individuals except in Mercenaria, There was a correlation
between ciliary activity and activity of the whole animal. At low salinity ciliary
action decreased, but oxygen consumption increased.

The senior author has shown in several papers cited at the end of this account
that among many motile estuarine organisms the young have a greater predilection

Salinity Problems

417

for low salinity waters than the larger sizes and the adults. This is demonstrated very
clearly in Tlmis haemastoma, the Gulf oyster borer. St. Amant (1938) has shown
that in Louisiana the adults come into the bays to where the salinity is around 15 to
18 ppt and he has named this general region the conch line. It amounts to a
demarcation because the large Viais break off abruptly and do not venture farther
up the bays. However, small conchs only a few millimeters long and apparently only
recently transformed from the larvae, are found a great deal farther inland at much
lower salinities, the lower limit of which has not been determined. Tlie senior
author has observed this phenomenon in Louisiana but has not specifically reported
it. Similar observations have been reported by Dr. J. G. Mackin in personal
conversations.

Although the number of species of typically estuarine molluscs is few com-
pared with marine species, they may occur in vast numbers. Examples are the
oyster, C. virginica, and the clam, R, cuneata. Such species are tolerant of wide
internal variation but they can survive extreme conditions only by closing their
shells. They can withstand rather long periods of unfavorable environment in this
manner. Rangia can stand at least seven months in salinity below 0.3 ppt. C.
virginica, which has a lower salinity limit of about 3 can survive fresh water at
low temperatures for two weeks with its shell tightly closed (Pearse and Gunter
1957). The shell cannot be closed indefinitely, however, so serves only as limited
protection against unusual or short-term adverse conditions. If the condition con-
tinues, such as in extended floods, death results. Oyster reefs have been completely
destroyed by severe floods in the estuarine area of the Mississippi River (see Gunter
1950, 1952), Along with the oysters, commensals such as polychaete worms,
barnacles and various small crabs which use the oysters as substrate and hiding
places may also be killed.

Changes in which there is an unusual increase in salinity, such as might be
produced by prolonged drought, can also be extremely harmful. Oysters can readily
tolerate salinities up to full sea water, but increased salinities allow certain predators
to move in. Tire oyster drills Thais on the Gulf coast and Vrosalpinx on the Atlantic
coast are particularly devastating. Since these gastropods have a lower salinity limit
of 8 to 10 7oo sea water, oysters in low salinities are protected from them, but
during periods of increased salinity they can become establi.shed in the beds. Other
harmful organisms that become more prevalent at high salinities are the stone crab,
Menippe mercenaria, the boring chm, Martesia, the boring sponge, Giona, the mud
worm, Polydora, and the flatworm, Stylochus (Gunter 1955). Periods of high
salinity coupled with high temperatures may result in mass mortality from the
fungus Labyrinthromyxa marinum (Mackin 1951), It has been estimated that this
fungus is responsible for 50% to 60% of oyster mortality during such periods.

A complete treatment of an organism and its relation to salinity is given in the
paper by Hopkins, Anderson and Horvath (1973) on the brackish water clam, R.
cuneata. They studied not only the osmoregulation of the organism as it relates
both to amino acids and eleclrolyles, but they reviewed all the known literature on
salinity distributions. They also considered the ecology and life history of this clam
as it relates to salinity and to other organisms.

They found that the clam usually lives where the salinity is 1.15 ppt, but that

418

Gunter, Ballard, and Venkataramiah

they could live in the laboratory at 32 ppt for months. The salinities had to change
to induce spawning and (he larvae only survived at 2—10 ppt saline. They found
that where salinities were too stable, apparently recruitment did not take place. The
chief importance of this work seems to be the discovery that Rangia requires a
changing salinity for its existence and that stabilization at any level will eventually
wipe out the population. This is ecologically important because this clam, accord-
ing to the authors, makes up 99% of the bottom biomass in the very low-salinity
waters of the Atlantic coast and Gulf bays from Chesapeake Bay southward.

The marsh clam Polymesoda caroliniam is found to the landward of R.
cuneata and sometimes is found in pure fresh water.

P. ARTHROPODA. The Arthropoda are the most numerous and the most
diversified of all the animals that live on the face of the Earth and they vary from
the primitive horseshoe crab, Limulus, which does not even have jaws, but triturates
its food with the bases of its forelegs, to the highly organized, socialized insects that
are so important on land. As Berry (1929) has said, they are the most abundant
forms in the oldest fossiliferous rocks (Cambrian), in the modem seas, and on the
land and in the air. All groups including the insects and Arachnida are represented
in the sea, except for the centipedes and nullipedes. There are no truly marine
spiders, but there is an insect, a water strider, on the high seas, and there is a water
boatman quite common in the plankton of the open Gulf of Mexico (Gunter and
Christmas 1959). There are many species of mites in the shallow sea, but practically
nothing is known about (hem.

Ail arthropods are members of the protostomia and they have spiral cleavage.
They are united by a type of segmentation, which is highly modified in some
instances, and by jointed appendages.

The chief aquatic arthropods are (he crustaceans. They have invaded fresh
water and even land, but they are far and away the dominant animals in the sea and
they have been referred to as (he “insects of the sea.” However, they are more
diversified than the insects. Basically the predominant larva is the nauplius which is
nothingat all like the modified trochophores of practically all the other protostomia
from the fiatworms (o the brachiopods, For that matter neither is the nauplius
similar in any manner to the grubs of the insects.

In this section we shall treat the crustaceans. There are now hundreds of
papers and possibly a few thousand which refer to some extent to the salinity
relationship of the crustaceans and here we have only summarized the essential
features as we recognize them.

Aquatic crustaceans, especially the larger Decapoda, (crabs, shrimp, lobsters,
marine crawfishes and the like) have a well-developed circulatory system and heart,
plus certain sinuses containing body fluids. They are generally covered with a hard
integument, but segments are joined by thinner chilinous membranes and the gills
are always exposed directly to the water. The animals are not generally covered by
slime as some of the fishes and molluscs are.

Among the invertebrates the crustaceans have developed the greatest powers
of osmoregulation. Their hard exoskeletons reduce their permeability to some

Salinity Problems

419

extent, but marine species are quite permeable. Their permeability poses no osmotic
problem, however, since like marine invertebrates in general they are in osmotic
balance, though not in ionic balance, with sea water. The strictly marine species
show no osmoregulatory ability and when placed in dilute media below about 70%
sea water most of them will swell and die, since they cannot regulate volume nor
tolerate dilution of the body fluids (Lockwood 1967). In their natural environment
the permeability of marine species to water may be an advantage since water is
required for production of the urine involved in ionic regulation, which is exhibited
by all species that have been studied.

Some crustaceans are euryhaline, inhabiting both the sea and low salinity
waters. A number live in estuarine waters subject to wide fluctuations in salinity.
Some species have adapted to fresh water and a few are able to live in hypersaline
waters. Permeability seems to be directly related to habitat. Brackish water species
are less permeable than marine species and freshwater species least of all (Gross
1957), yet none are completely impermeable. Exchange of water and salts can
occur as a result of gradients between internal and external fluids.

The larger, motile crustaceans can respond to salinity changes by actively
moving from place to place, and barnacles can close their shells against unfavorable
conditions; but most species must adjust to fluctuating osmotic conditions either
by tolerating wide changes in blood concentration or by holding such changes to a
minimum. Although they vary in their capacities, most eury'haline crustaceans are
able to maintain hyperosmoticity at low salinities. They are generally isosmotic at
high salinities, but a few species such as the prawn wrwrrs (Panikkar

1941), the brine shrimp Artemia salina (Cro^an 1958), and the shrimp Macrobra-
chium equidens (Denne 1968) can hyporegulate. The same factors are involved in
determining salinity tolerance and osmoregulatory ability in crustaceans as have
been described for polychaete worms, that is, degree of permeability, degree of
toleration to intern^ changes in concentration, degree of development of active
transport mechanisms, and activity of the excretory organs.

If only passive exchanges were in operation, the blood of brackish and fresh-
water crustaceans would become intolerably dilute. Instead, it is maintained at
hyperosmoticity by active uptake of salts. The few species that can hyporegulate do
so presumably by taking in sea water and excreting salts. Even though many
crustaceans can maintain a concentration gradient between blood and medium,
none can maintain a constant internal concentration at ail salinities, although a few
can approach it (Panikkar 1941, Croghan 1958). Maintenance of such a condition
requires expenditures of energ>' since on either side of the isosmotic point increasing
amounts of energy are required to move salts against greater and greater concentra-
tion gradients. It is conserving of energy if the animal, thougli remaining hyper-
osmotic or hypo-osmotic, can tolerate some changes in blood concentration which
parallel changes in the external medium, thus reducing the gradient between the
two fluids. Nearly all euryhaline crustaceans exliibit an osmoregulatory pattern in
which the concentration of the blood falls as the concentration of the medium
decreases, and rises as the concentration of the medium increases. This method of
reducing osmotic work requires tolerance to some degree of internal change.

Tolerance to changes in blood concentration implies that there is osmoregula-

420

Gunter, Ballard, and venkataramiah

tion at the cellular level. Croghan (vide Lockwood 1967) has made some interesting
calculations in which he shows that even if the cells could tolerate swelling, a
50% drop in blood concentration would result in total withdrawal of the circulating
blood into the cells, assuming a hypothetical animal in which the blood volume
constitutes 50% of the total volume. It is obvious that cellular regulation of some
sort is necessary for maintenance of blood volume as well as for maintenance of
proper cell volume and composition.

Tlius, estuarine crustaceans must regulate at both the blood-medium boundary
and at the cell-blood boundary. In addition, there must be mechanisms for varying
both types of osmotic processes to meet the demands of a fluctuating environment.
Regulation al the blood-medium boundary involves active transport of inorganic
salts against a concentration gradient, whereas regulation at the cell-blood boundary
involves variations in concentration of organic substances, principally amino acids.

The excretory organs of the higher crustaceans, the antennal glands, function
in essentially the same way as the metanephridia of annelids, the major structural
modification being the reduction of the coelom to an end sac draining into a tubule
which may be expanded and folded at its upper end to form a labyrinth and dilated
at its lower end to form a bladder. The antennal glands, like the metanephridia, may
function in ionic and in volume regulation. Many fresliwater species such as crawfish
and amphipods get rid of excess water and conserve ions by excreting a hypotonic
urine (Lienemann 1938, Riegel and Kirschner 1960, Lockwood 1961), Marine,
brackish water, and a few freshwater species produce a urine that is isosmotic with
the blood but differs in ionic composition. For example, the magnesium level of the
blood of most higher marine decapods is maintained at a lower level than that of the
surrounding sea water by the activity of the antennal glands which excrete this ion.
The urine has a higfier magnesium level than the blood but a lower level of other
ions so that the two fluids are isosmotic. Changes in salinity may produce changes
in urine flow which may be accomplished by variations in the rate of movement of
substances into the erid sac or by variations in the rate of reabsorption of fluids,
possibly under hormonal control, although this has not been proven.

In addition to being subjected to fluctuating osmotic conditions, it is charac-
teristic of a number of estuarine species, including some commercially important
crustaceans, to move across salinity gradients as a normal part of their life cycles.
Environmental requirements differ at different life stages. The life cycles of the
larger, motile crustaceans, principally shrimp and crabs, follow a general pattern
characteristic of a number of estuarine species. Spawning takes place in high-salinity,
offshore waters with the larvae then moving shoreward toward low-saiinity, nutrient-
rich estuarine waters to feed and grow. Sexual maturation is accompanied by migra-
tion back toward the sea where the cycle starts over again (Pearse and Gunter 1957).

Feeley and Wass (1971) gave a figure showing the salinity range of 21 species
of gammerid amphipods found in lower Chesapeake estuaries. Three species were
found in fresh water, seven at 10 ppt and sixteen at 20 ppt. The salinity range was
0 to 24 ppt.

A number of workers have noted that the white shrimp, Penaeus fluviatilis,
spawns at sea but the postlarvae enter low-salinity waters to develop (Viosca 1920,

Salinity Problems

421

Weymouth et al. 1933, Gunter 1950, Lindner and Anderson 1956). The blue crab,
Callinectes sapidus, has a similar life cycle but differs in that mating takes place in
low-salinity waters when the female is in the soft shell stage of the final molt. The
adult female then moves seaward to spawn. Males need not be present in the spawn-
ing area and most of them remain in low-salinity, inshore waters. Several studies
have shown that the larvae of C sapidus will not develop normally in low salinity
waters (Sandoz and Rogers 1944, Costlow and Bookhout 1959),

After reviewing some of the literature on brachyuran species Roberts (1971)
stated, “Salinity strongly affects survival with tolerance ranges unique for each
developmental stage and each species.” He showed that eggs of the anomuran,
Pagunis longicarpus, would not hatch at 10 hatched slowly at 15 and
developed normally at 20—30 °/oo.

Although the general patterns of osmoregulation of estuarine crustaceans are
known, factors that might account for differences in salinity preference in the same
or closely related species are not well understood. Adult male and female C. sapidus
show some differences in osmotic response (Tan and Van Engel 1966, Ballard and
Abbott 1969) but it is not certain that the differences are sufficient to account for
observed differences in distribution. The near segregation of the sexes may be largely
behavioral responses related to reproduction.

The three species of commercially important shrimp belonging to the genus
Penaeus show differing salinity preferences. All three species have access to wide
salinity ranges yet they distribute themselves by species according to salinity
(Gunter, Christmas, and Killebrew 1964). In Texas waters the white shrimp P.
fluviatUis is most abundant at salinities below 10 %o, the brown shrimp P. azfecus
at 10 to 20 7oo, and the pink shrimp P. duorarum at 18 and above. Commercial
catch data correspond to field studies in indicating tire salinity optima of the three
species. Pink shrimp are taken in greate.st abundance in the high-salinity waters of
the Dry Tortugas of Florida and Campeche Bay of Mexico. The greatest numbers of
white shrimp are taken in the Mississippi River estuarine area of Louisiana, where
salinities are low, and the largest catches of brown shrimp are made off the dry,
somewhat salty Texas coast. Differences in the lower salinity limits of the three
species indicate that the observed differences in salinity preference may be related
to differences in osmoregulatory ability but comparative studies of such responses
have not been made. In the northern Gulf of Mexico P. fluviatUis has a lower limit
of 0.42 7oo* P- aztecus. 0.8 7oo (Gunter and Shell 1958), and P. duorarum, 2.7 7°°
(Hoese 1960). In keeping with the known fact that there is maximum invasion of
fresh waters in tropical regions, P duorarum occurs in lower salinities in southern
Florida than is indicated above.

Whether the occurrence of P. aztecus and P, duorarum in lower salinities in
the southernmost part of their ranges is related to uicreased osmoregulatory ability
at high temperature is not certain. Temperature is known to affect blood concentra-
tion and salinity tolerance in a number of crustaceans but the effect is not the same
for all species. In many there is an inverse relationship between temperature and
blood concentration. This situation exists in such diverse species as the ainphipod
Gammarus duebeni (Kinne 1952, Lockwood 1967), tire Palaemonetes varians
(Pannikkar 1940), and the crab C sapidus (Rees 1966, Ballard and Abbott 1969).

422

Gunter, Ballard, and Venkataramiah

Wlien temperature drops blood concentration increases, and high temperatures
result in lowered blood concentration. On the other hand, species such as the isopod
Aselltis aqwjdcus (Lockwood 1967) and the crab Potamon niloticus (Shaw 1959)
show a drop in blood concentration with a drop in temperature, and increased
blood concentration with increased temperature. Venkataramiah et al. (1974) noted
the same thing for Penaeus aztecus.

There are also species differences in effect of temperature on salinity
tolerance. P. varians, Leander serratus, P. aztecus and P. duoranm tolerate low
salinities better at high temperatures. This phenomenon may account for maximum
invasion of low salinities in tropical areas, as already indicated for P. aztecus and P.
duorarum, or in the summer for some species such as C. sapidus (Hay 1904, Gunter
1938, Pearson 1948). Venkataramiah et aL (1974) found that P tolerated

wider salinity range at higli temperatures. However, other species such as Gammarus
duebeni and Rhithropanopeus harrisii tolerate subnormal salinities best at the lower
part of their temperature ranges (Kinnc 1964),

The juvenile brown shrimp, Penaeus aztecus, exliibiled good ionic regulation
of blood Na and Cl in a salinity range of 8.5 to 34.0 ppt at temperatures of 26 and
3l‘’C, which they generally encounter in estuarine habitats (Venkataramiah et al.
1974). On the other hand, at low temperature, 21°C, the young shrimp seem to
lose the ions to the media in low salinities of 8.5 and 17.0 ppt, while in the higher
concentrations of 25.5 and 34.0 ppt there was a tendency towards a slight
isotonicity with the external media.

in laboratory experiments juvenile brown shrimp exhibited 100% survival in
a salinity concentration range of 8.4 to 34.9 ppt at an ambient temperature of 26*^0
(Venkataramiah et al. 1972, 1974). Sudden temperature fluctuations influenced the
salinity tolerance of these shrimp, especially in abnormal concentrations outside the
range of 8.5 to 34.0 ppt when tested over a broad salinity range of 0.34 to 59.9 ppt.
At 26°C, the shrimp from the same temperature background exliibiled better
salinity tolerance in the entire salinity range than those tested at 21 and 31®C.
Following a direct transfer from 26 to 31°C, the shrimp became hyperactive
tliroughout the test media, more so in abnormal salinities, with (he result that their
chances of survival were impaired more than those tested at 21 “^C.

When the animals were preacclimated at 21 and Sl^’C and tested in the same
media, it appeared that the low temperature (21 °C) acclimated animals were
adversely affected when they were forced to face sudden temperature rises as often
happens in the estuarine conditions during summer. On the contrary, the high
temperature (31°C) acclimated animals seem to face the sudden temperature fluc-
tuations more successfully. However, the shrimp acclimated at medium temperature
(26'’C) conditions were far better equipped to meet the high or low fluctuations.

There are unexplained seasonal effects that appear to operate differently from
temperature per se. Tlie blood concentration of Asellus is higher in winter than in
summer. Since there is a direct relationship between temperature and salinity in this
species, it would be expected that low winter temperatures would result in lowered
blood concentration (Lockwood 1960).

Salinity Problems

423

On the Gulf of Mexico and the South Atlantic coasts of the United States,
most of the Important fishery organisms are tied to the estuaries because of their
life histories. Most of them spawn in high-salinity waters and move back into the
bays in larval or very young stages. There they begin to grow and then move toward
the sea. This puts them in ever increasing salinities as they become larger. Some of
them may return to the estuaries after spawning and this is especially true of fishes
which have a life cycle of a few years. On the other hand, the short-lived species,
such as the shrimp especially, never return to low-salinity waters. Thus many species
of fishes show larger fish in saltier waters and smaller fish in low-salinity waters and
in the shrimp there is a close relationship between size and the salinity gradient.
These matters have been set forth in Gunter (1945, 1947, 1950, 1956a, 1961a, b,c,
1967a) Gunter, Christmas and Killebrew (1964) and Pearse and Gunter (1957).

There is some indication from the field data that younger shrimp can with*
stand lower salinity than tlie larger shrimp. In any case, only smaller shrimp are
found in the low-salinily, cool waters of the estuaries during the winter. Pliysio-
logical proof of this observation was shown by Venkataramiah et al. (1974) who, by
salinity tolerance studies made with the different size gjoups of brown shrimp,
Penaeus aztecus^ postlarvae of 13—20 mm and two sizes of juveniles of 21—45 mm
and 50—75 mm, showed that salinity tolerance was related to size. Among the three
groups, the postlarvae exhibited 100% survival in 8.5 to 51.0 ppt salinity while the
juveniles in the increasing order of their size exhibited mortality in 51.0 ppt and
47.6 ppt salinities respectively. However, in salinities below 8.5 ppt, although the
postlarvae survived better numerically, the juveniles survived longer in the same
stress media before their death.

The blue crab, C. sapidus, became very scarce in south Texas bays during a
drought that culminated in the dry year of 1966, and was replaced by C. danae, a
high-salinity species generally found offshore. After the drought was broken, C.
danae disappeared from the bays and was replaced by C sapidus (personal com-
munication S. H. Hopkins). It has been shown that commercial production of the
white shrimp, P. fluviatilis, a low-salinity shrimp, is directly correlated with rain-
fall of the Texas coast, apparently because salinily is a limiting factor to this shrimp
on this rather dry coast. On the other hand, the high-salinity shrimp, P. aztecus,
shows no correlation with rainfall on the same coast (see Gunter and Edwards 1 969).
In Louisiana waters Barrett and Gillespie (1 973) found a rather close correspondence
between river discharge and brown shrimp production in the Barataria-Caminada
area; they also found that salinity and annual production were related and that the
optimum for brown shrimp seems to be around 19 ppt.

The commercial shrimp of the family Penaeidae, composed chiefiy of three
species along the South Atlantic and Gulf coasts have for a number of years
supported the most important fisheries in North America. Consonant with their
commercial and biological importance, they have been rather extensively studied.
Certain people, chiefly laboratory scientists, or those who have devoted time to the
open ocean rather Uian to the estuaries, have questioned some of the ideas set forth
above. In part the questions are erroneous, or they are based upon a misunderstand-
ing. As a side issue almost, in the beginning we mi^it say that much has been made
of the statement by Lindner and Anderson (1956) that the size gradient of shrimp

424

Gunter, Ballard, and Venkataramiah

is correlated more with locale than with salinity. As a matter of fact, Lindner and
Anderson only made this statement and did not prove it. Furthermore, it will be
logically a very difficult matter to handle because year in and year out points in the
bays, sounds and passes, the locales have an average and characteristic salinity.

Actually, the three common penaeid shrimp, the white shrimp, P. fluviatilis,
the brown shrimp, P. aztccus, and the pink shrimp, P. duorantm, are almost com-
pletely euryhaline, in that they are found in almost fresh water and in pure sea
water and even in hypersaline water, at various stages of their life history. Apparently
the shrimp are osmoc on formers and can acclimate to a great range of salinity, as
would be expected of an organism that lives over a wide salinity range. Nevertheless,
the statements of Zein-Eldin (1963), Zein-Eldin and Aldrich (1965) and Parker
(1970) that salinity has little effect on distribution, survival, growth and, by implica-
tion, on other biological phenomena of shrimp are simply untenable and in some
ways can be disproven by their own papers. In fact this can only be true when we
find shrimp spawning, eggs hatching, larvae living and juveniles growing up in the
same salinities and the same place.

In her 1963 paper, Zein-Eldin showed that shrimp at salinity levels of 2-5-10-25
and 40 ppt grew about as well at all of these salinities except at 40 ppt where the
final results of growth were about 70% less. Growth at 2% and 5% was actually
higher than at the other salinities. The initial material was postlarval shrimp seined
from nearby surf zones, which means the Gulf beach. The shrimp were approxi-
mately 5 mg in weight, but the lengths are nowhere clearly set forth. Furthermore,
the species were mixed as the author slates, and the mortality rate is not given. The
author states that growth rate between 2 and 40 ppt is not significantly different.
The data in this paper arc impossible to analyze as presented, but they leave the
impression that shrimp will grow over a wide salinity range.

The paper by Zein-Eldin and Aldrich (1965) gave results of two sets of studies
at salinities ranging from 3 to 41 ppt. The animals were caught in the surf and kept
for 24 hours at a salinity of 24-25 ppt and temperature of 24-26°C. They were
then placed in the varying salinities at temperatures of 7-15-25-30 and 35^C. In all
600 shrimp were used. The results are summarized as follows:

Salinity (ppt) 3-7 8-11 23-27 32-34 36-41

Mortality (Percent) 49.0 35.5 10.8 7.5 18.5

The results show the highest mortalities were at the lowest salinities and the lowest
mortality was at the range 32-34 ppt after a 24-hour period. This is all to be
expected, for 12-mm postlarvae were subjected to the greatest abrupt osmotic
change at 3 ppt, and so on. This proves what was generally known before, namely
the greater the abrupt salinity change the higher the mortality, whether it be up or
down.

In the second experiment 100 animals each were placed in the salinities
shown below at temperatures of 1 1-18-25 and 32°C. The shrimp were kept 28 days.

SALINITY PROBLEMS

425

Salinity (ppt) 2 5 15 26 35 Average

Survival (Percent) 5.2 51.8 80.8 87.8 94.0 63.9

There was almost a 95% mortality at a salinity of 2 ppt and the greatest survival was
at a salinity of 35 ppt. The results actually show that the small shrimp live better at
high salinities. This is of no particular comfort to proponents of the idea that
shrimp do better in low salinities or to proponents of the idea that salinity does not
make any difference. Additionally, the total mortality was 37% in 28 days and
except at the two highest salinities, nearest to that from which they came, the
experimental shrimp were not living under a situation which would have carried
them through the summer.

Recent work at this laboratory has shown that postlarvae survive high salinities
better than juvenile shrimp, as would be expected from the life history.

We have found that wild populations of shrimp are true to their name, being
wild, and agonistic or even antagonistic and that they introduce disease into the
laboratory.

In accordance with what may be called Lund’s Dictum, because he continually
emphasized it (E. J. Lund, personal communication), we feel that experimental
animals should be those of known history, living and growing under conditions that
are known, normal and controllable. Under these Conditions with a mortality rate
of about 2% of the 640 experimental animals in six weeks time, it was shown by
Venkataramiah, Lakshmi and Gunter (1974) that brown shrimp grow fastest and
utilize their food most efficiently at 8.5 ppt and 1 5 ppt salinity as compared with
all higher salinities. These observations correspond with field observations that
small shrimp are found mostly in low-salinity waters, which presumably they seek
out.

Parker (1970) says, “no evidence is presently available to indicate that im-
mature brown shrimp cannot thrive and grow in salinities ranging between 1 and
35 %o.” This remark is refuted by the paper of Zein-Eldin and Aldrich (1965)
which showed poor survival at 5 ^/qo and below. Parker also implies that data from
one bay (Galveston) are better than data from the whole Texas coast for showing
brown shrimp distribution. He does not mention that the University Marine Science
Institute was carrying on a large project which assumed a detectable, low level of
harmful pollution in all Galveston Bay waters, nor that the proportion of high
salinity waters westward and southward on the Texas coast make Galveston Bay
and the whole coast difficult to compare. The data of Gunter, Christmas and
Killebrew (1964) remain the best and most extensive for the distribution of brown
shrimp in Texas as a whole.

Parker’s data show, if anything, that he found the small shrimp were most
abundant at lower salinities, which Gunter has contended for a long time, Gunter’s
idea, more or less inherited from Percy Viosca, applied chiefly to the white shrimp,
Petiaeus fluviatilis, but that shrimp is declining everywhere now and the brown
shrimp is taking over its ecological niche, and is being found at low salinities where
apparently it was not seen abundantly in former years.

426

Gunter, Ballard, and Venkataramiah

Q. PHORONIDA. This is a phylum of benthic worms living in tubes in the
bottom from low water down to about 30 fathoms. Some live with or in the shells
of other animals. They are protostomes and have a larva called an actinotroch
which is a sort of aberrant trochophore. The most distinguishing character is a
horseshoe-shaped circlet of cilia-covered tentacles at one end, called the lophophore.
The digestive tract is looped and both ends lie within the lophophore. This latter
organ relates the group to the Bryozoa and the Brachiopoda.

Some phoronids are estuarine and Wass (1963) reported the Chesapeake Bay
species, Phoronis architecta at salinities as low as 18.0. Larvae have been seen in the
Gulf of Mexico, but adults have not been reported (Hedgpeth 1954b). This is
another rather unimportant group from the ecological point of view.

R. BRYOZOA or ECTOPROCTA. This phylum is made of colonial animals
growing in arborescent colonies or flattened encrusting mats as “fouling” organi-sms.
The individuals are quite small but some of the arborescent colonies arc somewhat
impressive. Each individual has a lophophore which can be withdrawn with the
mouth. The anus opens just outside the lophophore. Encrusting forms live individ-
ually in what is essentially a small calcareous box. Some species have avicularia,
somewhat like the pedicellariae of the echtnoderms, which act as antifoulmg mech-
anisms. The bryozoa are nearly all marine, but there arc a few fresh w'ater species.
Their mass is comparatively small and except as fouling organisms they are not of
much ecological sign i Tic an ce.

In one species, Zoobotryon pellucidum, in the sliallow Gulf of Mexico the
zooids are on long chitinous stolons and the colonial masses wash up in windrows on
the outside beaches and are sometimes abundant enougli to interfere with fisher-
men’s trawls (Gunter 1950). He reported none at salinities below 35.0. Christmas
and Langley (1973) reported Bugula neritina in Mississippi Sound at 2 to 35.5 ppt
saline, with over half the specimen.s taken at 25 to 30 ppt, but they added that many
were probably dead when taken. Tt seems safe to conclude that this common species
lives mostly above salinities of 25 ppt. Gosner (1971) listed 20 Atlantic species as
euryhalinc among a total of 120 recorded, but the term is probably quite loosely
applied. Tire most widespread br>'ozoan, Victorella pavida, reported from England,
Egypt, Japan, Australia, India and Chesapeake Bay, is said to tolerate salinities from
fresh water to 27 ppt (Braltstrom 1954).

S. BRACHIOPODA. The brachiopods are coeloinate, lophophorate pro-
tostomes, all benthic and all marine. I'hey have a pedicel passing out between the
unequal shell valves. They feed on plankton and detritus. They are not estuarine
and apparently not often subject to low-salinity waters. Crania and Lingula have
existed without much change since the Ordovician (see Berry 1929). They are not
abundant today, and mostly confined to offshore waters and are not often seen.
Their ecological importance is small,

T. CHAETOGNATHA. This is a dart-shaped group of organisms with fins,
and a circlet of chitinous spines around the mouth. Arrow-worms have no circulatory
or excretory systems, but they have a large “brain” and nervous system. One genus
is benthic but all the others are drifting free as nekton. They are generally motion-

Salinity Problems

427

less but arc capable of sudden swimming movement after prey. They are quite small,
the largest species being only a few inches long, but they are present in enormous
numbers at times and they are voracious feeders on copepods, larvae of all kinds
and any animal they can subdue. Thus they are important components of the
plankton.

Pierce (1954) has listed 14 species from the Gulf^ 5 from inshore waters.
Salinity relations are not mentioned, Gosner (1971) says a few species enter estuaries
but that they are more common in “relatively undiluted” sea water. Cronin et al.
(1962) recorded Sagitta elegans in water as low as 11.4 ppt in Delaware Bay.

U. POGONOPHORA. This peculiar group of animals lives m tubes in the
abyss. Strangely, there is no alimentary tract and all digestion is done outside the
body and within the tubes. The animals are very elongate. Anatomical and develop-
mental characters show affinities to the Hemichorda. Recently several new species
have been described from the South Atlantic and Gulf. They will be among the last
animals on Earth to feel the effects of anything man does to the sea.

V. ECHINODERMATA. The echinoderms are coelomate, radial animals
with five branches. They are generally covered with calcareous platelets and spines
except for the sea cucumbers which are soft-bodied. The coelom branches into
small tubular extensions which extend through the body wall and perform several
functions. In the starfish they are organs of locomotion. The early echinoderms of
the Cambrian arc all bilateral and not radiate. Modern species are ail marine. They
have the modified diplcurula larva that shows kinship to the lower chordates. They
feed on detritus, plankton and various molluscs, and they are quite adept at catching
certain motile animals. In general they are high-salinity organisms and are not often
taken in estuarine situations.

Hedgpeth (1 950) recorded five species of starfish, sea urchins and sand dollars
from the Texas coast jetties of ihe passes to the Gulf. Gunter (1950) took three
species in trawls. The lower salinity range for each specks {Mellita quinquiesperforata,
Astfopecten artkulatiis and A, duplicatus) was 29.7 ppt. Five specimens of A,
articulatiis were taken in an inside channel near the Gulf, All the others were in the
open sea.

In Pine Island Sound, Florida, Gunter and Hall (1965) took 378 specimens of
sand dollars, sea urchins .starfish, and serpent stars and one sea cucumber, compris-
ing 1 1 species and 3,000 specimens of the serpent star Ophiolepis elegans, at
salinities ranging from 21.4 to 37.2 ppt. The average low-salinity range for all
species was 23.5.

Gosner (1971) notes that Atlantic coast starfish in general show lillle tolerance
for low salinities, but says that Asterias forbesi and A, vulgaris, well-known oyster
enemies, can survive in waters of 14 and 18 ppt respectively. He also lists Vrasterias
lincki as being found in salinities as low as 1 5 ppt.

In general the echinoderms live in high-salinity waters and are not subject to
the saline changes of the bays. Starfish predators of oysters do not exist in the Gulf
of Mexico.

428

Gunter, Ballard, and Venkataramiah

SOME GENERAL CONCLUSIONS AND COMPARISONS
CONCERNING INVERTEBRATES

Except for certain flagellates and ciliates that are numerous in the plankton
the protozoa are not greatly important to the life of most estuaries. In many areas
at certain salinities, lack of sufficient circulation and the accumulation of organic
materials and nutrient salts lead to flagellate plankton blooms. This in turn leads to
fish-kills through the production of poison or by consumption of dissolved oxygen.

Certain ctenophores are quite abundant in estuarine waters where they are
very important consumers of larval fishes, bivalves, crustaceans and other ctenophores
(c.f Gillespie 1971). When the salinity of their environment is changed beyond their
internal tolerance range they are killed in great numbers.

The various worms and related sessile or burrowing organisms can withstand
sudden freshets or floods by pulling back into their holes or closing up. Many poly-
chaete worms are higlily motile and can escape salinity changes by swimming. The
mass of these animals is considerable and they are important ecologically as food
animals. Certain species will be killed by severe salinity changes, but even so, growth
and reproduction are fast and life cycles are generally short. When salinity reverts to
normal even after a considerable kill the worms return quickly. In cases of perma-
nent salinity changes various species are moved up and down the bay.

Crustaceans are best represented in estuaries by the higher decapods such as
shrimp and crabs which, in addition to being efficient osmoregulators, are motile.
Adults are not likely lo be killed by salinity changes, but may move to more pre-
ferred salinities. It is now recognized that cool springs with flood waters kill incom-
ing brown shrimp larvae, which causes a bad shrimp year.

The estuarine molluscs arc sessile or feebly motile. They can withstand exces-
sive fresh or salty water for a time by closing up but extended osmotic extremes
will kill them, either directly by producing changes in blood concentration beyond
their tolerance range or indirectly by favoring predators and disease organisms.

Since species drop out along the decreasing salinity gradient in estuaries, fewer
species are present than in the marine environment. However, there are often larger
numbers of individuals of each species, possibly due to decreased competition. The
individuals tend to be small, sometimes because the low salinity is close to the limit
of tolerance, but more often because estuaries are nursery grounds for younger ani-
mals which must reach such areas to develop (Gunter 1961a, 1967b). The same pat-
tern of decrease in number of species, increase in number of individuals, and
decrease in size occurs in hypersaline waters, but such areas are not required for
completion of life cycles.

Salinity limits are sometimes quite sharp. SegerstrSle (1953) reported exten-
sion of the range of a number of marine species when salinity in certain areas of the
Gulf of Finland rose from 5.2 '^/oo to only 5.8 °/oq. Dahl (1956) comments that in
the Skagerrak, 75% of marine species disappear with a drop in salinity from 34 %o
to 30 °/oa. A number of workers have shown that the distribution of invertebrates
in estuaries and hyperslaine lagoons show definite patterns related to salinity (Ladd
1951, Gunter 1956b, Parker 1959). Correlations between seasonal salinity changes

Salinity Problems

429

and distribution have been demonstrated (Gunter 1950, Gunter et al. 1964), as well
as effects of long periods of drought (Gunter and Hildebrand 1954, Hoese 1960)
and floods (Gunter 1952).

Whetlier the limits are physiological, ecological, or behavioral, and whether
they arc imposed on early stages of the life cycle or on adults, salinity has an effect
on distributions of animals. Large changes will clearly affect distribution patterns as
some forms are killed and others move, eitlier immediately or in successive steps in
succes.sive generations. Even regulators vary in degree of regulation, with each
species having its own salinity limits and salinity preference, so that any large or
long-term change in salinity will result in changes in the composition of the fauna
of the area affected.

Low-salinity periods, freshets and floods may be the norm in most estuaries
and in killing out predators, parasites and competitors they seem to benefit oyster
beds from time to time, and possibly crustaceans, too, as during the Bonnet Carre
Spillway openings.

W. HEMICHORDATA. The chordate animals are basically characterized by
a dorsal supporting rod, the notochord, above the intestine, a tubular nervous
system lying above the notochord and gill slits in the pharynx. In the true Chordata
all of these characters are clear and sharp. A wormlike group, of two quite different
types and showing some of these features, have been thrown together as the Hemi-
chordala.

These two groups are the Pterobranchia and the Enteropneusta. The first has
few or no gill slits but they are abundant in the latter. The Pterobranchia have a
solid nerve chord, while the Enteropneusta have a dorsal nerve tract which is tubular
anteriorly. Both groups have a diverticulum of the foregut, which is said to be a
primitive notochord because of the similarity of embryonic origin with the noto-
chord of amphioxus. On the otlier hand, the embryogenesis and the dipleurula larva
show affinities of the two groups and relations to the Echinodermata.

The Pterobranchia are nearly all from deep water. A few species are found
intertidally in the tropics. They have plumes extending from near the gill slits used
in food capture. They are not common.

The Enteropneusta, commonly called acornworms, are found in the shallows
of all seas of the world. They are wormlike with a proboscis, and a collar under
which the mouth opens. They have numerous gill slits. Osmoregulation characteris-
tics are unknown but tliese animals live in the bays in Mississippi and Texas where
they are sometimes subjected to quite low salinities.

Acornworms live in u-shaped tubes in the mud and they are extremely soft.
There is an unnamed giant species in Louisiana and Mississippi bays near the river.
It may be three feet in length and breaks under its own weight when picked up.
Saccoglossus kowalevskii is found on the Gulf and Atlantic coasts. Gosner (1971)
lists it as euryhaline.

The acornworms smell strongly of iodoform and sometimes chloroform. At
times the commercial shrimp and bottom feeding fishes of the shallow Gulf of

430

Gunter. Ballard, and Venkataramiam

Mexico waters take on the same odor reputedly from feeding on acornworms. If the
surmise is correct, the acornworms must be much more numerous than is generally
realized. Salinity relations are unknown.

X. PROTOCHORDATA. All members have the dorsal, tubular nervous sys-

tern, gill slits and well-developed notochord at some stage. The group could be
included under the Chordata which would then be separated into the Acraniata and
the Cranlata. The Acraniata are the tunicates or sea squirts and Amphioxus. The sea
squirts begin with a tadpolc-like larva with a well-defined notochord. This is lost
when the animal sets individually on (he bottom or forms colonies by budding and
sometimes floats on the high seas. A small individual species, manhattensis,

is found in the lower bays of the Gulf of Mexico and South Atlantic coast. Gunter
and Hall (1965) reported it at 27.5 ppt salinity in the Caloosahatchee Estuary,
Florida. The salinity ranges of three other species were: Molgiita occidentalis at
22.5-34.2 in the Caloosahatchee Estuary and San Carlos Bay;5o^e/fl plicata, 24.8-
33.8 San Carlos , Amaroucium stellatumr 24,5-35.0 San Carlos Bay.

Gosner (1971) lists M manhattensis as euryhaline because it is found where
the water drops to 10 7*o the Patapsco River. But the animals die off in the
winter and this little solitary tunicate is far from being euryhaline.

The Cephalochorda or Amphioxus have as fine a notochord as any animal but
their head amounts to nothing and even the nerve cord does not end in a frontal
ganglion, and the only skeletal element is the somewhat stiff notochord itself. The
lack of a cranium sets the amphioxi off from all higher chordate animals. They have
a circle of tentacles around the vestibule in front of the mouth and running from
the mouth dowit the pharynx is a peculiar ciliated canal, the endostyle, which helps
move the food and possibly to digest it. Supposedly it is the progenitor of the
thyroid gland of higher organisms. An endostyle also exists in the pterobranchs, the
balanoglossids and the tunicates, further establishing the kinship of this strange
assortment of animals.

The lancelet-like amphioxus lives in the bottom and will dive in quickly and
out of sight either head first or tail first. In Mississippi Sound it w'as never found on
fine sand or clay, but on mixtures of coarse sand and silt. Boschung and Gunter
(1962) reported a maximum of 72 animals per square meter over an area of several
square miles, involving a population in the billions. The mean salinity was 24.3 and
the range was 1 5.4 to 33.1 per mille. The species was Branchiostoma floridae Hubbs.

Later on Dawson (1965) showed that the lancelet population in Mississippi
Sound was practically annihilated by low salinities following heavy rains and flood-
ing on the Mississippi coast. So it is apparent that low salinities will kill amphioxus
on the Gulf coast and that they are organisms of some trophic importance.

Y. VERTEBRATA. Among the vertebrates the groups that are affected
directly and greatly by salinity change are essentially those with a living skin and
which breathe through the water. They are truly aquatic. They are the Cyclostomata
(hagfishes and lampreys), Elasmobranchii (sharks and rays), Osteichthyes (true
fishes) and Amphibia (frogs, salamanders, etc.). Of these only the hagfishes are
completely marine and only the amphibia are primarily fresh-water.

Salinity Problems

431

Almost all fishes have internal salt concentrations different from that of their
external environment and so must solve osmotic problems. Among the amphibians,
a very few species of frogs and toads occur in brackish waters. Marine reptiles and
mammals do not have the same problems as fishes in that they do not have per-
meable respiratory surfaces exposed to the environmental water. Nonetheless, they
lose water in excretion of nitrogenous wastes and by respiratory evaporation, and
this loss must be made good in some fashion, Certain birds that spend considerable
time at sea or feed on sea life are classed as marine.

Of vertebrates occurring in coastal areas, particularly in estuaries, some are
more or less permanent members of the fauna but many are temporary inhabitants
consisting of many essentially marine forms able to withstand low salinities, a few
invaders from fresh water, and species that migrate back and forth between the sea
and fresh water. Of particular importance are those species which must spend parts
of their life cycles in estuarine waters.

Many of the general considerations already described for invertebrates also
apply to vertebrates. They, too, vary in their ability to tolerate salinity changes.
Most species can osmoregulate and thus hold changes in internal osmoconcentra-
tion to a minimum. Some can only hyporegulate; others can only hyperregulate.
Such species are, of course, stenohaline. A large number of vertebrates are, however,
curyhaline and withstand more or less wide variations in salinity. They do so by
tolerating changes in internal osmoconcentration, by varying the rate of osmo-
regulatory activity, or by both hyporegulating and hyperregulating.

The same major organs are involved in osmoregulation in vertebrates as are
used by invertebrates; namely, the gut, gills and excretory organs. The skin of
amphibians presents a permeable surface across which water and salts may pass, but
the integument of other quadrepeds is virtually impermeable to these substances.
Certain vertebrate groups have additional structures for excretion of excess salts.
Examples are the rectal glands of sharks and the nasal and orbital glands of marine
birds and reptiles.

Some scientists accept the theory that vertebrates have secondarily invaded
the sea from a fresh water, or fre.sh water to land to sea origin and that, since
adaptation can only involve modification of structures already present, marine
species have had to make use of kidneys originally adapted for handling osmotic
problems imposed by a freshwater enviornment. Most biologists question a fresh-
water origin of all vertebrates although the typical fish kidney may have developed
in dilute sea water or in fresh water (Pearse and Gunter 1957). But the kidney of
the highly marine hagfishes seems to be primitive or structurally similar to that of
freshwater fishes, and this group has no known freshwater ancestry. In any case, the
kidney of all vertebrates is based on the same general plan typified by the “primi-
tive” kidney of freshwater fishes. Therefore, a brief review of its structure is in
order, A detailed review has been presented by Hickman and Trump (1969).

The kidney of freshwater fishes is adapted to excretion of excess water taken
into the body by osmotic inflow to a more concentrated internal environment and
to conservation of salts that tend to diffuse outward to a more dilute external
environment. The organ is made up of varying numbers of basic units, the nephrons.

432

Gunter, Ballard, and Venkataramjah

Each nephron consists of a knot of capillaries, the glomerulus, surrounded by a
space, the Bowman’s capsule, which is drained by a long, variously looped tubule.
The tubule is, in turn, surrounded by capillaries; and certain parts, such as the
proximal and distal convoluted tubules plus various intermediate segments, are
specialized for specific functions. Blood enters the glomerulus under pressure; and
various materials, including salts and water, are filtered through the capillary walls
and the Bowman’s capsule into the tubule. As the ultrafiltrate passes down the
tubule, certain substances are reabsorbed by way of the peritubular capillaries, and
some secretory products are added to form the final product, the urine. The kidney
has a number of functions, but the handling of water, salts, and sometimes certain
organic products such as urea is of importance in osmoregulation.

Obviously, if there is maximum passage of water from the blood into the
tubules, minimum water reabsorpiion, and maximum salt reabsorption, a relatively
large volume of dilute urine will be formed. Such is the case in freshwater fishes. On
the other hand, if there is little passage of water into the tubules, maximum water
reabsorption, and little salt rcabsorption, the urine will tend to be scanty and con-
centrated. Tliis is Uie general pattern of kidney function in marine fishes. It should
be noted that a large glomerular surface favors water passage into the blood, and a
well-developed distal convoluted tubule is associated with salt reabsorption. In
addition, in some vertebrates, chiefly the sharks and their relatives, but also in the
coelocanths and certain frogs, urea and trimethylamine oxide reabsorption is of
importance in osmoregulation.

The kidney is not the only organ involved in maintenance of a proper water-
salt balance. Salts passively diffuse across the permeable gill membranes and are lost
from freshwater fishes and taken up by marine fishes. However, the gills are able to
compensate for these movements by active uptake or secretion of salts against a
concentration gradient. Thus they serve as important extrarenal pathways for salt
exchanges. The rectal, nasal^ and orbital glands of certain marine groups have
already been mentioned as functioning in secretion of excess salts.

Adaptation to the variety of habitats in which vertebrates occur involves the
use of one or more of the osmoregulatory mechanisms described above.

REMARKS ON GENERAL CLASSIFICATION

It was stated above that we would follow the general phyla of the Animal
Kingdom and we have done so without particularly noting the larger groupings.

Animal life begins with populations of unicellular organisms feeding as ani-
mals. The early Protozoa were probably derived from algae as shown by the similarity
of the Flagellata to the algal germ cells.

These changed by simple association into the Parazoa and Metazoa. The
Parazoa or sponges are a sideline group and the Mesozoa are of uncertain affinity.
Presumably the Metazoa or Eumetazoa are more closely akin.

The so-called Radiata or radially symmetrical forms, the Coelenterata and the
Ctenophora, are two-layered organisms with an endoderm and ectoderm. They may

Salinity Problems

433

be called the Diploblastica. Affinities with the next higher group, the flatworms, are
a matter of argument but some crawling ctenophores resemble flatworms.

All remaining organisms are triploblastic and bilateral. The most primitive
group with a solid mesoderm with no spaces is comprised of the Platyhelminthes
and Nemertea. lliese two phyla are the only bilateral Metazoa without a body
cavity between the alimentary tract and the body wall. They are known, therefore,
as the Acoelomata.

The next group has a body cavity or a series of them but there is no epithelial
lining and they are not of mesodermal origin and arise from the blastocoel, so they
are said to be pseudocoeloms and the animals collectively are called pseudocoels.
These phyla are the Aschelminthes, Acanihocephala and the Entoprocta.

The remaining phyla of the Kingdom Animalia all have a coelom, although in
some it is very small. They are furtlter divided by the Protostomia and the Dcuteros-
tomia distinction. The protostomeshave spiral, determinate, total and unequal cleav-
age, with the mouth developing at the blastopore or original opening of the gastrula.
This is the flatworm, annelid, molluscan, crustacean line. The larva is always a troch-
ophore or modified trochophore, except in the Crustacea. It includes several miscel-
laneous worm groups and a group of animals with a lophophore, a coiled, tentaculate,
ciliated feeding organ in the Phoronida, Ectoprocta and Brachiopoda. The
lophophorate animals have some deuterostome characteristics and are placed last
in the Protostomia series, which begins with the acoelomate flatworms and nemer-
teans and may be more fundamental than the presence or absence of a coelom.

In the Deuterostomia the cleavage is radial, generally holoblastic and in-
determinate, that is a separate animal will develop from each blastomere. The
blastopore of the gastrula becomes the anus. Essentially this is the chordatc related
line. The recognized phyla are the Chactognatha, Pogonophora, Echinodermata,
Hemichordata, Urochorda, CephaJochorda and Vertebrata. The last four are the
superphylum Chordata. The echinoderms show their connections with the Hemi-
chordata by the similar diplcurula larva and a dorsal nervous system. The hemi-
chords show their relations to the higher chordates by the dorsal, tubular, ecto-
dermal nerve cord and a small, anterior gut infundibulum which embryologically
seems to be a notochord. Tire Urochorda and Cephalochorda have an excellent
notochord, at least for part of their life, but they are separated from the
higher Chordata because essentially they are headless and could be called the
Acraniata.

As yet we do not know enough to discuss osmoregulation and salinity rela-
tionships along phyletic or evolutionary lines, but it is a matter to be held in mind
by future workers.

OSMOREGULATION IN FISHES IN GENERAL

Because a great deal of the coastline of the United States is bordered by
estuaries, and because estuaries are areas of variable salinity, fishes of coastal waters
are largely euryhaline species. Not only must they tolerate typical salinity variations

434

Gunter, Ballard, and Venkataramiah

of the estuary but, in addition, many species are migratory and cross salinity
gradients in their migrations to and from the estuary or through the estuary.
Anadromous and catadromous species represent extreme curyhalinity in their life-
times for a part of their life cycle is spent in an oceanic environment and a part in
fresh water. Yet, at any given stage they may be stenohaline (Krogh 1939, Hunts-
man and Hoar 1939, Black 1951b). Other euryhaline species may move freely
across salinity gradients. Like estuarine invertebrates, a great many coastal fishes
grow up in low-salinity waters, especially at smaller stages, and they seem to have a
proclivity at this time for invading low-salinity or even fresh water (Gunter 1957b),
whereas the adults arc seldom or never found there. Gunther (1880) pointed out
this relationship for the common herring in the Thames Estuary many years ago.

Although the emphasis of the present discussion is on coastal species, nearly
all euryhaline fishes osmoregulate in the same manner as freshwater fishes when in
fresh water and in the same manner as marine fishes when in sea water. Thus a
discussion of osmoregulation of coastal fishes must include some remarks concern-
ing the special problciiis imposed by freshwater and marine habitats, as well as
those that must be solved in adapting to varying salinities.

Smith (1932) is generally credited with giving the first comprehensive descrip-
tion of osmoregulation in fishes, but several earlier papers by Sumner (1905, 1906,
1907 and J9I2) indicate that the basic mechanisms were known much earlier.
Among scientists who have given reviews on osmotic processes in fishes are Black
(1957), Gordon (1964), Parry (1966), Holmes and Donaldson (1969), Hickman and
Trump (1969), and Conte (1969).

OSMOREGULATION IN FRESHWATER FISHES

Aspects of water and salt regulation in freshwater fishes have already been
mentioned in describing general kidney function. As with all freshwater animals,
fishes have a body fluid osmoconcentration greater than that of the surrounding
water. In order to maintain this situation they must compensate for osmotic inflow
of water and loss of salts by diffusion. The kidney is well adapted for this purpose.
The relatively large glomerular surface allows for passage of con.siderable water into
the kidney tubules. The tubules have low water permeability, but they strongly
absorb monovalent ions. More than half of the filtered water is excreted, yet
only small amounts of sodium and chloride are lost in the dilute urine.

Although the glomerular kidney possessed by nearly all freshwater fishes
presents a large filtration area which facilitates water excretion, it is not necessary
for survival in fresli water. Several species of pipefish occur in fresh water (Grafflin
1937, Whatley 1962), Like the marine members of their family (Syngnathidae)
they possess aglomerular kidneys (Grafflin 1937). Occurrence of this type kidney in
freshwater fishes is rare and possibly indicates recent immigration from the sea
(Potts and Parry 1964a). The typical kidney of freshwater fishes is of the glomerular
type, and biologists have demonstrated a relationship between degree of glomerular
development and salinity of habitat (Marshall and Smith 1930, Lozovik 1963).
Ogawa (1961) described atrophy of the glomeruli of freshwater goldfish adapted to
one-third sea water.

Salinity Problems

435

Kidney reabsorption conserves salts but does not replace all those lost in
diffusion and excretion. An additional extrarenal uptake of salts occurs. Sumner
(1905) found that the general integument of bony fishes is impermeable to salts
and suggested that the gills are sites of salt transport. Keys (1931) and Krogh (1937,
1939) demonstrated that such is the case. Keys and Willmer (1932) designated
specific cells of the gill epithelium which they believed to function in osmoregula-
tion as “chloride secreting cells." Although there is not universal agreement as to
their role in osmoregulation, there is evidence that these same cells may function in
salt absorption and in salt secretion (Pettengill and Copeland 1948, Copeland 1950,
Philpoii and Copeland 1963). The function of the cells is postulated to be transport
of chloride, and probably other monovalent ions, against a concentration gradient
from an area of lesser concentration to one of greater concentration. Thus, these
same cell types could be utilized by freslrwater, marine, and euryhaline fishes, with
the direction of salt transport depending on the relative internal and external con-
centrations (Black 1951a).

Certain species of otherwise anadromous groups of fishes are confined to
fresh water. Examples are the several water lampreys which are sienohaline. There
are also certain freshwater trouts which are confined to fresh water, belonging to
the genus Saimo, But when the trout are experimentally placed in sea water they
show the same tolerance as anadromous races of the same species (Gordon 1959,
Conte and Wagner 1965), such as Saimo gairdnerii, which is the rainbow in fresh
water and the steelhead when it goes to sea.

A number of elasmobranchs occur in fresh water. Most are euryhaline but
some are true freshwater species. Elasmobranchs handle their osmotic problems in a
different manner than teleost fishes, and the special problems of the freshwater
species will be taken up with the general discussion of this primarily marine group.

OSMOREGULATION IN MARINE FISHES

A. TELEOSTS. Most marine fishes are hyporegulators. Primitive hagfishes
and elasmobranchs are exceptions and will be considered separately. The osmocon-
centration of the body fluids of marine teleost fishes is less than that of sea water,
hence these fishes face an opposite condition to that faced by freshwater fishes.
There is a constant osmotic loss of water which can only be replaced by drinking of
sea water. Excess salts, taken in with the ingested water together with those that
diffuse inward, must be excreted from the body. There are three different ion
excretion pathways, witli the gills being the most important in osmoregulation.
Water, monovalent ions, and some divalent ions are absorbed from the gut. Most of
the magnesium and sulfate ions are not absorbed and pass throu^ the gut to be
excreted with the feces. The small amounts of these ions that are absorbed are
secreted into the kidney tubules and eliminated with the urine. Excess monovalent
ions are transported across the gills to the outside, presumably by the chloride
secreting cells.

The kidneys of marine fishes are based on the typical vertebrate plan but
show varying degrees of degeneration of certain parts. Since osmotic flow of water
is outward rather than inward, little is filtered into the kidney tubules. Therefore,

436

Gunter, Ballard, and Venkataramiah

a large glomerular surface is not advantageous to marine fishes. The kidneys of some
species, such as pipefishes, sea horses, toadfish, midshipmen, and angler fishes are
totally or partially agiomerular (Edwards 1928, Marshall 1929, Marshall and Smith
1930, Ogawa 1962). In some species the neck section between the glomerulus and
tubule is restricted, and in others the vascular supply is reduced to the extent that
the glomeruli are nonfunctional (Potts and Parry 1964a, Hickman and Trump 1969).
These features might be considered modifications for a marine existence. However,
many marine fishes have functional glomerular kidneys and, as previously noted,
certain freshwater ones do not. In any case, reduction of the glomeruli is not
disadvantageous to marine fishes and it has occurred in several groups. In addition,
the distal convoluted tubule is often absent (Hickman and Trump 1969). Us salt
reabsorptive function is of little value to marine fishes since their need is to excrete
salts.

In summary, marine teleosts maintain a normal body fluid concentration by
drinking sea water, excreting excess salts largely by way of the gills, and eliminating
a small amount of urine that is nearly isosmotic with the blood. The kidneys seem
to function primarily in elimination of magnesium and sulfate ions.

B. HAGFISHES. Blood of primitive hagfishes is essentially isosmotic with
sea water. The two fluids have nearly the same sodium and chloride content although
they differ in ratios of other ions such as magnesium, sulfate, potassium, and
calcium (Robertson 1954, 1963, McFarland and Munz 1965, Morris 1965). There is
virtually no net exchange of salts and water between the body fluids and the sur-
rounding sea water.

The kidney is glomerular but the filtration rate is low, and neither sodium
chloride nor water is reabsorbed from the tubules (Munz and McFarland 1964). The
kidney is not needed for osmoregulation and it serves primarily for ionic regulation.

Possession of blood isosmotic to sea water and no mechanism for salt re-
absorption points to a marine ori^n of hagfishes. Yet they have glomerular kidneys
which lend themselves to excretion of excess water. Hickman and Trump (1969)
sugge.st that possession of such kidneys may be of survival value since hagfishes
sometimes occur in waters of varying salinity, but this theory is doubtful. The idea
is unlikely. These fishes are highly permeable to water (McFarland and Munz 1965),
and survival in dilutions of sea water would presumably require a mechanism for
excreting osmolically derived water at approximately the same rate that it enters.
The large Ultra lion area provided by the glomerular kidney would facilitate passage
of water into the tubules and, since water cannot be reabsorbed, would contribute
to formation of increased amounts of dilute urine. Studies by McFarland and Munz
(1965) on the hagfish, Polistotrema stoutii, showed an initial rapid gain in weiglit
when exposed to 80% sea water but the weight returned to normal within 7 days,
indicating excretion of excess water.

C. ELASMOBRANCHS. Salt concentration of elasmobranch blood is some-
what higher than that of marine teleosts but, similarly, lower than that of sea water.
However, total blood osmoconcentration is somewhat higher than tliat of sea water
because ofa uniquely high concentration of urea and trimethylamine oxide (Stadeler
and Frerichs 1858, Suwa 1909, Smith 1931, Burger 1967, Forster 1967). The filtra-

Salinity Problems

437

tion rate of the glomerular kidney is high, but the osmotic inflow of water is not
great and much of it is reabsorbed. The result is low urine output. As much as 95%
of the filtered urea and trimethylamine oxide are also reabsorbed to contribute to
the total concentration of the blood (Forster 1967), Salts diffuse inward because of
their lower concentration in the blood. Some salts arc excreted with the urine and
some by way of the gills (Maetz and Lahlou 1966, Chan et al. 1967). However, the
most important organ for excretion of excess salts is the rectal gland which secretes
an almost pure sodium chloride solution (Burger and Hess 1960, Bulger 1963,
Burger 1965).

Many elasmobranchs are euryhaline and their occurrences in fresh water are
not uncommon, particularly in tropical areas where some live exclusively in fresh
water (Smith 1936, Gunter 1942, 1956c, Hcrre 1955). The blood concentration of
elasmobranchs in fresh water is lower than that of marine elasmobranchs largely
because of a reduced urea content. Urist (1961) compared the serum composition
of the freshwater shark Carcharinus leucas of Lake Nicaragua with that of marine
shark C leucas and found that the total serum concentration of the freshwater
shark is 83% and the urea content only 30% of that of the marine shark.

Even though the blood concentration of freshwater elasmobranchs is lower
than that of marine forms it is higher than that of freshwater teleost fishes. The
large concentration gradient between internal and external environments results in
increased osmotic uptake of water and increased urine production over that of
marine elasmobranchs. However, as pointed out by Hickman and Trump (1969), no
new renal mechanisms are required. Since marine elasmobranchs arc also somewhat
hyperosmotic to their environment and have adequate glomerular surface, activity
of mechanisms already present can simply be increased in dilute or fresh water. An
increase in ^oraerular filtration rate with resultant increase in urine output results
in increased rate of urea loss and reduced blood concentration. However, urea re-
absorption is usually sufficient to retain a fairly high blood concentration in com-
parison to that of teleost fishes and to produce a urine that is hypo-osmotic to the
blood. The completely landlocked ray, Fotamotrygon, is unique among elasmo-
branchs in that it apparently does not reabsorb urea at all for the blood is free of
this substance (Thorson et al. 1967).

In euryhaline elasmobranchs the filtration rate and tubular permeability of
the kidneys can be varied to accommodate changes in environmental salinity, but
the adjustments require time. Price and Creaser (1967) found that the skate. Raja
eglanteria, requires 48 hours to reach osmotic equilibrium after only a 2.5 °loo
change in salinity, and 70 hours after a 10.0 change. Holmes and Donaldson
(1969) postulate that elasmobranchs living in fluctuating estuarine conditions may
never reach osmotic equilibrium.

Freshwater elasmobranchs living in waters with access to the sea, such as Lake
Nicaragua and Rio San Juan, are thought to be recent immigrants. They retain a
relatively high blood urea and are thought to be able to osmoregulate in sea water
(Thorson 1967). However, certain groups show tendencies toward becoming steno-
haline freshwater fishes. The lack of urea in Fotamotrygon has been mentioned.
The rectal glands are not needed for salt secretion in a freshwater environment, and

438

Gunter, Ballard, and Venkataramiah

they have become degenerate and nonfunctional in Lake Nicaragua sharks (Oguri
1964).

OSMOREGULATION IN EURYHALINE FISHES

Most euryhaline fishes maintain a fairly constant blood concentration in all
salinities (Potts and Parry 1964a). Some tolerance to internal change is required of
certain anadromous and catadromous fishes as they migrate between the sea and
fresh water. These species are able to osmoregulate to some extent in either medium
and are never at isosmoticily for long. In general, the wide changes in environmental
salinity tolerated by euryhaline species involve shifts between the osmoregulatory
mechanisms used by marine fishes and those used by freshwater fishes. Many species
require gradual adaptation to changed osmotic conditions, but some are able to
adjust osmoregulatory processes very quickly. The tide pool blenny, Blennius, can
change from sodium uptake to sodium excretion within minutes after transfer from
fresh water to sea water (Hoese, vide Potts and Parry 1964a). Studies by Black
(1948a) showed that the euryhaline killifish, Funduliis heterociitus^ adapts to trans-
fer from fresh water to 100% sea water in only 6 hours. Copeland ( 1 948) described
histological changes in the chloride cells of F. heteroclitus that indicate a change in
function from salt absorption to salt secretion within two days after transfer from
fresh water to sea water. In view of Black’s and Copeland’s results it seems probable
that some immediate but temporary response may occur in the interval between
lime of transfer and time of reversal of normal osmoregulatory processes. Such
responses as reduction of glomerular filtration rale and temporary storage of salts in
muscle have been described for other species (Black 1951a, Oide and Utida 1968,
Hickman and Trump 1969), Rate of adaptation may be related to direction of trans-
fer or to acclimation period. Although in Black’s experiments F. heteroclitus
adapted faster when transferred from fresh water to sea water, chum and coho
salmon fry adapted faster when transferred from sea water to fresh w-ater (Black
1951b). In both cases adaptation was faster when the transfer was made in the
direction of the normal environment of the experimental animal. In the flounder,
Platichthys flesus, the speed of adaptation to sea water depends on how long the
fish has been in fresh water (Motais 1961).

Most euryhaline species have a glomerular kidney, but aglomerular species
such as the toadfish Opsanus can withstand varying salinities. Opsanus occurs natu-
rally in very low salinities, and O, tau can live experimentally in fresh water (Lahlou
et a). 1969, vide Hickman and Trump 1969). The distal convoluted tubule may or
may not be present in the kidneys of euryhaline fishes. Its presence presumably
favors salt reabsorplion in fresh water but it is absent in some euryhaline species
(Edwards and Schnitter 1933, Trump 1968 vide Hickman and Trump 1969). Renal
adaptation to salinity changes involves changes in glomerular filtration rate, in
tubular permeability to water, and in salt reabsorption (also urea reabsorption in
elasmobranchs). The kidneys of marine fishes appear to be more adaptable than
those of freshwater fishes. Gun let (1956c) listed approximately ten limes as many
marine fishes collected in fresh water as freshwater fishes collected in sea water. It
should be noted that, contrary to what might be expected, the fishes of hypersaline
waters are euryhaline species rather than stenohaline marine species. Fishes adapted

Salinity Problems

439

to coping with fluctuating osmotic conditions appear to be better equipped to
handle hypersaline conditions than species living in constant high salinities (Hedg-
peth J947, Gunter 1967a).

The general response of euryhaline fishes to increased salinities is reduction in
glomerular filtration rate and resultant decrease in urine production. This response
immediately reduces water loss and allows time for tubular changes to occur. The
tubules become increasingly more permeable to water and increasing amounts are
reabsorbed. In some species the glomerular filtration rate returns to near normal in
time, but the Urine tlow remains low because of compensating water reabsorption
(Oide and Utida 1968, Hickman and Trump 1969). Tire gills shift to salt secretion
to compensate for diffusion of salts into the body from the more concentrated
environment and the fish may drink the medium. Thus when a euryhaline teleost
fish is in sea water it osmoregulates in the same fashion as a marine teleost.

When a euryhaline fish moves into fresh water it may reduce its drinking, but
water is taken in by osmosis. Initially the urine becomes more concentrated because
of the high rate of water reabsorption from the permeable tubules. However, the
water pemeability of the tubules becomes reduced, and salts can be reabsorbed with
little water reabsorption. The result is excretion of increased amounts of dilute
urine. The gills shift from salt secretion to salt uptake, and transformation to the
same osmoregulatory processes used by freshwater fishes is complete.

Many euryhaline fishes show definite migration patterns. Some migrations are
cyclic and predictable and are often related to spawnifig activity or to seasonal
effects on salinity or temperature. Others are sporadic, although they are probably
related to some environmental factor such as food supply.

A number of factors may influence migratory patterns. Migrations related to
life cycles, such as movement of adults from one salinity to another to spawn, or
return of the young from the spawning grounds, are stimulated by internal factors.
There is little doubt that hormones are involved, but the effects of the various
endocrine glands responsible for all the observed internal changes have not been
identified.

Seasonal migrations are difficult to interpret because of coinciding physical
changes such as temperature, day length, and river discharge. Seasonal variations in
rainfall with resultant changes in river discharge cause fluctuations in the .salinity of
estuaries and movements of isohalinc lines. Gunter, Chrisimasand Killibrew (1964)
attribute the seasonal fluctuations of faunal assemblages in the northern Gulf of
Mexico in part to the effect of alternating wet and dry seasons on salinity. Varia-
tions in river discharge may also be of importance to anadromous fishes which may
make use of rheotaxis in locating mouths of rivers and in choosing one stream over
another during the course of their migrations (Russell 1937, Vilter 1944).

In describing seasonal movements of fishes in and out of the bays of the
Texas coast, Gunter (1945) pointed out that they coincide with temperature cycles.
Although it is difficult to attribute such migrations to a single factor, temperature
undoubtedly contributes to observed phenomena because of its effect on metabo-
lism and therefore on active transport mechanisms. Temperature is known to affect

440

Gunter, Ballard, and Venkataramiah

osmoregulatory ability. At low temperatures sodium and chloride levels in the blood
increase in marine fishes (Pearcy 1961, Gordon et al. 1962) and decrease in fresh-
water fishes (Parvatheswararao 1967, Houston and Madden 1968), indicating inhibi-
tion of active transport mechanisms and decreased osmoregulatory ability. This
effect has been verified in studies of euryhaline fishes. At low temperatures blood
sodium and chloride decrease in freshwater adapted fishes (Toews and Hickman
1969) but increase in the blood of the same species adapted to salt water (Rao
1969).

Reduction in ability to maintain normal salt concentration of the blood
would tend to stimulate movement of euryhaline fishes out of low-salinity waters at
low temperatures, in accordance with observed mass movements out of Texas bays
with the approach of winter, as described by Gunter (1945).

Fresh water with a higli calcium content favors maximum invasion by marine
species (Breder 1933). Calcium reduces permeability and, therefore, passive inflow
of water and loss of salts, Active hyperregulation is not required, and even some
otherwise stenohaline marine fishes enter such waters. A high calcium level probably
accounts for the large number of marine species found in Florida fresh waters.
Odum (1953), however, attributes their presence to the high chloride content of
these waters.

Gunter (1945, 1947, 19.57a, 1961a, 196 lb) has reiterated many times the
correlation of salinity with size of motile euryhaline animals, with the smaller sizes
occurring in lower salinities. Many of the small fishes found in low-salinity waters
are the young of species that live at sea as adults but exhibit the typical estuarine
life cycle already described for large motile invertebrates such as crabs and shrimp.
June and Chamberlin (1959) mentioned these questions with regard to menhaden.
Spawning takes place in offshore waters and the larvae move slioreward to low salin-
ities to feed and grow. After a time they return to the sea, and since their seaward
migration is accompanied by growth, there is a direct relationship between size and
salinity. The relationship is related to life cycle and might be considered behavioral.
There is little doubt that a period of growth in nutrient rich waters where they may
escape from less euryhaline predators is advantageous to young fishes, but the need
to reach low salinities is more than behavioral. Physiological adaptations have devel-
oped that appear to require that early growth take place in low salinities. The
ability of small fishes to tolerate greater dilutions than larger specimens may be
related to size of gill area in relation to body size. Keys (1931) was able to cor-
relate ratio of head length to body length with salinity tolerance in the Pacific
killifish, Fundulus paryipinnis. He concluded tliat small fishes have a relatively
larger gill area than larger ones and are better able to cope with the increased
respiratory demands imposed by a dilute environment.

Hormonal influence on migration and osmoregulation is not clear. Observa-
tions of thyroid activity indicate that this gland is involved in adaption to varying
salinities and in producing internal changes related to migration, but its control of
osmotic processes is questionable (Koch and Heuls 1942, Hoar 1951, Kawamoto
et al, 1958, Harris 1959). Because of the known role of the pituitary and adrenal
glands in water and salt regulation in mammals, attempts have been made to demon-
strate that these glands are involved in osmoregulation in fishes (Keys and Bateman

Salinity Problems

441

1932, Burden 1956, Pickford 1959). The results have been almost completely
negative. However, Burden found that hypophyseclomized F. heterocUtus dies in
fresh water but not in sea water. He attributed the deaths to lack of some as yet un-
known pituitary factor necessary to maintenance of the mucous cells of the gills.
The fishes in fresh water lost considerable amounts Of chloride ^ but the chloride
secreting cells appeared unaffected, pointing to a protective role of the mucous
cells.

Changes in osmoregulatory ability have been correlated with breeding activity
in some studies. Gueylard (1924) and Koch and Heuts (1943) observed reduced
tolerance to sea water during the breeding season in normally euryhaline stickle-
backs which breed in fresh water.

Several workers have noted internal changes that might induce migration in
anadromous and catadromous fishes. These species meet particularly complex osmo-
regulatory problems. Often they are stenohaline at a given stage in their life cycle,
yet they must completely reverse osmoregulatory processes at some point as they
pass from one osmotic extreme to another. The picture is complicated by species
differences in life cycles and by different osmotic responses a I different ages.
Reviews of osmoregulation in anadromous and catadromous fishes are given by
Black (1951a), Potts and Parry (1964a), and Hickman and Trump (1969). The
variations in life cycles are too numerous to describe in detail here, but a few
examples are given below:

(1) Anadromous lampreys. Except for the handling of divalent ions, lamp-
reys in the sea and in brackish water osmoregulate in essentially the same manner as
marine teleosts. As the adults ascend rivers to spawn they become less and less
tolerant of sea water, and they finally become stenohaline freshwater fishes. They
are more permeable than freshwater teleosts, but they handle greater water uptake
by excretion of larger amounts of urine. Once they become adapted to fresh water
they cannot return to the sea, and they die after spawning. Little is known of
osmotic adaptations of the ammocoete larvae as they migrate seaward. Gordon
(1968) states that they are euryhaline, but he gives no supporting evidence nor
indication of the age at which they become euryhaline. Freshwater lampreys osmo-
regulate in the same fashion as freshwater teleosts.

(2) Shad (Alosa sp.J. Adult shad are unable to osmoregulate in fresh water.
Their blood concentration falls as they migrate up rivers. Most individuals die after
spawning, but some survive to make their way back to the sea. The latter survive
changes in salinity because of an ability to tolerate changes in blood concentration
rather than ability to osmoregulate (Fontaine 1930).

f3J Salmonids (Salmon and trout). Salmonids vary in their life cycles and
show corresponding variations in osmoregulatory responses. Most are anadromous,
but some races complete their life cycles in fresh water. Examples are the rainbow
trout, Salmo gairdnerii and the brown trout, S. trutta. They are typical freshwater
hyperregulators but retain their ability to hyporegulate. When placed in sea water
Iheir osmotic behavior is no different than that of anadromous races of the same
species.

442

Gunter, Ballard, and venkataramiah

Adults of some species of anadromous salmon die after spawning whereas
others return to the sea. The Pacific genus Oncorhynchus does not survive after
spawning but the Atlantic and Pacific Salmo does. The survival of the adults of
some species and the death of others is not attributable to differences in osmo-
regulatory ability since blood concentration differs little in the two groups.

There are, however, differences in osmotic behavior of the young of various
species which can be related to differences in life cycles, Comparative studies have
shown differences in chum salmon (O. keta) and coho salmon {O. kisutch). Chum
salmon migrate to sea Immediately after hatching. The fry are euryhaline and can
withstand transfer back and forth between fresh and sea water. Coho salmon, how-
ever, remain in fresh water for a year before moving seaward. The fry are stenohaline
and can withstand direct transfer to salinities no higher than 14 %o. When chum
and coho fry are placed in sea water they both initially lake on chloride ions. How-
ever, the chum fry soon begin to excrete these ions, and the blood returns to nonnal
within 36 hours. On the other hand, coho fry continue to take on chloride until
death occurs (Black 1951b). The development of a chloride secreting mechanism
necessary to movement to the sea occurs at different ages in different species. Hoar
(vide Black I95Ib) found chloride secreting cells in chum salmon at the fry stage
but was unable to discern them in coho salmon until they reached the yearling stage
just prior to migration to the sea.

Keys (1933) and Copeland (1948) suggest that development of chloride secret-
ing cells in euryhaline fishes is stimulated by increased blood chloride due to
increased environmental salinities and subsequent drinking of sea water. However,
the development of these cells is not environmentally induced in young salmon
since they develop prior to migration while the fish is still in fresh water. Rather,
their development is controlled by some internal factor or factors which produce
changes that, in effect, seem to force the young fish to seek higher salmilies. In
addition to increased salt loss due to development of chloride secreting cells, salmon
have been found to lose body fat or show a change in type of fai at the time of
smolt metamorphosis, There is an increase in cholesterol/fatty acid ratio which is
postulated to result in tissue imbibition of water (Lovern 1934), Increased water
uptake coupled with increased salt loss could stimulate young salmon to seek a
more concentrated environment. Similar changes have been noted in the adult eel
just prior to its seaward migration (Fontaine 1948). In summary, adult salmon
enter fresh water to spawn but they vary in their ability to return to the sea. Young
salmon vary in the time spent in fresh water and in the development of chloride
secreting cells.

(4) Eels. Eels are euryhaline from the elver stage, the time at which they
reach coastal waters, until, maturity (Firly 1932). The freshwater adults have low
permeability to water, and the glomerular kidneys are able to handle water excre-
tion with low urine output. The kidneys must also function in almost complete
reabsorption of salts since the gills, though effective in salt secretion, are ineffective
in chloride uptake (Krogli 1937). As in young salmon, adults ready to migrate from
fresh water to the sea e.xhibil chloride loss and reduction in fat (Fontaine and
Callamand 1940). Nothing is known of the physiology of adults after they migrate
to sea to spawn or of the early leplocephalus larval stage.

Salinity Problems

443

Freshwater fishes that are sometimes found in estuaries are not truly eury-
haline. Their appearance in the estuary is usually correlated with periods of heavy
rainfall or some other condition that reduces the salinity. Most freshwater species
can tolerate environmental salinities no higher than their normal blood concentra-
tion. and few preferentially choose to leave fresh water at all. Certain species, how-
ever, are regularly found in inshore estuarine waters. A notable example is the
alligator gar, Atractosteus spathula, of the Gulf coast. The heavy ganoid scales
together with the somewhat reduced gill area in relation to body size of this air-
gulping fish probably make it less permeable than most freshw'ater teleosts.

Stenohaiine marine fishes cannot ordinarily withstand salinities lower than
their normal blood concentration, Migrations into estuaries are correlated with
seasonal variations in salinity or periods of unusually high salinity due to droughts
or otlier factors. The movement of marine fishes into fresh waters of high calcium
content has already been mentioned. These fishes are not strictly euryhaline in the
general sense of the word.

In summary » as stated by Gordon (1962), the euryhaline lampreys and teleosi
fishes are excellent osmoregulators and can generally hold witliin 10% of constancy
over a range of 0.1 to 31 %o. About 90% of the osmotic regulation concerns NaCl.
The blood salt concentration of the elasmobranch fishes (Chondryichthyes, sharks
and rays) are comparable with those of other fishes. Additionally, they have a high
blood content of urea and trimcthylamine oxide which raises the osmotic pressure
to hypertonic even in sea water. By dropping this organic concentration in ways
unknown, many species become euryhaline. They can drop excessive salt loads by
excretion through rectal glands.

OSMOREGULATION IN VERTEBRATES OTHER THAN FISHES

Included among the relatively few tetrapods that have invaded marine or
brackish waters are various species of turtles, crocodiles, iguanas and water monitors,
certain snakes, whales and other cetaceans, seals and their relatives, and some
amphibians. A number of birds are also classed as marine.

Except for the amphibians, these animals arc all hypo-osmotic air breathers
with internal respiratory surfaces. Few amphibians are truly marine, but several
species of toads and frogs enter brackish waters. Their permeable skins pose osmo-
regulatory problems not faced by other tetrapods, and the problems are not solved
in the same way by all amphibians. The European green load, Bufo viridis, with-
stands salinities up to 19 %© by tolerating increased blood concentration with
increased salinity (Gordon 1962). The major substances contributing to the in-
creased blood concentration are sodium and chloride. A different adaptive mecha-
nism is used by the frog, Rana cancrivora, which inhabits mangrove swamps of
southeastern Asia. R. cancrivora can withstand even higlter environmental salinities
than B. viridis (up to 28 ®/oo). The salt concentration of the blood is lower than
that of the surrounding water, but tJie total osmoreconcentration is increased by a
high urea content (Gordon et al. 1961). Thus, this frog osmorcgulates in much the
same manner as elasmobranch fishes. Since the urine salt content is low in spite of
inward diffusion of salts, an extrarenal pathway for salt excretion must exist.

444

Gunter, Ballard, and Venkataramiah

In this country the salt water Reptilia are the diamondback terrapin, from
Cape Cod to south Texas, the alligator from Virginia to Texas and the American
crocodile in south Florida. Generally these animals move in and out wth tlie
salinities they prefer and which nobody knows much about. The crocodile is more
of a salt-water animal than the alligator, but the alligator has been seen swimming a
mile out in the Atlantic off South Carolina and large ones are sometimes taken in
trawls off the Louisiana coast. Water moccasins are commonly found in brackish
water marshes, such as around the Gulf Coast Research Laboratory, but no one
knows exactly what the salinity influences are. Most probably they are all indirect,

Tliere are also four species of marine turtles that haul out on the sea beaches
to lay eggs from South Carolina southward. Occasionally, some of these animals are
found in the lower bays. Presumably, they arc never hurt by salinity changes unless
heavy rains wash down the beaches and destroy the eggs by wetting them, washing
them out or packing' the sand so the young cannot get out after they hatch.

After heavy rains and flooding the senior author once picked up a common
snapping turtle swimming at the mouth of Biloxi Bay. The salinity record was lost.
Following a harsh drought on the south Texas coast, from 1948-1958, the diamond-
back terrapins of the brackish waters of Copano Bay were forced to leave because
their environment became hypersaline, up to 61.0 per mille. They made their way
some forty miles to the coastal passes where, being in a weakened condition, some
were captured by hand and kept for a few years on the dock laboratory of the
Institute of Marine Science at Port Aransas,

Marine reptiles and birds have orbital or nasal salt glands that are histologically
and functionally similar to the rectal glands of elasmobranchs. They, too, secrete a
concentrated sodium chloride solution, thus allowing excretion of salts with mini-
mum water loss. Birds further conserve water by excreting a hyperosmotic urine.
The kidneys of marine reptiles and birds are unable to excrete large salt loads and
thus these animals would die in high salinity environments were it not for the extra-
renal pathways for salt excretion.

The blood of birds and reptiles, as well as that of mammals, is hypo-osmotic
to sea water but since all these animals are impermeable, they do not face a need to
get rid of excess salts taken in by diffusion. Although water loss is kept at a mini-
mum, some is lost in excretion of nitrogenous wastes and from the Iung.s and must
be replaced. Presumably, the salt glands of marine birds and reptiles could handle
excess salts taken in by drinking sea water but with the exception of the albatross,
these animals are not known to drink sea water. Their methods of handling excess
salts and of replacing lost water are not clear. Mammals that feed on fishes have the
advantage of osmotic work already done by their prey; that is, their food has a salt
content nearly the same as that of their own body fluids. Those that eat in-
vertebrates, however, take in food of nearly the .same concentration as sea w'aler.
Some scientists have not ruled out the possibility of an extrarenal structure for
secreting salts (Fetcher and Fetcher 1942, Potts and Parry 1964a), Others believe
that the hyper-osmotic urine produced by mammals is sufficient to handle excess
salts. Some workers have made calculations which indicate that marine mammals
can maintain osmotic equilibrium on either a fish or an invertebrate diet with no
other water source and without extrarenal salt secretion. Calculations have been

Salinity Problems

445

made for seals (Irving et al. 1935) and for whales (Krogh 1939).

There are four marine mammals that invade the bays on the Gulf. One is a
small unidentified porpoise known as the dog porpoise, which is seen occasionally
and which some of us have been after for years, but none has been captured, at
least by a cetologist. California sea lions have been reported from eastern Canada to
Miami and several locations in the Gulf (see Gunter 1968). They could undoubtedly
establish themselves on the Atlantic coast, but the escapees are generally persecuted
until tltey die out. Tlte bottle-nose dolphin, Tursiops truncatus, is the common
marine mammal of the United States coast. They invade rivers for a few miles, but
they do not stay. In the Gulf they are seldom seen beyond five miles offshore.
However, in the Atlantic off Florida some stay so much offshore that they develop
large parasitic copepods and barnacles like the whales, while others in bay waters
never have these parasites (Caldwell and Caldwell 1972).

It is well known that the manatees, Trichecus mamtus, which live on the
marine grasses of Biscayne Bay spend their resting time in the Miami River in down-
town Miami. Biscayne Bay has approximately the salinity of full sea water. No
doubt this salinity change prevents fouling growths on manatees.

As far south as North Carolina the harbor porpoise, Phocaem phocaena,
comes into the bays and still farther north, in New England, the Harbor seak/^^oca
phoca, comes in. But the salinity relationships are unknown.

SOME RELATIONS OF AQUATIC PLANTS TO SALINITY

The great efflorescence and diversity of plant species is on land and not in the
sea, in spite of the fact that more photosynthesis probably takes place in the sea.
In the sea there are the diatoms, dinoflagellates, red and brown algae, a few green
algae and that is about all. The flowering plants are miniscule in number and those
that will grow with their roots in the water are not numerous relatively, but they
form the vast marshes at the edge of the ocean.

The osmotic relationships are largely unknown. There are no organ systems
for salt excretion and ordinarily the cells cannot swell in hypo-osmotic solutions
because of the thick cell walls, but there are salt glahds present in certain vascular
plants. Some vascular plants withstand higli salt concentrations in the soil water
solution by passing the salt water through the plant and out through salt glands lo-
cated on the leaves. Others compensate by increasing the salt concentration in the
internal solution of the individual cells and thus become succulent. The mechanism
by which the remainder are able to tolerate hypersaline solution is unknown. We
know something about the salinity ranges at which the few salinophile plants wiU
live, but even this type of information is scarce.

The Louisiana Marsh, of which the east Texas and Mississippi marshes were
until recent years unbroken and continuous extensions, is the largest in the world.
Characteristics of it were described by Penfound and Hathaway (1938) and O’Neal
(1949). Unfortunately this marsh is declining rapidly and wasting away at about
17 square miles a year in Louisiana because leveeing of the Mississippi River has cut
off its sediment supply. A quantification of the loss for one area was given by

446

Gunter, Ballard, and Venkataramiah

Heuterius (1971). The importance of marsh areas is now becoming recognized
everywhere and the state legislatures of coastal states are struggling with protective
measures. Odurn (1961) maintained that 60% of Georgia’s estuarine productivity
came from the low marshes.

In recent years certain aspects of the Mississippi marshes have been examined
by Eleuterius (1972b). He has found that there are 66,931 acres of marsh; the
mainland contains 63,982 acres of salt marsh and 823 acres of freshwater marsh; of
the salt marsh 96% is dominated by Jancus roemerianus, Spartina altemiflora 3%,
S. patens 0.7% and Scirpus olneyi 0.1%. The barrier island marshes were found to
be of lower salinity than the surrounding water. He found further that /. roemerianus
increased in density but the leaves were shorter in length with increased salinity.
Hypersaline soil water conditions however, produced dwarf plants. The increase in
density was attributed to the removal of competitive species from these regions of
the marsh.

Another salinity factor was a determination of 400 grams per square meter of
freshwater marsh plants and 2 kilograms for a saltwater marsh, as standing crop,
which was also very close to the annual production. On a dry weight basis the
maximum annual production of Mississippi marshes was estimated at more than
three million tons.

Eleuterius (1972b) reported that there were over 300 species of vascular
plants in the Mississippi marshes and said, page 155, “Each estuarine system sampled
showed a progressive increase in vascular plants from saline to freshwater.” This is
a reverse gradient from that reported in animals, but it is a reflection of the fact
that the higher plants in general are salinophobes, especially with regard to sodium
chloride. He found that during the spring and early summer the plants generally
found in fresh and low-salinity waters, extended far into brackish and upper saline
marsh due to the abundance of fresh water in the spring. “The fluctuation in plant
distribution over the salinity gradient was a response primarily to changes in
salinity.”

Eleuterius (1972a) has also studied the flowering submerged plants in Mis-
sissippi Sound using the transect method. About 20,000 acres are covered with
plants. Grass beds are mostly inside the barrier i.slands. Vallisneria americana
occurred in the shallows of rivers and upper h-Ayous, Ruppia maritima was found
along muddy shores of shallow bays and bayous. North of the barrier islands, turtle
grass, Jlialassia testudinum, was next offshore and manatee grass, Cymodocea
manatorum, was found at depths of 4 to 6 feet. Some beds were mixed with all
three species.

Around Cat Island there was an area of shoal grass and algae and algae alone
some 4 to 6 square miles in extent. This consisted of mostly red, fewer brown and
very few green algae.

After this was written a summary paper by Earle (1972) on benthic algae
and seagras.scs of the Gulf of Mexico just came to hand.

Salinity Problems

447

SOME EXAMPLES OF COASTAL WORKS CAUSING
SALINITY CHANGES AND THEIR EFFECTS

Various activities occur from time to time along or near the coasts which
result in temporary or permanent changes in the salinity of coastal waters over
considerable areas. These changes may be unheralded or unrecognized and in the
long run they are forgotten. The history of the structural works are usually buried
in the stored files of a Corps of Engineers District Office, and are sometimes diffi-
cult to unearth. Nevertheless, certain instructive examples are worth examination
and we have perforce selected some which became known to the senior author over
the years. The documentation is not complete, but the cases are essentially correct
as described.

The Laguna Madre of Texas and its connecting bays, Baffin and Alazan, were
notorious for high salinities and heavy fish-kills for many years prior to the 1940’s.
Salinities up to 1 12 ppl were reported and every ten years or so before the 1940’s a
vast destruction of fishes took place. Porpoises did not venture into the area, blind
fish from the Laguna were often reported in South Texas and the higher Crustacea,
shrimp and crabs, were extremely rare or absent in the immediate area. On the
other hand, it produced large amounts of a few species of fishes and molluscs.

Tlie senior author discussed certain hydrographic features in an article for
laymen and Hedgpeth (1947) gave the first professional description of the area.
Both of us opposed the virtual damming of the upper Laguna by a dirt causeway
with only the proposed Intracoastal Waterway as the exchange area between the
Laguna and Corpus Christi Bay. We thought the high-salinity problems of the
Laguna would become devastating. Instead, as soon as the Waterway was dug the
length of the Laguna down to Brazos Santiago Pass, the whole situation grew
better and there has not been a big fish-kill in the Laguna Madre since then, even
thou^ a 50O-yeai dough I occurred from 1948 to 1958. The salinities in the I.aguna
have been materially reduced. The reason for this beneficial effect of the Waterway
is the high head of water maintained in Corpus Christi Bay by the steady southeast
winds. This causes an almost continuous flow southward through the Waterway,
flushing the Laguna out through Santiago Pass,

The Laguna Madre is still a high-salinity area but not a lethal one. Its biological
characteristics have been described in some detail by Simmons (1957).

In 1932 a sentient operator contracted to clean out the log raft in the lower
Colorado River of Texas, which at that time entered Matagorda Bay at the town of
Matagorda. This impediment to free flow of the river caused flooding for the lower
20 to 30 miles of the stream, including the county seat and courthouse, which had
been built within the. natural floodway of the river, as human structures often are.

Dynamite was placed at strategic places and exploded just in front of a flood
bearing down upon the lower river. This action was highly successful. Enou^ of
the raft was loosened and shoved out to allow the force of the water to loosen the
remainder, after which the river also removed large amounts of sediment. In short,
the lower delta was removed from the mainland and spewed out into the narrow

448

Gurn’ER, Ballard, and Venkataramiah

east arm of Matagorda Bay. Within three weeks time it crossed the bay and breached
the offshore island, commonly and erroneously known as Matagorda Peninsula. In
the process Mad Island, Dog Island and Tiger Island Oyster reefs were covered with
mud. These reefs produced approximately one-fourth of annual oyster production
of the State of Texas at that time. They were later dug up as mudshell or dead reef
shell by Parker Brothers Dredging Company. The process went on so fast that soon
after a blacktop road was laid down the east bank of the river, passing in one place
an almost buried navigation marker which said “This channel is 14 feet deep.”

Needless to say the fresh water and nutrients which formerly emptied into
Matagorda Bay and enhanced its productive e.siuarine nature now enter largely into
the open Gulf where they are dissipated quickly by the highly saline waters. Actually
the whole event amounted to a speeding up of a geological process. The Braxos
River to the east of the Colorado had gone through the same process naturally and
emptied into the sea at the time the Europeans came to Texas. Nevertheless, man-
kind probably always loses when the rivers are prevented from building up their
floodplains.

Later on* locks had to be constructed where the Intracoastal Waterway crossed
the Colorado River because the water levels were not often the same. Quite often
this permitted large amounts of fresh water to flow westward. During the 1940’s
the Waterway was cut along the edge of Oyster l^ke, which was a blind body of
water with one opening into the main part of Matagorda Bay, and highly productive
of oysters. It turned fre.sh quickly and the Oyster Lake Reef died and silted over.
The same thing happened to Deep Reef just off Oyster Lake in Matagorda Bay.
Two good oyster reefs were destroyed through lack of understanding of the effects
of freshwater flow.

Three great environmental changes have taken place since this continent was
settled by the European. The first was the destruction of the solid hardwood forest
east of the Mississippi by the subsistence farmer-not the lumberman— the farmer.
The second was the agriculturization of both the short and tall grass western
prairies and the destruction of its animals, the chiefs of which were the buffalo and
its Indian predator. The third, and possibly as important as the others, has been the
leveeing of the Mississippi River and its occlusion from its floodplain and valley.
The following quotes are from Gunter (1952):

“The alluvial plain includes both the floodplain and the alluvial plains which
are not covered by flood waters. Streams of the valley have large stage variations
and in their natural state periodically overflow their banks. Sediments deposited on
the banks by high water form natural levees sloping away from the river at a
gradient of about seven feet to the first mile; thus large flood basins, which are cut
off from the channel at low water stages, exist between the river and escarpments
of the valley. The river and its tributary streams drop sediments in these basins and
aggrade the valley. The Mississippi floodplain covers 35,000 square miles, including
15,000 square miles of deltaic plain.

“The Mississippi watershed is exceeded only by those of the Amazon and the
Congo and covers 1,224,000 square miles of approximately one-third of the United
States and 13,000 square miles of Canada. The average annual rainfall over this area

Salinity Problems

449

is about 30 inches, of which about one-fourth travels to the sea by way of the river.
The annual water discharge at the mouth of the Mississippi has been estimated at

785.190.000. 000 cubic yards and the sediment carried into the sea is between

1 .000. 000 and 2,000,000 tons a day.”

“Russell and Howe (1935) have pointed out that the Mississippi River may be
termed the ‘Father’ of Gulf coast geology and geomorphology, It has a commensu-
rate relation to the estuarine life of the region” (Gunter 1952). Le Page du Pratz
(1758) the engineer for the early French colonialists stated it differently, saying
Louisiana is a land that “is gathered from the sea.”

According to Gunter (1956a), “The annual flood made levees necessary from
the time of the first settlement of the white men in Louisiana. The first levee of the
Mississippi River was constructed around the City of New Orleans when it was
founded in 1717. It was not completed until 1727. This was in the area known as
the Vieux Carre or now the French Quarter. The levee was 5,400 feet long and
built in the form of a quadrangle because there were no adjoining levees up and
down the river and the protected area had to be completely enclosed to prevent the
backwaters from coming in behind. The levees were only about three feet high,
which was sufficient in that day. It was called in French ‘banquette.’ The enclosed
area was often muddy and impassable to pedestrians, who walked instead upon the
higlier ground of this low levee. For that reason the people of New Orleans to this
day refer to their concrete sidewalks as ‘banquettes.’ This beginning of the levee
system and the long fight against the river, which has now been carried on for two
hundred and forty years, was so small and weak that, as an indicator of future
events, it can scarcely be said to have cast its shadow before.

“More and more the banks of the main river, and finally its tributaries, were
leveed. Maps of the present system, show a complicated tracery and the total levee
system now exceeds 2,500 miles. The floods grew ever higlier as the river was cut
off from its flood basins and, in the lower river, from its distributaries (see Gunter
1956a), The Carrollton (New Orleans) gauge registered 14.95 feet in 1882. 16 feet
in 1890 and 21 feet in 1912. The greatest flood of all came in 1927, when numerous
crevasses in the lower river modified flood heights, making them useless for com-
parison.

“The flood heights have increased simply because the river has been cut off
from its vast overflow areas, which formerly covered 35,000 square miles. The
The river, probably due to its faster flow and straighter channels, has, if anything,
incised its bed and is probably deeper than ever before.

“In the southern reaches at least, the river was formerly filled with aquatic
life, not only within itself but along the channels, bayous, lakes and swamps nearby.
It was the habit of most of this aquatic life to spawn in the spring, and live in the
quiet backwaters, rather than the swift and muddy main stream. No one actually
knows what is now in the river for a biological study of it has never been made, but
the effect of flood control on the life in the main river has doubtless been quite
harmful. Within the swamps and former overflow areas the effect has also been bad
and this question is much more important than the life of the main river itself The
swamps have not been wholly destroyed. Some of them remain, although they are

450

Gunter, Ballard, and Venkataramiah

going. There is quite enough land left in the United States so that people do not
have to live in drained swamps, with all of its attendant problems. Therefore, I do
not count living space or living room as good causes for the draining of the swamp.

“Years ago Viosca (1927) pointed out some of the advantages which would
have accrued if the white man had, in the beginning, started out to live with the
river instead of fighting it. His concern was with aquatic resources, both fresh water
and marine, in the State of Louisiana. The problem is larger than that, but the ideas
presented here are an extension of his. Living with (he river entirely from the
beginning would have involved building all houses on low stilts, with low levees
only around cities on the flood plain. Thus the river would have spread out naturally
every year without harming the human population or the property along its banks.

“The Mississippi River is one of the greatest resources on this continent. Yet
it is sometimes paraphrased, and looked upon, as America’s sewer. It is used as a
sewer, as a local water supply and a navigation channel. Its more bountiful resources
are not used. It should be used as a land builder, a supplier of water for vaster
areas and as a creator of wildlife and aquatic resources. The river should be given
back some of its overflow basins, all that can possibly be spared, and not canalized
so that it hurries ever faster to the sea with its great load of the continent’s soil.

“In spite of lack of knowledge of specific problems, it seems clear that a
broad program of River Use, in all of its vastly beneficial potentialities, should
supplant flood control alone and opposition to the river. Such a program would
slowly enhance and upbuild all life along the banks of the Father of Waters, includ-
ing human society. To use the language of another day, it would increase human
felicity on earth, at least in the Mississippi Valley.”

With regard to coastal salinities, the levees are still being built right to the
mouth of the river due to Louisiana laws which cast doubt upon the ownership of
areas not behind a leveed section of the river. The present situation funnels water
out of the river and starves the adjacent areas, so that the oyster areas close by are
dying. By the same token the marshes are eroding away. Over in the Alchafalaya
area only is land building up, and there an estuarine area with extensive oyster reefs
is being created in the open sea. It has not been documented yet in print, but tlie
dichotomy of water flow exists and the continuous fanlike delta feeding the whole
Louisiana and Mississippi coast no longer exists. The estuarine area which supports
the largest fishery in North America is diminishing not through decline of water
flow, but its misdirection.

About one-fourth of the river floodplain remains. It would seem that an
economic and ecologically dirtwise program of saving this part of the Earth by
reverting the floodplain to its river is of the highest order.

A small part of the Mississippi River problem is that of the Bonnet Carre
Spillway— named for a small red cap the French liberals used to wear, called a
“Square Bonnet.” It is scheduled to overflow or to be opened when the Carrollton
flood gauge reaches 20 feet. This is set to reduce the flood pressure agamst the New
Orleans levees, where under the docks, wharves, storage areas, etc., the official trust
is not complete.

Salinity Problems

451

This spillway has been opened three times, in 1937, 1945 and 1950. The
senior writer (Gunter 1953) studied the 1950 opening carefully. The 1937 and
1950 openings were beneficial. They began in February and ended in March and
never got above 220,000 second-feet or a total of 12,000,000 acre-feet. The 1945
opening began in March and ended in May. It attained a flow of 320,000 cfs and
almost 30,000,000 acre-feet. The exposure to low salinity was longer, more intense
and at a higher temperature than at the other openings. The effect was described as
devastating. In other words, it caused a catastrophic mortality, of oysters and
associated organisms, which the other two openings did not cause (Gunter 1953,
Viosca 1938).

The oyster production in New Jersey, which came from Delaware Bay, ranged
from about 7 to 10 million barrels from 1880 to 1931. In 1932 this production was
reduced about one-half, and it remained so until 1956 when it fell sharply again.
The present production runs about 70,000 barrels or less.

New Jersey was one of the main oyster production slates of the United States
and during some years it ranked very close to the top. This stepwise decline was
caused apparently by the diversion of the river water, which normally flowed into
Delaware Bay largely to the City of New York. This was done by Federal court
order. Now the oyster industry in the State of New Jersey is virtually a thing of the
past. These developments were opposed completely by the late Dr. Thurlow C.
Nelson, the dean of American oyster biologists at that time, but his efforts were to
no avail for the needs of the oysters could not prevail over those of the people of
New York City. The oyster statistics, which are the remaining evidence and data in
this development, are given in Lyles (1965).

SOME GEOGRAPHIC CONSIDERATIONS

The northern and western Gulf of Mexico along with the area from about
Cape Canaveral, Florida, to Cape Hatteras, North Carolina, is quite similar in its
fauna. This area is known to the zoographers as the Carolinian. This area is also
labeled by the climatologists as subtropical, wet, cool. In its inshore areas this
region is biologically characterized by oysters, menhaden and blue crabs in the
estuaries in addition to the shrimp and croakers.

It is best characterized in its offshore or shallow waters as being dominated
by the penaeid shrimp and by the croaker family of fishes, the Sciaenidae. In this
region most of the estuarine organisms have the characteristic life history described
before, in which the adults spawn offshore in high-salinity waters and the young
make their way into the estuaries to grow up. When the estuaries change salinity
due to droughts or to floods the fauna changes and some of it will die out, only to
be reconstituted when conditions change to normal. This area changes to a tropical
marine fauna at about the southern end of the Indian River on the east coast of
Florida, and at about the Caloosahatchee Estuary on the west.

This is the area of the big estuaries for the United States coast and it is the
area of greatest fisheries production. The most productive of all is the stretch around
the Mississippi River, which has been previously called the Fertile Fisheries Crescent
(Gunter 1963),

452

GUNTER, Ballard, and venkataramiah

Papers from the University of Miami concerning Whitewater Bay and the
southern tip of mainland Florida, plus others concerning Biscayne Bay, have charac-
terized the tropical area at the end of the Florida Peninsula. Salinity change will not
be great in southern Florida except for hurricanes and manipulation of the waters of
Lake Okeechobee, The papers of Springer and Woodburn (1960) and Gunter and
Hall (1965) describe the west coast in the transition zone between the tropics and
subtropics. The east coast transition zone is described by Gunter and Hall (1963).

The northern and west coast of the Gulf are described by papers emanating
from the Institute of Marine Science at Port Aransas, Texas. Menhaden, shrimp and
to a smaller extent crabs and oyster fisheries arc typical of the Carolinian region.

Northward from Cape Hatteras things change rather abruptly faunistically to
temperate zone. The shrimp disappear although the menhaden, blue crabs, and the
oysters remain. The general fisheries population changes and there are even records
of lobsters taken offshore from Chesapeake Bay. The various clams and the striped
bass become more important in the fisheries. The inshore waters from the Carolinas
to the middle Atlantic states are particularly noted for the shad fisheries, the
elements of which run up (he rivers in typical anadromous fashion. The middle
Atlantic states have been characterized marine biologically by Hilderbrand and
Schroeder (1928) and the various shorter papers that have come out from the New
Jersey contingent of oyster workers and more recently from the Chesapeake Bay
laboratories of Virginia and Maryland. In recent years the Virginia Institute of
Marine Science has turned out many papers. Over the years a number of papers
from the two university laboratories and one Federal laboratory at Beaufort, North
Carolina, have described this area.

This temperate area of coast extends roughly from Cape Hatteras to Cape
Cod. To the north of Cape Cod the water becomes cooler. The offshore fauna has
been characterized by the papers of Bigelow (1924) on the plankton and Bigelow
and Welsh (1925) on the fishes of the Gulf of Maine. In general the cod and their
relatives are more abundant offshore.

One good guide to the fauna of any local area is the Fisheries Statistics of the
United States which has been published annually by the National Marine Fisheries
Service and its predecessors with more appropriate cognomens, the Bureau of Com-
mercial Fisheries and the Bureau of Fisheries.

The northern region, the cool temperate zone, is characterized by its lobster
and herring fisheries and particularly by the cod and cod-related fisheries of the
offshore waters, recently becoming greatly overexploited because of foreign fishing
boats. Unfortunately, especially in (he lower New England region, pollution is such
over-riding consideration that salinity changes do not amount to much.

The Pacific coast of the United Stales, south of Alaska, is cool temperate and
south of San Francisco Bay it is dry. Thus there are no estuaries south of there on
the California coast and as Hedgpeth pointed out, they are scarce on the Pacific
coast. Nationally there are only two worthy of the name. These are Puget Sound
and San Francisco Bay and there is or was a fairly characteristic estuarine fauna
among which was a caridean shrimp Crago nigricanda that supported a fishery

Salinity Problems

453

forty years ago. However, land filling and pollution have changed this whole area
considerably and today the only shrimp produced is Artemia, which is really not a
shrimp. It supports a thriving industr>' around the salt pans because it is used by
the ever-expanding pet fish and aquarium industry as food for young aquatic
organisms. This region has been extensively studied by the California Department
of Fish and Game under the title of Hcological Studies of the Sacramento-San
Joaquin Estuary (Skinner 1972). This constitutes the largest most extensive estu-
arine study on the West Coast. The area is of particular importance, and changing
because a so-called “Peripheral CanaT’ will carry much of northern California water
southward to drier regions of the state. Up and down the Oregon and Washington
coast there are small estuaries such as Willapa Harbor and Grays Harbor, where
oysters grow, as they also do in Tomales Bay, California.

The so-called Columbia River estuary is a misnomer. This area is merely the
lower part of the river, where salt water comes in and extends upstream as far as
thirty miles on the bottom or goes away completely during high water. The situa-
tion works back and forth.

In fact there is none of the great faunal exchange movement in and out of the
bays, estuaries and Uie production of vast fisheries in the nursery waters such as we
have on the South Atlantic and the Gulf coast of the United States. Similarly there
is not a great deal of information upon the salinity limits of the Pacific coast
animals and a search for this information is quite frustrating.

The situation is such that Hedgpeth (1968) remarked that the chief environ-
mental factor in the estuaries is the absence of the pounding surf, and that may well
be true. The very fine book “Between Pacific Tides” lists the habitat and a great
deal about biology of almost all of the organisms that will be encountered on the
Pacific coast, but it gives only such information as “found in low salinity waters,”
etc. This book, an original product of Edward Rickets and Jack Calvin, is becoming
more and more a contribution of Hedgpeth, wherein he has fleshed out considerably
the original conception. It is a pity that similar works for the Gulf and Atlantic
coasts do not exist. We might say, however, that the book by Gosner (1971) covers
part of the ground but not in the similar fashion. On the other hand he gives a good
bit more information on salinity, probably because on the East Coast it is more
important in the large estuarine areas.

The recent book by Remane and Schlieper (1971), “Biology of Brackish
water,” is the most complete of all on the ecology and physiology of the organisms
in low-salinity waters and no student of these areas and organisms can neglect this
important source book by two men who did so much to establish knowledge in the
field. For generalities it is excellent, but data concerning specific organisms are
different from the United States coasts because there is small overlap in species.
The vast size of the Baltic estuarine area as compared to our coastal bays also
presents a somewhat different situation.

SOME GENERAL REMARKS

There are some coastal areas of the United States where there is little land

454

Gunter, Ballard, and Venkataramiaii

drainage and, therefore, relatively high salinity, but such waters comprise only a
small part of the coastline. They support a variety of species but the species do not
occur in great abundance nor do they include the many commercially important
species found in estuaries. The effect of man on life of the sea is much more likely
to be exerted on estuarine forms, since areas of heavy population tend to be around
streams and areas where streams enter the sea.

Upsetting of the ecological balance of an estuary, or estuarine pollution, can
take many forms including sewage, detergents, insecticides, factory effluents of
various kinds, thermal pollution, siltation, changes in salinity, and changes in circula-
tion patterns. Salinity effects are more likely to be overlooked than some of the
more obvious and more publicized effects. Yet dilution of salt water by excess fresh
water and vice versa can have a definite and sometimes drastic effect on the flora
and fauna of the area affected. ^Idom are there massive fish-kills from changes in
salinity. Only a sudden or drastic change that does not allow time for migration or
for adaptive osmoregulatory processes to lake place will actually produce mortality
in adult eury'haline fishes. However, there can be greater effects on the young fishes
with less mobility and less well-developed powers of osmoregulation. If the young
fishes which use the estuarine areas as nursery grounds are not killed directly,
changes in salinity that affect their food supply such as worms, shrimp, small crabs,
and so forth, will just as effectively banish them from their former habitat.

Coastal projects of various kinds may modify the salinity of estuaries. They
may change the proportions of .salt and fresh water, affect the timing of salinity
changes, alter water circulation patterns and flushing, or even convert former marsh-
lands into freshwater ponds or lakes. Impoundment of marshes for mosquito control
or construction of coastal highways that cut off marshlands from the sea can turn
these important nursery grounds for marine fishes into freshwater bodies of water.
Rerouting or enlarging of channels can change water flow patterns, and rerouting of
rivers or withdrawal of water from them for irrigation purposes reduces the fresh-
water inflow into estuaries. Water control or flood control projects affect not only
the amounts of fresh water entering an estuary but also the timing. Sudden dumping
of large amounts of fresh water into an estuary on an irregular basis does not have
the same effect on living organisms as gradual, cyclic seasonal changes which allow
time for migration oi gradual acclimatization.

Estuarine species are, by the very nature of the normal physical characteristics
of an estuary, tolerant of short-term, moderate changes in salinity. But either large
scale changes for a short period of time or lesser changes for a long period can
change the kinds and distribution of organisms. If the changes are drastic and
frequent, the areas involved may become uninhabitable by either saltwater or fresh-
water species.

There is still a great deal of information to be gained about the salinity
relationships of most marine organisms. Tlie salinity ranges for most of them are
unknown and the salinity preferences, and how this varies with life stages, are
known precisely for only a few species. Even so, considering the large number of
species of organisms, what we know about them altogether seems to be almost over-
whelming. For that reason we have tried to hold to principles. Individual species
have to be considered and we have used the phyletic approach. This is reasonable

Salinity Problems

455

because the various phyla differ quite considerably in their salinity relationships.
But finally, this report will not solve the problems of the engineer. We hope that it
will open the literature and present some ideas to the biologists who must be called
to make predictions or give judgments concerning the effects of salinity changes.

Coastal projects are not necessarily harmful. When properly planned and
managed they may be beneficial. Gunter and Hall’s study (1963) of the effect of
St. Lucie Canal on St. Lucie Estuary of Florida showed no harmful effects on com-
mercial fisheries or low-salinity sports fishes. The high-salinity sports fishes that
move into the lower estuary when the floodgates are closed are temporarily driven
out when the gates are opened. But this effect is more than compensated for by the
bringing into the estuary of nutrients that can be used by small food and bait fishes
and the young of sports and commercial fishes which are normal inhabitants of
estuaries. The importance of estuarine areas as nursery grounds for a number of
marine species, particularly the Atlantic and Gulf coasts of the United States cannot
be overemphasized. Such areas arc essential for completion of the life cycles of a
number of commercially important species. Cronin et al. (1969) pointed out that
flood control measures which increase the salinity of bays may destroy certain com-
mercial species such as oysters but^ on the other hand, increasing the salinity of
low-salinity bays may increase their productivity of useful saltwater species. Viosca
(1938)and Gunter(1952, 1 953) commented on increased production of commercial
species following opening of the Bonnet Carre spillway of the Mississippi River.

Coastal engineering projects have the effect of modifying the composition
and distribution of living organisms. Although general guidelines for evaluating their
effect may be set up, every estuary is a complex ecological entity and, as pointed
out by Cronin et al. (1971), each must be studied as carefully as possible, and
predictions of possible effects must be based on specific knowledge of the particular
area involved. Such studies require coordination between engineers and biologists
as well as preconstruction and postconstruction ecological studies. In this manner,
increasingly more useful guidelines for the Corps of Engineers may be established,
and understanding of estuarine systems may be increased. Engineers and biologists
will have to work together to solve specific and finite problems in any local area for
ail of these are different in physical and biological characteristics.

ACKNOWLEDGMENTS

We are much indebted to Dr. Sewell H. Hopkins, of Texas A&M University,
who has worked up an “Annotated bibliography on effects of salinity and salinity
changes in coastal waters,” based mostly upon material in the Texas A&M University
Library. It contains 1,416 items and by no means pretends to complete coverage.
However, it is a fairly broad and selective summary on animal salinity problems of
the coastal United States. This was placed on large cards in alphabetical order by
author and it has been cross-indexed by general subject matter and by phyla and
classes of the Animal Kingdom. We have used the Hopkins bibliography particularly
on all animal groups other than Mollusca, Arthropoda and Chordata on which we
have utilized mostly our own material.

Dr. Adrian Lawler, of this Laboratory, pointed out some references we had
not seen.

456

Gunter, Ballard, and Venkataramiah

LITERATURE CITED

ABBOTT, W., C. E, DAWSON and C. H, OPPENHEIMER

1971. Physical, chemical and biological characteristics of estuaries, fn: Water and
Water Pollution Handbook, Marcel Dekker, Inc., New York, 1:51-140.

ALLEN, KENNETH

1961. The effect of salinity on the amino acid concentration in Rangia cuneata
(Pelecypoda). Biological Bulletin, 1 21 (3):4 19-424.

AMOS, WILLIAM H.

1957. Animals of the estuary. Estuarine Bulletin. (University of Delaware Marine
Laboratory), 2(6):3-4.

ANDREWS, E. A.

1915. Distribution of Folliculina in 1914. Biological Bulletin, 29(6):373-380.

1940. The snail, Neritim virginea L., in a changing salt pond. Ecology, 21:335-346.

AYALA-CASTANARES, AGUSTIN and LUIS R. SEGURA

1968. Ecologia y Distribucion de los Foraminifexos Recientes de la Laguna Madre,
Taniaulipas, Mexico. Boletin Numero 87- Universidad Nacional Autonama de
Mexico, Inslituto de Gcologia. pp. 1-89.

BAHL, K. N.

1947. Excretion in tlie Oligochaeta. Biological Review, 22: 109-147.

BALDWIN, ERNEST

1937. An introduction to comparative biochemistry vii + 112 pp. Cambridge Uni-
versity Press.

BALLARD, BUENA S. and WALTER ABBOTT

1969. Osmotic accommodation in Callinectes sapidus Rathbun. Comparative Bio-
chemistry and Physiology, 29:671-687.

BARRETT, B. B. and MARILYN C. GILLESPIE

1973. Primary factors which ihfluenx commercial shrimp production in coastal
Louisiana^ Technical Bulletin No. 9, pp. vii + 28, Louisiana Wild Life and
Fisheries Commission.

BAUMBERGER, J. PERCY and J. M. D. OLMSTED

1928. Changes in the osmotic pressure and water content of crabs during the molt
cycle, Physiology and Zoology, 1:531-544.

BAYER, FREDERICK M.

1954. Gulf of Mexico, its origin, waters, and marine life. Anthozoa; Alcyonaria.
Fishery Bulletin of the Fish and Wildlife .Service, 55:279-284.

BAYLY, L A. E,

1967. The fauna and chemical composition of some atlralassic saline waters in New
Zealand. New Zealand Journal of Marshes and Fresh Water Research, 1:105-
117.

BEADLE, L. C.

1931, The effect of salinity changes on the water content and respiration of marine
invertebrates. Journal of Experimental Biology, 8(3):2l 1-277.

1934. Osmotic regulation in Gimda ulvae. Journal of Experimental Biology, 11:
382-396.

1937. Adaption to changes of salinity in the polyehaetes. I. Control of body volume
and of body fluid concentration in Nereis diversicolor. Journal of Experimental
Biology, 14:56-70.

BELIAEV, G. M. and M. N, TSCHUGUNOVA

1952. Die physiologischen Unterschiede zwischen den Mytili (My t Hus) der Barentsee
und dcr Ostsee. Vortr. d. Akad. d. Wiss. d. UDSSR. Okologie 85:223-236.
In: W. T. W. Potts dnd G. Parry, 1964. Osmotic and ionic regulation in ani-
mals. The Macmillan Company, N.Y. 423 pp.

BERGER, V. Ya., and V. K. LEBSKIl

1969. 1 zmenenii solenostno ustoichioosti v ontogeneze polikheiz Eulalia viridis (L.)

(Change of salinity resistance during ontogeny of the polychzete Eulalia viridis
(L.) Dokl. Akad. Nauk. SSSR, 186(6):1422-1428.

BERNARD, CLAUDE ^

1878. Le probleme de la physiologic generale. In: La science experimentale. Pp. 99-
148. Paris; Balliiere et Fils.

SALINITY Problems

457

BERRY, EDWARD W.

1929. Paleontology. McGraw-Hill Book Company, Inc. New York, London, xii + 392.

BETHE, A.

1908. Die Bedeutung der Elektrolyten fur die rhytmischen Bewegungen der Medusen.

1. Theil: Die Wirkung der in Seewasser enthalthenen Salzc auf die normale
Meduse. Pfluger’s Archiv fur die gesamte Physiologic des Mensclien und der
Tiere, 124:541-577.

1930. The permeability of the surface of marine animals. Journal of General Physi-
ology, 13:437-444.

BEAUDANT, F. S.

1816. Sur la possibility de faire vivre dc Mollusqucs d’cau douce dans les eaux salines
et des Mollusques marins dans les eaux donees. Annales de Chimie et de
Physique, 2:32-41.

BIGELOW, HENRY B.

1924. Plankton of the offshore waters of the Gulf of Maine. Bulletin of the United
States Bureau of Fisheries, Volume 40, pt, II, 509 pp.

BIGELOW, HENRY B., and W. W. WELSH

1925. Fishes of the Gulf of Maine. Bulletin of the United Slates Bureau of Fisheries,
Volume 40, pt. 1, 567 pp.

black, V. S.

1948a. Changes in density, weight, chloride and swim-bladder gas in the killifish,
Fmdulus heterodiius, in fresh water and sea water. Biological Bulletin, 95:
83-93.

1948b. Unpublished report. In: W. S. Hoar and D. .1. Randall (eds.). Fish Physiology.
I. Academic Press. N. Y.

1951a. Osmotic regulation in leleost fishes. In: Some aspects of physiology of fish.

Ontario Fisheries Research Laboratory, 71:53-^89. (University of Toronto
Biological Service 59).

1951b. Changes in body chloride, density and water content of chum {Qncorhynchus
keta) and coho iO. kisulch) salmon fry when tran.sferred from fresh water to
sea water. Journal of Fisheries Research Board of Canada, 8:164-176.

1957. Excretion and osmoregulation. In: M. E. Brown (Ed.) The physiology of
fishes. I. Academic Press, New York, 163-205,

BOSCHUNG, H. T. and GORDON GUNTER

1962. Distribution and variation oi Branchiostoma caribaeum in Mississippi Sound.
Tulane Studies in Zoology, 9(5):245-257.

BRATTSTROM, H.

1954. Note.s on Victorellu pavida Kent. Lunds University arsskrift. N.F. 50(9): 1-29.

BREDER, C. M., JR.

1933. The significance of Ca to marine fishes on invading fresh water. Anatomical
Record. 57:57.

BRICTEAUX-GREGOIRE, S., G. DUCHATEAU-BOSSON, C. JEUNIAUX and M. FLORKIN

1964. Conslituants osniotiquemenl actifs des muscles adducteurs de My tilus edulis
adapiee a I’eau de mer ou a I’eau saumatre. Archives Internationales de
Physiologie et de Biochemie. 72:1 16-123.

BROWN, F., and W. D. STEIN

1960. Water, electrolyte and nonclectrolyte balance. /«; M, Florkin and K. S. Mason
(eds.). Comparative Biochemistry. II. Academic Press, New York. 685 p.

BULGER, R.

1 963. Fine structure of the rectal (salt-secreting) gland of Squalus acanthias. Anatom-
ical Record. 147:95-127.

BURDEN, C E.

1956. The failure of hypophysectomized Fundulus heteroclitus to survive in fresh
water. Biological Bulletin, 110:8-28,

BURGER, J. W.

1965. Roles of the rectal gland and the kidneys in salt and water excretion in the
spiny dogfish. Physiological Zoology, 38:191-196.

Problems in the electrolyte economy of the spiuy dogfish, Squalus acanthias.
In: P. W. Gilbert, R. F. Mathewson, and D, P, Rail (eds.), Sharks, skates and
rays. pp. 177-185. Johns Hopkins Press, Baltimore, Maryland.

1967.

458

Gunter, Ballard, and venkataramiah

BURGER, J. W. and W. HESS

1960. Function of the rectal gland in the spiny dogfish. Science 131:670-671.

CALDWELL, DAVID K. and MELBA C. CALDWELL

1972, Ihe World of the Bottlenosed polphin. pp. 1-157. J. B. Lippincott Company,
Philadelphia and New York.

CAPSTICK, C. K.

1959. Tire distribution of free-living nematodes in relation to salinity in the middle
and upper reaches of the River Blyth estuary. Journal of Animal Ecology,
28{2):189-210.

CARLGREN, OSKAR and JOEL W, HEDGPETH

1952. Actinaria, 2!!oantliaria and Ceiiantharia from shallow water in the northwestern
Gulf of Mexico. Publications of the Institute of Marine Science, 2(2); 143-172.

CASPERS, H.

1967. Estuaries. Analysis of definitions and biological considerations, pp. 6-8. In:

Lauff, G. H., ed. Estuaries. American Association for the Advancement of
Science. No. 83. Washington, D. C., xv + 757 pp.

CASTAGNA, M. and P. CHANLEY

1973. Salinity tolerance of some marine bivalves from inshore and estuarine environ-
ments in Virginia waters on the western mid-Atlantic coast. Malacologia, 12(1):
47-96.

CHAN, D., J. PHILLIPS, and T. JONES

1967. Studies on electrolyte changes in the lip-shark Hemiscyllurn plagiosum (Ben-
nett) witli special reference to hormonal influence on the rectal gland. Com-
parative Biochemistrj' and Physiology, 23:185-198.

CHITWOOD, B. G.

1951. North American marine nematodes. Texas Journal of Science, 3(4):617-672.

CHITWOOD, B. G., and R. W. TIMM

1954. Free-living nematodes of the Gulf of Mexico. Gulf of Mexico, its Origin,
Waters, and Marine Life. Fishery Bulletin 89. Fishery Bulletin of the Fish and
Whdlife Service. 55.313-323.

CHRISTMAS, J, Y. and WALTER W. LANGLEY

1973. Estuarine invertebrates, Mississippi, In: Cooperative Gulf of Mexico Estuarine
Inventory and Study, Mississippi, Phase IV - Biology, pp, 255-319. Gulf
Coast Research Laboratory, Ocean Springs, Mississippi.

CLARKE, F. W.

1924. The data of geochemistry: U. S. Geological Survey Bulletin, 770:1-841.

COE, W. R.

1954. The nemertean fauna of the Gulf of Mexico, pp. 303-309. In: Gulf of Mexico,
its Origin, Waters, and Marine Life. Fishery Bulletin of the Fish and Wildlife
Service, Volume 55, Washington.

CONKLIN, R. and A. KROGH

1938. A note on the osmotic behavior of Eriocheir in concentrated and Mytilus in
dilute sea water. Zeitsclirift fur vergleichende Pliysiologie. 26:239-248.

CONTE. F. P.

1969. Salt secretion. In: W. S. Hoar and D. J. Randall (eds.), Fish Physiology, pp.
241-292. Academic Press, New York.

CONTE, F. P. and H. WAGNER

1 965. Development of osmotic and ionic regulation in juvenile steelhead trout, Salmo

^airdneri. Comparative Biochemistry and Physiology, 14:603-620.

COPELAND, D. E.

1948. Tlie cytological basis of chloride transfer 'm the gills of Fundu/ux /reteroc/irus.
Journal of Morphology, 82:201-208.

1950. Adaptive behavior of the chloride cell in the gill of Fundulus heterocUtus.
Journal of Morphology, 87:369-379.

COSTLOW, J. D., JR. and C G. BOOKHOUT

1959. The larval development of Cailinectes sapidus Rathbun, reared in the labora-
tory. Biological Bulletin. 116:373—396.

COWLES, R. P.

1930. A biological study of the offshore waters of (Chesapeake Bay. Bulletin of the
United States Bureau of Fisheries, 48:277-381.

Salinity Problems

459

CROGHAN, P. C.

1958. The survival of Artemia salim. (L.) in various media. Journal of Experimental
Biology, 35:213-242.

CRONIN, L. E„ JOANNE C. DAIBER and E. M. HULBERT

1962. Quantitative seasonal aspects of zooplankton in the Delaware River estuary.
Chesapeake Science, 3(2)t63-93.

CRONIN, L, E.. G. GUNTER and S. H. HOPKINS

1969. Effects of engineering activities on coastal ecology. Interim report. United
States Corps of Engineers. 40 pp.

1971. Effects of engineering activities on coastal ecology. Report to the Office of the
Chief of Engineers. 48 pp. Corps of Engineers, U. S. Airoy.

DAHL, E.

1956. Ecological salinity boundaries of poikilohaline waters. Oikos. 7:1-23.

DANGLADE, ERNEST

1919. The flatworm as an enemy of Florida oysters. Report U. S. Commercial Fish-
eries, 1918, App. V, U. S. Bureau of Fisheries, Document No. 869:1-8, pis. I
and II.

DAVIS, CHARLES C.

1948. Gymnodinium brevis sp. nov., a cause of discolored water and animal mortality
in the Gulf of Mexico. Botanical Gazette, 109(3): 358-360.

1953. Concerning the flotation mechanism of A^oc/j7ucc. Ecology, 34(1): 190- 192.

DAWSON, C. E.

1965, Rainstorm induced mortality of lancelets, Branchiostonm, in Mississippi Sound.
Copeia, 4:505-506.

DAWSON, C. E. and F. G. WALTON SMITH

1953. The Gulf of Mexico sponge investigation. Florida Stale Board of Conservation.
Technical Series, No. I. 28 pp.

DENNE, L. B,

1968. Some aspects of osmotic and ionic regulation in the prawns Afnc/iroftrac/iium
australiense (Holthuis) and M. equidens (Dana). Comparative Biochemistry and
Physiology, 26:17-30.

DICE. JAMES F., JR.

1969. Osmoregulation and salinity tolerance in the polychaete annelid Cirriformia
spirabrancha (Moore 1904). Comparative Biochemistry and Physiology, 28:
1331-1343.

DITTMAR, W.

1884. Report on researches into the composition of ocean water, collected by
H. M. S. (Challenger. Challenger Reports. Physics and (Chemistry, 1:1-251.

DREGOL^SKAYA, I, N.

1961 . Viryanie solenosti morskoi vody na rcploustoichivost’ mertsaternogo epiteliya

aktinii. English title (The effect of sea water salinity on heat resistance of

ciliated epithelium of Actinia), Tsilologiya 3(4):475-477, Referativnyi
^ zhurnal. No. 23A236.

DUCHATEAU. G. and M. FLORKIN

1955. Concentration du milieu exterior el etat stationnaiie du pool des amines non
proteiquesdes muscles. Archives internationales de physiologic et de biochimie,
^ 63:249-251.

DUCHATEAU-BOSSON, G., M. FLORKIN and C. JEUNIAUX

1961. R8le de la variation de la composanie amino-acide intracellulaire dans I’eury-
halinite d’Arenicola marina L. Archives internationales de physiologic et de
biochimie, 69:30-35.

DU PRATZ, LE PAGE

1758. Histoire de la Louisiane, 2 volumes. Paris.

EARLE, S. A.

1972. Benthic algae and seagrasses, pp. 15-18 in Chemistry, primary productivity
and benthic algae of the Gulf of Mexico, pp. 1-29, 6 plates. Folio 22, Serii
Atlas of the Marine Environment. American Geographical Society.

EBBS, N. KENNETH, JR. and JON C. STAIGER

1965. Some osmotic adaptations of Onuphis magm (Polychaeta: Onuphidae). Bul-
letin of Marine Science, Gulf & Caribbean. 15:835-849.

460

Gunter, Ballard, and Vrnkataramiah

EDWARDS, J. G.

1928. Studies on aglomerular and glomerular kidneys. I. Anatomical. American
Journal of Anatomy, 42:75-107.

EDWARDS, J. G. and C. SCHNITTER

1933. Tlie renal unit in the kidney of vertebrates. American Journal of Anatomy,
53:55-87.

ELEUTERIUS, LIONEL N.

1971. Recent changes in the Louisiana Marsh near Vermilion Bay. Gulf Research
Reports, 3(2):259-263.

1972a. Submerged plant distribution in Mississippi Sound and Adjacent waters. Journal
of the Mississippi Academy of Sciences, 17:9-14,

1972b, The marshes of Mississippi. Castanea, 3W30):153-168.

ELLIS, W. G.

1937. The water and electrolyte exchange of Nereis diversicolor (Muller). Journal
of Experimental Biology. 14:340-350.

1939. Comparative measurements of water and electrolyte exchange in a stenohaline
and in a eury haline polychaete. Journal of Experimental Biology, 16:483-486.

EMERY, K. O.

1967. Estuaries and lagoons in relation to continental shelves. Pp. 9-1 1. In: Lauff,
C. H. (ed.). Estuaries. American Association for the Advancement of Science.
Publication No. 83. Washington, D. C., xv + 757 pp.

EMERY, K. O. and R. E. STEVENSON

1957, CTiapter 23. Estuaries and lagoons. Treatise on Marine Ecology and Paleo-
ecology. Vol. 1. Ecology. Pp. 673-749. Memoir 67, Geologic^ Society of
America.

ESTCOURT, I, N.

1967. Ecology of bejithic polychaetes in the Heathcote Estuary, New Zealand. New
Zealand Journal of Marine and Freshwater Research, 1:371-394.

FEELEY, j. B. and M, L. WASS

1971. The distribution and ecology of the Gammaiidea (Crustacea; Amphipoda) of
the lower Cliesapeake estuaries. Special Papers In Marine Science No. 2, pp.
iii-58. (Processed) Virginia Institute of Marine Science.

FETCHER, E. S. J. and G. W. FETCHER

1942. Experiments on the osmotic regulation of dolphins. Journal of Cellular and
Comparative Physiology, 19:123-130.

FIELD, LOUISE R.

1949. Sea anemones and corals of Beaufort, North Carolina. Duke University, Ma-
rine Station Bulletin No. 5, pp. 1-39.

FINGERMAN, MILTON and LAWRENCE D. FAIRBANKS

1956, Osmotic behavior and bleeding of the oyster Crassostrea virginica. Tulane
Studies in Zoology, 3:151-168.

FIRLY, S. B.

1932. Influence des variations de salinite sur la pression osmotique des civelles.

Compte rendu des seances et memoires de la Societe de biologic, 110:247—
248.

FONTAINE, M.

1930. Modifications du milieu interieur des poissons potamotoques au cours de la
reproduction. Compte rendu de TAcademic bulgare des sciences, 191:736-
737.^

1948. Du role joue par les facteurs internes dans certaincs migrations de poissons;

Etude critique jle diverses methodes d’investigation. Journal du Conseil, 15:
284-294.

FONTAINE, M. and 0. CALLAMAND

1940. Sur le determinisme biochimique du retour a la mer de Tanguille fcmelle
d’avalaison. Compte rendu de I’Academie bulgare des sciences, 211:357-359.

FORSTER, R. P.

1967. Osmoregulatory role of the kidney in cartilaginour fishes (Chond rich thy s). /«/
P. W. Gilbert, R. F. Mathewson, and D. P. Rail (eds.). Sharks, Skates and Rays,
pp. 187—195. Johns Hopkins Press, Baltimore, Maryland.

Salinity Problems

461

FRANKS, JAMES S., J. Y. CHRISTMAS, WALTER L. SILER, RALPH COMBS, RICHARD

WALLER and CHARLES BURNS

1972. A study ol‘ nektonic and benthic faunas of the shallow Gulf of Mexico off the
State of Mississippi, Gulf Research Reports, 4(l);iv + 148.

FRASER, J. H.

1969. Experimental feeding of some medusae and Chaetognatha. Journal of Fisheries
Research Board of Canada, 26(7)t 1743-1762.

FRETTER, VERA

1955. Uptake of radioactive sodium ( Na) by Nereis diversicolor Mueller and
Perinereis culirifera (Grube). Journal of Marine Biological Association of the
United Kingdom, 34:151-160.

GESSNER, G.

1959. Hydrobotanik, Volume 11, Deutscher Verlag der Wissenscaften. Berlin.

GILLESPIE, MARILYN C

1971. Analysis and treatment of zooplankton of estuarine waters of Louisiana. In:

Cooperative Gulf of Mexico Inventory and Study, Louisiana. Phase IV. Pp.
109-175. Louisiana Wild Life and Fisheries Commission.

GORDON, M. S.

1959. Osmotic and ionic regulation in Scottish brown trout and sea trout (Salmo
trutta L), Journal of Experimental Biology. 36:253-260,

1962. Osmotic regulation in the green toad (Bufo virtdis). Journal of Experimental
Biology, 39:261-270.

1964. Animals in aquatic environments: Fishes and amphibians. In: D. B. Dill (ed,),
Handbook of physiology, pp. 697-714. 4. American Physiological Society,
Washington, D. C.

1968. Animal funetjuu; principles and adaptations. 560 pp. The Macmillan Company,
New York.

GORDON, M. S., B. H. AMDlIR,and P. F. SCHOLANDER

1962. Freezing resistance in some northern fishes. Biological Bulletin, 122:52-62.

GORDON, M. S., K. SCHMIDT-NIELSEN, and H. M. KELLY

1961. Osmotic regulation in the crab-eating frog iRana cancrivora). Journal of Ex-
perimental Biology. 38:659-678.

GOSNER, KENNETH L.

1971. Guide, to Identification of Marine and Estuarine Invertebrates, Cape Hatteras
to the Bay of Fundy. xix + 693. Wiluy-lntcrscieiice. New York.

GOYACHEVA, N. V.

1969. Veizanie solenosti, temporary i osveschennosli na cazmnoz henie zhgotik
onostsed Bodo marina. (The effect of salinity, temperature and illumination
on the reproduction of the mastigophoran Bodo marina). Tr. Inst. Biol. Unutr.
Vod. Akad, Nauk, SSSR., 19(22): 105-108.

GRAFFLIN, A. L.

1937. Tile problem of adaptation to fresh and salt water in the teleost, viewed from
the standpoint of the structure of the renal tubules. Journal of Cellular and
Comparative Physiology, 9:469-475.

GROSS, WARREN

1957. An analysis of rc.sponsc to osmotic stress in selected decapod Crustacea.
Biological Bulletin, 112:43—62.

GUDGER, E. W.

1943. Some ctenophore fish-catchers. The Scientific Monthly, 57:73-76.

GUEST, WILLIAM C.

1959. The occurrence of the jellyfish Chiropsalmus quadrurnanus in Matagorda Bay,
Texas. Bulletin of Marine Science of the Gulf and Caribbean, 9(l):79-83.

GUEYLARD, F.

1924. De {’adaption aux chaligcments dc -salinite. Recherches biologiqueset physico-
chimiques sur I’epinoclie (Gasterosteus leiurus Cuv. et VaL). These. Paris.

GUNTER, GORDON

1938. The common blue crab in fresh waters. Science, 87(2248):87-88.

1942. A list of the fislies of the mainland of North and middle America recorded

from both fresh water and sea water. American Midland Naturalist, 28:305-
326.

462

Gunter, Ballard, and Venkataramiah

GUNTER, GORDON

1945. Studies on marine fishes of Texas. Publications of the Institute of Marine
Science, University of Texas, 1:1-190.

1947. Size of marine fishes entering fresh water. Anatomical Record, 4(99):87.

1950. Seasonal population changes and distributions as related to salinity, of certain
invertebrates of the Texas coast, including the commercial shrimp. Publications
of the Institute of Marine Science, University of Texas, 1(2):7-51.

1952. Historical changes in the Mississippi River and the adjacent marine environ-
ment. Publications of the Institute of Marine Science, University of Texas
2(2):1 19-139.

1953. Tire relationship of the Bonnet Carre Spillway to oyster beds in Mississippi
Sound and the “Louisiana marsh,” with a report on the 1950 opening. Pub-
lications of the Institute of Marine Science, University of Texas, 3(1); 17-71.

1955. Mortality of oysters and abundance of certain associates as related to salinity.
Ecology. 36(4):601-605.

1956a. Land, water, wildlife and flood control in the Mississippi valley. Proceedings of
Louisiana Academy of Sciences, 19:5-11.

1956b. Some relations of faunal distributions to salinity in estuarine waters- Ecology,
37:616-619.

1956c. A revised list of euryhaline fishes of North and middle America. American Mid-
land Naturalist, 2(56):345-354.

1957a. Wildlife and flood control in the Mississippi valley. Transactions of the North
American Wildlife Conference, March 4, 5, and 6, pp. 191-196.

1957b. Predominance of the young among marine fishes found in fresh water. Copeia
1:13-16.

1961a. Some relations of estuarine organisms to salinity. Limnology and Oceanogra-
phy, 6:182-190.

1961b. Salinity and size in marine fishes. Copeia 2:234-235.

1961c. Habitat of juvenile shrimp (family Penaeidae), Ecology, 42(3):598-600.

1963. The fertile fisheries crescent. Journal of the Mississippi’ Academy of Sciences,
9:286-290.

1967a. "Vertebrates in hypersahne waters. Contributions in Marine Science, 12:230-
241.

1967b. Some relationships of estuaries to the fisheries of the Gulf of Mexico. Pp.

621-638.//?; Lauff, G. H., (ed,). Estuaries. AAAS Publication 83. American
Association for the Advancement of Science, Washington, D. C. xv -t- 757 pp.

1 968. lire status of seals in the Gulf of Mexico with a record of feral otariid seals off
the United States Gulf Coast. Gulf Research Reports 2(3): 301 -307.

GUNTER. GORDON, B. S. BALLARD and A. VENKATARAMIAH

1973. Salinity problems of organisms in coastal areas subject to the effect of engineer-

ing works. Contract Report H-73-3. Pp. x + 1 76. U. S. Army Engineers, Water-
ways Experiment Station, Vicksburg, Mississippi.

GUNTER, GORDON and J. Y. CHRISTMAS

1959. Corixid insects as part of the offshore fauna of the seas. Ecology, 49(4):724-
725.

GUNTER, GORDON, J. Y. CHRISTMAS and R. KILLIBREW

1 964. Some relations of salinity to population distributions of motile estuarine organ-
isms, with special reference to penaeid shrimp. Ecology, 1(45): 1 81-185.

GUNTER, GORDON and JUDITH C. EDWARDS

1969. The relation of rainfall and fresh-water drainage to the production of the
penaeid shrimps {Penaeus fluviatiUs Say and Penaeus azlicus Ives) in Texas
and Louisiana waters. FAO Fisheries Report 3(57):875-892.

GUNTER. GORDON and RICHARD A.GEYER

1955. Studies on fouling organisms of the northwest Gulf of Mexico. Publications of
Institute of Marine Science, 4(1); 39-67.

GUNTER, GORDON and GORDON E. HALL

1963. Biological investigations of the St. Lucie Estuary (Florida) in connection with
Lake Okeechobee discharges through the St. Lucie Canal. Gulf Research Re-
ports, 1(5): 189-307.

Salinity Problems

463

GUNTER, GORDON and GORDON E. HALL

1965. A biological investigation of the Caloosahalchee Estuary of Florida. Gulf
Research Reports, 2Cl):l-71.

GUNTER, GORDON and H. H. HILDEBRAND

1954. Tlie relation of total rainfall of the state and catch of the marine shrimp
{Penaeus setifenis) in Texas waters. Bulletin of Marine Science of the Gulf and
Caribbean. 4(41:95-103.

GUNTER, GORDON, J. G. MACKIN and R. M. INGLE

1 964. A report to the District Engineer on the effect of spoil from the inland water-
way, Chesapeake and Delaware Canal, in upper (Chesapeake Bay. U. S. Army
Engineers District. Philadelphia, Pennsylvania, 51 pp. 3 pi. Appendix 23 pp.

GUNTER, GORDON, and W. E. SHELL, JR.

1958. A study of an estuarine area with water-level control in the Louisiana marsh.
Proceedings of the Louisiana Academy of Science, 21 :5-34.

GUNTER, GORDON, ROBERT H. WILLIAMS. CHARLES C, DAVIS and F. G. WALTON

SMITH

1948. Catastrophic mass mortality of marine animals and coincident phytoplankton
bloom on the west coast of Florida, November 1946 to August 1947. Ecological
Monographs, 18(3): 309-334.

GUNTHER, A. C. L. G.

1880. An introduction to the study of fishes, xvi + 720 pp. A. & C. Black. Edinburgh.

HAND, W. G., P. A. COLLARD, and D. DAVENPORT

1965. Tlie effects of temperature and salinity change on swimming rate in the dino-
flageUates, Gonyaulax and Gyrodinium. Biological Bulletin, 128:90-101.

HARDER, WILHELM

1968. Reactions of plankton organisms to water stratification. Limnology and Ocean-
ography, 13(1): 156- 168.

HARRIS, P. J.

1959. A study of thyroid function in Fundulus heteroclitus. Biological Bulletin,
l(117):89-99.

HAY, W. P.

1904. The life history of the blue crab, Callinectes sapidus. Report of United States
Commercial Fisheries, 347-413.

HEDGPETH, J. W.

1947. Tlie Laguna Madre of Texas. Transactions of the North American Wildlife
Conference, 12:364-380.

1950. Annotated list of certain marine invertebrates found on Texas jetties, pp.
72-86. Appendix to Whitten, Roseneand Hedgpeth. (1950).

1954a. Miscellaneous vermes. Gulf of Mexico, Its Origin, Waters and Marine Life.
Fishery Bulletin of the Fish and Wildlife Service, 55:419-420.

1954b. Phoronida. Gulf of Mexico, Its Origin, Waters, and Marine Life. Fishery Bul-
letin of the Fish and Wildlife Service, 55:367.

1957. Estuaries and lagoons. II. Biological aspects. In: Treatise on Marine Ecology
and Paleoecology. Vol. 1 J. W. Hedgpeth (ed.). Memoir 67 Geological Society
of America. 1:693-729.

1968. Between Pacific Tides. (Ricketts and Calvin) 4th Ed. Revised, xiv + 614.
Stanford University Press, Stanford, California.

HEMPEL, CHRISTINE

1957, Zur oekologie einiger Spioniden (Polycliaeta Sedentaria) der deutschen Kusten.
Kieler Meeresforsch., University of Kiel, 13:275-288.

HERRE, A. W. C. T. .

1955. Sharks in fresh water. Science, 122:417.

HICKMAN, C. P., JR., and B. F. TRUMP

1969. The kidney. In: W, S. Hoar and D. J. Randall (eds.). Fish Physiology, pp.
91-239. 1. Academic Press, New York. 465 pp.

HILDEBRAND, SAMUEL F, and WILLIAM C. SCHROEDER

1928. Fishes of Chesapeake Bay. Bulletin of the United States Bureau of Fisheries,
Volume 43, pt. 1, 366 pp.

464

Gunter, Ballard, and Venkataramiah

HILL, M. B.

1967. Tlie life cyele and salinity tolerance of the serpulids Mercierella enigynatica
(Fauvel)and Hydroidcs ucimta (Philippi) at Lagos, Nigeria. Journal of Animal
Ecology, .'?6(2):^03-321.

HOAR, W. S.

1951. Hortiioiifs in fish- hi: Some aspects of physiology of fishes. Ontario Fisheries
Research Laboratory, 71;1-51.

HOESE, H. D.

1960. Biotic changes in a bay associated with the end of a drought. Limnology and
Oceanography, 5(3):326-336.

HOGUE, E. WAYNE and LARRY C. OGLESBY

1972. Further observations on salt balance in the sipunculid worm Themiste dyscri-
lum. Comparative Biochemistry and Physiology, 42At915-926,

HOLMES, W. N. and E. M. DONALDSON

1969. The body compartments and the distribution of electrolytes. In: W. S. Hoar
and D. J. Randall (ed.s.). Fi.sh Physiology, pp. 1-89. I. Academic Press, New
York. 465 pp*

HOPKINS, SEWELL IL

1956. Notes on the boring sponges in Gulf coast estuaries and their relation to
salinity. Bulletin of Marine Science of the Gulf and Caribbean, 6(l):44-58.

1962. Distribution of species of Ctiona (Boring Sponge) on the eastern shore of
Virginia in relation to salinity. Cliesapeake Science, 3(2): 121-124,

HOPKINS, SEWELL H., J ACK W. ANDERSON arid KALMAN HORVATH

1973. Tile brackish water clam Rangia cuneato as indicator of ecological effects of
salinity changes in coastal waters. Contract Report H-73-1, U. S. Army Engineer
Waterways Experiment Station, CF,, Vicksburg, Miss.

HORNE, R. A.

1 969. -Marine Chemistry, vii t 568 pp. John Wiley & Sons. New York.

HOUSTON, A. H. and J. A. MADDEN

1968. Environmental temperature and plasma electrolyte regulation in the carp,
Cvprin us carpio. Nalu re, 217:969:970.

HUBENDICK, B. '

1948* Sur les variations de lu taille du rein cUqz Lymnaea limosa (L.). J. Conchyliol.
88 : 5 - 10 .

HUNTSMAN, A. G. and W, S, HOAR

1939. Resistance of Atlantic salmon to sea water. Journal of Fisheries Research
Board. Canada, 4:409-41 1.

IRVING, L., K. C. FISHER and F C. MC INTOSH

1935, Tlie water balance of a marine mammal, the seal. Journal of Cellular and
Comparative Physiology, 6:387-391.

JANSSON, BENGT-OWE

1962. Salinity resistance and salinity preference of two oligochaetes Akiedhlus
monospetmatecus Knocllncr and Marionina preclitellocbaeta n. sp. from the
interstitial fauna of marine sandy beaches* Oikos. 13(2): 293-305.

JEUNIAUX, G., G. DUCHA TEAU-BOSSON and M. FLORKIN

1961. Variation de la composante amino-acide des ti-ssus et euryhalinite chez Perinereis
cultrifera Gi, et Nereis diversicolor (O. F. Miillcr). Journal of Biochemistry
49(6);527-531.

J0RGENSEN, C. B. and R. P. DALES

1957. Tlie regulation of volume and osmotic regulation in some nereid polychaetes.
Physiologia Comparata et Oecologia. 4:357-374.

JUNE, F. C. and L. CHAMBERLIN

1959. Tlie role of the estuary in the life history of the Atlantic menhaden. Proceed-
ings of the Gulf and Caribbean Fisheries Institute. Eleventh Annual Session.
Pp.41-45.

KAHLER, H. H.

1970. Ueber den Einfluss der Adaptations-temperatur und des Salzgehalles auf die
llitze-und Gcfrierrcsislenz von Enchytraeus alhidus (Oligochaeta). Marine
Biology (Berlin) 5(4):3l5-324.

Salinity Problems

465

KALMUS, 11.

1929. Contractile vacuole responses in a marine ciliate. Archiv filr Protistenkunde,
66:409-420.

KANOSHIRO, E. S., P. B. DUNHAM and G. G. HOLZ, JR.

1969, Osmoregulation in a marine ciliate, Miamiensis avidus. 1, Regulation of in-
organic ions and water. Biological Bulletin, 135;63-'75.

KAWAMOTO, N. Y., T. KONDO and T. NlSHll

1958. On the salt adaptation of medaka, Oryzias talipes (T. et S.) with reference to
the influence of thyroid hormone and antithyroid agents. Japanese Journal of
Ecology, 1(8): 1-6.

KELLEY, B. J., JR. and W. D. BURBANCK

1972. Osmoregulation in juvenile and adult Cyathura polHa (Stimpson) subjected to
salinity changes and ionizing gamma irradiation (isopoda, Anthuridea). Chesa-
peake Science, Volume 13, No. 3, p, 201-205.

KEYS, A.

1931. Chloride and vva ter secretion and absorption by tlie gills of the eel. Vergleichende
Physiologie. 15:364-388.

1933. The mechanism of adaptation to varying salinity in the common eel and the
general problem of osmotic regulation in fishes. Proceedings of the Royal
Society t London) B,, 1 12:184-199.

KEYS, A. and J. B. BATEM.AK

1932. Branchial responses to adrenaline and to pitressin in the eel. Biological Bulletin,
2(63):327-336.

KEYS, A. and E. WILLMER

1932. “Chloride secreting cells’* in the gills of fishes with special reference to the
common eel. Journal of Physiology (London), 76:368-378.

KINNE, O.

1952. Zur Biologie und Physiologic von Gammams duebeni Lilij. III. Zahlenverhaltnis
der GeschJechter und Geschlecisbestimmung. Kieler Meeresforschungen, 9:
126-133.

1963. The effects of temperature and salinity on marine and brackish water animals.

I, Temperature. Oceanogr. Mar. Biol. Ann. Rev., 1:301-340.

1964. The effects of temperature and salinity on marine and brackish water animals.

II. Salinity and temperature-salinity combinations. Oceanogr, Mar. Biol.
Aim. Rev., 2:281-339.

1971, Cliapter 4, Salinity. Invertebrate.?. Pp. 821-995, In: Marine Ecology, Vol, 1,
Part 2. ix + 1244. Wiley-Inteiscicncc, London.

KLESCH, W. L.

1 970. Tlic reproductive biology and larval development of Laeonereis culvert Webster
(Polychaeta; Nereidae). Contributions to Marine Science, University of Texas,
15:71-85.

KNIGHT, JAMES M.

1966. Some biochemical aspects of osmoregulation in Crassostrea virgmico (Gmelin).

Preliminary report. Journal of Mississippi Academy of Science, 12:208-212.
KNUDSEN, MARTIN

1901. Hydrographical tables. G. E. C. Gad, Copenhagen, 63 pp.

KOCH, H, J, and M. J, HEUTS

1942. Influence dc Thormone thyroidienne sur la regulation somotique chez
Gasterosteus aculeatus L. forme gynmurus Cuv. Ann. Soc. Roy. Zool. Belgique,
73; 165-172.

1943. R^ulation osmotique, cycle sexuel et migration de reproduction chez les
epitnoches. Archives Internationales de physiologie et de biochimie, 53:253-
266.

KROGH, A.

1937. Osmotic regulation in fresh water fishes by active absorption of chloride ions.
Z. Vergleich. Physiol, 24:656 666.

1939. Osmotic Regulation in Aquatic Animals. 242 pp. Cambridge University Press,
London and New York.

466

Gunter, Ballard, and venkataramiah

KROMHOUT, G. A.

1943. A comparison of the protonephridia of fresh-water, brackish-water and marine
specimens of Gyratrix henrwphroditus. Journal of Morphology, 72; 167-181.

LADD, H. S.

1951. Brackish water and marine assemblages of the Texas coast, with special
reference to mollusks. Publications of the Institute of Marine Science, 2(1):
125-^163.

LAHLOU, B., 1. W. HENDERSON and W. H. SAWYER

1969. Renal adaptations by Opsanus tau, a euryhaline aglomerular teleost, to dilute
media, American Journal of Physiology, (In press).

LANDERS, W. S. and E. W. RHODES, JR.

1970. Some factors influencing predation by the flatworm, Stylochus ellipiicus
(Girard), on oysters. Chesapeake Science, 1 l(l):55-60.

LANDERS, W. S. and R. C. TONER

1962. Survival and movements of the flatworm, Stylochus ellipticus, in different
salinities and temperatures. Biological Bulletin, 123(1):146-153.

LANGE, R.

1963. The osmotic function of amino acids and taurine in the mussel, ATyri/MS edulis.
Comparative Biochemistry and Pliysiology, 10:173-179.

LASSERE, P.

1970. Action des variations de salinite sur le metabolisme respiratoire d’Oligocheies
euryhalins du genre Marionina Michaelsen. Journal of Experimental Marine
Biology and Ecology, 4(2); 150-155.

LAZAREVA, L P.

1961. O pogloshchenii kisloroda grebnevikami Pleurobrachw pileus O, F. Muller,
raznykli razmerov v zavisimosti ot temperaturyi solenosti ok ruzhayushchei
sredy. Tr. Karadagsk. Biol. Sta. Akad, Nauk. Uzbeksk. SSR. 17:85-96.
Referai. Zhur., Biol, 1963, No. 1D62.

LIENEMANN, LOUISE JOANNE

1938. The green glands as a mechanism for osmotic and ionic regulation in the cray-
fish {Cambarus c/ar/rn Girard). Journal of Cellular and Comparative Physiology,
11:149-161.

LINDNER, MILTON J. and WILLIAM W, ANDERSON

1 956. Growth, migrations, spawning and size distribution of shrimp Penaeus setifents.

United States Fish and Wildlife Service, Fisheries Bulletin No. 106, 56:555-
645,

LOCKWOOD. A. P. M.

1960. Some effects of temperature and concentration of the medium on the ionic
regulation of the isopod, Asellus aquatkus (L.). Journal of Experimental
Biology, 37:614-630.

1961. The urine of Gammarus deubeni and G. pulex. Journal of Experimental
Biology, 38:647-658.

1962. The osmoregulation of Crustacea. Biological Review, 37:257-305.

1967. Aspects of the physiology of Crustacea, W. H. Freeman and Company, San
Francisco, California, x + 328 pp.

LOESCH, H. C.

1 965. Distribution and growth of penaeid shrimp in Mobile Bay, Alabama. Publica-
tions of the Institute of Marine Science, University of Texas, 10:41-58.

LOOSANOFF, V. L.

1959. Condylostonw ^an enemy of bivalve larvae. Science, 129(3342): 147.

LOOSANOFF, V. L. and J. B. ENGLE

1943. Poiydora in oysters suspended in the water. Biology Bulletin, 85(l):69-78.

LOSOVSKAYA, G. V.

1961. Otno-shenie nekotorykh chernomorskikh polikhet K izmeneniyu colenosti,
gasovogo rezhima i grynta. (The relationship of some Black Sea polychaetes to
change of salinity, gas regime and bottom). In: Voprosy ekologii Vysshaya
Shkola; Moskow 5:115-117. Refcrat. Zhur., Biol., 1962, No. 19Zh47),

LOVERN, J. A.

1934. Fat metabolism in fishes. V. The fat of the salmon in its young freshwater
stages. Biochemical Journal, 28:1961-1963.

Salinity Problems

467

LOZOVIK, V. I.

1963. Effect of water salinity on the development of the glomerular apparatus in the
kidf|,eysof marine Teleostci. Dokl. Akad. Nauk. SSSR, 153:225-228.

LYLES, CHARLES H.

1965. Fishery Statistics of the United States, 756 pp. United States Department of
the Interior, Washington, D. C.

LYNCH, MAURICE P. and LANGLEY WOOD

1966. Effects of environmental salinity on free amino acids of Crasmstrea virgmica
Gmclin. Comparative Biochemistry and Physiology, 19:783-790.

LYSTER, I. H. J.

1955. The salinity tolerance of polychaete larvae. Journal of Animal Ecology, 34:
517-527.

MCFARLAND^ W. M. and F. W. MUNZ

1965. Regulation of body weight and serum composition by hagfish in various media.
Comparative Biochemistry and Physiology, 14:383-398.

MCHUGH, J. L.

1966. Management of estuarine fisheries. In: A Symposium on Estuarine Fisheries.
Special Publication No. 3: 133-154, American Fisheries Society. Washington,
D. C.

MACALLUM, A, B.

1903. On the inorganic composition of the medu.sae, Aurelia flavidula and Cyanea
artica. Journal of Physiology, 29:213-241.

MACKIN, J. G.

195L Histopathology of infection of Crassostrea virginica (Gmelin) by Dermocysti-
dium marinum Mackin, Owen, and Collier. Bulletin of Marine Science, Gulf
and Caribbean, 1:72-87.

MAETZ, J. and B. LAHLOU

1966. Les Changes de sodium et de chlore chez un elasmobranche, Scylliorhinus
mesurcs a I’aide des isotrope 24^^ et seQ journal de Physiologie, 58:249.

MANGUM, C. P.

1964. Activity patterns in metabolism and ecology of polychaetes. Comparative
Biochemistry and Physiology, 11:239-256.

MARSHALL, E. K., JR.

1929. The structure and function of the kidney oi Lophius piscatorius. Bulletin of
Johns Ilopkin.s Hospital, 43:205-230,

MARSHALL, E. K., JR. and H. W. SMITH

1930. The glomerular development of the vertebrate kidney in relation to habitat.
Biological BuUeiin, 59:135-153.

MARTIN. G, W. and TIIURLOW C NELSON

1929. Swarming of dino flagellates in Delaware Bay, New Jersey. The Botanical
Gazette, 88(20):21 8-224.

MEGLITSCH, PAUL A.

1967. Invertebrate Zoology, sii + 961, Oxford University Press, New York, London,
Toronto.

MILNE, ALEC

1 940. Some ecological aspects of the intertidal area of the estuary of the Aberdeenshire
Dee. Transactions of the Royal Society Edinburgh 60, Part 1, No. 4:1 17-139.

MOHAMMAD, M. B. M.

1966. Effects of temperature and salinity on the development oi Axiotehlla mucosa
(Andrews). Bulletin of Biological Research Center (Baghdad), 2:1-20,

MOORE, DONALD R.

1958. Notes on Blanquilla Reef, the most northerly coral formation in the western
Gulf of Mexico. Publications of the Institute of Marine Science, 5:151—155.

MORRIS, R.

1965. Studies on salt and water balance in Myxine glutinosa (L), Journal of Experi-
mental Biology, 42:359—371.

MOTAIS, R. ^ ^

1961. Qnetique des echanges de sodium chez un teleosteen euryhalin {Platichthys
flesus L.) au cours de passages successifs eau de mer, eau douce, eau de iner en
function du temps de sejour en eau douce. Compte Rendu, 253:2609-2611.

468

GUNTER, Ballard, and Venkataramiah

MUNZ. F. W. and W. N. MC FARLAND

1 964. Regulatory function of a primitive vertebrate kidney. Comparative Biochemistry
and Physiology, 13:381-400.

MUUS, B. J.

1 967, Some problems facing the ecologist concerning races and subspecies of brackish-
water animals. Pp. 558-563. In: Lauff, G. H.. ed. Estuaries. AAAS Publica-
tion 83, American Association for the Advancement of Science, Washington,
D. C. XV 757 pp.

NEGUS, MICHAEL, R. A.

1968, Oxygen consumption and amino acid level in Hydrohia ulvae (Pennant) in
relation to salinity and behavior. Comparative Biochemistry and Physiology,
24(2): 3 1 7-325.

NELSON, THURLOW C.

1925. On the occurrence and food habits of ctenophores in New Jersey inland
coastal waters. Tlie Biological Bulletin, 48(2):92-l 1 1.

NEUMANN, GERHARD and WILLIARD J. PIERSON, JR.

1966. Principles of Physical Oceanography, vii + 545 pp. Prentice-Hall, Inc. Engle-
wood Cliffs, New Jersey.

NICOL, J. A. C.

1 967. Tire Biology of Marine Animals. 2nd cd. John Wiley and Sons, lire.. New York,
699 pp.

ODUM, E. P.

1961. The role of tidal marshes in estuarine production. New York State Conserva-
tion, 15:12-15, 32.

ODUM, H. T.

1953. Factors controlling marine invasion into Florida fresh waters. Bulletin of Ma-
rine Science in the Gulf and Caribbean, 2(3); 134-156.

OGAWA, M.

1961. Histological changes of the kidney in goldfish in sea water. Science Reports of
the Saitarna University, 04:107-129,

1962. Comparative study on the interna! structure of the teleostean kidney. Science
Reports of the Saitarna University, B4; 107-1 20.

OGLESBY, L. C

1965. Water and clrloride fluxes in estuarine nereid polychaetes. Comparative Bio-
chemistry and Physiology, 14:621 -640.

1 966. Responses of N. limnicola to osmotic stress. American Ztrology , 6:507.

1969, Inorganic components and metabolism, ionic and osmotic regulation; An-
nelida, Sipuncula, and Echiura. Chemical Zoology, 4:211-310, Academic
Press, New York and London.

1973. Salt water balance in lugwornis (Polychaeta: Arenicolidae), with particular
reference to Abarenicola pacifica in Coos Bay, Oregon. The Biological Bulletin
145(1);180-199.

OGURI, M.

1964. Rectal glands of marine and fresh water sharks: Comparative histology.
Science, 144:1151-1152.

OIDE, H. and S. UTIDA

1968. Changes in intestinal absorption and renal excretion of water during adapta-
tion to sea water in the Japanese eel. Marine Biology, 1 : 1 72-1 77.

O’NEAL, TED

1949. The muskrat in the Louisiana coastal marshes. Louisiana Department of Wild
Life and Fisheries, pp. xii + 155, New Orleans.

PANIK.KAR, N. K.

1940. Influence of temperature on osmotic behavior of some Crustacea and its bear-
ing on problems of animal distribution. Nature, London, 146:366—367.

1941. Osmoregulation in some palacmonid prawns. Journal of Marine Biological
Association of the United Kingdom, 25:317-359.

PANTIN, C. F- A.

1931a. Tlie adaptation of Gunda ulvae lo salinity. 1. The environment. Journal of
Experimental Biology, 8:63-72.

Salinity problems

469

PANTIN, C. F. A.

1931b. The adaptation of Gunda ulvae to salinity. III. The electrolyte exchange.
Journal of Experimenlal Biology, 8;82-94,

PARKER, JACK C.

197U. Distribution of juvenile brown shrimp (Penaeus azlecus) Ives in Galveston
Bay, Texas, as related to certain hydrographic features and salinity. Contribu-
tions in Marine Science, 15:1-12.

PARKER, R. H.

1959. Macro-invertebrate assemblages of central Texas coastal bays and Laguna Madre.

Bulletin of American Association of Petroleum and Geology, 43:2100-2166.

PARRY, G.

1966. Osmotic adaptation in fishes. Biological Reviews. 41:392-444.

PARVATHESWARARAQ, V.

1 967. Some mechanisms underlying thermal acclimation in a fresh water fish, Etroplus
macidatus (Teleostei). Comparative Biochemistrv and Physiology, 21:619-
626.

PEARCY, W, G.

1961. Seasonal changes in osmotic pressure of flounder sera. Science, 134:193-194.

PEARSE, A. S,

1928. On the ability of certain marine invertebrates to live in diluted sea water.
Biological Bulletin, 54:405-409.

PEARSE, A. S. and G. W. WHARTON

1938. The oyster 'leech,** Siylochus inimicus Palombi, associated with oysters on
the coasts ofFlorida. Ecological Monographs, 8:605-655-

PEARSE, A. S. and G. GUNTER

1957. Salinity, /n.‘ Treatise on Marine Ecology and Paleoecology, 1:129-157. Geo-
logical Society of America Memoirs 67.

PEARSON. JOHN C.

1948. Fluctuations in the abundance of the blue crab in Chesapeake Bay. Research
Report. Llnitcd States Fish and Wildlife Service, 14:1—26.

PENFOUND, W. and E. S. HATHAWAY

1938. Plant cornmunities in the marshlands of southeastern Loui.siana. Ecology,
8:1-56.

PERRY, HARRIET M. and J, Y. CHRISTMAS

1973. Estuarine zooplankton, .Misskvippi. In: Cooperative Gulf of Me.xico Estuarine
Inventory and Study, Mississippi. Phase IV-^Biology. Gulf Coast Research
Laboratory', Ocean Springs, Mi-ssksippi,

PETTENGILL, O. and D. E. COPELAND

1 948. Alkaline phosphotase activity in the chloride cell of Fundulus heteroclitus and
its relation to osmotic work. Journal of Experimental Zoology, 108:235—241.

PHILLIPS, PHILLIP J.. W. DAVID BURKE and EI.IZABETH J. KEENER

1969. Ob.servations on the trophic significance of Jellyfishes in Mississippi Sound
with quantitative data op the associative behavior of small fishes with medusae.
Transactions of the American Fisheries Society, 98(4):703-712.

PHILPOTT, C. W, and D. £, COPELAND

1963. Fine structure of chloride cells from three species of Fundulus. Journal of
Cellular Biology, 1 8:389-404.

PICKFORD, G. E.

1959. Endocrinological studies on the euryhaline killifish, Fundulus heteroclitus
(Linn.). Yale Journal of Biological Medicine, 6(31 ):34l-362.

PIERCE, E. LOWE

1954. Notes on the Chaetognatha of the Gulf of Mexico. Gulf of Mexico, Its Origin,
Waters, and Marine Life. Fishery Bulletin of the Fish and Wildlife Service,
55:327-329.

PILGRIM, R. L. C.

1953. Osmotic relations in molluscan contractile tissues. II. Isolated gill preparations
from Lamellibranchs (Mytilus edulis L., Ostrea edulia L., Anodonta cygnea
L). Journal of Experimental Biology, 30:318—330.

470

GUNTER, Ballard, and Venkataramiah

POTTS, W. T. W.

1954a. The inorganic composition of the blood of Mytilus edulis and Anodonla
cygnea. Journal of Experimental Biology, 31:376-385.

1954b. The energetics of osmotic regulations in brackish and fresh water animals.
Journal of Experimental Biology. 31:618-630.

1958. ITie inorganic and amino acid compo-sition of some lamcllibranch muscles.
Journal of Experimental Biology, 35:749-764.

POTTS, W. T. W. and C. PARRY

1964a. Osmotic and Ionic Regulation in Animals. 423 pp. Macmillan Company, New
York.

1964b, Sodium and chloride balance in the prawn, Palaemonetes varians. Journal of
Experimental Biology, 4lr591-601.

PRICE, J. B. and G. GLTNTER

1964. Studies of the chemistry of fresh and low-salinity waters in Mississippi and the
boundary between fresh and brackish water. International Revue gesammte
Hydrobiologie, 49(4):629-636.

PRICE, K. S. and E. P. CREASER

1967. Fluctuations in two osmoregulatory components, urea and sodium chloride,
of the cleamose skate. Raja cglanteria Bose 1802. I. Upon laboratory modifi-
cation of external salinities. Comparative Biochemistry and Physiology, 23;
65-76.

PRITCHARD, DON W.

1951. The physical hydrography of estuaries and some applications to biological
problems. Transactions of the Sixteenth North American Wildlife Conference,
pp. 368-376.

PROSSER, C. L.

1964. Perspectives of adaptation: theoretical aspects. /n; Adaptation to the Environ-
ment. Pp. 11-25. Handbook of Physiology. American Physiological Society.

PROSSER, C. L. and F. A. BROWN, JR.

1961. Comparative Animal Physiology, 2nd edition. W. B, Saunders Company,
Philadelphia, ix + 688 pp.

RAMAMURTHI, R.

1 968. Oxygen consumption of the common Indian cattle leech Poecilobdella granulosa
in relation to osmotic stress. Comparative Biochemistry and Physiology, 24:
283-287.

RAMSAY, J. A.

1949. The osmotic relations of the earthworm. Journal of Experimental Biology,
26:46-56.

RANKAMA, K. and T. G- SAHAMA

1950. Geochemistry, 912 pp. University of Chicago Press.

RAO, G. M. M.

1969. Effect of activity, salinity and temperature on plasma concentrations of rain-
bow trout. Canadian Journal of Zoology, 47:131-134.

REES, GWENDOLEN

1941. Tlie resistance of the flatworm Monocelis fusca to changes in temperature and
salinity under natural experimental conditions. Journal of Animal Ecology,
10:121-145.

REES, G. H.

1 966. Blue crab studies. Informal Progress Report. United States Bureau of Com-
mercial Fisheries, Beaufort, North Carolina^

REMANE, A. and C. SCHLIEPER

1971. Biology of Brackish Water. 2nd Revised Ed. Die Binnengewasser. Vol. 25.,
pp. viii +- 372 pp. Wiley and Sons, New York.

RIEGEL, J. A. and L. B. KIRSCHNER

1960. The excretion of inulin and glucose by the crayfish antennal gland. Biological
BuUctin, 118:296-307.

ROBERTS, MORRIS H., JR.

1971. Larval development of Pagums longicarpus Say reared in the laboratory. II.

Effects of reduced salinity on larval development. The Biological Bulletin,
140:104-116.

Salinity Problems

471

ROBERTSON, J. D.

1 949. Ionic regulation in some marine invertebrates. Journal of Experimental Biology,
26(2): 182-200.

1953. Further studies on ionic regulation in marine invertebrates. Journal of Experi-
mental Biology, 30:277-296.

1954. The chemical composition of the blood of some aquatic chorda tes including
members of the Tunicata, Cyclostomata and Osteichthyes. Journal of Experi-
mental Biology, 31:424-442.

1957. Osmotic and ionic regulation in aquatic invertebrates. Pp. 229-246. In:

Recent Advances in Invertebrate Physiology, vi + 304 pp. B. T. Scheer, ed.
University of Oregon Publications. Eugene.

1960. Osmotic and ionic regulation. In: Waterman, T. H., ed. The Physiology of
Crustacea, Metabolism and Growth. Academic Press, New York, xvii + 670 pp.
1:317-339.

1963. Osmoregulation and ionic composition of cells and tissues. In: A. Brodal and
R. Fange (eds.) Biology of Myxine. Oslo University Press, Oslo. Pp. 503-515.

1964. Osmotic and ionic regulation. In: Physiology of Mollusca, K. M. Wilbur and
C. M. Yonge (eds.). Academic Press. New York. 473 pp.

ROUGH LEY. T. C.

1922. Oyster culture on the George’s River, New South Wales. Government of New
South Wales, Sydney. 69 pages.

ROUNSEFELL, GEORGE A. and WALTER R. NELSON

1966. Red-tide research summarized to 1964 including an annotated bibliography.
Special Scientific Report-Fisheries No. 535, iii-85.

RUBEY, W. W.

1951. Geologic history of sea water. An attempt to state the problem. Geological
Society of America Bulletin, 62; 1 1 1 1 -1 148.

RUDZINSKA, M. A. and R. CHAMBERS

1951. Contractile vacuole activity of a suctorian. Biological Bulletin, 100:49-58.
RUSSELL, E. S.

1937. Fish migrations. Biolc^ical Reviews, 12:320-337.

RUSSELL. R. J. and H. V. HOWE

1935. Cheniers of southwestern Louisiana. Geographical Review, 25(3);449-461.
SANDERS, OTTYS and RUTH M. SANDERS

1963. A new jellyfish (Pelagia) from the Gulf of Mexico. The Texas Journal of
Science, 10(1):3-14,

SANDOZ, M. and R. ROGERS

1944. The effect of environmental factors on hatching, moulting and survival of zoea
larvae of the blue crab, Callinectes sapidus Rathbun. Ecology, 25:216-228.
SCHEER, BRADLEY T.

1948. Comparative Pliysiology. x + 563. John Wiley & Sons, Inc., New York,
C’hapman & Hall, Ltd., London.

SCHLIEPER, C.

1929. Uber die Einwirkung niederer Salzkonzentrationen auf mariner Organismen.
Zeitschrift fur Vergleichende Physiologie. 9:478—513.

1 930. Die Osmoregulation wasserlebender Tiere. Biological Reviews, 5: 309-356.
SCHWABE, C. W. and A, KILEJIAN

1968. Chemical aspects of the ecology of platyhelminths. Chapter 6, pp. 467-549.

Chemical Zoology, Vol. 2 Porifera, Coelenterata and Platyhelminthes. M.
Florkin and B. T. Scheer, eds., xx + 639 pp.. Academic Press, New York and
^ London.

SEGERSTRALE, S. G.

1953. Further notes on the increase of salinity of the inner Baltic and its influence
on the fauna. Societas Scien. Fenn. Comm. Biol. 13:1—7.

1957. Baltic Sea. Pp. 751-800. Chapter 24. In: Hedgpeth, J. W., ed. Treatise on
Marine Ecology and Paleoecology.^ Geological Society of America Memoirs 67.
Vol. I. Ecology, viii + 1 296 pp.

SHAW, J.

1959. Salt and water balance in the East African fresh water crab Potamon niloticus
(M.Edw.). Journal of Experimental Biology, 36:157-176.

472

Gunter, Ballard, and Venkataramiah

SHAW, J, B.

I960. The mechanisms of osmoregulaiion. Pp. 471-518, Chapter 9, Free energy and
biological function, Vol. 11, Comparative Biochemistry, Florkin and Mason
(eds.) The Academic Press, New York.

SHELFORD, VICTOR E.

1915- Principles and problems of ecology as illustrated by animals. Journal of
Ecology, 3: 1-23.

SHOUP, C. S-

1932. Salinity of the medium and its effect on respiration in the sea anemone.
Ecology, 13:81-85.

SIMMONS, E, G.

1957. An ecological survey of the upper Laguna Madre of Texas. Publications of the
Institute of Marine Science, University of Texas, 4(2): 156-200.

SIMPSON, JOHN W.. KENNETH ALLEN and JORGE AWAPARA

1959. Free amino acids in some aquatic invertebrates. Biological Bulletin, 1 17: 371-
381.

SKINNER, J. F. (Compiler)

1972. Ecological studies of (he Sacramento-San Joaquin Estuary. Delta Fish and
Wildlife Protection Study Report No. 8, pp. 1-94. California Department of
Fish and Game.

SMITH, F. G. WALTON

1945. Tlie discovery of Coeloplana on American shores, Science, 101 (26 10): 17.

SMITH, H. W.

1931. Tlie absorption and excretion of water and salts by the elasmobranch fishes.
11, Marine Elasmobranchs, American Journal of Physiology, 98:296-310.

1932. Water regulation and its evolution in the Fishes. Quarterly Review of Biology,
7:1-26.

1936. Tlie retention and physiological role of urea in the Elasmobranchii. Biological
Reviews, 1 1:49-82.

SMITH, RALPH L

1953. The distribution of the polychaetc Neanthes lighii in Ihe Salinas River Estuary,
California, in relation to salinity, 1948-1952. Biological Bulletin, 105:335-
347.

1955a. Salinity variation in interstitial water of .sand at Karnes Bay, Millport, with
reference to the distribution of Nereis diversicolor. Journal of Marine Biological
Association of the United Kingdom, 34:33-46.

1955b. On the distribution of Nereis diversicolor in relation to salinity in the vicinity
of Tvarminne, Finland, and the Isefjord, Denmark, Biological Bulletin, Woods
Hole. 108:326 345.

1955c. Comparison of the level of chloride regulation by Nereis diversicolor in dif-
ferent parts of its geographical range. Biological Bulletin. 109(3);453-474.

1956a. Tlie ecology of the Tamar estuary. VIl. Ob.servations on the interstitial salinity
of intertidal muds in the estuarine habitat of Nereis diversicolor. Journal of
Marine Biological Association of the United Kingdom, 35(1):81 — 104.

1956b. Comparison of the level of chloride regulation by Nereis diver skolor in dif-
ferent parts of its geographical range. Journal of Marine Biological Association
of the United Kingdom, 35:644.

1963. A comparison of salt loss rate in three species of brackish water nereld
polychaetes. Biological Bulletin, 125:332-343.

1964a. D 2 O uptake rate in two brackish water nereid polychaetes. Biological Bulletin,
126:142 149.

1964b. On the early development of Nereis diversicolor in different salinities. Journal
of Morphology, 114:437-464.

SPEKTOROVA. L. V.

1970. Morkaya flagcUata Platymoms viridius Rouch sp. n. kak ob •• ekt dlya
massovogo kul’tivirovaniya. (The marine flagellate Platytnonas viridius Rouch
sp. n- as an object for mass cultivation). Dokl, Akad, Nauk. SSSR, 192(3):
662-664.

Salinity Problems

473

SPRENT, J. F. A,

1972. Class L Nematoda, pp. 235-265 in Section 6, Phylum Aschclminthes, Text-
book of Zoology, Invertebrates. A. J. Marshall and W, D. Williams, Eds. xix
+ 874 pp. Macmillan, London.

SPRINGER, V. G. and K. D. WOODBURN

I960. An ecological study of the fishes of the Tampa Bay area. Florida State Board
of Conservation Professional Papers No. 1, 104 pp.

STADELER, G., and F. T. FRERICHS

1858. Uber das Vorkommcn yon Harnstoff, Taurin and Scyllit in den Organen der
Plagiostomen. Journal filr praktische Chemie, 73:48-55.

ST. AM ANT, L. S. ^

1938. Studies of the biology of the Louisiana oyster drill, Thais jloridana haysae
Clench. Thesis, Department of Zoology, Louisiana Slate University. 108 type-
script pp.

STEAD, DAVID G.

1 907. Preliminary note on the wafer {Leploplana australis)^ a species of dendrocoelous
turbcllarian worm, destructive to oysters. Department of Fisheries New South
Wales. (Australia). November 1907:1-6.

STORR, JOHN F.

1964. Ecology of the Gulf of Mexico commercial sponges and its relation to the
fishery. Special Scientific Report-Fisheries No. 466. U. S. Department of the
Interior, iii 73.

STUNKARD, H. W. and RUTH C. SHAW

1931. Tire effect of dilution of sea water on the activity and longevity of certain
marine cercariae, with descriptions of two new species. Biological Bulletin,
6 1(2): 242-27],

STYCZYNSKA-JUREWICK. EWA

1971. Tolerance to salinity in some marine and fresh water cercariae. Acta. ParasitoJ.
Pol. l9(]9-28):257-268.

SUMNER, F. B.

1905. The physiological effects upon fishes of changes in density and salinity of
water. Bulletin of the U. S. Bureau of Fisheries, 25:53-108.

1906. The osmotic relations between fishes and their surrounding medium (pre-
liminary note). Biological Bulletin, 6(10): 298-306.

1907. Further studies of the physical and chemic.al relations between fishes and their
surrounding medium. American Journal of Physiology, l(l9);6l-96.

1912. The causes of death of marine fishes in fresh water and vice versa. Proc^eding.s
of the Seventh liitenialional Zoological Congress, August 19-24, 1907:284-
288.

SUWA, A.

1 909. Untersuchungen liber die Organextrakte dcr Selachier. Pfilig. Arch. Ges. Physiol.,
128:421-426,

SVERDRUP, H. U., M, W. JOHNSON and R. H. FLEMING

1942. The Oceans, Their Physics, Chemistry and General Biology, x + 1087 pp.
Prentice-Hall, New York.

TAN ENG-CHOW and W. A. VAN ENGEL

1 966. Osmoregulation in the adult blue crab, Callinectes sapidus Rathbun. Chesapeake
Science, 7:30-35.

THORSON, T. B.

1967. Osmoregulation in fresh water elasmobranchs. Jn: Sharks, Skates and Rays.
P. W. Gilbert, R. G. Mathewson, and D. P. Rail (eds.)., Johns Hopkins Press,
Baltimore, Maryland, pp. 265-270.

THORSON, T. B., C M. COWAN, and D. E. WATSON

1967. Potamotrygon spp.: Elasmobranchs with low urea content. Science, 158:375-
377.

TIETJEN. J. H. and J. J. LEE

1972. Life cycles of marine nematodes. Influence of temperature and salinity on
Monhystera denticulala Timm. (Abstract). Abstracts of Papers submitted for
the 25th Annual Meeting, American Society of Limnology and Oceanography,
Inc., Tallahassee, Florida, March 19-22.

474

Gunter, Ballard, and Venkataramiah

TIMM, R. w.

1952. A survey of the marine nematodes of Chesapeake Bay, Maryland. Chesapeake
Biological Laboratory, Solomons Island. Maryland, Publication No. 95. 70 pp.
TODD, MARY E.

1 964a. Osmotic balance in Littorina litlorea, L. liftoralis, and L. saxatilis (Littorinidae).
Physiology and Zoology, 37:33-44,

1964b. Osmotic balance in Uydrobia utvae and Potamopynis jenkinsi (Gastropoda:
Hydrobiidae). Journal of Experimental Biology, 41:665-677.

TOEWS, D. P. and C. P. HICKMAN, JR.

1969. Tire effect of cycling temperatures on eicctroltye balance in skeletal muscle
and plasma of rainbow trout Salmo gairdneri. Comparative Biochemistry and
Phy.siology, 29:905-918.

URIST, M. R.

1961. Calcium and phosphorus in the blood and skeleton of the elasmobranchii.
Endocrinology, 69:778-801.

VAN WINKLE, JR., W.

1 972. Ciliary activity and oxygen consumption of excised bivalve tissue. Comparative
Biochemistry and Physiology, 42A:473-485.

VAUGHAN, T. W.

1915. Reef corals of the Bahamas and southern Florida. Carnegie Institution of
Washington, Yearbook No. 12:222-226.

VENKATARAMIAH, A,. G, J. LAKSHMI and GORDON GUNTER

1972. Tlie effects of salinity and feeding levels on the growth rates and food con-
version efficiency of the shrimp Penaeus aziecus. In: Proceedings of the Third
Annual Workshop, World Maricuiture Society, pp. 267—283.

1974. Studies on the effects of salinity and temperature on the commercial shrimp,
Penaeus aztecus Ives, with special regard to survival limits, growth, oxygen
consumption and ionic regulation. Contract Report H-74-2. Pp. xii + 134 pp.
U.S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi.
VILLADOLID, D. V. and D. K. VILLALUZ

1938. Animals destructive to oysters in Bacoor Bay, Luxon. Philippine Journal of
Science, 67:393-399.

VILTER.W.

1944. Rheotropisme delacivelle et activite thyroidienne. Compte rendu de la Societe
de biologie, 138:668-669.

VIOSCA, PERCY. JR.

1920. Report of the biologist: Louisiana Department of Conservation, Fourth Bienn.
Report 1918-1920, pp. 120-130.

1927. Flood control in the Mississippi Valley in its relation to Louisiana fisheries.

Transactions of the American Fisheries Society, 57;49-61.

1938. Effect of Bonnet C^rre Spillway on fisheries. Louisiana Conservation Review,
Winter Issue, pp. 52-53.

WALDRON, ROBERT P.

1963. A seasonal ecological study of Foraminifera from Timbalier Bay, Louisiana.
Gulf Research Reports, 1(4); 132-188.

WASS, M. L.

1963. Check list of Uie marine invertebrates of Virginia. Virginia Institute of Marine
Science. Special Science Report, 24:1-56.

WEBB, K. L., R. E. JOHANNES and S. J. COWARD

1971. Effects of salinity and starvation on release of dissolved free amino acids by
Dugesia dorcftocephala and Bdelloura Candida (Platyhelminlhes, Turbellaria).
Tlie Biological Bulletin, 141:364-371.

WEBB, K. L., ANN L. SCHIMPE and JANET OLDON

1 972. I’ree amino acid composition of scy phozoan polyps oi Aurelia aurita, Chrysaora
quinquccirrha and Cyanea capillata at various salinities. Comparative Bio-
chemistry and Physiology, 433:653-663.

WEIL, E. and C. F. A. PANTIN

1931. The adaptation of Gunda ulvae to salinity. 11. The water exchange. Journal of
Experimental Biology, 8:73—81.

Salinity Problems

475

WELLS, G. P. and LEDINGHAM, L C.

1940. Physiological effects of a hypotonic environment. 1. The action of hypotonic
salines on isolated rhythmic preparations from polychaete worms (Arenicola
marina. Nereis diversicolor, Perinereis cultrifera). Journal of Experimental
Biology, 17:337-352.

WELLS, G. P., L C. LEDINGHAM, and M. GREGORY

1940. Physiological effects of a hypotonic environment. 11. Shock effects and ac-
commodation in cilia {Pleurobrachia, Mytilus, Arenicola) following sudden
salinity change. Journal of Experimental Biology, 17:378-385.

WEYMOUTH, F. W., M. J. LINDNER and W. W. ANDERSON

1933. Preliminary report on the life history of the common shrimp Penaeus setiferus
(Linn.). Bulletin of the Bureau of Fisheries, 48:1-25.

WHATLEY, E. C.

1962. Occurrence of breeding Gulf pipeFish, Syngnathus scovelli, in the inland fresh
waters of Louisiana. Copeia, 1 :220.

WHITTEN, H. L., HILDA F. ROSENE and J. W. HEDGPETH

1950. The invertebrate fauna of Texas coast jetties; A preliminary survey. Publica-
tions of the Institute of Marine Sciences, 1(2); 5 3— 87.

ZEIN-ELDIN, Z. P.

1963. Effect of salinity on growth of postlarval penaeid shrimp. Biological Bulletin,
125:188-196.

ZEIN-ELDIN, Z. P. and DAVID V. ALDRICH

1965. Growth and survival of postlarval Penaeus aztecus under controlled conditions
of temperature and salinity. Biological Bulletin, 1 29(1): 199-226.

Gulf Research Reports

Volume 4 Issue 3

January 1974

A Rubber Band Around an Adantic Croaker

Robin M. Overstreet

Gulf Coast Research Laboratory

Charles H. Lyles

Gulf Coast Research Laboratory

DOI; 10.18785/grr.0403.06

Follow this and additional works at: http:/ / aquila.usm.edu/ gcr

Recommended Citation

Overstreet, R. M. and C. H. Lyles. 1974. A Rubber Band Around an Atlantic Croaker. Gulf Research Reports 4 (3): 476-478.
Retrieved from http:/ / aquila.usm.edu/gcr/vol4/iss3/ 6

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A RUBBER BAND AROUND AN
ATLANTIC CROAKER'

by

ROBIN M. OVERSTREET and CHARLES H. LYLES
Gulf Coast Research Laboratory
Ocean Springs, Mississippi

A rubber band permanently girdled an Atlantic zxodkti Micropogon undulatus,
resulting in considerable malformation and pathological alterations of the fish. On
12 July 1973 at Graveline Bayou, Jackson County, Mississippi, Mrs. Buster Blades
caught on hook and line a 175 mm standard length (102.1 g) croaker that she
immediately separated from the rest of her catch as a suspected parasitized fish.
Later upon closer examination, she realized that a rubber band encircled the fish,
and so she brouglit the fish to us. The band had deformed the prcpelvic isthmus
(Fig, 1), restricted movement of the pectoral fins, and permanently encircled the
fish through a hole in the dorsum. Much of the elasticity was lost, but the band was
entire and free to rotate through the perforation below the first dorsal fin. The
tissue above the perforation, including the tissue of the dorsal fin, was complete
and not severed, although several scales were regenerated. These observations, in
addition to the malformed ventral area, suggest a lengthy association between band
and fish.

The croaker, a benthic feeder, probably became entangled in the band during
its bottom foraging. Testing the ability of several brands of rubber bands to floal,
we found most to sink rapidly immediately upon breaking the water’s surface
tension. Other bands, however, floated in both fresh and salt water. On the croaker
the band apparently lodged between two anterior dorsal spines and on the slight
protuberance of the prepelvic isthmus. Rather than becoming dislodged, the band
subsequently girdled the fish in one of two ways. It either constricted the fish and
severed the fish’s tissue or surrounded the fish and stimulated its tissue to grow
around the band.

We are puzzled, not so much by the presence of the band, but rather by the
band remaining on the fish. Extracting the band could be accomplished by
entangling the band on an object or by swimming backwards. On the other hand, we
would expect the fish, its movements being somcw'hal restricted, to be attractive to
predators and the band to be attractive to fishes or invertebrates w-hich pick at
fishes or foreign objects on them. Several such “pickers” are recognized for remov-
ing external parasites, and Hoese (1966) found that juvenile sea catfish, felis,
scraped the sides of croakers apparently feeding on mucus and scales. The catfish,

'This study was conducted in cooperation with the U. S. Department of Commerce,
NOAA, Office of Sea Grant, under Grant No. 04-3-I58-53. The U. S. Government is authorized
to produce and distribute reprints for governmental purposes notwithstanding any copyright
notation that may appear hereon.

476

Gulf Research Reports
Vol.4,No. 3.476-478, 1974

Atlantic Croaker

477

Figure 1. Micropogon umtulatm witli a rubber band permanently attached.

at least, is abundant in local waters, and other cleaning species may be present. In
any event, this croaker, similar to other fishes likewise entangled in rubber or
plastic bands (Gudger 1928, Schwartz I96.T Honma 1964), avoided natural preda-
tion.

Wliereas the present association between croaker and encircled band is doubt-
less accidental, other organisms may habitually enter orifices similar to that pro-
vided by a rubber band. Ikaver (1964) reviewed several findings of the intestinal
parasitic nematode Ascaris Utmbricokks entering orifices in shoe-eyclcts and but-
tons, as well as in the ampulla ofVatcr, an inflamed appendix, and other openings.
Such observations of nonaccidental actions led loan Understanding of the relation-
ship between a genital girdle and estrus in these worms (Beaver and Little 1964).

LITERATURE CITED

BEAVER. P. C.

1964. Aacark siranalcd in a shoc-cyclct. The American Journal of Tropical Medicine &
Hy-icne. 1 3(2R295-296.

BEAVER. P.C., and M. D. LITfLE

1964, I hc aunitat eirdic in relation to estrus and malini: \i\ Ascaris hinibricoides. The
Jouriial of Parasitology. 50( I ): 1 28-130.

GUDGER, E. W.

1928. A mackerel (Scomber scomhrus) with a rubber band rove through its body.
American Mu.seuni Novitates. (310): 1-6.

478

OVERSTREET AND LYLES

HOESE, H. D.

1966. Ectoparasitism by juvenile sea catfish, Galeichthys felis. Copeia. (4): 880-881.
HONMA, Y.

1964. Notes on the specimens of halfbeaks, Hcmirhamphus sajori (T. & S.), with heads
or trunks bound with rubber bands. Collecting and Breeding (in Japanese). 26(2):
1-3.

SCHWARTZ, F. J.

1963. Bluefish from CTiesapeake Bay deformed by plastic band. Chesapeake Science.
4(4):196.

Gulf Research Reports

Volume 4 Issue 3

January 1974

Cetacean Notes. 1. Sei and Rorqual Whales on the Mississippi Coasp A Correction. II. A
Dwarf Sperm Whale in Mississippi Sound and Its Helminth Parasites

Gordon Gunter

Gulf Coast Research Laboratory

Robin Overstreet

Gulf Coast Research Laboratory

DOI: 10.18785/grr.0403.07

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Part of the Marine Biology Commons

Recommended Citation

Gunter^ G. and R. Overstreet. 1974. Cetacean Notes. I. Sei and Rorqual Whales on the Mississippi Coast; A Correction. II. A Dwarf
Sperm Whale in Mississippi Sound and Its Helminth Parasites. Gulf Research Reports 4 (3): 479-481.

Retrieved from http:// aquila.usm.edu/gcr/vol4/iss3/7

This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean
Research by an authorized administrator of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu.

CETACEAN NOTES. 1. SEI AND RORQUAL WHALES
ON THE MISSISSIPPI COAST, A CORRECTION.

11. A DWARF SPERM WHALE IN MISSISSIPPI
SOUND AND ITS HELMINTH PARASITES

by

GORDON GUNTER AND ROBIN OVERSTREET
Gulf Coast Research Laboratory
Ocean Springs, Mississippi

I. Gunter and Christmas (1973) described the events leading to the stranding
of a baleen whale on Ship Island, Mississippi, in 1968, giving the species as
Balaenoptera physalus, the Rorqual. Unfortunately the identification was in error,
but fortunately good photographs were shown. The underside of the tail was a
splotched white, but there was no black margin. The specimen also had fewer
throat and belly grooves than the Rorqual, as a comparison with True’s (1904)
photograph shows. Dr. James Mead {in litl.) pointed out that the animal was a Sei
Whale, Balaenoptera borealis. This remains a new Mississippi record and according
to Lowery’s (1974) count, it is the fifth specimen reported from the Gulf of
Mexico. The stranding of a sixth Sei Wliale on Anclote Keys in the Gulf, west of
Tarpon Springs, Florida on 30 May 1974, was reported in the newspapers and by
the Smithsonian Institution (1974).

II. Gunter, Hubbs and Beal (1955) gave measurements on a Pygmy Sperm
Whale, Kogia breviceps, which stranded on Mustang Island on the Texas coast and
commented upon the recorded variations of proportional measurements in this
species. Then according to Raun, Hoese and Moseley (1970) these questions were
resolved by Handley (1966), who showed that a second species, Kogia simus, the
Dwarf Sperm Wliale, is also present in the western North Atlantic. Handley’s
argument is based on skull comparisons and it seems to be rather indubitable.
According to Raun et al. (op. cit.), the stranding of a species of Kogia on Galveston
Island recorded by Caldwell. Ingles and Siebenaler (1960) was/f. simus. They also
say that Caldwell (in lilt.) had previously come to the same conclusion. Caldwell
et al.also recorded anotlier specimen from Destin, Florida, which is now considered
to have been a specimen of simus. The known status of these two little sperm
whales in the Gulf is summarized by Lowery (op. cil.).

Here we wish to record a third specimen of Kogia simus in the Gulf of
Mexico and the first from the Mississippi coast. The events were set forth in three
newspaper articles by Richard Glaczier in the Gulfport-Biloxi newspaper, The Daily
Herald, for October 3, 4 and 5, 1973, According to these accounts, a young whale
was found on the beach at Biloxi on October 2, 1973 by Seale Gruich. It was
removed to the Marine Life Aquarium at Gulfport, and Gerald E. Dukes, D.V.M,,
concocted a formula for feeding with the advice of Dr. William Walker of the
Marine World in Los Angeles. The animal weighed seventy-three pounds (33.1 kg)
and it was fifty-two inches (122 cm) long when received by the Gulfport aquarium.

Gulf Research Reports
Vol. 4, No. 3,479-481, 1974

479

480

Gunter and Overstreet

Although the whale ate well and apparently tried to play with its keepers, it
experienced convulsions at about 1 1 :00p.m,.and died soon thereafter on October 5,
1973, thus bearing out the unhopeful prediction of Mr. Don Jacobs, owner of
Marine Life,

The whale was autopsied by Doctor Dukes, of the Handsboro Animal
Hospital, and the junior author, i:oologi.st with the Gulf Coast Research Laboratory.
Althougli this little female whale, estimated to be about 4 months old, had been
bruised arid showed signs of teeth marks, no wounds that would have caused death
were seen and no gross pathology was discovered that would have caused death.
Copies of the post-mortem report dated October 5 were distributed to various
people, Aseven page undated, typed report was issued by the Marine Life Aquarium
after October 5. It recorded the events leading up to the death including all
observations and the food formula.

Necropsy of the trunk of the whale provided three parasites. The forestomach
and pyloric stomach contained nematodes in larger numbers than the fundic
stomach. Both Stofnachus typicus and Terranova sp. were present; a single small
specimen of the latter was also embedded in the liver. Two specimens of the
telraphyllidean cestode ''Phyllobothrium delphini larval type 4,” as suininarized
by Delyamure (1955), occurred in the blubber adjacent to the anal orifice.
Stofnachus typicus^ as well as S, catodontis, was reported from one of three speci-
mens of Kogia sinms off the northeastern coast of Florida (Zam, Caldwell and
Caldwell 1971). Davey (1971) considered both S. catodontis and S. kogiae as
synonyms of Anisakh simplex, a species which has been reported from the related
K. breviceps. Phytlobothrium delphini and Phyllobothnum sp. were reported from
K. simus by Zam et al. (1971) and Dailey and Brownell (1972), respectively.
Terranova sp. could not be identified specifically, but is a new host record. Dollfus
(1966) briefly described an unidentified species of Terranova from a stranded
K. breviceps in France which appears to differ sliglUly from our specimens, but
could be the same species. Van Thiel (1966) listed Phocanema sp. from the same
host and locality. Whether that genus is a synonym of Terranova is questionable,
which suggests the species is the same as that reported by Dollfu.s.

The presence of these parasites, which all use intermediate hosts, in the whale
suggests that she had been obtaining some food from sources other than her
mother. The specimen of Terranova sp. in the liver, however, suggests that that
species might also be obtained from the mother through the placenta or from
nursing.

After death the iced head was shipped to Dr. James Mead at the U.S. National
Museum of Natural History, and the body was brought to the Gulf Coast Research
Laboratory where it was autopsied and subsequently sent to the National Museum.
Doctor Mead confirmed his tentative identification of the. species as Kogia simus.
This is the third known specimen of this species reported from the Gulf of Mexico.

LITERATURE CITED

CALDWELL, D. K., A. INGLES, and J. B. SIEBENALER

1960. Sperm and pygmy sperm whales stranded in the Gulf of Mexico. Journal of
Mammalogy, 41(1): 1 36- 1 38.

Whales in Mississippi sound

481

DAILEY, MURRAY D. and ROBERT L BROWNELL. JR.

1972. A checklist of marine mammal parasites. In: Mammals of the Sea: Biology and
Medicine. Sam, H. Ridgway, (editor). Charles C. Thomas, Publisher, Springfield,
Illinois, pp, 528-589,

DAVEY, J. T,

1971, A revision of the genus Anisakis Dujardin, 1845 (Nematoda: Ascaridata). Journal
of Helminthology, 45{l)'.5l-72.

DELYAMURE, S. L.

1955. Helminthofauna of Marine Mammals (Ecology and Phylogeny). Academy of
Science USSR, Moscow. Israel Program for Scientific Translations, 1968.

DOLLFUS, ROBERT PH.

1966. Helminthofaune de Kogia breviceps (Blainville 1838) Cetace Odontocete recoltes
du Dr R. Duguy. .Annales de la Societe des Sciences Naturelles de la Charente-
Maritlme, 4(5): 3-6, 16 figs.

GUNTER, GORDON, C. L. HUBBS and M. A. BEAL

1955. Records of Kogia breviceps from Texas, with remarks on movements and dis-
tribution. Journal of Mammalogy, 36(2):262-270.

GUNTER, GORDON and J. Y. CHRISTMAS

1974. Stranding records of a finback whale, Balaenoptera physalus, from Mississippi and
the goose-beaked whale, Zlphius cavirostris, from Louisiana. Gulf Research Re-
ports, 4 (2): 169- 173.

HANDLEY, C. O., JR.

1966. A synopsis of the genus Kogia (pygmy sperm whales). In: Wliales, Dolphins, and
Porpoises. K. S. Norris, (editor). University of California Press, Berkeley, pp.
62-69.

LOWERY, GEORGE H., JR.

1974. The Mammals of Louisiana and Its Adjacent Waters, vii + 565 pp. Louisiana
State University Press, Baton Rouge.

RAUN, GERALD G., H. DICKSON HOESE and FRANK MOSELEY

1970. Pygmy sperm whales, genus Kogia, on the Texas Coast. The Texas Journal of
Science, 21(3):269-274.

SMITHSONIAN INSTITUTION

1974, Anclote Keys Sei whale stranding. Event Notification Report 1871. Center for
Short Lived Phenomena, Cambridge, Massachusetts.

TRUE, F. W.

1904. Whalebone whales of the western North Atlantic compared with those occurring
in European waters with some observations on the species of the North Pacific.
Smithsonian Contributions to Knowledge, 33. vii + 332 p., 50 pis., 97 figs.

VAN THIEL, P. H.

1966. Tlie final hosts of the herringworm Anisakis marina. Tropical and Geographical
Medicine, 18:310-328.

ZAM. STEPHEN G., DAVID K. CALDWELL and MELBA C. CALDWELL

1971. Some endoparasites from small odontocete cetaceans collected in Florida and
Georgia. Cetology, 2:1-11.

Gulf and Caribbean Research

Volume 4 Issue 3

January 1974

Milton J. Lindner (1908-1973)

Gordon Gunter

Gulf Coast Research Laboratory

DOI; 10.18785/grr.0403.08

Follow this and additional works at: http:/ / aquila.usm.edu/ gcr

Recommended Citation

Gunter^ G. 1974. Milton J. Lindner (1908-1973). Gulf and Caribbean Research 4 (3): 482-484.
Retrieved from http:/ /aquila.usm.edu/gcr/vol4/iss3/ 8

This Editorial is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean
Research by an authorized administrator of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(Dusm.edu.

MILTON J. LINDNER
1908-1973

Wlien he retired from the U.S. National Marine Fisheries Service in 1970, the
following information about Mr. Lindner was distributed by his colleagues in the
Service. It is presented here in toto. A four and one-half page list of his publications
followed.

Lindner, Milton J(erome), fishery biologist; born, Jerome, Arizona,
September 9, 1908; son of Edward A. and Mollie A. (McCale) Lindner; B.A.,
Fresno State College, 1930; student Stanford; married Carmen C. Rouede,
December 13, 1932; children-Milton Jerome, Jr., Colette R. Weber. Marine
Biologist California Fish and Game Commission, 1928—30; In Charge of
Shrimp Investigations U.S. Bureau of Fisheries and Fish and Wildlife Service,
1931-43; Cliief U.S. Fishery Mission to Mexico, 1941-55; Commodity-
Industry Analyst Fish and Wildlife Service, 1955—56; Regional Fisheries
Officer Latin America, Department of State, 1956—62; Laboratory Director,
U.S. Fish and Wildlife Service, Bureau of Commercial Fisheries Biological
Laboratory, Galveston, Texas, 1963-70. Advisor: U.S. Delegations Conv,
Establishment International Commissions Scientific Investigation of Tuna,
Mexico, 1948; Latin American Fisheries Council, Lima, Peru, 1951; UN
International Technical Conference Conservation Living Resources Sea, Rome,
1955; Santiago Negotiation on Fishery Conservation Problems, 1955; Inter-
American Specialized Conference Conservation Natural Resources, Continental
Shelf and Marine Waters, Ciudad Trujillo, 1956; 5th FAO Regional Conference
for Latin America, San Jose, Costa Rica, 1958; Concurrent OAS and FAO
Inter-American Conferences on Agriculture, Mexico, D. F., Mexico; United
States-Honduras Fishery Negotiations, Tegucigalpa, Honduras, 1967; United
States-Mexico Fishery Conferences, Washington, D.C.and Mexico, D.F., 1967.
Lecturer, in Spanish, for United Nations, FAO Second Latin American Center
for Fishery Talent, Mexico, 1954; Invited Lecturer, Venezuelan Association
for the Advancement of Science, XVI Session, Caracas, Venezuela, 1966;
Convener, Resource Appraisal Section, World Scientific Conference on the
Biology and Culture of Shrimps and Prawns, United Nations, FAO, Mexico,
D.F., Mexico, June 12—21, 1967; Review Lecturer, on Shrimp Resources of
the Caribbean Sea and Adjacent Regions, Symposium on Investigations and
Resources of the Caribbean Sea and Adjacent Regions, UNESCO-WMO,
Willemstad, Curagao, Netherland Antilles, November 18-26, 1968. Member:
A.A.A.S., American Fisheries Society, American Institute of Biological Sci-
ences, American Society of Ichthyologists and Herpetologists, Ecological
Society of America, World Mariculture Society. Honors: Salutatorian, High
School Class, 1925; Salutatorian, College Class, 1930; Especially Meritorious
Promotion, 1945; Received the award of Naval Merit from the Government of
Mexico, 1945; Honorary Member, Sailfish and Tarpon Club of Mexico, since
1947; Honorary Member, Venezuelan Association for the Advancement of
Science, 1966; Superior Performance Award, 1968; U.S. Department of the

482

Gulf Research Reports
Vol-4,No. 3,4 8 2 -484,1974

Milton J. Lindner

483

Milton J. Lindner

Interior Meritorious Service Award, 1970. Home: 4923 Crockett Boulevard,
Galveston, Texas 77550.

On March 31, 1970, Mr. Lindner retired after 40 years of Federal
service; the last 7 years were spent as Director of the Bureau of Commercial
Fisheries Biological Laboratory, Galveston, Texas.

This is a good official summary of the man’s accomplishments and it covers
nearly all matters of importance. The only thing I know that was left out was the
fact that he was listed in Who’s Who in America. However, such things are only
sketches of bare bones so to speak. There is more to be said in the proper appraisal
of a man’s life.

To begin at the beginning, there was the first “Fishery School” in North
America which developed from the small but powerful coterie of ichthyologists
that David Starr Jordan gathered around him at Stanford. Frank W. Weymouth,
who was a medical physiologist also, was a powerful member of this group and
Lindner took courses with him. He thus became a fishery biologist. When Weymouth
was sent to New Orleans by the U.S. Bureau of Fisheries charged with settingup a
study program on shrimp in 1931, he brought Lindner with him. W. W. Anderson

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Milton J. Lindner

was already at work in Georgia and Lindner employed me later that year. The
Shrimp Investigations was a joint program with the states from North Carolina to
Texas. Due to the terminal illness of his wife, Weymouth was only in and out and
finally left at the end of two years.

Thus the responsibility of the Shrimp Investigations was left to Lindner. He
had a small budget by today’s standards but he set to with a will and carried on a
successful program until 1943 when he went to Mexico. He published 20 papers on
the Gulf and South Atlantic states shrimp during his life and two are classics-
Weymouth, Lindner and Anderson (1933), and Lindner and Anderson (1954).

But his importance to this era and place was a great deal more than mere
contributions to shrimp biology and to the shrimp industry. Essentially he was the
first man with the modern knowledge and outlook of fishery biology to come to
the Gulf Coast and stay. He was one of those fortunate individuals who was
intensely interested in what he was doing and he spread the story of fishery
biology and marine science far and wide. He held innumerable conferences with
state officials, legislative committees and individuals, wrote hundreds of letters and
gave talks to various public groups and held many newspaper interviews. Tills was
not a planned campaign on his part, but it was carried out as part of tlie work he
had to do and in fulfillment of his own interests. Only in looking back can we see
the powerful influence he had. It may well be the most important contribution he
made to society. In Mexico and South America from 1943 to 1962 he carried on
essentially the same kind of work.

In the early days Lindner and Weymouth more or less introduced W, W.
Anderson, Kenneth Mosher and me to fishery theory. Later Albert Collier came
under his influence and we all have carried the peculiar ecological slant which the
science imparls.

From 1963 to 1970 Mr. Lindner directed the federal fishery laboratory at
Galveston. In some quarters he was reputed to be too soft to apply the crunch to
people when necessary. But 1 remember well that he applied the same leniency to a
very callow, very shy and introspective youth from Louisiana and Texas forty-five
years ago and in looking back on my career 1 have concluded that Lindner was
right.

Lindner’s integrity was absolute and his enthusiasm was contagious. He
impressed his listeners and contributed greatly to the growth of marine biology in
the Gulf of Mexico, He was one of the “salt of the Earth” types who stave off the
chaos and disorganization which continually erode society and its foundations.
Scientists on flie Gulf Coast are particularly indebted to him.

He died of circulatory troubles in Galveston on 20 September 1973 and his
ashes were buried in New Orleans.

Gordon Gunter

Gulf Coast Research Laboratory
Ocean Springs, Mississippi