GULF RESEARCH REPORTS Volume 3, Number 2 The E. A. Richmond Memorial Number Ocean Springs, Mississippi December, 1971 Gulf Research Reports Volume 3 Issue 2 January 1971 Edward Avery Richmond ( 1 887- 1 970) Gordon Gunter Gulf Coast Research Laboratory DOI; 10.18785/grr.0302.01 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Recommended Citation Gunter^ G. 1971. Edward Avery Richmond (1887-1970). Gulf Research Reports 3 (2): 156-158. Retrieved from http:/ / aquila.usm.edu/gcr/vol3/iss2/ 1 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. — 156 — Edward Avery Richmond 1887-1970 Edward Avery Richmond was born June 10, 1887 at Brock- ton, Massachusetts, and he lived his life in a manner that con- vinced all who knew him that he was the finest type of New Eng-land gentleman. He devoted considerable time during his last 25 years to studying the fauna and flora of Horn Island, which lies off of the Mississippi Gulf Coast. Through Doctor Richmond’s work the species of living organisms of Horn Island are better recorded than those of any island on the South Atlan- tic and Gulf Coasts of the United States. Avery or Ned Richmond, as he was known to his various associates, had a long and varied professional career as an ento- mologist and botanist. Between 1913, when he was teaching as- sistant at Cornell, and 1957, when he retired as foreign plant quarantine inspector of the U. S. Department of Agriculture, he served in the Medical Corps during World War i and the Chem- ical Warfare Service during World War TI; was a county agent at Massachu.setls State College; an industrial chemist and an industrial field entomologist and crop protection inspector. In- terspersed among these activities were various teaching posts at Dartmouth College, New York University, Columbia Uni- versity, Simmons College, and Rhode Usland State College. For a good many of his adult years Doctor Richmond's tal- ents were utilized by the U. S. government, first at the Japanese Beetle Laboratory (1924-29), and later as foreign plant quaran- tine inspector (1945-56). His numerous published works in- clude “Studies on the biology of the aquatic Hydrophilidae" (1920), several articles on the Japanese beetle (1927, 1929, and 1931) ; “M*P, a safe and effective spray for insects'' (1932) ; and “Mosquito survey of Horn Island, Mississippi” and miscel- laneous newspaper articles. During the period from February 26, 1944 to February 4, 1945 Doctor Richmond was stationed on Horn Island as health officer with the U. S. Army. It was during this time that he be- came interested in the wildlife he found existing there and de- cided to observe and record the animals and plant.s of the is- land. Not being sponsored by any organization, the expense and time devoted to hi.s study were his own personal contributions. He was still in the Army during the first year; later, realizing the value of it to the i'egion, I was glad to have Doctor Rich- mond accept an invitation to live and work at the Gulf Coast Research Laboratory. Later in connection with this work, facilities at the II. S. National Museum and at the Academy of Natural Sciences at Philadelphia were placed at his disposal. He made good use of — 157 — the records of marine fauna of Mississippi which have been maintained in manuscript form since 1950 in a reference col- lection at the Gulf Coast Research Laboratory. Doctor Richmond received his B. S. from Dartmouth Col- lege in 1912, an M. A. from Cornell University in 1924, and his Ph.D. degree from Massachusetts State College in 1930. In ad- dition to his previously listed teaching posts, he lectured at col- leges throughout the east coast. In the early 1930’s he did extensive work in the control of pests in the Cape Cod cranberry bogs and also invented a trap to eliminate Japanese beetles. Doctor Richmond’s second marriage was to Leona Watland Terrell of Washington, D. C., in November of 1952. At the time of his retirement from the U. S. Department of Agriculture, he was stationed at McGuire AP’D, N. J., and they made their home in Moorestown, N. J., where they continued to live until his death on July 14, 1970. His personality found social expression outside the field of science and he was a Mason, a Shriner, and a Rotarian, as well as a deacon in the Congregational Church. He also held memberships in the American Entomological Society. Entomo- logical Society of America, Phi Kappa Psi, Acacia and Sigma Xi. E. A. Richmond was a dollar-a-ycar man at this Laboratory for nine years beginning in 1959, and his contributions to the biology of Mississippi were considerable. His papers on that subject are cited herewith : Richmond, E. A. 1962, The flora and fauna of Horn Island, Mis- sissippi. Gulf Research Reports 1(2); 59-106. 1968. A supplement to the flora and fauna of Horn Is- land, Mississippi. Ibid 2(3) : 213-254. Gordon Gunter Gulf Coast Research Laboratory Ocean Springs, Mississippi —158 Gulf Research Reports Volume 3 Issue 2 January 1971 Notes on Insect Occurrences on the Mississippi Gulf Coast and Offshore Islands Bryant Mather DOI: 10.18785/grr.0302.02 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Mather, B. 1971. Notes on Insect Occurrences on the Mississippi Gulf Coast and Offshore Islands. Gulf Research Reports 3 (2): 161-164. Retrieved from http:/ / aquila.usm.edu/gcr/vol3 /iss2/2 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. NOTES ON INSECT OCCURRENCES ON THE MISSISSIPPI GULF COAST AND OFFSHORE ISLANDS^ by Bryant MatheU 213 Mt. Salus Drive, Clinton, Mississippi 39056 Dr. Gordon Gunter (1970) has written that, through the work of Dr. E. A. Richmond, . . The species of living organ- isms of Horn Island are better recorded than those of any large island on the South Atlantic and Gulf (ioast'’ It is to be hoped that Dr, Richmond’s work will inspire others to contribute much more to the knowledge of the fauna and flora of the Gulf Coast and its offshore islands. I give here a few notes to place some of Dr. Richmond's work in context, to recognize work by others, and to indicate the paucity of the data. COLEOPTERA — Cicindelidae The tiger beetles (Cicindelidae) are among the best known and most widely collected of any group of beetles. Yet R. L. Huber, editor of the quarterly Cicmdelo.., wrote me in 1968: “Mississippi is one of the few states that has nothing published on Cicindelidae.” Today, the only published lists of Mississippi Cicindelidae are those of Dr. Richmond (1962 p. 86, 1968 p. 234) in which five names are listed: C. dorsalis saulcin- (Guer.), C, trifasem ascend ens (Lee.), C, hamafa lacerata (Chd.), C. h. monti Vaurie, and M. Carolina li, A. recent summary (Mather 1970) indicated that records were available for 22 species from 35 counties of Mississippi. The additional available Gulf Coast records are : Cidndela repanda Dej.: Harrison and Jackson Counties. Cimndela punctulata Oliv. : Hancock and Harrison Counties. Cicitidela blanda Dej, : Jackson County. Cicindela wapleH Lee. : All three counties. C. dorsalis and C. hamata are known from Deer Island and Ship Island ; C. trifascia ascendens is known from Ship Island. NEUROPTERA As was noted above to be the case with Cicindelidae, so far as I am aware, the only published lists of Mississippi Neuroptera are those by Dr, Richmond (1962 p. 79, 1968 p. 231) . In these he reported the following: iCuntrjbuUon No. 19f>, Bureau of EntomoloRy, Division of Plant Industry, Florida De- partment of Apricullure and Consumer Services, Gainesville, Florida. ^Research Associate, Florida State Collection of Arthropods, Division of Plant Industry, Florida Department of Agriculture and Consumer Service.'., Gainesville, Florida. — 161 - Sympherobius amiculus (Fitch) : The only other Mississippi record known to me is one female taken by R. and B, Taylor at Handsboro, Harrison County, in October 1966. Chrysopa oculata Say: This is known from Gulfport and Biloxi. Brachyneniurus longieaudis (Burm) : The only other Missis- sippi records of this known to me are of specimens taken by R. and B. Taylor at Biloxi and Handsboro. Myrmeleon crudelis (Walker) : This is also known from Biloxi and Ocean Springs (Taylors) and from Jackson and State College. ParmithacUsis hageni (Banks) : Dr. Richmond’s Horn Is- land record remains the only one from Mississippi known to me. Heocilsis americana (Drury) : The only supplementary Mis- sissippi record that I know of is based on a specimen in the col- lection at Mississippi State University taken in Lumberton, La- mar County, in 1917 by 0. A. Davis. Uhdodes hageni (Weele) : Widely taken throughout the state. LEPIDOPTERA The history of the study of Mississippi butterflies has been summarized by Mather and Mather (1958). Two early collectors, Frank Morton Jones and Harold L O’Byrne, confined their work, in 1910 and 1921 and 1929-1933, respectively, to the Gulf Coast. As far as is known, they did not collect on offshore islands. Neither published his results. Forket (1900) published notes of his observations at Ocean Springs. Skinner (1920) published a report which I quote in full : “Sir. W. C. Dukes of Mobile, Alabama, has recently sent me two specimens of Syn- tomidae from a new locality. They were taken on Cat Island, Mississippi. They are Cosmo 80 w.a auge TJnn. and Didasys belae Grote. The former is found in Florida, the West Indies, Central America and South America; the latter, so far as I am aware, has not been recorded outside the State of Florida.” This, so far as I know, is all that has ever been published on the Lepidoptera of Cat Island. Cosmoso7na auge, now known as C. myrodora Dyar, is now also known from Ship Island, Horn Island (Rich- mond 1962), Walthall, WTlkinson, and Covington Counties. Didasys belm Grt, is known from Mississippi only from Skin- ner’s 1920 report of its occurrence on Cat Island and from Dr. Richmond’s report (1962) of its occurrence on Horn Island. Robeidi and Barbara Taylor (1965) summarized the results of their work at Biloxi as it related to the Sphingidae and some other moths. They took specimens representing 24 of the 40 — 162 — species of sphinx moths then known from Mississippi. They took one male of Epistor higubns (Linn), which is the only record of this species from the Gulf Coast other than that given by Richmond (1962). Dr. Richmond's 1962 list included Speyeria cyhele cyhele (Fabr), the great spangled fritillary. The significance of this record has been discussed elsewhere (Mather 1966) and is sum- marized below: Mather and Mather (1958) listed S. cybele cyhele (Fabr) among the butterflies that were not then known to have been found in but were of probable occurrence in Mis- sissippi. They noted that Lambremont (1954) had reported one male taken at Lafayette, Louisiana, on 2 October 1931, in the collection at Southwestern Louisiana Institute ; that H. A. Free- man (1961) had reported it as usually rather scarce in Ark- ansas; and that Roever had taken it in southwestern Tennessee. They noted that dos Passos and Grey (1947) had listed it for Tennessee, Illinois, Arkansas, and Oklahoma but not for Missis- sippi or Louisiana. Through the courtesy of Dr. Gordon Gunter, Director, Gulf Coast Research Laboratory, we were put in touch with Dr. E. A. Richmond whose work on Horn Island (1962) includes a reference to S. cybele cybele. Dr. Richmond said (in litt.) that his records indicate that this specimen was taken on 23 September 1944; they do not indicate the determiner of or the disposition of the specimen. Most of the determinations were made at the U. S. National Museum. In January 1962 a search was made in the collections there and it was established that no specimen of S. cyhele from Mississippi could be found. It was then concluded that while this represented a probable oc- currence it could not be regarded as a confirmed record. On 10 June 1963 at Oxford, Lafayette County, Mr. John Daniel took a male of S. cybele cyhele. Thus S. cybele cyhele is added to the list of butterflies known to have been taken in Mississippi. In 1969-1970 there has been a most encouraging increase in the study of the Lepidoptera of the Gulf Coast regions of Mississippi and Louisiana, primarily through the work of Mr. Rick Kergosien of Bay St. Louis and Mr. Gayle Strickland of Baton Rouge. Each of these workers ha.s established the occur- rence of a number of species not previously known to exist in the area. Skinner (1920) noted that the two species he recorded for Cat Island were previously khowm from Florida, and, in one case, only from Florida. Strickland's work has revealed a num- ber of species resident in coastal Louisiana not previously known to occur north of peninsular Florida. Dr. Richmond and I corresponded between 1961 and 1967. I met him at the Gulf Coast Laboratory in April 1965. When we met he gave me a moth that he had collected on Horn Island the night before. I spread it and sent it to Dr. J. A. Powell of the University of California (Berkeley) who determined it as — 1 63 — Bactra verutaria verutaria Zell; it remains (Richmond 1968, p. 232) the only species of the Family Olethreutidae recorded from Horn Island. LITERATURE CITED Forket, C. 1900. Some notes about the weather and some butter- flies in South Mississippi, from March 1900. Ent. News 11; 512. Gunter, Gordon. 1970. Quarterly Report, Gulf Coast Research Laboratory. July-September 1970. Freeman, H. A. 1951. Southeast — Florida to Louisiana, north to Arkansas and Maryland (compiled by Ralph L. Ghermock). Lepid. News 5: 101-102. Lambremont, Edward N. 1954. The butterflies and skippers of Louisiana. Tulane Stud. Zook 1 : 125-164. Mather, Bryant, 1966. Speyeria cybele in Mississippi (Argyn- ninae; Argynnis). Jour. Res. Lepid. 5: 253-254. 1970. Mississippi Cicindelidae. (in press). , and Katharine Mather. 1958. The butterflies of Missis- sippi. Tulane Stud. Zook 6 : 63-109. Dos Passes, Cyril F. and L. P. Grey. 1947. Systematic catalogue of Speyeria (Lepidoptera, Nymphalidae) with designations of types and fixation of type localities. Amer. Mus. Novi- tates 1370: 1-30. Richmond, E. Avery. 1962. The fauna and flora of Horn Island, Mississippi. Gulf Research Reports 1: 59-106. 1968. A supplement to the fauna and flora of Horn Island, Mississippi. Gulf Research Reports 2: 213-254. Skinner, Henry. 1920. Two Syntomidae new to Mississippi (Lep.). Ent. News 31: 263. Taylor, Robert and Barbara Taylor. 1965. Collecting Sphingids and other moths on the Mississippi Gulf Coast. Jour. Lepid. Soc. 19; 189-190. —164 Gulf Research Reports Volume 3 Issue 2 January 1971 Observations on the Biology of Mudshrimps of the Genus Callianassa (Anomura: Thalassinidea) in Mississippi Sound Philip J. Phillips Gulf Coast Research Laboratory DOI: 10.18785/grr.0302.03 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Phillips; P.J. 1971. Observations on the Biology of Mudshrimps of the Genus Callianassa (Anomura: Thalassinidea) in Mississippi Sound. GulfResearch Reports 3 (2): 165-196. Retrieved from http :// aquila.usm.edu/ gcr/ vol3/iss2/ 3 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. OBSERVATIONS ON THE BIOLOGY OF MUDSHRIMPS OF THE GENUS CALLIANASSA (ANOMURA: THALASSINI- DEA) IN MISSISSIPPI SOUNDS by Philip J. Phillips" ABSTRACT The apparent habitat isolation of the mudshrimps Callia- nassa islagrtmde Schmitt and Callianassa jamaicense louisia^i- ensifi Schmitt (Anomura: Thalassinidea) in Mississippi Sound is a function of species-related differences in ability to burrow and survive in the si^ificantly different substrates of each habitat. C. islagrwnde is found only in sand bottomed beaches of the offshore barrier islands, whereas C. j. louisianensis is found only in the muddy backwaters of the mainland and Deer Island. Both form.s produce deep and extensive permanent or semipermanent burrows in their respective habitat and are probably of some significance in sediment turnover. Laboratory studies show that C, /. louisianensis can only burrow efficient- ly in mud and cannot burrow or survive in sand unless there is sufficient available mud with which this form constructs its burrow walls. The inability of C. islagrajide to tolerate silt limits its ability to burrow and survive in mud. For this reason C. islagrande cannot inhabit the muddy inshore w'aters. The poor burrowing efficiency of C. j. loumanensis in sand is due to a mechanical inability to handle uncohesive sand grains. The foliaceous third maxillipeds and comparatively larger second and third pereipods of C. islagrmide (compared with those of C. j. lomsiamnsis) are adaptations to a sandy habitat, enabling greater burrowdng efficiency per unit of effort. Adults and juveniles exhibited the same behavior patterns in aquarium studies. Settling juveniles probably exhibit the same behavior pattern as adults and juveniles. INTRODUCTION The purpose of this study was to determine whether sub- strate type is a factor influencing distribution of the thalassinid crustaceans, Callimiassa jamaicense loumanensis Schmitt and Callianassa islagrande Schmitt, within Mississippi Sound. These forms produce extensive permanent or semipermanent burrows in the littoral and shallow neritic bottoms. Willis (1942) in a study of the mudshrimps of Grand Isle, Louisiana, found C. islagrande only in the clean shifting sand beaches facing the iModifieti from a thesis submitted to the faculty of Mississippi State Utiiveraity in partial fulfillment of the requirements for the rtepvee of Master of Science. -Department of Zoolofiy^ Mississippi State University, State Collwe, Mississippi, and Gulf Const TResearch Laboratnvy, Ocean Springa, Mississippi. ■ 165 Gulf of Mexico and C. jamaiceme only in sheltered, mudbottom- ed backwaters. A similar situation occurs in Mississippi Sound, wherein C. iskigrmde is found only in the sandy beaches of the offshore barrier islands and C. j. loumamnsis is found only in the muddy inshore beaches. Other than the original descriptions of these taxa (Schmitt 1935) and the report by Willis (1942), there have been no published studies on these callianassids. An unpublished master’s thesis (Friedrichs 1955) for the most part consists of a reiteration of Schmitt’s original descriptions, and does not contain any pertinent ecological observations. COLLECTING STATIONS 1. Ocean Springs (Beach) 7. Horn Island (West End) 2. Marsh Point 8. Horn Island (near lagoon) 3. Deer Island 9. Horn island (chimney) Gravcllne Boy 10. Ship Island (Quarantine Station) 5. 6. Bella Fontaine Biloxi (Beach) n. Ship Island (Fort Massachusetts) 89^ 00' 88® 30' Figure 1 Mississippi Sound Collecting Stations C. j. louisianensis was collecte*! only at Stations 1 through 6. C. islagrande was collected only at Stations 7 through 10. — 166 — METHODS AND MATERIALS Collections: Collections were made at selected stations in Mississippi Sound (Fig, 1). C, islagrande were taken only along the north beaches of Horn and Ship Islands, whereas C. j. louisianensis were found only along beaches of the mainland and Deer Island (Table 1, Fig. 1). Initial collections were made using sieve and THUMBHOLES // Figure 2 The "Yabby” Pump Used to Collect C. j. louisian&nsis shovel. Toward the latter part of this study a “yabby"' pump (Fig. 2), essentially a hand coring device, was used to collect C. j. louisianensis. The use and construction of this pump was described by Hailstone and Stephenson (1961). After the cylin- der is pushed into the substrate and extracted with the thumb- holes closed, the core is released into a sieve and the mud- — 167 — Table 1; Collection Data for Callianassid Crustaceans in the Mississippi Sound A'. C. ). louisianensis Number of Females No. of w/Ripening Salinity Speci- Ovarian Locality Station Date (g/kgi Tide mens Eggs Ovigerous ‘ Ocean’ 1 1 -24-67 4.6 low 4 Springs 1 2-9-67 12.2 low 2 Beach 1 2-10-67 12.2 low 3 1 2-13-67 11.9 low 7 1 2-14-67 12.0 low 3 1 3-17-67 16.7 low 5 1 3-27-67 20.6 high 1 6-19-67 25.0 high 6 1 Marsh 2 2 16‘67 10.6 high 8 Point 2 2-21-67 14.0 low 3 2 2-24-67 12.0 high 2 3-3-67 21.6 high 1 2 3-8-67 19.0 tow 30 2 4-3-67 20.8 high 10 Marsh 2 4-17-67 22.8 high 10 Point 2 4-24-67 25,0 low 20 1 2 4-27-67 24.0 low 17 2 2 6-1 7-67 23.0 low 6 1 2 6-22-G7 25.0 high 41 6 3 (1 with early Ova, 2 with eyespot ova) Deer 3 2-27-67 17.2 high Island 3 3-3-67 24.0 high 3 4-11-67 22.3 high 2 Graveline Bayou 4 3-1 3-67 15,6 high 3 Belle Fontaine 5 3-13-67 17.6 high 2 Biloxi Beach 6 6-1 3-67 28.0 low 3 1 B: C. islagrande: Horn Island, 7 12-2-66 Not measured low 12 west end 7 3-1-67 22.5 high 7 3-18-67 24.0 high 7 3-22 67 29.4 high 7 2 Horn Island, near lagoon 8 b-14-6/ 30.0 high 7 Horn Island, 9 4-11-67 27.4 high 4 Chimney 9 4 12-67 27.6 high 3 1 Ship Island, 10 3-20-67 30.0 high 15 3 Quarantine 10 4-2-67 30.0 low 37 3 Station 10 4-22-67 28.2 low 103 9 3 with early ova Ship Island, 11 3-21 -67 27.2 high Fort Massachusetts *2 ovigerous females were collected 6-25-51 at Marsh Point; attached ova were at eyespKJt stage. — 168 — shrimps are recovered. The same spot is repeatedly sampled until no more mudshrimps are obtained. This pump is most successfully used on exposed mudflats and considerably less so in sand. The term “yabby” is the Australian common name for CalliaruLssa australiensis Dana. Callianassid collections are best made during periods of low tide with little or no surf action. This combination of fac- tors was seldom encountered. Data for each collection (Table 1) include the following: location, salinity, tide, species, number of specimens and the gross gonadal condition of adult females. Salinity was measured with a sea water hydrometer corrected for temperature. Burrowing Appendages of C. j. louisinyiensis and C> ishifjrande A: Right third maxilliped of C. j. louisimi^ensiii, B: Right third maxilliped of C. islagrande, C: Right second pereiopod of C. f. louisiammsis. D : Right second pereiopod of C, islagrande. E : Right third pereiopod of C. j. louuianensis. F; Right third pereiopod of C. islagrandn. Lines “b” and “h” indicate the length and breadth of the inerusischium on the third maxillipeds. Lines "b" and "h” indicate the propodal length and breadth on pereiopods. — 169 — The two species may he distiii.u-uished l)y tlil’ferences in Lhe siiape oC the third maxillii)eds (I'd'V- ■>) and uropodal endopo- dites. In (’. iMufjronde the third maxillii)eds ai'e loliacGons and the !iropodal endopodites are iVnir limes as lone' as broad. C. InttiiilaiiVifxl'i has perii’orm third maxilliipeds and the iiroi)odal endopodites arc aljout one-and-oue-haU’ times as lone as broad. Sex, in both species, was determined by examiinalion of the first and second pairs of pleopods. The second jiair td‘ i)leopods of the male are more than twice the length of the first, whereas the first and second pairs of pleopods in the female are of sub- eqnal lontrth. Riitenintt ovariuii in adult IVmiales appear brijtht yelknv to orauj^e through the translucent abdominal ex- oskeleton. Ovigerous females are those having ova attached Figure 4 Sexual Dimorpliisni of the I^lajor Cheliped in C. laUujrmide The top and bottom ppoeimens, females, have major cholipeds less than one-iind-ono-half times the length of the minor cheliped. The two middle spoeime-or', males, have majtir clielipeds at least one-and-one-liaif times the length of the minor cheliped. the pleopodal setae. During their early development, ova at- tached to pleoj^odnl setae are bright orange and these receiitly “berried” females may also have some bright orange ovarian eggs. More advanced ova, in the eyespot stage, have a dull ycl- — 170 — low color, and females bearing these lack ovarian eggs. Large males of C. islagrande have a slender major cheliped which is one-and-one-half times the length of the minor chelii^ed (Fig, 4). Females of C. islagrande have a major cheliped which is less than one-and-one-half times the length of the minor cheliped. There is little sexual dimorphism in cheliped shape of C. j. louisianensis and, in, both sexes, the major cheliped is less than one-and-one-half times the length of the minor cheliped. Female callianassids may also be recognized by the opening of the oviduct on the coxa of the third pereiopod. These openings are larger and more easily distinguished in (7. j, louisianensis than in C. islagrande. Specimens which could not be sexed were class- ified as juveniles. Mudshrimp were fixed in 20% formalin for 7 days and then transferred to 70% ethanol. Table 2: Frequency Distribution of Carapace Lengths of Mississippi Sound Callianassids Studied Juveniles Juveniles Juveniles Carapace C.jJouisia- C.isla- C.j.louisia- C.isla- C.j.louisia- C.isla- Length (mm) nensis grande nensis grande nensis grande 2 1 3 6 1 4 48 5 5' 40 1 1 6 12 12 4 3 7 12 9 6 5 2 1 8 6 3 8 5 2 9 1 4 8 2 4 10 1 6 9 8 9 11 1 5 6 8 11 12 3 8 3 9 13 9 5 14 6 11 1 8 15 11 2 2 16 2 4 4 17 1 4 3 18 19 1 Totals 99 44 41 87 39 51 Mean (Carapace Length (mm) 5.0 5,7 11.8 12.1 12.3 11.3 Variance (sq mm) (±) 2.3 16.1 14.8 11.4 11.7 34.1 Standard Deviation (±) 1.5 4.0 3,8 3.4 3.4 5.8 Carapace lengths and apparent sex ratios of all study material, including specimens from the Gulf Coast Research Laboratory Museum are given in Table 2. Carapace length is — 171 — the straight line distance from the tip of the rostrum to the pos- terior margin of the carapace. All measurements of mudshrimp were made with dividers or calipers and recorded to the nearest one-half mm. Measurements were made of the propodus of the second and third right pereiopods and merus and ischium of the right third maxillipeds (Table 3). Certain parameters derived from these data are used in the discussion of the behavior of these callianassids. Table 3: Proportional Measurements (mm) and Surface Area Indices* ofC. islagrande and C. j. touisianensis in Mississippi Sound A: C. islaQraride CarapaceThird Maxilliped Second Pereiopod Third Pereiopod Length h b Index h b Index h b Index 8 3.0 4.5 1.70 2.0 2.0 0.50 2.5 4.0 1.25 8 3.0 4.0 1.66 2.0 2.0 0.50 2.0 4.0 1.00 10 4.0 5.0 2.00 2.5 3.0 0.75 2.0 5.0 1.00 10 4.0 6.5 2.60 3.0 3.0 0.90 3.0 6.0 1.80 11 4.0 6.0 2.09 2.0 2.5 0.45 2.5 5.5 1.25 13 4.0 7.0 2.15 4.0 4.0 1.23 3.0 6.0 1.38 15 6.0 9.0 3.60 3.5 4.0 0.93 3.0 8.0 1.60 15 5.0 8.0 2.66 3.5 4.0 0.93 3.0 8.0 1.60 15 5.0 7.0 2.33 3.5 4.0 0.93 4.0 7.0 1.87 17 6.0 9.0 3.18 4.0 4.0 0.94 4.0 8.0 1.87 Mean indices 2.40 0.81 1.46 B: C. j. iouisianertsis Carapace Third Maxilliped Second Pereiopod Third Pereiopod Length h b Index h b Index h b Index 8 1.5 3.5 0.66 2.0 1.0 0.25 1.5 2.5 0.47 8 1.5 3.0 0.56 2.0 1.5 0.38 1.5 2.5 0.47 10 2.0 4.0 0.80 2.5 2.0 0.50 2-0 4.0 030 n 2.0 5.0 0.91 2.5 2.0 0.46 2.0 4.0 0.73 12 2.0 5.0 0.83 2.0 1.5 0.25 2.0 4.0 0.66 14 3.0 7.0 1.50 4.0 2.5 0.71 3.0 6.0 1.29 15 3.0 7.5 1.50 4.0 2.5 0.66 2.5 5.0 1.25 15 3.0 8.0 1.60 5.0 3.0 1.00 3.0 7.0 1.40 16 3.0 8.0 1.50 5.0 3.0 0.94 3.0 7.0 1,30 16 3.0 9.0 1.69 4.0 3.0 0.75 3,0 5.5 1.03 Mean Indices 1.12 0.59 0.94 * Length (fU x Breadth (b) . . , _ , Carapace Length Surface Area (rrtm) (Fig. 3). Substrate A^ialysis: Bottom samples from inshore and offshore collecting sites were analyzed for their relative sand and silt contents by elutria- tion, the gravimetric fractionation of an unstable suspension (Priddy ei al. 1955). Approximately 200 ml samples of fresh bottom material were homogenized for 15 min in a blender and then decanted into 1-liter graduated cylinders. Volumes were adjusted to 1 liter with sea water and the cylinders were shaken vigorously to resuspend the sediments. The samples were allowed to stand for 72 hrs. and then examined to determine the relative proportions of sand and silt by recording the volu- metric percentages of the sand and silt layers. The volumetric compositions of bottom samples are given in Table 4. Table 4: Volumetric Analysis of Selected Mississippi Sound Substrates Substrate Occurrence Percentaaa Composttion by Volume Sand Silt Sand Offshore littoral and neritsc zones 98 2 Sand Inshore hUoral zone 80 20 Hard Mud Inshore littoral and neritic zones 50 50 Clay Inshore littoral and ncrilin zones 10 90 Soit Mud Inshore littoral and neritic Zones traces 100- Aquarium Studies: The objective of these studies was to determine the ability of these mudshrimps to burrow and survive in various sub- strates from Mississippi Sound and to determine if these cal- lianassids are selective when given a choice of substrates. Aquar- ium studies of both species were divided into the following cate- gories: (1) tests on individual substrates, (2) tests on strati- fied substrate columns, (3) tests of superimposing substrate on burrowed specimens and (4) substrate preference tests. Half- liter beakers, graduated cylinders (250 ml, 500 ml, and 1000 ml), shallow pans (26 x 23 x 5 cm and 32 x 26 x 8 cm), mason jars (1 qt), test tubes and 5 and 10 gal tanks served as aquar- ium vessels. All were aerated by means of an airstone suspended just below the water surface. Except where noted to the con- trary, Mississippi Sound water from the habitat of each species was used in these experiments and water depth was never less than 2.5 cm. Specimens were released at the water surface. In all of the columnar experiments the depth of the upper layer was 8-15 cm and that of the lower was 12-15 cm. In cases where substrate was superimposed on an established mudshrimp colony the depth of the superimposed substrate was 8-9 cm and that of the original substrate layer was about 14 cm. In the substrate preference tests two substrates were placed in ap- position in shallow pans. Mudshrimps were released above the interface of the two substrates. The arrangements of substrates in the substrate preference teats are shown in Fig. 5. The .sub- — 173 — 1 2 B B 5 6 A ■ B B B B C Figure 6 Substrate Arrangements in Preference Tests A: Test 5. Sectors 1, 4, 5 contain hard mud whereas sectors 2, 3 and G contain inshore sand. B: Test 6. Sectors 1 and 4 contain hard mud, whereas sectors 2 and 3 contain inshore sand. C; Arrangement of All Other Tests; Sector 1 contains one substrate and Sector 2 the other. In all instances “X” indicates the site at which mudshrinips were released. strate preference tests, summarized in Table 5, are discussed according to the following categories: (1) sand inshore vers^ts sand offshore, (2) sand, either type, verstis hard mud, (3) sand, either type, versus clay and (4) hard mud versus clay. Table 5. Summary of Behavior in Substrate Preference Tests of CalUanassa of Mississippi Sound Preference Substrate Combination C. j. louisianensis C. islagrande Sand, inshore versus Sand, offshore No Preference Equally Preferred Sand versus Hard Mud Hard Mud Sand Sand versus Clay Clay Sand Hard Mud versus Clay Equally Preferred Hard Mud Salinity tolerance tests were conducted to determine wheth- er salinity affects the gross behavior of callianassids in the tests involving substrate. The tests (Table 6) show the re- sponses of burrowed and free specimens to the same salinity changes. These experiments were conducted at room tempera- ture (21.1-23.9*0). Salinity tests on free shrimp were conducted by placing the animals in waters of varying salinity. For bur- 174 — rowed shrimp, salinity was adjusted by decanting supernatant water and adding water of the desired salinity. Table 6: Salinity Tolerance Tests on C. j. louisianensis and C. islagrande A: Freerswimming Mudshrimps Salinity (g/kg) No. of Observations From To Change Species Specimens One Hour Two Days Five Days 20 20 0 C. i. louisianensis 6 All active All active AM dead 29 29 0 C. islagrande 6 All active All active All dead 20 29 +9 C. j. louisianensis 6 All active All active All dead 29 20 -9 C. i- louisianensis 6 All active All active All dead 29 20 -9 C. islagrande 6 4 dead 2 torpid All dead 29 tap -29 water C. j. louisianensis 7 All active All active All dead 29 tap -29 water C. islagrande 4 All dead B: Burrowed Mudshrimps 20 20 0 C. j. louisianensis 10 All active AM active AM active 29 29 0 C. islagrande 6 All active All active AM active 20 29 +9 C. j. louisianensis 7 All active All active All active 29 20 -9 C. j. louisianensis 6 All active AM active All active 29 20 -9 C. islagrande 6 All active All active All active 20 tap -20 C. j. louisianensis 7 All active All active All active water 29 tap -29 water C. j. louisianensis 6 All active All active AM active 29 tap water C. islagrande 4 Two dead AM dead Stomach Content Analyses: The stomach contents or recently collected specimens of both taxa and of animals used in the aquarium studies were analyzed. The stomachs were removed and opened. Aliquots of the contents were placed on a slide and examined with a com- pound miscroscope fitted with an ocular micrometer. These analyses were performed to determine the nature and size range of particulate stomach contents. FIELD OBSERVATIONS The bottoms of the inshore Mississippi Sound stations, pre- dominantly muddy, vary from sand to extremely soft mud, whereas those of the offshore stations are uniformly sandy. The compositions of representative bottom samples from the two environments are given in Table 4, The presence of mudshrimps in a beach can be recognized by their characteristic burrow openings (Fig. 6). There is no apparent species-related difference in the shape or structure — 175 — Figure 6 Openings of C. j. loidsiane^isiti Burrows Callianassid burrow openings in the natural habitat resemble those pro- duced in the laboratory. This figure shows the surface of vSubstrate Preference Test 12, 24 hr after the start of the experiment. Although 10 out of lo C. j. loiiisianevsis were recov'erecl from clay, num- erous burrow openings appeared in sand. of burrow openings. The openings, resembling those reported for other callianasids (Hailstone and Stephenson 1961, Lunz 1937, Pearse et al. 1942, Pohl 1946, Weimer and Hoyt 1964), are raised mounds (0.5-^ cm high) with an opening, 0.5-1 cm in di- ameter, in the center. Openings, often surrounded by fecal pel- lets, are most abundant in the intertidal bottoms below the belt of surf action and in the shallow rieritic zone. On several occas- ions burrow openings in the inshore and offshore habitats were seen through a maximum water depth of 1.2 m. The incidence of burrow openings is quite variable in the offshore habitat. At Station 7, the west end of Horn Island (2 December 1966), there was a low tide count of 100-|- openings per sq m. During the spring months at the same station there were less than 5 openings per sq m. At Station 9, Ship Island Quarantine Station, during April 1967, there were 100 h open- 176 — ings per sq m. There were no burrow openings at this station on 11 June 1967. No such drastic fluctuations in number of burrow openings were observed in the inshore habitat. It is pos- sible that the fluctuation in number of C. islagrande burrow openings results from wind and surf action and does not neces- sarily represent variations in population density. Certain struc- tural features of the C, j, louisiayieyisib' burrow wall, discussed later, may also serve to establish a situation wherein the burrow remains long after the mudshrimp has died or otherwise de- parted. The persistent burrow walls of C. loidsianensis may at times be left protruding as much as 5 cm above the bottom following the displacement of surrounding substrate by strong surf action. The in situ depth of 20 C, j, lowisianensis burrows, meas- ured by the insertion of flexible plastic tubing, ranged from 32-187 cm (mean, 77 cm). The extreme fragility of burrows of C. islagrande prevented similar measurements for that species. Pohl (1946), using this method, found that burrows of C. major Say reached a depth of 210 cm. Burrow walls of both forms vary from 5-15 mm in thick- ness, but show significant differences in composition. Walls of C, j. loidsianensis burrows are of very cohesive clay-like mud with a smooth mucilaginous lining, whereas those of C. isla- grande are composed of loosely cemented sand with no apparent lining. Wall texture of C. j. louisianensis burrows is the same, regardless of the composition of the surrounding substrate. BURROWING BEHAVIOR ON SUITABLE SUBSTRATES Although Willis (1942) reported an ovigerous C. islagrande swimming near the water surface, free-swimming mudshrimps were never encountered in this study. Both taxa treated here are certainly capable of at least short term swimming activities. Forward propulsion is achieved by pleopod motions and back- ward motion is achieved by rapid and repeated flexure of the abdomen. Mudvshrimps will swim for a short period, usually for less than 1 min and for a distance of less than 1 m, when first released in an aquariurn. They will then invariably cease swimming and burrow headfirst into any acceptable substrate and will be completely hidden within 1 min. All observations of burrowing behavior and burrow con- .struction were made in the laboratory. Fortunately burrows were frequently constructed again.st the aquarium wall (Figs. 7 and 8) and direct ob.?ervation could be made of subsurface activities. In initiating a burrow a mudshrimp usually backs out of the burrow one or more times, depositing displaced sub- .strate near the burrow opening. Excavated material i.s carried in a basket formed by the third maxillipeds. The burrow ex- — 177 — Figure 7 C. j. loimiancnsis and C. islagrande Burrows in Suitable Substrates A : Burrows of 2 C. isLagrande after 2 days in offshore sand, B and C: Burrows of C. j. louman<^nsis, 2 animals in each column, after 5 days in mud. D : C. j. louisimiensis in burrow in habitat substrate. — 178 — —179 A shows that within 3 days one C, islagravde extended its burrow throufifh superimj)Osed nmd, B, C and I) show progressive thickening of C. j. louisianensis mud-lined burrow walls in superimposed sand at 3, 11 and 21 days> respectively. Disturbance of the sand (upper) — mud (lower) interface by the burrowing activities of C. j, lOHiaianensib' is also evident (B, C, D). tends downwards vertically or at a slight angle to the vertical axis (a maximum of 30*). When the burrow is 3-4 times the carapace length of the burrowing animal, an expanded chamber (about twice the diameter of the rest of the burrow) is con- structed, This chamber enables the animal to turn around. When these soft bodied animals turn around there is flexure of almost 180* at the junction of the cephalothorax and first abdominal segment. Laboratory observations indicate that muclshrimp only rarely leave the burrows after the construction of the first turning chamber. Additional turning chambers are constructed periodically throughout the burrow. Substrate displaced by fur- ther burrowing operations is usually tamped into the burrow walls and, less often, pushed out of the burrow opening. The complexity of individual burrows increases with time and the aquarium substrate may eventually resemble a maze (Fig. 7). Burrows within aquaria may be deepened at a con- siderable pace. It was not unusual for both forms, given suit- able substrate, to burrow 36 cm, the maximum depth available, within 24 hrs (Fig. 7). This represents a minimum burrow construction rate of the order of 1.5 cm per hr. There is no ap- parent difference in burrowing rate with respect lo size. The di- ameter of the burrow is usually about twice the breadth of the animal but may vary from 1-5 times this dimension. Present observations suggest that, under natural conditions, each burrow is occupied by a single callianassid. On one occasion when 20 specimens were held in an aquarium containing 600 ml of substrate, two individuals w^ere seen in the same burrow. The possibility of similarly crowded conditions ever occurring in the natural habitats of local mudshrimp is difficult to con- ceive. in both forms, the ehelipeds, third maxillipeds and second and third pairs of pereiopods are used in burrowing. The cheli- peds and third maxillipeds are essential for burrowing. If both ehelipeds or both third maxillipeds are missing burrowing does not occur. The ehelipeds and third maxillipeds arc used to dis- place substrate in front of the mudshrimp. The third maxillipeds and, to a lesser extent, the second and third pereiopods are em- ployed to tamp displaced substrate into the burrow wall. The third maxillipeds are also used to carry substrate from one portion of the burrow to another. The second and third pereio- pods also function in displacing substrate, but to a considerably lesser extent than the ehelipeds. The dactyls of the fourth pair of pereiopods are brushlike and are used in cleaning the body surfaces, branchiae and, in the case of ovigerous females, at- tached ova. The fifth pair of pereiopods function in balancing the mudshrimp against the burrow walls. Callianassids produce a cementing substance used in con- struction of the burrow wall. Weimer and Hoyt (1964) stated — 180 — that C, major produces a cementing substance over the entire body surface and that this cementing material is collophonite, an amorphous calcium phosphate. In the case of C. j. louisianen- and C. isUir/rande, sand grains and other particulate matter are often embedded in mucoidal strands originating in the vicin- ity of the third maxilUpeds. Possibly secretion of the cementing substance is localized in the vicinity of the third maxillipeds in the taxa included in this study. Within their burrows, callianassids generate currents which may be involved in respiration with their pleopods (MacGini- tie and MacGinitie 1949). Kespiratory currents are produced in the branchial chambers by rapid beating of the scaphognaths of the second pair of maxillae and by occasional flushing of the branchial chambers by lateral contraction of the carapace, The epipodites of the first pair of maxillipeds form a shield over the anterior opening of the branchial cavity and possibly func- tion as a barrier to the entry of foreign particles. FEEDING Feeding behavior appears to be variable in Callianassa. Pohl (1946) stated that C, major feeds primarily by sifting the sub- strate for useable organic material, whereas MacGinitie and MacGinitie (1949) considered Callianassa af finis Holmes to be a filter feeder. Stomach content analyses of five recently col- lected specimens of both C. j. louisianensis and C. islagrand-e indicate that these taxa feed, at least in part, by sifting through the substrate. In both eases recognizable stomach contents con- sisted of about 50% sand grains by particle count. Grain diameter ranged from 10-800u and averaged about 107u. The re- maining particulate matter con.sisted of diatom^s of the genera Navicula, Pletirosxgjna, Tabellaria, Synedra and PinnMlaria, bac- teria (cocci and bacilli), and significant quantities of shredded brown material which was probably of vegetable origin. Similar stomach contents have been reported for C. major (Pohl 1946). COMMENSALS AND PARASITES About ten percent of the C. islagrande collected were in- fested with the copepod ectoparasite Clausidmm sp. These were found on all portions of the exoskeleton and not confined to any specific anatomical region. Pohl {op. cit.) reported finding a similar parasite of the genus Clausidmm infesting C. major on the Atlantic coa.st. No ectoparasites were found on C. j. Imiisi- ane7isis. Burrows of both Mississippi Sound mudshrimps har- bored pinnixid crabs {Pinnixia cHstata Rathbun), about one to five crabs per burrow. The Pinnixia inhabiting islagrande bur- rows e.xhibited considerable polymorphism with respect to colo- ration. Those infesting jmiaicense burrows were uniformly black and were covered with a dense hydroid growth. The sig- nificance of the pinnixid polymorphism is unclear, but it is probably related to substrate. — 181 — AQUARIUM STUDIES Responses to Selected Bottom Types: a. Sand (inshore and offshore types). C. j, louisianensis does not burrow readily. Only one speci- men of 15 reached the bottom of a 10 cm sand column within 4 days. Remaining specimens constructed only shallow burrows, up to 3 cm deep, and were observed to leave these burrows and swim more or less continuously for periods of up to 8 hours. As much as 16 min. was required to construct a 3 cm burrow, where- as a similar burrow may be constructed within 1 min. in a mud substrate. The single deep burrowing individual survived for 6 weeks, at which time it died of unknown causes outside its burrow. All other specimens exposed to sand died within 5 days. Examination of the burrow wall of the deep burrowing speci- men revealed no conspicuous lining. Stomach contents of 10 specimens, five exposed to each sand type (including the sole deep burrowing individual) consisted of a few bacteria only. There was no difference in response to either offshore or in- shore sand ; both sand types were equally unsuitable. C. islagrande burrows readily in sand of either source. Shallow burrows were usually constructed within 1 minute. Burrows were deep and extensive (Fig. 7) . Five specimens were kept in aquaria containing either inshore sand or offshore sand for as long as 2 months, at which time the experiment was terminated. Among five specimens exposed to each sand type, stomach contents consisted of a few bachteria only. Evidently the feeding behavior of C. islagrande, in suitable substrates, is al- tered in the laboratory environment. b. Hard Mud. C. louisianensis burrow very readily and burrows 3 cm deep are constructed within 1 minute. Burrows in hard mud were deep and very extensive (Fig. 7). The burrow walls were very similar to those in the natural habitat. Mortality over a 2-month period was low, being 3 out of 35 specimens (8.6%), Stomach contents of five specimens kept in aquaria 2 months were very similar to those of recently collected specimens. C. islagrande does not burrow readily in hard mud. Only 22% (4 of 18) burrowed and survived in mud for 5 days. C. islagra'nde which did construct burrows in hard mud did so just as rapidly as in sand. This species evidently has the abil- ity to burrow into mud, although it seldom does so. Death is preceded by blackening of the margins and articulating borders of the exoskeleton and occlusion of the branchial chambers with silt. — 182 — c. Clay. C, j, louisianensis burrowing behavior was the same as on hard mud. C. islangrande did not survive on clay for more than 5 days. Specimens swam constantly and seldom attempted burrowing. One specimen of the 10 tested constructed a shallow burrow but died in the burrow within 1 hr. As was the case on hard mud, death was preceded by blackening of the exoskeleton and occlu- sion of the branchial chambers with silt. d. Soft Mud. C. y. louisianensis exhibited the same behavior as on hard mud or clay. C. islagrande exhibited the same behavior on soft mud as on clay with the exception that none of the 15 tested specimens burrowed or attempted to burrow. Table 7: Burrowing Responses and Survival of Callianassa on Selected Mississippi Sound Substrates* Substrate Survival C.i. louisianensis C. islagrande Construction of Burrows at Least 10 cm Deep C.). louisianensis C. islagrande Sand, inshore Poor Good Rare Frequent Sand, offshore Poor Good Rare Frequent Hard Mud Good Poor Normal Rare Soft Mud Good Poor Frequent Never Clay Good Poor Frequent Never *A minimum of 15 spocimans of each laxon was tested on each substrate. Behavior in this series of tests is summarized in Table 7 with respect to survival and the relative number that constructed burrows deeper than 3 cm. C. islagrande survives well and bur- rows deeply only in sand, whereas C. j, louisianensis shows opti- mal survival and burrowing activity in mud or clay environ- ments. Effects of Columns Composed of Two Substrate Layers on Bur- roiving Behavior a. Offshore Sand Above Hard. Mtid. C. f, louisiamnsis showed essentially the same behavior pattern in this test as when tested on said previously. Of six specimens, only two had constructed shallow burrows by the sec- ond day. After 4 days one of the two specimens that had con- structed a shallow burrow reached the lower mud layer and the 183 — five remaining specimens were dead on the sand surface. The mudshrimp reaching the lower mud layer immediately began to line the upper sand burrow with mud. After 2 weeks the entire burrow had a thick mud wall similar to that found in the nat- ural habitat. C. islagrande burrowed' readily into the sand, and all four specimens, in two separate trials, reached the bottom of the sand layer within 6 hrs. One burrow was continued into the mud layer 5 days after the start of the experiment, but no additional mud burrows were seen during the 2-week test. All specimens were recovered alive from the sand layer at the termination of the experiment. b. Hard Mud Above Offshore Sand. C. j. louisianensis all burrowed into the mud within 1 min. and reached the bottom of the sand layer within 24 hrs. Within 2 weeks the layering between the sand and mud was sufficiently disturbed by burrowing activities to partially obliterate the previously distinct substrate interface. Burrow walls were sim- ilar to those found in the natural habitat. C. islagrande reacted to the hard mud as they did in prev- ious tests. Only one of the four specimens succeeded in burrow- ing through the mud into the sand layer during a 4-day period. The remaining specimens repeatedly constructed shallow bur- rows, then left them and spent most of the time swimming. Within 4 days all free specimens were dead. The burrowed individual died 'within 8 days. In each case the branchial cham- ber was occluded with sill and the margins and articulating surfaces of the exoskeleton were blackened. Evidently C. j. louisianensis can burrow through sand if there is mud available for burrow wall construction. Availabil- ity of sand does not facilitate burrowing or survival of C. isla- grande in mud. Behavior of Colonies to Sugerimgosed Substrate: In this series of tests approximately 250 ml of hard mud or offshore sand were superimposed on established colonies of 10 C. j. louisianejisis in approximately 400 ml of hard mud or 4 C. islagrande in the same volume of offshore sand. Depth of the superimposed layer was approximately 8.5 cm and the depth of the base layer was approximately 14 cm. C. j, louisianensis extended their burrows through super- imposed mud or sand within 6 hrs. Burrows extending through sand were lined with mud layers which were thickened through- out the course of the test (Fig. 8). Mud linings of the burrows in sand resembled those found in the natural habitat and some disturbance of the sand-mud interface was noted (Fig. 8). — 184 — C. islagrande burrows were extended through superimposed sand within 6 hours and all four specimens were recovered alive after 4 weeks* One burrow was extended through the superim- posed mud layer by the third day (Fig. 8) and all four animals were found dead in the sand layer at the end of 4 days. Portions of the exoskeletons of the dead test animals were blackened and in each case the branchial chambers were occluded by silt. C, islagrande, even when established in a suitable substrate, can- not tolerate silt in the environment. Substrate Preference Tests: The results of these tests, detailed in the Appendix, are summarized in Table 6, and discussed according to each cate- gory. Observations were made of the numbers of test animals burrowing into each substrate, speed of burrowing (rapid or slow) into each substrate and the number of test animals re- covered from each substrate after a minimum period of 24 hrs. Category 1: Sand offshore versus sand inshore (see Appendix Tests 1-4). C. j. louisianensis exhibited the same behavior pattern as when tested on either substrate alone. Both sand types are equally unacceptable and no preference was shown. C, islagrande showed the same response to each sand type. Approximately equal numbers of test animals burrowed into and were recovered from each substrate. Both substrates were equally suitable and burrowing was rapid (within 1 min) in each. Category 2: Sand (inshore or offshore) versus hard mud (see Appendix Tests 5-11). C. j. loidsianensis overwhelmingly preferred mud. After one or two attempts to burrow into sand, test animals usually bur- rowed into mud upon coming into physical contact with it. Numerous burrow openings appeared in sand although most mudshrimp.s were recovered from the mud, C, islagrande preferred sand. Although a significant num- ber (27%) burrowed rapidly into the hard mud and almost all left their mud burrows within 1 hr and burrowed into the sand upon coming into contact with it. The majority were re- covered from the sand. Those specimens recovered from mud had occluded branchial chambers and partially blackened exo- skeletons. Category 3: Sayid (inshore or offshore) versus clay (see Appen- dix Tests 12-14). C, j. louisianensis exhibited the same behavior as in Cate- gory 2. The muddy substrate was preferred. — 185 — C. islagrande never initiated burrows in clay. All test ani- mals were recovered from the sand. Category k' Hard mud versus clay (see Appendix Tests 15, 16). C, j. louisiauensis did not favor either substrate. Both clay and mud were equally suitable. C. islagrande did not burrow into clay. Mud was favored, although it was an unsuitable substrate. Behavior on mud ap- proximated that of previous tests, wherein specimens would re- peatedly construct shallow burrows, leave them and swim for varying periods of time, Despite the fact that it is a lethal choice, C. islagrande favors mud rather than clay >vhen forced to choose between these substrates. The lower silt content of hard mud makes it more acceptable than clay. These substrate preference tests showed that C. j. louisian- ensis favors the muddy substrate as opposed to sand and did not show any favoritism between clay or mud. C. islagrande selected sand as opposed to mud or clay and did not show any favoritism between inshore and offshore sands. When it comes into contact with a substrate in which it can burrow and sur- vive, the callianassid stays there. Salinity Tolerance Tests: On two occasions (substrate preference tests 4, 11 Appen- dix) 10 out of 25 (40%) and 13 out of 25 (52%) C. islagrande died within 1 hr. To determine if this mortality was the result of osmotic shock, salinity tolerance tests were conducted. The results (Table 6) show that free C. Islagrande cannot withvstand salinity changes from 29 g/kg to 20 g/kg or lower and that the same salinity variations have no apparent effect on C, j, lo-uisimtensis. As burrow’ed C. islagrande did not show any apparent response to a change from 29 g/kg to 20 g/kg, the substrate probably acts as a buffer against rapid in situ salinity changes within the burrow. These tests have shown that, al- though extreme salinity change may cause mortality in C, isla- gra'nde, less drastic changes have no apparent effects on the gross behavior of these callianassids. DISCUSSION The habitat isolation, within Mississippi Sound, of C. j. louisianensis and C, islagrande is apparently a function of spe- cies- related differences in ability to burrow and survive in sub- strates of each habitat. C. j. louisianensis, because of poor bur- rowing efficiency and poor survival in sand is incapable of in- habiting the C, islagrande habitat (7. islagrayide, conversely, as a result of an inability to survive in a silty environment, is in- capable of inhabiting the muddy inshore waters. The condition that enables C. j. louisianensis to burrow and survive in the —186 sandy littoral zone of some inshore beaches is the availability of mud with which to construct burrow walls. Although the mean salinity of the offshore environment is higher than inshore (Christmas et al. 1966), both environments are subject to drastic short term salinity fluctuations (Christ- mas et al. 1966, Daw'son 1965). The salinity tolerance tests (Table 6) were insufficient to determine whether salinity has any influence on the distribution of these callianassids. Although the salinity records (Table 1) show a lower salinity for the in- shore stations than for the offshore stations, there is consider- able overlap during the spring months. Drastic salinity change may be responsible for population variations in the natural habitat but apparently has little or no influence on the apparent habitat isolation of these species. Survival is dependent upon burrowing. MacGinitie (1934) stated that C. calif orniensis Dana soon die if their body sur- faces are not in contact with either glass tubing or burrow walls. Pohl (1946) stated that free C. major die as a result of starva- tion. With respect to the forms considered here, starvation is not the cause of death. Both free and burrowed mudshrimpa (C. islagrayide survived 2 months in sand, and the sole C. /. louisianensis survived 6 weeks in sand) had stomach contents consisting only of a few bacteria. Evidently feeding is not cruc- ial for short term survival providing the animal can burrow into the substrate. There is at present no adequate explanation for the apparent necessity of burrowing per se for survival. These forms were never observed to leave burrows in suit- able substrates during the course of the aquarium studies. Gun- ter (1945) reported C. /. louisianensis from the stomach con- tents of the sea catfish, Galeichthys felis (Linneaus) and Dar- nell (1958) reported Callianassa sp. from the stomach contents of the blue channel catfish, Ictalumis furcatus (Le Sueur). Therefore, callianassids probably leave their burrows on oc- casion and are subject to predation by these and other bottom feeders. Although C. islagrande has the ability to burrow into hard mud, this form seldom does so and exhibits poor survival in such bottoms even when burrowed. The mortality of C. isla- grande on muddy substrates is not exclusively a result of an inability to burrow but also of an inability to tolerate silt. The poor survival of C. j, louisianensis on sand can only be cor- related with an inability to burrow, which is possibly due to a mechanical inability to handle sand, a considerably less co- hesive material than mud. MacGinitie (1934) stated that C. calif oimiensis could only live in sand-mud bottoms tenacious enough for the construction of burrow walls. C. j, louisianensis evidently requires a more — 187 — cohesive substrate than sand. The greater surface areas of both the third maxillipeds and the second and third pereiopods in C. islagrande (Fig. 8, Table 3) are probably adaptations for living in a sandy bottom. The relatively smaller surface areas of the corresponding appendages of C. f. loiiisianensis limit this form to the effective handling of only muddy sub- strates. If the product of the. length and breadth (b and h, Fig. 3) for the digging surface of each appendage, divided by the carapace length, is taken as an index of surface area, G. isla- grande has a considerably greater indexed area than C. loitisiamnsis (Table 3). The merus-ischium surface area of the third maxilliped (Fig. 3) is strikingly different in these species. The pediform third maxilliped of G. i. loiiisiaTiensis has a mean index of 1.12, whereas the foliaceous third maxilliped of G. isla- grarhde has a mean index of 2.40. The other two appendages show less striking differences in gross morphology (Fig. 8), but the mean propodal indices of the second and third pereiopods arc considerably greater in C. islagrande (Table 3). The fact that the sand inhabiting G. major also has foliace- ous third maxillipeds (Pohl 1946) lends support to the conclu- sion that a foliaceous third maxilliped is an adaptation to a sandy environment. Since the cementing substance may, in large part, be localized in the vicinity of the third maxillipeds, a greater merus-ischium surface area could also serve to enhance the efficient use of the cementing substance. Greater surface area would likewise be advantageous in feeding, enabling the organism to sift through larger quantities of substrate per unit of effort. This would be especially important in the G. islagrande habitat where sand grains account for 98% of the volu- metric composition of the substrate (Table 4). Sand grains, however, only account for 50% of the recognizable stomach contents of C. Islagrande. Evidently this species selectively rejects large quantities of sand. Additional evidence supporting this is shown by the fact that sand grains in the stomach con- tents were considerably smaller than those of the substrate. Of five specimens examined, the size of ingested sand ranged from 10-800 u with a mean of 107u, whereas that of the substrate ranged from lO-lOOOu, with a mean of about 400Uf The pediform third maxillipeds of C. j. louisianeywis are apparently inadequate for feeding in sandy bottom. This is sup- ported by the fact that the sole specimen that burrowed and survived 6 weeks in sand had only a few bacteria in its stomach. There are no gross anatomical differences in the remaining oral appendages of these two forms. This indicates that the major anatomical differences related to feeding activities are the size and shape of the third maxillipeds. Pearse (1935) noted that there was a habitat isolation of G. major and the burrowing thalassinid, Upogebia af finis (Say), — 188 - at Beaufort, North Carolina. XJ. af finis was found only in muddy bottom and C. major was found exclusively in sand. This paral- lels the situation in the present study. Upogebia, however, is not comparable to C. j. louisianensis because it is a filter feeder (Pearse 1935, MacGinitie 1930, MacGinitie and MacGinitie 1949) and because adult Upogebia, when moved from their burrows, are incapable of constructing new burrows (Pearse 1935, MacGinitie 1930). Pearse (1935) states that U. af finis is well adapted for inhabiting a muddy bottom but did not attempt to explain its apparent absence from sand. From an ecological viewpoint, one group of organisms comparable with callianassids are those polycheates which feed by the ingestion or sifting of substrates. Both groups are re- sponsible for .sediment overturn. MacGinitie (1934) and Mac- Ginitie and MacGinitie (1949) compared Callianussa with terrestrial earthworms, stating that both perform the same role in their respective environments. The concept that mud- shrimps are responsible for sediment overturn is supported by the fact that C. j. louisianensis, over a relatively short period of time, partially obliterated the originally distinct substrate interface in columnar studies (Fig. 8). Gordon (1966) demonstrated that the deposit feeding poly- chaete PectinatHa gouldii (Verrill) was responsible for consider- able substrate overturn (10 worms per sq m overturning a 6 cm thick surface layer every 15 years). MacGinitie (1934) .stated that an average size C. calif orniensis is responsible for complete turnover of 1 sq in. of substrate to a depth of 30 in, in a period of 240 days. There are no quantitative data on the populations of burrowing Mississippi Sound animals and one cannot estimate the relative importance of callianassid populations in the turn- over of Mississippi Sound sediments. Hailstone and Stephenson (1961) reported that C. australi- erisis carry attached ova for 6 weeks, at which time hatching occurs and planktonic larvae invade the bottom within 9 months. The settling larvae resemble small Juveniles and have a carapace length of 1-6 mm. In the ca.se of Mississippi Sound calliana.ssids, ovigeroiis females were taken in the spring and summer months (Table 1). If a similar growth rate can be projected in Missis- .sippi w.aters, planktonic juveniles apparently enter the substrate during winter and spring months. Most juveniles collected had a carapace length of 4-7 mm (Table 2) and this suggests that entry into the substrate occurred in smaller size classes. There were no detectable differences in the tested behavior patterns of juveniles and adults. Therefore, settling juveniles are presumed to have the same behavior patterns as the test animals, survival being dependent upon fortuitous contact with a suitable substrate. —189 ACKNOWLEDGEMENTS I would like to express my appreciation to the National Science Foundation for financial support through NSF Re- search Grant Number GB 3452 to the Gulf Coast Research Laboratory. Acknowledgement is also made to the Gulf Coast Research Laboratory for additional facilities and support. I would also like to express my appreciation to the people who have aided me in this work. I am especially indebted to Mr. C. E. Dawson and Dr. Walter Abbott for aid in preparation and critical review of the manuscript. I would like to thank Mr. 0. D. Ballard for his aid and advice in the preparation of photo- graphs. Many thanks go to Mr. James Franks for his valuable help in collecting callianassids. I would also like to thank Capt. Fred Tliompson and Mr, J. Y. Christmas for making many of the field trips possible. 1 also want to thank the members of my committee for their constructive criticisms. Special thanks go to my wife Carol for her encouragement and patience and to my parents for their unflinching support. APPENDIX Results of Substrate Preference Tests Except where otherwise noted, substrate arrangement con- sisted of two equal rectangular sectors (Fig. 5). Category 1 : Sand, inshore versus sand, offshore C. j. louisianensis: Test 1: Number of Test Animals : 6 Salinity : 10 g/kg No, Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, inshore 3 Slow 2 (2) Sand, offshore 3 Slow 2 Additional Observations: Test animals repeatedly con- structed shallow burrows, left them and swam continuously for as long as 8 hrs. Burrowing time ranged from 10 min. to 1 hr. Two free specimens were found after 24 hrs. — 190 — C. islagrande: Test 2: Number of Test Animals: 20 Salinity: 25 g/kg No. Burrowing- Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, inshore 11 Rapid 9 (2) Sand, offshore 9 Rapid 11 Test 3: Number of Test Animals: 20 Salinity: 25 g/kg Substrate No. Burrowing Within 1 hr. Burrowing Speed No. Recovered After 24 hrs. (1) Sand, inshore 8 Rapid 10 (2) Sand, offshore 12 Rapid 10 C, j. louisianensis and C. islagrande: Test k: Number of Test Animals : 25 G. islagrande 12 C. j, louisianensis Salinity of Test: 20 g/kg Salinity of C. islagrande Colony : 29 g/kg No. Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, inshore 5 Slow 3 C. /. louisianensis C. j. louisianensis 8 Rapid 8 C. islagrande C. islagrairide (2) Sand, offshore ^ ^ 7 Slow 3 C. j. louisianensis C. j. louisianensis 7 Rapid 7 C, islagra'Tide C. islagrande Additional Observations : The behavior of C. y. louisianensis was similar to that in Test 1. Three free C, j. louisianemsis were recovered after 24 hrs. Ten free C. islagrande died within 1 hr., death apparently due to osmotic shock (Table 6 ). — 191 — Category 2: Sand (inshore or offshore) versus Hard Mud C. j. louisianensis : Test 5: Number of Test Animals: 4 Salinity: 8 g/kg Arrangement of Substrates: Six juxtaposed sectors, 3 of mud and 3 of sand (Fig. 5). No. Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, inshore 0 0 (2) Hard Mud 4 Rapid 4 (2 in sector 4, 1 each in sectors 1 and 5) (Fig, 5A) (Same number re- covered from sectors of initial burrowing) Test 6: Number of Test Animals: 4 Salinity: 8 g/kg Substrate Arrangements: Four juxtaposed sectors, 2 of mud and 2 of sand. No, Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, inshore 0 0 (2) Hard Mud 4 Rapid 4 (2 in sector 1, (Same number re- 2 in sector 4) covered from (Pig. 5) sectors of initial burrowing) Test 7: Number of Test Animals : 7 Salinity: 15 g/kg Substrate No. Burrowing Within 1 hr. Burrowing Speed No. Recovered After 24 hrs. (1) Sand, offshore 1 Slow 1 (2) Hard Mud 6 Rapid 6 — 192 — C. islagrande: Test 8: Number of Test Animals: 12 Salinity: 26 g/kg No. Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, inshore 9 Rapid 6 (2) Hard Mud 3 Rapid 2 Additional Observations: All test animals recovered from mud had occluded branchial chambers and exhibited black- ening of the margins and articulating surfaces of the exo- skeleton. Four free specimens were dead after 24 hrs., their branchial chambers occluded and exoskeletons blackened. Test 9: Number of Test Animals : 8 Salinity: 27 g/kg No. Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, inshore 7 Rapid 7 (2) Hard Mud 1 Rapid 1 Additional Observations : All specimens recovered from mud had blackened exoskeletons. Test 10: Number of Test Animals: 20 Salinity: 27 g/kg No. Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, offshore 14 Rapid 14 (2) Hard Mud 6 Rapid 1 Additional Observations: Five free specimens were found dead, their branchial chambers occluded with silt and mar- gins of the exoskeleton blackened. The specimen recovered from mud exhibited only blackening of the exoskeleton. — 193 — C. j. louisianensis and C. islagrande: Test 11: Number of Test Animals; 25 C, islagrande 10 C. y. loidsianensis Salinity of Test : 20 g/kg Salinity of C. islagrande Colony: 29 g/kg No. BuiTowing' Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, offshore 8 Rapid 8 C. islagrande G, islagrande 2 Slow 1 C. j. louisianensis C,j, louisianensis (2) Hard Mud 4 Rapid 4 C. islagrande C. islagrande 8 Rapid 8 C. j. louisianensis C. j. louisianensis Additional Observations: Thirteen free C. islagrande died within 1 hr. due to osmotic shock (Table 6). All C. isla- grande recovered from mud were dead, their branchial cavities occluded with silt and the margins and articulating surfaces of the exoskeleton blackened. Category d: Sand, (inshore or offshore) versus Clay C. j. louisianensis: Test 12: Number of Test Animals: 13 Salinity: 20 g/kg No, Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, inshore 2 Slow 3 (2) Clay 11 Rapid 10 Additional Observations: Numerous buri'ow openings ap- peared in sand and clay sectors (Fig. 6). Test 13: Number of Test Animals: 8 Salinity: 20 g/kg No. Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. 0 8 (1) Sand, offshore (2) Clay —194 Rapid 2 6 C. islagrande: Test lA: Number of Test Animals: 18 Salinity: 29 g/kg No. Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Sand, offshore 18 Rapid 18 (2) Clay 0 — 0 Category U: Hard Mud versus Clay C. j. louisianensis : Test 15: Number of Test Animals : 16 Salinity : 15 g/kg No, Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Hard Mud 8 Rapid 8 (2) Clay 8 Rapid 8 C. islagrande: Test 16: Number of Test Animals : 9 Salinity: 29 g/kg No. Burrowing Burrowing No. Recovered Substrate Within 1 hr. Speed After 24 hrs. (1) Hard Mud 9 Rapid 8 (2) Clay 0 — 0 Additional Observations : All specimens had their branchial chambers occluded with silt and the margins and articu- lating surfaces of the exoskeleton blackened. LITERATURE CITED Christmas, J. Y., G. Gunter and P. Musgrave. 1966. Studies of annual abundance of postlarval penaeid shrimp in the es- tuarine water.s of Mississippi, as related to subsequent com- mercial catches. Gulf Research Reports 2 : 177-212. Darnell, R. M. 1958. Food habits of fishes and larger inverte- brates of Lake Pontchartrain, Louisiana, an estuarine com- munity. Publ. Mar. Sci. Univ. Texas 5: 3e53-416. — 195 — Dawson, C. E. 1965, Rainstorm induced mortality of lancelets, Branchiostoma, in Mississippi Sound. Copeia: 505-606. Friedrichs, A. V. 1965. Descriptions of the Calliayiassa of Grand Isle, Louisiana. Unpubl. master’s thesis, Dept. Zool., Louis- iana State Univ., Baton Rouge. 50 p. Gordon, D. C., Jr. 1966. The effects of the deposit feeding poly- cheate Pectinaria gouldii on the intertidal sediments of Barnstable Harbor. Limnol. Oceanog. 11: 327-332. Gunter, G. 1945. Studies on marine fishes of Texas. Pnbl. Inst. Mar, Sci. Univ. Texas 1: 1-190. Hailstone, T. S. and W. Stephenson 1961. The biology of Cal- Uanassa (Trypea) anstralmms Dana 1852 (Crustacea, Tha- lassinidea). Univ. Queensland Pap. (Zool.) 1: 259-285, Lunz, G. R. 1937. Notes on CaUianassa major Say. Charleston Museum Leaflet No. 10 : 1-15. MacGinitie, G. E. 1930. The natural history of the mud shrimp Upogebia pugettemis (Dana). Ann. Mag. Nat. Hist. 6: 36-44. 1934. The natural history of CaUianassa ealiforn- iensis Dana. Amer. Midi. Nat. 15: 166-177. and N. MacGinitie 1949. Natural Histomj of Marine Anmuils. McGraw-Hill, Inc., New York. 473 p. Pearse, A. S., H. J. Humm and G. W. Wharton 1942. Ecology of the .sand beaches at Beaufort, North Carolina. Ecol. Mono- graphs 12: 136-180. Pearse, A. S. 1935. Ecology of Upogebia affinis (Say) Ecology 26: 71-80. Pohl, M. E. 1946. Ecological observations on Callianasm major Say at Beaufort, North Carolina. Ecology 27 : 71-80. Priddy, R. R., R. M. Crisler, C. P. Sebren, J. D. Powell and H. Burford 1955. Sediments of Mis.sissippi Sound and inshore waters. Bull. Mississippi State Geol. Surv. 82: 7-54. Schmitt, W. L. 1935. Mud Shrimps of the Atlantic Coast of North America. Smithsonian Miscellaneous Collections 93 (2) : 1-21. Weimer, R. J. and J. H. Hoyt 1964. Burrows of Calliayiassa major Say, indicators of littoral and shallow neritic environments. J. Paleontol. 38: 761-767. Willis, E. R. 1942. Some mud shrimps of the Louisiana coast. Occ. Pap. Mar. Lab. Baton Rouge, La. 2: 1-6. — 196 — Gulf Research Reports Volume 3 Issue 2 1971 Survival of the Oyster Crassostrea virginica (Gmelin) in the Laboratory Under the Effects of Oil Drilling Fluids Spilled in the Laguna de Tamiahua^ Mexico Jorge Cabrera Universidad Nacional Autonoma de Mexico DOI: 10.18785/grr.0302.04 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Cabrera, J. 1 97 1 . Survival of the Oyster Crassostrea virginica (Gmelin) in the Laboratory Under the Effects of Oil Drilling Fluids Spilled in the Laguna de Tamiahua, Mexico. Gulf Research Reports 3 (2): 197-213. Retrieved from http:// aquila.usm.edu/gcr/vol3/iss2/4 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. SURVIVAL OF THE OYSTER CRASSOSTREA VIRGINICA (GMELIN) IN THE LABORATORY UNDER THE EFFECTS OF OIL DRILLING FLUIDS SPILLED IN THE LAGUNA DE TAMIAHUA, MEXICO by Jorge Cabrera^ ABSTRACT In 1965, 970.12 m" of oil drilling fluid were spilled in the Laguna de Tamiahua, Mexico. Laboratory experiments were car- ried out to determine possible effects of this upon the oyster Crassostrea virginica. It was found that drilling fluid reduced the survival of oysters to a significant degree in concentrations above 200 ppm. At turbidities between 200 and 500 ppm, there was 60% survival on the seventh day. Tanino in concentrations between 90 and 170 ppm had a drastic effect upon survival which was 50^ between the fourth and fifth days. Bentonita in 110 to 190 ppm resulted in 50% survival on the eighth day. Barita in concentrations between 50 and 65 ppm did not produce nox- ious effects on the survival of the oysters. Natural mud in con- centrations from 200 to 500 ppm was favorable for the sur- vival of oysters. INTRODUCTION With the appearance and increase of internal combustion engines, which increased the demand for oil production, the problem of marine pollution became more pronounced (Yee 1967). This problem occurs in marine waters, coastal lagoons and other aquatic media as well, but when a fisheries resource is involved, the problem acquires importance beyond the purely biological Uelds. Yee (op. cit.) presented selected references on pollution of marine waters as the result of oil drilling and re- lated activities. His work includes articles written since 1950, in many of which the ramifications of this problem are dis- cussed. Sugimoto et al. (1964, 1965) pointed out that on the fish- ing grounds of the Seto Inland Sea, damage to the fisheries in- creased with increasing oil pollution. The mortality of oysters in relation to natural environ- ments and to oil fields has been analyzed by Mackin and Hopkins Unatituto de Biolog:ia, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-233, Mexico 20. D. F. — 197 — (1962) in Louisiana. Daugherty (1950, 1951) reported experi- mental results of the effect of some chemicals used in oil well drilling on marine animals, including the oyster (C. vinjinica) \ this author explains the reason for his work as follows: “With the recent increase of oil wells in Texas bays, the possibility of pollution from chemical compounds used in drilling became important. Exact knowledge of the effect of these compounds on marine organisms was needed.” The magnitude of the problem is in contrast to the amount of information available, as previous works relating to the ef- fect of fluids from oil drilling on animal life, including the oyster, are very few and deal only with adults, Nothing has been published to date concerning the larval stages of oysters, to which the damaging effects of strange elements in the en\'iron- ment could be even more important. Very little is known of the relationship that may exist be- tween the turbidity produced by muds, normally found around oyster beds in the Laguna de Tamiahua, and herein called nat- ural muds, and the survival of oysters under similar conditions as mentioned also by Mackin and Hopkins (oy. cit.). In Mexico we have had occasion to watch several spills, fortunately most of them without drastic biological results, of oil drilling fluids into Tamiahua Lagoon, Veracruz, one of the most important oyster producing localities of Mexico (fig. 1). In this lagoon, 970.12 m’ of oil drilling fluids were spilled be- tween April and December 1965; this material was composed of 314.79 m’ of material extracted from the different geological strata and 655.33 m"* of industrial materials introduced during the drilling {fide Villalobos et al. 1968, mimeographed). This investigation was undertaken to clarify the alleged “mortality” and “extermination” of the oyster reefs in Tami- ahua Lagoon. The oil company was sued for a considerable sum of money as recompense for the alleged damage. However, the claim has never been proven by any evidence. The Institute of Biology of the National Autonomous University of Mexico was asked to undertake research on this matter and to give an ex- pert opinion. This was included in the work cited (Villalobos et al.) along with some of the data in the present article. The purpose of this article is to report some results of ex- periments conducted under laboratory conditions to determine the effects of (a) oil drilling fluids used by Pemex in Tamiahua Lagoon; of (b) several compounds used in the drilling fluids; and of (c) natural mud, on the survival of the local oyster. ACKNOWLEDGEMENTS The author wishes to thank Dr. Alejandro Villalobos-Figu- eroa, leader of the project, whose direction and support were — 198 — the principal factors in the progress of the project; and Dr. Gordon Gunter, Director of the Gulf Coast Research Labor atorjs Ocean Springs, Mississippi, USA, who kindly joined us in camp at Cucharas and in the Laboratory in Mexico City during September 1967 and whose advice and constructive recommenda- tions were appreciated. It must be noted that Doctor Gunter feels that the experiment reported here should be repeated until the results ai'e more satisfactorily proven. The author is in agreement, but considering the lack of economic resources need- ed, wished to make these incomplete results available to persons interested in this matter. Dr. Sammy M, Ray was kind enough to provide us with copies of the articles of F. M. Daugherty cited herein, and with other interesting information as well. Many of my co-workers and friends helped in the construc- tion of aquaria in Cucharas, and also in many other ways; special thanks are hereby expressed to the following: Guadalupe de la Lanza, Fernando Manrique, Samuel Gomez, Andres Resen- dez, Virgilio Arenas, Alberto Ramirez, Gerardo Green and Luis Soto. Many of the residents of Cucharas and La Laja, Veracruz, were of great help in the every day course of our experimental work, for which I am also very grateful. Drs. A. Villalobos and G. Gunter reviewed and criticized this article. Dr. Allan Phillips assisted in the preparation of the English version. I also wish to thank: ingenieros Graciano Bello, Guillermo Bernal, Enrique Noguera, Ignacio Cervantes and their collabora- tors, for their extensive assistance in the field work. The ex- perimental work was made possible by the economic support of Petroleos Mexicanos (PEMEX), under contract to the In.sti- tuto de Biologia, Universidad Nacional Autdnoma de Mexico. MATERIAL AND METHODS The oysters used in the experiments came from the Laguna de Tamiahua, particularly from the oyster reefs known as fol- lows: Restinga de Cucharas, La Martinica and Boqueron de Burros (fig. i). These organisms belong taxonomically to Cras- sostrea virgmica (Gmelin), and their medium size was 8 cm in length, with a range from 7 to 12 cm. These oysters were col- lected with “gafas,” an instrument composed of two wooden rakes, 3 meters long, joined a third of the way up, the teeth being nails set in two lines, one opposite the other. These instru- ments are modified oyster tongs made of wood and nails. Oys- ters were kept under laboratory conditions for 3 to 5 days be- fore being used in the experiments. A working place was improvised in the Pemex camp, in the village of Cucharas (fig. 1). A system with a capacity to supply — 199 — Fig. 1. Laguna de Tamiakua: 1) Catdn oil well 2) Acamaya oil well 3) Village and estuary of Cucharas 4) Rcstinga de Cucharas (oyster reef) 5) Restinga la Martinica (oyster reef) 6) Eoquer&n de Burros (oyster reef) 7) Campanario (mud test site) — 200 — 201 Fig. 2. Diagram of the system used to supply water and suspended material to the aquaria : 1) Aquaria 2) Plastic tubing 3) Suction tube for suspended material 4) Plastic pump to inject suspended material 5) Pump to raise water to the upper tanks 6) Outlet 7) Intake 8) Aquaria with one oyster each 80 aquaria, each containing 8 liters, was built (fig. 2). Propor- tions of the aquaria were 20 x 20 x 20 cm, in units of two, back- to-back (fig. 2). Each one had a glass excess drainage tube to regulate the water level. Wooden tables covered with water- proof resin were made as well as supports for the aquaria. The whole system was installed in a wooden cottage. The water used in the experiments came from the Estero de Cucharas (fig. 1), at a point where a little pier extended some 10 meters from the shore in front of the encampment. It was taken at 40 to 60 cm above the bottom in water of 2 or 2.5 meters deep (fig. 2) . The water was raised by ''Sentinel” pump, model C IV 2 A, powered by a Briggs and Stratton 4-cycle gaso- line engine. The water was stored in three asbestos-cement tanks having total capacity of 600 liters. These tanks were lo- cated on top of a metal tower 5 meters high. Water was then distributed by gravity, using a system of plastic and P.V.C. tubing and valves, to adjust the water flow in each aquarium. Water was changed simultaneously in all the aquaria three times a day, each change taking 15 minutes at a flow of two liters per minute; this was done at intervals of approximately eight hours. At the time of changing the water, either test fluids or muds were added to the system by means of a plastic pump (Desmo Plastic-Tec, S. A.) driven by a ti H. P. electric motor (Power Electrica S. A.) There was some difficulty in running electric motors in Cucharas, as (at the time of this work) the village lacked public power, so a small diesel electric plant was used according to our needs. Ingenieros Melesio Munoz R. and Hector Soto Rosiles, of the Drilling Department of Pemex, provided the drilling fluids needed for the experiments. They also provided information on the chemical compositions of the drilling fluids, which we were not in a position to analyze. According to this information, the drilling fluid was composed of two fractions: one a combina- tion of different commercial substances and the other the var- ious materials extracted from the geologic strata. The fluid used in the experiments came from a drilling located dose to the Laguna de Tamiahua, and made at the .same time that the oyster survival experiments were run. The two above-mentioned engineers were of the opinion that the geologic structure of this drilling was quite similar to that found in the Laguna de Tamiahua; that there were no im- portant differences in the drilling procedures; and that the drilling fluids used in the oyster survival experiments were very similar quantitatively and qualitatively to these .spilled in the Laguna de Tamiahua. The following list of materials introduced in the drilling in the Laguna de Tamiahua, and in what proportions, was pro- vided by the personnel of Pemex (the names of the chemicals are those known in Mexico, with their sources). Kg. % Barita 6000 6.5 (Industria Mexicana, S. A., Av. Madero 16, despacho 305, Mexico, D. F.) Bentonita 20300 22.0 (Industria Mexicana, S. A.) Pirofosfato tetrasodico 1330 1.4 (Hooker Mexicana, S. A., Apartado Postal 7529, Mexico 1, D. F.) Tanino Cabel 815 0.8 (Productos Cabel, S. A., Genova 39-105, Mexico 6, D. F.) Tinex 200 0.2 (Oleoquimica Monterrey, S. A., Montana 13, 7*’ Piso, Mexico 18, D. F.) C.M.C. 240 0.2 (Deribados Macroquirnicos, S. A., Durango 283, Mexico, D. F.) Obturante #8 350 0.3 (Productora y Abastecedora, S. A., Apartado Postal 19-512, Mexico, D, F.) Lubrisesa - - 26 0.1 (Sosa Escamas, S. A., Apartado Postal 45, Santa Clara, Estado de Mexico) Cromato de Sodio 120 0.1 (Dow Chemical, Mexico, D. F.) Diesel. 59500 64.7 (PEMEX Mexico) Cemento Portland 3000 3.2 (Mexico) Turbidity was estimated by the method and with the instru- ments of Jackson, using a turbidimeter 75 cm long. After each change of water in the aquaria, samples were taken for the measurements of turbidity, which was estimated twice in each sample. The maximum of turbidity decreased because of both the sedimentation of suspended material itself and the capacity of oysters to subtract suspended material from the water. The aquaria were cleaned once a day by emptying them and scouring their walls and floor. — 203 — Chlorinity was estimated according to the method of Mohr- Knudsen, dissolved oxygen by the Winkler method, and tem- perature was taken with a Celsius thermometer. The frequency of these estimations was varied according to the conditions of each experiment; the minimum frequency was once every other day. Nine experiments are considered in this article: two of a preliminary nature; three to estimate the effect of drilling fluids; three more to show the effect of some components of such drilling fluids in certain concentrations; and one experi- ment using natural mud. In most of these experiments survival was observed in two samples — an experimental and a control sample — each contain- ing 20 oysters. One oyster was placed in each aquarium; a total of 320 oysters was used in these experiments. The experiments were run between March and August 1967, during periods when I had the opportunity to stay in the encampment. RESULTS In figures 3 to 11 the results of the experiments are repre- sented graphically. Figure 12 shows the index of 50% of oyster mortality in various concentrations of drilling fluids. Table 1 presents information on the variation of the environment in the aquaria. % N® 3 100 20-j^ • 75 t5 ■ 50 10- 25 5 - ■ : 5 iO 15 20 25 26 % N® Fig. 3. After 26 days, during which the water was changed three times a day, 85% of the oysters had sur- vived, sho\Ning a high index of survival. The ordinate shows the percentage and number of suriv- ors; the abscissa the number of days tested. Fig. 4. Mortality was high when water was not changed ; 50% s u r- vival was reached af- ter 14 days. In the ordinate, survival; in the abscissa, time. ■ 204 - Preliminary experiments. A first experiment was conducted to obtain information on oyster survival under the optimum conditions of changing water which could be maintained for a long time; this w'ould give an index of high survival. A second experiment, without changing the water, was set up to get an index of low survival^ in contrast with the first. After 26 days of the first experiment, during which the water was changed three times a day as mentioned above, 85% of the oysters had survived (fig. 3). This percentage was con- vsidered a sufficiently high index of survival, so this frequency of changing water was judged adequate for running the sub- sequent experiments. The second experiment shows that 50% mortality was reached after 14 days (fig. 4) ; this was considered a low in- dex of survival, as it showed that mortality could be high if the water were not changed. Effects of the drilling fluid. Three experiments were es^ tablished to test the effects of three different ranges of turbidity and of the drilling fluid. % N« Fig. 5 Survival of two samples, the experimental (dotted line) and the control (continuous line). The first one was treated three times a day with drilling fluid up to 1000 to 2000 ppm of initial tur- bidity; 50% mortality was reached on the sixth day. In the ordinate, survival ; in the abscissa, time. % N« Fig. 6 Survival of two samples, the experimental (dotted line) and the control (continuous line). The first one treated three times a day with drill- ing fluid in initial turbidity between 200 and 500 ppm. 60% mortality occurred on the seventh day. In the ordi- nate, survival; in the abcis- sa, time. — 205 — The substances were used in the same form in which they are sold commercially. The concentration of each was arbitrary, always starting from the same volume of dry material suspend- ed or dissolved in a given volume of water. As the properties of each substance are different in regard to solubility and sus- pensibility, the resulting turbidity was different for each com- ponent. Tanino in turbidity between 90 and 170 ppm: 50% mor- tality was reached between the fourth and the fifth day in the experimental sample; mortality was total on the seventh day. The controls only reached 20% mortality on the seventh day (fig-. 8). % N? Fig. 9. Surivftl of two samples, the experimental ) dotted line) and the control (continuous line). 1’he first one treated three times a day with Ben- ton itn in initial turbidity between 110 and 190 ppm. 50% .survival occurred on the eighth day. In the ordi- nate, survival; in the abscis- sa, time. % N9 Fig. 10. Survival of two samples, the e.xperimental (dotted line) and the control (continuous line). The first one treated three times a day with Bari- ta in initial turbidity be- tween 50 and 65 ppm. Both survival curves were quite similar, so that no lethal effect was shown. In the ordinate, survival ; in the abscissa, time. Bentonita in concentrations between 110 and 190 ppm: 50% survival in the experiment sample occurred on the eighth day; at this time the control lot reached 20% mortality (fig. 9). Barita in concentrations betiveen 50 and 66 ppm: on the ninth day, survival was 80%^ in the experimental sample and 85% in the control. The survival cur\^es were quite similar, so that no lethal effect was shown (fig. 10). — 207 — Daugherty (1951) reported some results on the action of Tanino, called in his paper “tannex"; he established that one lot of 24 oysters survived 22.5 hours in increased concentrations up to 140 ppm in a system with recirculating water and con- stant turbidity, and also found that a similar lot survived 20.5 hours in increased concentrations up to 450 ppm. From this the author concluded that tannex was not toxic to oysters; how- ever, he proved that it is toxic to other marine organisms in concentrations of 70 to 450 ppm over the same period of time. Apparently the results of Daugherty and those presented in this article are not in agreement, but what caused the difference is probably the methodology. The main factor may be the length of time the experiment was run; however, the concen- trations used and their variations, and the frequency of chang- ing the water in the aquaria, also may be significant factors. In my opinion, Daugherty’s experiments did not last long enough to show' any mortality of oysters. The Bentonita in 110 to 190 ppm proved to cause signi- ficant mortality in the experiment here reported; but in the opinion of the experts of Pemex this substance forms com- pounds of high density in the drilling fluid, so that its suspensi- bility is not great and it could not be scattered over a broad area in sufficient concentration at one time, to produce a .significant mortality in the Laguna de Tamiahua. This opinion is supported and discussed also by Villalobos et al (1968) re- ferring to the total drilling fluid. Daugherty (1951) reported that the “aquagel,” a trade name for a high quality Bentonita, did not kill any oysters dur- ing 22 hours in concentrations as high as 7500 ppm. This author considered “aquagel” as non-toxic to marine animals. A.s in the case of the Tanino, the results obtained in the present ex- periments are apparently in disagreement with Daugherty^. The same major objection applies again: Daugherty’s did not last long enough to kill the animals. The Barita in the concentrations used in this experiment did not produce any apparent mortality as can be seen from the survival curves (fig. 10). In this respect Daugherty (1951) using '‘baroyd,’' made of selected Barita, also found this sub- stance to be non-toxic either to the oyster or to the other marine animals of his experiments. Our findings are in agreement des- pite differences in methodology. It is interesting to add that Daugherty (1950) found “sod- ium acid pyrophosphate” to be toxic to oysters in concentra- tions of 500 ppm and greater. This substance W'as not te.sted in our experiments. In my opinion none of the information reported by Daugh- erty (1950-1951) or such of the present articles as concerns — 210 — the effect of components of the drilling fluids could be appli- cable to the case of the Laguna de Tamiahua, as none of these substances was spilled in its commercial form ; rather, they were used as components of the drilling fluid which was then used in the drilling, and it was only at the end of the drilling operations that the fluid was spilled. For these reasons it is assumed that the only information available that could be ap- plicable to the case of the Laguna de Tamiahua is that pre- sented herein referring to the effect of the drilling fluid upon the oysters. The applicability of this information, however, is not so obvious, and even it may be of doubtful value for many reasons. The most important of these reasons is that the labora- tory experiments are not a complete reproduction of what hap- pened at the time when the drilling fluids were spilled. Fur- thermore these experiments deal only with oysters and drilling fluid, without taking into consideration the whole ecosystem of which the oysters were a component; the drilling fluid, as a foreign substance, probably affected the usual functioning of the ecosystem, but at present no information is available on this difficult and complex problem. What is most desirable is to avoid the spilling of any foreign substance into coastal la- goons such as Tamiahua, without limiting the activities of the oil industry and other industries. This despite the opinion of Daugherty (1951) that the compounds tested, for him, were sufficiently low in toxicity to be of little danger when released in open bay waters. As to the effect of natural mud on the survival of oysters, the high survival of the experimental lot in contrast with the controls, seems to show that this substance favors survival. Mackiu and Hopkins (1962) x.)ointed out that in certain local- ities in TiOuisiana, natural mortality of oysters was in inverse proportion of the water’s turbidity; in places and periods with high turbidity, the mortality was lower. These results are in agreement with mine, but the reasons for this effect are not clear. During the experiments variations were recorded in tem- perature, chlorinity and the concentrations of dissolved oxy- gen. This information did not require special treatment so only the limits were reported (Table 1). Temperature varied from 23“ to SO^C, as a result of seasonal variations from spring to sum- mer. Chlorinity varied between 4.40 and Lower values were found during a short period in August in relation to the rainy season in summertime. The concentrations of dissolved oxygen varied between 3.0 and 7.6 ml/L; it was highest during the intake of water. Low values of oxygen were found only at the end of the second ex- periment, probably due to fermentation and oxidation in the .stagnant water. It seems logical to believe that temperature, — 211 — chlorinity and dissolved oxygen fluctuated between narrow limits so as to give comparable results in the various experi- ments. Availability of food was not controlled, but it seems that oysters can survive long periods without abundant food, ac- cording to experiments conducted by Dr. Sammy M* Ray (per- sonal communication). CONCLUSIONS Drilling fluid reduced the survival of oysters significantly in concentrations of over 200 ppm in laboratory aquaria. In turbidities between 200 and 500 ppm, 50% mortality was reach- ed on the seventh day. According to Villalobos et al (1968), these concentrations could hardly be maintained in time and space sufficient to produce significant mortality or the claimed extermination of the oyster reefs in the Laguna de Tamiahua. This conclusion is the only one that could be applicable to the case of the Laguna de Tamiahua, as all the others deal with commercial components of the drilling fluid, and these were not spilled as components. Nothing is known about the effect of drilling fluid upon the ecosystem to which oysters belong. Tanino in concentrations between 90 and 170 ppm had a drastic effect upon survival, which was 50% between the fourth and fifth days. Bentonita in 110 to 190 ppm resulted in 50% survival on the eighth day. Barita in concentrations between 50 and 65 ppm did not produce noxious effects on the survival of the oysters. Natural mud in concentrations from 200 to 500 ppm was favorable for the survival of oysters. LITERATURE CITED Daugherty, F, M., Jr. 1950. The effect of sodium acid pyro-phos- phate on Ostrea mrgmica Gmelin. The Texas Journal of Science 4: 539-540. 1951, Effects of some chemicals used in oil well drill- ing on marine animals. Sewage and Industrial Wastes 23(10) : 1282-1287. Mackin, J. G. and S. H. Hopkins. 1962. Studies on oyster mor- tality in relation to natural environments and to oil fields in Louisiana. Publ. Inst. Mar. Sci. 7 : 1-319. Sugimoto, H. M. and 0. Takeuchi. 1964. Studies of oil pollu- tion on the fishing ground in Seto Inland Sea. 1. Distribu- tion of oily wastes in the Sea. Bull. Japanese Soc. Sci. Fish. 30(7) : 542-563, (In Japanese with English summary). — 212 — 1965. Studies of the oil pollution on the fishing ground in Seto Inland Sea. II. Distribution of oil wastes in the mud of sea bottom. Bull. Japanese Soc. Sci. Fish. 31 : 24-32. (In Japanese with English summary). Villalobos, A., J. Cabrera, J. G6mez, V. Arenas, F. Manrique, A. Resendez, and G. de la Lanza. 1968. (unpublished). In- forme final de las investigaciones realizadas en la Laguna de Tamiahua (segun contrato con Petroleos Mexicanos). Mimeographed 1968, Institute de Biologia, Universidad Nacional Autdnoma de Mexico. 72 p. Yee, J. E. 1967. Oil pollution of marine waters. TJ. S. Depart- ment of the Interior, Department Library Washington, D. C. November 1967, Bibliography No. 5, 27 p. — 213 — Gulf Research Reports Volume 3 Issue 2 January 1971 A Bibliography of Anomalies of Fishes^ Supplement 2 C.E. Dawson Gulf Coast Research Laboratory DOI: 10.18785/grr.0302.05 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Dawson^ C. 1971. A Bibliography of Anomalies ofFishes, Supplement 2. Gulf Research Reports 3 (2); 215-239. Retrieved from http:/ / aquila.usm.edu/gcr/vol3/iss2/ 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 Research by an authorized administrator of The Aquila Digital Community For more information, please contact Joshua.Cromwell^usm.edu. A BIBLIOGRAPHY OF ANOMALIES OF FISHES Supplement 2 C. E. Dawson Gulf Coast Research Laboratory Ocean Spring's, Mississippi This listing- adds 213 titles to the original bibliography (Gulf Res. Repts. 1(6), 1964) and the 1966 supplement (Gulf Res. Repts. 2(2) :169-176). Although a number of previously overlooked references are included, there are 137 citations of works published during the 1965-70 period. The frequency of recent publications offers some indication of the current world- wide interest in problems of fish teratology. Apparently in response to increased interest in the environ- ment, some American authors are now attempting to relate anomalies in natural or “wild^’ populations of fishes to pollu- tion levels. While this may be a useful area of investigation, the results should be evaluated with caution. It is obvious that only sub-lethal conditions are observed and there are few data, espe- cially in marine or estuarine environments, upon which to es- tablish a “normah' survival potential for a particular abnorm- ality in any species. Those hoping to use publi.shcd records to establish a “base-line” .should bear in mind that, with few ex- ceptions, both old and recent publications report only the most obvious and striking conditions (macro-anomalie.s) . Investiga- tors attempting to determine frequencies of abnormalities should include data on the less obvious and possibly very common micro-anomalies. This supplement includes an Index of Sources and Abbrevi- ations covering those journals not included in the original bibli- ography. As in the previous supplement, titles are serially num- bered and prefixed by the letter “S”; the prefix has been omitted from the index listings. Corrections to be made in the original bibliography are indicated under Corrigenda. I again wish to express my continuing appreciation to those colleagues who have provided reprints of their papers or otherwise contributed to this bibliography. — 215 — BIBLIOGRAPHY S-92 Acara, A. H. 1968. A normal, synchronous hermaphro- dite Dolly Varden char. Trans. Amer. Fish. Soc. 97 (2) :201-202, fig. S-93 Amin, 0. M. 1968. Deformed individuals of two species of suckers, Catostomus iiisignis and C. clarhii, from the Gila river system. Copeia 1968(4) ;862-863. S-94 Anon. 1968. Xiphophorus maculatus (Gunter). Pearl albino platy. Trop. Fish Hobbyist 17(4) :33-34, 3 figs. S-95 Anwand, K. 1963. Uber einige Abnormitaten und Miss- bildungen beim Hering (Clupea hareng'ns L.). Z. Fisch. 11(7/8) :533-538. S-96 Arme, C. 1966. A hermaphrodite specimen of roach, Rutiltis nitilus (L.). Proc. Leeds phil. lit. Soc. 9(11) : 277-281, 2 figs. S-97 Atz, J* W., Kallrnan, K. D., and Nigrelli, R. F. 1963. Position effect as a factor in the production of mela- nosis and melanoma in the fish Xiphophorus. Proc. int. Congr. Zool. 16(2) :206. S-98 Bakhshi, P. L. and Saxena, D. B. 1966. Observations on an abnormal shark, Scoliodon walbeehmi Blkr. Proc. nat. Acad. Sci. India, Sect. B. (Biol. Sci.) 36(1) :85- 88. 5 figs. S-99 Bapat, S. V, and Radhakrishnan, N, 1968. A note on the occurrence of abnormal specimens of mackerel, Rastrelliger kanagurta (C.) on the Karwar coast. J. Mar. biol. Ass. India 1966, 8(1/2) :363-364, fig. S-100 Bartholomew, M. A., DiVall, J., and Morrow, J. E. 1962. Silver pike, an atypical Esox lucius, in Alaska, a first record. Copeia 1962(2) :449-450. S-101 Baruah, M. C. 1968. A case of albinism in Heteropneti- stes fossilis (Bloch). J, Bombay nat. Hist. Soc. 65:495- 496. S-102 Bastos, J. R. 1966. Um caso anomalo em Scomberomorus macutatus (Mitchill). Arq. Estac. Biol. mar. Univ. Cleara 5(2) :215. S-103 Beamish, R. J. 1969. Asymmetry in the trunk vertebrae of Lota lota lacustris (Walbaum). Canad. J. Zool. 47 (4) :537-538. S-104 Beni, G. and Sterba, G. 1964. fiber einen merkwurdigen Fall doppelseitiger, partieller Mehrfachbildung bei Protopterus dolloi Blgr. (Pisces, Dipnoi). Zool. Anz. 173 :360-363, 2 figs. — 216 — S-105 Bennet, P, S. 1964, On an abnormal ray from Vizhin- gam (Rhynchobatus djiddensis) . J. Mar. biol. Ass. India 6(2) :316-317, fig. S-106 Bensam, P. 1964. On certain gonadial abnormalities met with in the Indian oil sardine Sardinella longiceps Va. J. Mar. biol. Ass. India 6(1) : 135-141, S-107 1965a. Regeneration of the caudal fin in the Indian oil sardine, Sardinella longiceps Valenciennes. J. Mar. biol. Ass. India 7(1) :102-107, 12 figs. S-108 1965b. On a freak embryo of the grey shark, CarchaHmis limbatus Muller and Henle. J. Mar. biol. Ass, India 7(1) : 206-207, 4 figs. S-109 Berland, B. 1967. A melanistic herring. Fauna, Oslo 20(4) :273-274. S-110 Bbhlke, J. E. 1956. A new pigmy sunfish from southern Georgia. Notul. nat. Acad. Philad. 294:1-11, 2 figs. S-111 Brady, L. E., Hulsey, A. H. and Watson, M. E. 1962. Pied channel catfish - a color mutation, Proc. Conf. stheast. Ass, Game Commrs. 16:360. S-112 Breder, C. M., Jr. 1927a. The fishes of the Rio Chucun- aque drainage, eastern Panama. Bull. Amer. Mus. nat- Hist. 57(3) :91-176. S-113 — 1927b. Tailless pearl roach. Bull. N. Y. zool. Soc. 28(3) : 72-74. S-114 1953. An ophichthid eel in the coelom of a sea bass. Bull. N. Y, zool. Soc. 38(18) :201-202. S-115 Brian, A. 1952. Caso mostruoso di un pescc privo di un occhio {Merluccitis escidentus Risso). Natura, Milano 43 :17-23, 2 figs. S-116 Briggs, P. T. 1966. A pugheaded tautog. N. Y. Fish Game J. 13(2) :237. S-117 Brown, C. J. D. 1962. An injured big skate. Raja binocto- lata. Proc. Mont. Acad, Sci. 22:93-94. S-118 and Fox, A. C. 1966. Mosquito fish {Gam- busia af finis) in a Montana Pond. Copeia 1966(3): 614-616. S-119 Bullough, W. S. 1940. A case of hermaphroditism in the herring {Clupea harengvSy Linn.). Proc. Leeds phil. lit. Soc. 3:638-641. S-120 Carufel, L. H. 1966. A three-headed trout. Progr. Fish. Cult. 28(1) :50, fig. — 217 — S-121 Carvalho, J. de P. 1946. Sobre 2 casos deformacao gular de peixes. Caca e Pesca 5(57) :28-30. S-122 Cavaliere, A. 1965. Anomalie della colonna vertebrale in Boo'ps salpa L. Boll. Pesca Pisci. Idrobiol., n. s., 20 (1) ;52-59, 5 figs. S-123 Chacon, J. O. 1954. Caso de hermafroditismo ern curi- mata comum, '‘Phochilodm sp.”-(Actinopterygii. Char- acidae, Phochilodinac). Publ. Serv. Piscic. Bras. 163: 1-19. S-124 Chidester, F. E. 1917. Hermaphroditism in F iindulus heferoclitus. Anat. Rec. 12:389-398. S-125 Ciechomski, J. D, de and Christiansen, H. E. 1968. Un caso de hermafroditismo en la merluza Merluccius inerlucc'hi^ hubbsi (Pisces, Merlucciidae) . Phv.sis, R. Aires 27(75) :423-428, 9 figs. S-126 Cohen, D. M, and Torchio, M. 1964. Comments on the identity of the Mediterranean fish Stnv^ia tinea. Ann. Mag. nat. Hist., 13th ser., 6(67) :389-390. S-127 Comfort, A. and Doljanski, F. 1958. The relation of size and age to rate of tail regeneration in Lebisfes reticu- latus. Gerontologia 2(5) :266-283. S-128 Compagno, L. J. V. 1967. Tooth pattern reversal in three species of sharks. Copeia 1967(1) .*242-244, 2 figs. S-129 Conrad, J. F. and Decevv, M. 1967, Observations on de- formed juvenile coho salmon. Res. Briefs 13(1) :129. S-130 Crane, J. M,, Jr. 1967. Albinoid coloring in a sand bass, Paralabrax nebulifer (Girard). Calif. Fish Game 53 (3) *.217-218, fig. S-131 Dahlberg, M. D. 1970. Frequencies of abnormalities in Georgia estuarine fishes. Trans. Amer. Fish. Soc. 1970 (1) :95-97. S-132 Daly, R. J. 1970. Systematics of southern Florida an- chovies (Pisces: Eiigraulidae) . Bull. Mar. Sci. 20 (1) : 70-104, 6 figs. S-133 Danielssen, D. and Tveite, S. 1968. Tagged saithe {Gadiis virens). Fauna, Oslo 21:137, 2 figs. S-134 Davenport, D. 1966. Colour variant of bocaccio (Sebas- todes pmicispinis) in British Columbia waters. J. Fish. Res. Ed. Can. 23(12) :1981. S-135 Dawson, C. E. 1967a. Notes on teratological gobioid fishes from Louisiana and Maryland. Proc. La. Acad. Sci. 30:74-79, 3 figs. — 218 — S-136 S-137 S-138 S-139 S-140 S-141 S-142 S-143 S-144 S-145 S-146 S-147 S-148 S-149 S-150 1967b. Three new records of partial albinism in American heterosomata. Trans. Amer. Fish. Soc. 96(4) :400-404, 6 figs. 1968. An adventitious dorsal fin-ray in Micro- gobivs gulosus (Pisces : Gobi idae) . Anat. Anz. 122: 498-501, 2 figs. 1969a, Three unusual cases of abnormal color- ation in northern Gulf of Mexico flatfishes. Trans. Amer. Fish. Soc. 98(1) : 106-108, 2 figs. 1969b. Cithai'ichthys ahbotti, a new flatfish (Bothidae) from the southwestern Gulf of Mexico. Proc. biol. Soc. Wash. 82:355-372, 7 figs. 1969c. Records of the barnacle Cone ho derma virgatum from tv.7o Gulf of Mexico fishes. Proc. La. Acad. Sci. 32:58-62, fig. Denoncourt, R. F. and Bason, W. H. 1970. Blind striped bass, Roccus saxatilis (Walbaum) from the Delaware River Estuary. Ghesapeake Sci. 11(2) :132-134, fig. Dhulkhed, M. H. 1965. On an unusual ovary of the Indian oil sardine Sardmella longlceps Val. J. Mar. biol. Ass. India 7(1) :210-211, fig. ‘ D’Ombrain, A. 1957. Game fishing off the Australian coast. Angus and Robertson, Sydney, xviii ' 230 pp. Drapkin, Y. L 1968. [A deformity of the sole Solea las- eans nasuta (Pallas) from the Black Sea.] Vop. Ikh- tiol. 8(2) :362, fig. Dryfoos, R. L, 1966. The life history and ecology of the longfin smelt in Lake Washington. Contr. Sch. Fish. Univ. Wa.sh. 212:36-37. Duffy, J. M. 1968. Deformed lateral line in a jack mack- erel, TraeJnmis symmetTiem (Ayres). Calif. Fish Game 54(4) :306, fig. Duijn, C. van, Jr. 1967, Diseases of fishes. Illiffe Books Ltd., London. 309 p. Easwaran, C. R. 1968. On an abnormal ray from the Gulf of Kutch. J. Mar. biol. Ass. India, 1967, 9(1) : 198-200, 2 figs. Edsall, T. A. and Saxon, M. I. 1968. Two hermaphro- ditic alewives from Lake Michigan. Copeia 1968(2) : 406-407, 2 figs. Essenberg, J. N. 1923. Complete sex-reversal in the vi- viparous teleost Xvphophorus helleii. Biol. Bulk, Woods Hole 45:46-96. — 219 — S-161 Fischer, J. L. 1965. On a malformation in the guppy {Lebistes reticulatus) . Bull. mens. Soc. linn. Lyon 34 (8) :339-340, 2 figs. S-152 Follett, W. 1. 1952. Annotated list of fishes obtained by the California Academy of Sciences during six cruises of the U, S. S. MULBERY, conducted by the United States Navy off central California in 1949 and 1950. Proc. Calif. Acad. Sci., ser. 4, 27 (16) : 399-432, 6 pis. S-153 and Dempster, L. J. 1966. Partial melanal- binism in a scorpaenid fish, Sebastodes melanostomus Eigenmann and Eigenmann, from Monterey Bay, Cal- ifornia, with selected references to melanism and al- binism in fishes, Wasmann J. Biol. 24(2) :189-198, pi. S-154 Forster, G. R. 1967. A note on two rays lacking part of the snout. J. Mar. biol. Ass. U. K. 47(3) :499-500, fig., 2 pis. S-155 Fowler, H. W. 1912. Hermaphrodite shad in the Dela- ware. Science, n. s., 36:18-19. S-156 Frank, S. 1968. Vergetarier unbeliebt? Aquar. Mag. 2: 18-19, 4 figs. S-157 Freund, L. 1909. Hermaphroditismus bei Clupea haven- gns. S. B. ‘LoW 57:97-98. S-158 Fulmer, B. A. and Ridenhour, R. L. 1967. Jaw injury and condition of king salmon. Calif. Fish Game 53(4) : 282-285, 2 figs. S-159 Fuster de Plaza, M. L. and Boschi, E. E. 1957. Desnu- tricion y deforrnaciones vertebrales en pejerreyes de los embalses de Cordoba. Rep. Argentina, Ministero de Agricultura y Ganaderia, Dept. Invest. Pesqueras, B. Aires. 39 p., illus. S-160 Geyer, F. 1940. Abnorme Seitenlinien bei Fischen. Z. Fisch. 38:221-254. S-161 Gill, C. D. and Fisk, D. M. 1966. Vertebral abnormalities in sockeye, pink and chum salmon. Trans. Amer. Fish. Soc. 96(2) :m-182, 11 figs. S-162 Godoi, M. P. 1947. Um caso de separacao entre as eber- turas genital e anal na piava-ussu, “Lepormv^*' sp. Rev. bras. Biol. 7(3) :307-309, fig. S-163 Goodwin, W. F. and Vaughn, T. L. 1968. An adult pug- headed American shad Alosa sapidissima. Trams. Amer. Fish. Soc. 97(1) :50, fig. ^220 S-164 Gorman, T. B. and Dunstan, D. J. 1967. Report on an attack by a great white shark off Coledale Beach, N. S. W., Australia, in which both victim and attacker were recovered simultaneously. Calif. Fish Game 53 (3) :219-223, 3 figs. S-165 Goss, R. J. 1956. An experimental analysis of taste bar- bel regeneration in the catfish. J. exp. Zool. 131:27-50. S-166 and Stagg, M. W. 1957. The regeneration of fins and fin rays in Fundidus heteroclitm. J. exp. Zool. 136(3) :487-607. S-167 Grimaldi, E. 1965. Frequenza delle malformazioni nella populazione di coregone bondella {Coregorms sp.) del Lago Maggiore. Mem. 1st. ital. Idrobiol. de Marchi 19 (1) :93-99. S-168 Grimpe, G. 1927. Uber eine merkwurdige Zwittergonade des Herings {Clupea harengus). S. B. naturf. Ges, Lpz. 1926:60-70. S-169 Gudger, E. W. 1922. Foreign bodies found embedded in the tissues of fishes. Nat. Hist., N. Y. 22(5) :462-457. S-170 1928. A mackerel {Scomber ccomhrm) with a rubber band rove through its body. Amer. Mus. Novit. 310:1-6. S-171 Gunstrom, G. K. 1966- The occurrence of a katadidymus Chinook salmon alevin. Trans. Amer. Fish. Soc. 96(2) : 214-216, 2 figs. S-172 Hansen, D. J. 1969. Vertebral anomaly in Micropogan undulatus. Quart. J. Fla Acad. Sci. 31(3) :207-208, fig. S-173 Hase, A. 1935. Uber ein hypertrophisches Flossenre- generat beim Goldfisch Carassius auratiis L. S.B. Ges. naturf. Fr. Berl. 1935:283-289. S-174 Hashmi, S. S. 1966. Colour variation : sex ratio and size frequency of Otolithm argenteus (Cuvier), (Silver- banded jew fish). Pakist. J. Sci. indust. Res. 9:283- 285, fig. S-176 Hass, G. 1936. Variationsstatistische Untersuchungen an Proben von Gohius microps Krdyer aus der Kieler Bucht und der Schlei. Schr. naturw. Ver. Schlesw.- Holst. 21(3) :419.426. S-176 Herald, E. S. 1941. Finst record of the hybrid flounder, Inopsetta ischyra, from California. Calif. Fish Game 27(2) :44-46, fig. — 221 — S-177 Hikita, T. 1965. Some cases of the anomalous coloration of the pink salmon, Oncorhijyickus gorbnscha (Wal- baum), caught in the north Pacific Ocean, Sci. Rep. Hokkaido Salm. Hatch. 19:75-77. S-178 Hildebrand, S. F. 1946. A descriptive catalog of the shore fishes of Peru. Bull. U, S. nat. Mas. 189:xi -fl- 530. S-179 Hillis, J. P. 1966. Abnormal thornback ray, Raja cla- vata, from Co. Kerry. Irish Nat. J. 15(6) :182. S-180 Hoeck, P. P. C. 1894. Die op een hermaphrodiet ex- emplaar van de rog {Raja clavata) betrekking hebben. Tijdschr. ned. dierk., Ver., ser. 4, 2:45-46. S-181 Hoff, F. H., Jr. 1969. Ambicoloration of an adult floun- der, Paralichthys albigiitta. Copeia 1969(1) : 208-209, 2 figs. S-182 Hoff, J. G. 1970. Vertebral anomalies in a humpbacked specimen of Atlantic silverside, Menidia rnenidia. Chesapeake Sci. 11(1) :64-65. S-183 Honma, Y. and Kitami, T. 1967. Notes on a peculiar spinal curvature in the file fish, Novadon modestus, from the Sea of Japan. Bull. Jap. Soc. sci. Fish, 33(1) : 20-23, pi. S-184 and Mizusawa, R. 1965. Record of a .speci- men of an orange-red (xanthuchroic) flounder, Mi- C7'ostomus achne (Jordan and Starks) from off Noh- machi. Sea of Japan. Collect. & Breed. 27(12) :452- 453, fig. S-185 Hourston, A. S. 1968. Abnormal ces.sation of growth in a herring otolith. J. Fish. Res. Bd. Gan. 25(11) :2503- 2504, pi. S-186 Hubbs, C. L. 1919. Records of abnormal variations among fishes. Copeia 70:45-46. S-187 1927. The related effects of a parasite on a fish. J. Parasit. 14(2) :75-84. S-188 — 1936. Fishes of the Yucatan Peninsula. Publ. Carnegie Instn. 457:167-287, 16 pis. S-189 Huet, M. 1970. Traitc de Pisciculture, 4th edn. Ch. de Wyngaert, Brussels, xxiiiT718p. S-190 Hulquist, R. G. 1967, First recorded xanthic sargo, An-isotreymi^ davidsonii (Steindachner) , from the Sal- ton .sea, California. Calif. Fish Game 53 (4) : 292-293, fig. — 222 — S-191 Huzita, S. and Nishino, K. 1966. An albino of Sebasto- lob'us macrochir collected off Cape Eimo, Japan. Jap. J. Tchthyol. 13(4) :210~212, fig. S-192 Imai, K. 1965. Malformed caudal neurosecretory sys- tem in the eel, Anguilla jwponica, Embryologia, Na- goya 9:78-97, 41 figs. S-193 Imaoka, Y. and Nishimura, S. 1964. Anomalies found in the flatfishes from the southern Japan Sea. Bull. Japan Sea Fish. Res. Lab. 13:137-140, 2 pis. S-194 Tredale, T. and Whitley, G. P. 1929. Captain Cook's leather jacket. Aust. Mus. Mag. 3(12) :421-425, 4 figs. S-195 Ito, K. 1965. On two abnormal forms of zuwai-gani, Chi- onoecetes opilio elongatus 0. Fabricus. Bull, Japan Sea Fish. Res. Lab. 14:91-93. S-196 Johnson, J. E. 1968. Albinistic carp, Cypt'iyius carpio, from Roosevelt Lake, Arizona. Trans. Amer. Fish. Soc, 97(2) :209-210. S-197 Jones, E. C., Rothschild, B. J. and Shomura, R. S. 1968. Additional records of the pedunculate barnacle, Con- choderma virgatum (Spengler), on fishes. Crustaceana 14(2) :194-196, 2 figs. S-198 Jones, S. and Patulu, V. R. 1954. A remarkable case of albinism in the freshwater eel, Anguilla bengalensis Gray. J. Bombay nat. Hist. Soc. 51(1) :285-287. S-199 King, A. D. 1966. Hermaphroditism in the common dog- fish {Scyliorhinus canicuUis) . J. Zool., London 148; 312-314, fig. S-200 Klay, G. 1969. 1969 model of thornback ray makes show- room debut at Cleveland aquarium. Drum and Croaker 69(1) :21, fig. S-201 Klinger, K. 1960. Wirbelsaulenverkriimmungen bei Fis- chen. Schweiz. Fisch Ztg. 68(5) :101. S-202 Kotthaus, A. 1967. Fische des Indischen Ozeans. A. Systematischer Teil I: Isospondyli und Giganturoidei. “METEOR” Forschungsergebnisse, Reihe D, 1:1-57, 59 figs, S-203 Lawler, G. H. 1966a. Pugheadedness in perch, Perea flavescens, and pike, Esox lucius^ of Heming Lake, Manitoba. J. Fish. Res. Brd. Can. 23(11) :1807-1808, fig. S-204 1966b. A second record of an accessory fin on Esox lucius. J. Fish. Res. Brd. Can. 23(12) :1969, fig. 223 — S-205 Lesnikova, T. V. 1965. [Malformations among- fishes of the Gorkovskiy Reservoir.] Izv. Gos. Nauch-Issled. Inst. Ozer. Rechn. Rybn. Khuz. 59:1.38-142. S-206 Lewis, R. M. 1966. Effects of salinity and temperature on survival and development of larval Atlantic men- haden, Brevoortm tyranmis. Trans. Amer. Fish. Sue. 95(4) -.42.3-426. S-207 Lieder, U. 1959. uber die Entwieklung bei mannehen- losen Stammen der Silberkarausche Carassmb‘ auratus gihelio (Bloch) (Vertebrata, Pisces). Biol. Zbl. 78:284- 291. S-208 Lillelund, K. 1965, Weitere Untersuchungen iiber den Hermaphroditismus bei Osmerns eperlanus (L.) aus der Elbe. Z. Morph. Okol. Tiere 55:410-424, 2 figs. S-209 Loeb, H, A. and Kelly, W. H, 1968, Eyelessness due to cannibalism in a population of stunted brown trout. N. Y. Fish Game J. 15(2) :197-20(). S-210 Liiling, K. H. 1952. Ein zwittriger Pilchard. Fischerei- welt 4 :46. S-211 Maheshw'ari, S. C. 1966. A case of abnormality in the testes of Mastacembelm annatus (Lacep.). Jap. J. Ichthyol. 14(1/3) :101-102, 2 figs. S-212 Malhotra, Y. R. 1968. Abnormal condition of ovaries in Schizothomx niger Heckel. Sci. & Cult. 34:469-470, 2 figs. S-213 Manion, P. J. 1967. Morphological abnormalities among lampreys. Copeia 1967(3) :680-681, fig. S-214 Mann, H. 1954. Die Wirtschaftliche Bedeutung von Krankheitcn bei Secfischen. Fischwirtschaft 6:38-39. S-215 Marcoux, R. G. 1966. Occurrence of a melanistic pad- dlefish (Polyodon spathula) in Montana. Copeia 1966 (4) :876, fig. S-216 Marlborough, D. and Meadows, B. S. 1966. A ‘pug- headed' perch {Perea fluviatdlis L.) from the River Lea. Lond. Nat. 45:98-99, pi. S-217 Matsumoto, W. M., Talbot, P. H., Collette, B. B., and Shomura, R. S. 1969. Pacific bonito (Sarda chiliensis) and skipjack tuna (Katsimonus pelamis) without stripes. Copeia 1969(2) :397-398. S-218 Mawdesley-Thomas, L. E. and Young, P. C. 1967. Cut- aneous malanosis in a flounder (Platichthys flesus L.). Vet. Rec. 81:384-385, 2 figs. — 224 — S-219 McKenzie, M. D. 1970. First record of albinism in the hammerhead shark, Sphyrna leioini (Pisces :Sphyrni- dae). J. Elisha Mitchill sci. Soc. 86(1) :35-37, fig. S-220 Menezes, R. S, de 1961. Ausencia de nadadeiras ventrais em Lycengraulis harboiiri Hildebrand, 1943. Bol. Soc. Gear. Agron. 2:57-58, fig. S-221 Menzel, R. W. 1959. Further notes on the albino catfish. J. Hered. 49(6) :284, 293. S-222 Michajlowa, L. 1968. Missbildungen bei einigen Siis- swasserfischen (Cyprinidae) . Z. Fisch. 16:139-153, 16 figs. S-223 Millikan, A. E. and Patiie, B. H. 1970. Hermaphroditism in a Pacific hake, Merluccius productus, from Puget Sound, Washington. J. Fish. Res. Bd. Can. 27:409-410. S-224 Moe, M. A., Jr. 1966. Hermaphroditism in mullet, Miigil cephulus Linnaeus. Quart. J. Fla. Acad. Sci. 29(2) :lil- 116, 2 figs. S-225 1968. A reversed, partially ambicolorate tongue- sole, Symphnrus dioniediiinus, from the Gulf of Mexico. Copeia 1968(1) :172. S-226 Monteiro, F. P. 1965. Casos de “albinismo” em cascudo preto {Rhinolepis aspera Agassiz) no Rio Piracicaba. An. Congr. Lat.-Amer. Zool. 2:199-202, 3 figs. S-227 Moore, D. 1969. A reversed southern flounder, Paralich- thys lethostigma Jordan and Gilbert, from the Gulf of Mexico. Tex, J. Sci. 21(1) :97-99, fig. S-228 Moore, G, A. and Curd, M. R. 1966. A pinhole camera eye in the white crappie, Pomoxis anmdaris, Copeia 1966(2) :359-360, fig. S-229 Muller, K. 1953. Die Schuppenmissbildungen bei der Torelle Sahno trutta Tv. und eine Deutung dieser Ersch- einung. Rep. Inst. Freshw. Res. Drottning. 1952:78- 86, 6 figs. S-230 Musick, J. A. and Hoff, J. G. 1968. Vertebral anomalies in humpbacked specimens of menhaden, Brevoortia tyrannus. Trans. Amer. Fish. Soc. 97(3) :277-278, 2 figs. S-231 Nakatsukasa, Y. 1965. An example of the hermaphroditic gonad found in Oncorhynchua keta (Walbaum). .Jap. J. IchthyoL 13(1/3) :59-63, 2 figs. S-232 Nayak, P. D. 1959. Occurrence of hermaphroditism in Polynemm keptadactylus Cuv. & Val. J. Mar. biol. Ass. India 1(2) :257-258, fig. — 225 — S-233 Nichols, J. T. 1921. The Miami aquarium. Nat. Hist., N. Y. 21(4) :359, S-234 Norton, J, 1968. Piebald hi>fin swordtail. Trop. Fish Hobbyist 16(5) :4-13, 11 figs. S-235 Okiyama, M. 1965. [A case of pugheaded ness in the rock fish, Sebastes oblongus Gunther.] Bull. Japan Sea Fish. Res. Lab. 14:85-89, 2 figs. S-236 Paris, J. and Quignard, J.-P. 1968. Quelques cas d'ambi- coloration et d'albinisme chez Solea vulgaris Quensel. Rev. Trav. Inst. Pech. marit. 32:507-510, 4 figs. S-237 Patnaik, S. 1967. Hermaphroditism in the Indian sal- mon Eleutheronema tetradactylum (Shaw). Curr. Sci. 36(19) ;625. S-238 Patten, B. G. 1966. An abnormally colored C-0 sole, Pleuronichthys coenosus. Underw. Nat. 1(1) :40, 2 figs. S-239 1968. Abnormal freshwater fishes in Wash- ington streams. Copeia 1968(2) :399-401. S-240 Penczak, T. 1967. An example of Blicca bjoercna (L.) deprived of pectoral fins and pelvic girdle. Przegl. Zool. 11 :363^364, 2 figs. S-241 Pener-Salomon, H. 1969. Atypical optic papillae in Bar- bus cams (Cyprinidae, Pisces). Israel J. Zool. 18:255- 262, 4 figs. S-242 Pflugfelder, 0. 1967. Weitere Untersuchungen iiber KyphoLordose und Scoliose nach Zerstdrung der Epip- hysenregion bei Fischen und Haushiihern. Roux Arch. EntwMech. Org. 158:170-187, 19 figs. S-243 Phillips, J. B. 1952, Yellow sablefish (black cod) taken in Monterey Bay. Calif. Fish Game 38(3) :437-439, fig. S-244 1957. A review of the rockfishes of California (family Scorpaenidae) . Fish Bull., Sacramento 104: 1-158, 67 figs. S-245 1964. Life history studies on ten species of rockfish (genus Sebastodes). Fish Bull., Sacramento 126:1-70, 35 figs. S-246 Pinto, J. dos S. 1953. Um caso de hermafroditismo em Sardinia pilchardus (Walb.). Notas Estud. Inst. Biol, marit. 5:1-5. S-247 Plehm, M, 1924. Praktikum der Fischkrankheiten. E. Schwiezerbart’sche Verlagsbuchhandlung, Stuttgart, 179 p. — 226 — S-248 Prabhakara Rao, A. V. 1969. A case of hermaphroditism with notes on two abnormal ovaries in the silver biddy, Gerres oyena (Forskal) from the Pulicat Lake. J. Mar. biol. Ass. India 1967, 9 (2) :339-345, 2 figs. S-249 Prawochenski, R. 1966. Anomaly in the structure of the skeleton in Chondrostoma nasiis (L.) from the Vistula river. Pr 2 egl. Zool. 10:415, fig. S-250 Radulescu, I. 1965. Deformari prin traumatisme con- statate la calcanul {Scophthalmus maeoticus (Pallas)] din Marea neagra. Bui. Inst, Cere, pise, 24(3-4) :108- 112, 2 figs. S-251 1967. Exostoze pe spinul hemal Pagrosom.'us auratiis, BuL Inst. Cere. pise. 26(4) :82-84, fig. S-252 and Iliescu, M. 1964. Brahignatie si anoftal- mie la salau Stizosiedion luci.operca (L.). Bui. Inst. Cere. pise. 23(4) :97-100, 2 figs. S-253 and Nalbant, T. T. 1969. Cazuri de brachig- natie la unele Gadidae si Zoarcidae din oceanul Atlantic de nord — vest. Bui. Inst. Cere. pise. 28(1) :81-84, 4 figs. S-254 Rajapandian, M. E. and Sundaram, K. S. 1968. A case of complete albinism in the marine cat-fish Trachy- sums dussumieri (Cuvier and Valenciennes). J. Mar. biol. Ass. India 1967, 9(1) :194-195. S-255 Raney, E. C. 1952. The life history of the striped bass, Rocctis saxatilis (Walbaum). Bull. Bingham oceanogi\ Coll. 14:5-97. S-256 Rangarajan, K. 1968, On an instance of reduced num- ber of anal spines in Scolopsis phaeops (Bennett) (Sco- lopsidae-Pisces) . J. Mar. biol. Ass. India, 1966, 8(1/2) : 369-370, S-257 Reed, M. 1968. Bent spine. Trop. Fish Hobbyist 16(6) : 85-87, 2 figs. S-258 Rees, E. I. S. 1965. A deformed thornback ray. Nat. in Wales 9 :227-228, fig, S-259 Reichenbach-Klinke, H. 1958. Ein Barsch mit “Mops- kopF’. Nachr. naturw. Mus. A.schaffenburg 61:85-88. S-260 1966. Krankheiten und Schadigungen der Fische, Gustav Fischer Verlag, Stuttgart, xii-f389 p. S-261 Reimers, P, E. and Bond, C. E. 1966. Occurrence of the Bidens (sp.) achene in the snout of chinook salmon and redside shiners. Progr. Fish Cult. 28(1) :61^ fig. —227— S-262 Rose, C. D. and Harris, A. H. 1968. Pugheadedness in the spotted seatrout. Quart, J. Fla. Acad. Sci. 31(4) : 268-270, fig. S-263 Rothschild, B. J, 1966. Observations on the alewife {Alosa pseudoharengus) in Cayuga Lake. N. Y. Fish Game J. 13(2) :188-195. S-264 Schaferna, K. 1934. Karpfen und Bai’sch mit abnorm verlangerten Plossen. Z. Fisch. 32:375-379. S-265 Schwartz, F. J. 1963. Rluefish from Chesapeake Bay de- formed by plastic band. Chesapeake Sci. 4(4) ‘.196, fig. S-266 Seshappa, G. 1966. On a case of reversal in Cyrwglossus se7mfasciatus Day. J. Mar. biol. Ass. India 6(2) ;319- 320. S-267 Shrivastava, S. S. 1968. Hermaphroditism in a teleost, Notopterus notopterus (Pallas). Curr. Sci. 37(17): 496-498, 2 figs. S-268 Shulyak, G. S. 1965. Effect of temperature on the devel- opment of abnormalities in the carp intestine. Gidrob- iol. Zh., Kiev 1(4) :39-47. S-269 Sindermann, C. J. 1966, Diseases of marine fishes. Ad- van, Mar. Biol. 4:1-89, 17 figs. S-270 Sivaprakasam, T. E. 1966, Ambicolouration in two spe- cies of flatfishes from Madras. J. Bombay nat. Hist. Soc. 63:758-759, 2 figs. S-271 Srnith, B. G. 1942. The heterodontid sharks: the natural history, and external development of Heterodontiis ja~ ponicns based on notes and drawings by Bashford Dean. Dean Memor. Vol., Amcr. Mus. nat. Hist. 8: 651-770, 8 pis. S-272 Sriramachandra Murty, V. 1969. Notes on hyperostosis in the fish Drepane punctata (Linnaeus). J. Mar. biol. Ass. India 1967, 9(2) :323-326, pi. S-273 Starks, E, C, 1913. The fishes of the Stanford expedi- tion to Brazil. Leiand Stanford Jr. Univ. Pubk, Univ. Ser., 1913 :l-77, 16 pis. S-274 Swan, M. A. 1968. Double-mouth deformity in a trout (Salmo Pnitta) and its cau.se. J. Zook, London 156(4) : 449-455, 2 figs. S-275 Takeuchi, K. 1960. A study of the mutant (wavy) in the medaka, Oryzias latipes. Annot, zool. jap. 33(2) :124- 131, 8 figs. — 228 — S-276 1966. “Wavy-fused" mutants in the medaka, Oryzias latipes. Nature, Lond. 211(5051) :866-867, fig. S-277 Talbot, G. B. 1967. Teratological notes on striped bass {Roccus saxat/ilis) of San Francisco Bay. Copeia 1967 (2) :459-461, 3 figs. S-278 Tandon> K. K. 1965. Absence of the right pelvic in Chdn- na pwictatus (Bloch). Res. Bull. Punjab Univ. Sci, 15: 351-362, fig, S-279 1966. Ovarian abnormality in Channa punc- tatus (Bloch). Res. Bull. Punjab Univ. Sci. 17:205- 206, fig. S-280 Tatarko, K. E. 1965. A study of the regeneration of the abdominal fins of the carp in conjunction with their anomalies. Vop. Ikhtiol. 5(2) :31 5-323, 2 figs. S-281 / 1966a. Deformities in the gudgeon (Gobio (jobio L.). Vop. Ikhtiol. 6(3) :572-575, illus. S-282 1966b. Anomalies of the carp and their causes. Zool. Zh. 45(12) 11826-1831, illus. S-283 Templeman, W. 1970. Vertebral and other meristic char- acteristics of Greenland halibut, Reinhardiiim hip- pogloasoides, from the northwest Atlantic. J. Fish. Res. Bd. Can. 27(9) : 1549-1562. S-284 Thomas, P. T. and Raju, G. 1964. Gonadial abnormalities in scombroid fishes. Symp. Scombroid Fishes. Mar. biol. Asa. India (ser. 1), 2:719-724, 10 figs. S-285 Tibaldi, E. 1966. Un caso teratologico in Di/plodus vul- (jaris (Geoffr.) (Pisces, Sparidae). Ann. Mus. Stor. nat. Genova 4(169) ;l-3, fig. S-286 Tomiyama, I. 1966. On the caudal fin of a serranid fish, Holanthias chrijsostictus (Gunther). Jap. J. Ichthyol. 13(4/6) :188-189, fig. S-287 Torchio, M. 1966. Su alcuni Onos (Risso) dei mari dTtalia ( Oateichthyes Gadiformes). Natura, Milano 57(3) :165-172, 5 figs. S-288 Townsley, P. M. and Hughes, M. 1j. 1963. Early stages in the recovery to injury in the dorsal fin of the Atlantic cod {Gad'us morhua). J. Fish. Res. Bd. Can. 21(2) : 347-354. S-289 Trilles, J, P. 1964. Morphological change in the skull of the teleosts, Sparidae and Centracanthidae, in relation to the existence on these fish of certain Cymothoidae parasites. Ann. Parasit. hum. comp, 39:627-630. — 229 — S-290 Unger, F. 1956. Bei Limia rnela^nog aster beobachtete Geschlechtsumwandlung. Aquar.-u. Terrar. Z. 9:308. S-291 Valentine, D. W. and Bridges, K. W. 1969. High inci- dence of deformities in the serranid fish, Paralabrax nebulife.r, from southern California. Copeia 1969(3): 637-638. S-292 Vayssiere, A. and Quintaret, G. 1914. Sur un cas d’her- maphroditisme d’un Scy Ilium stellar e L. C. R. Acad. Sci., Paris 158:2013-2014, S-293 Veen, J. F. de 1969. Abnormal pigmentation as a pos- sible tool in the study of the populations of the plaice {Pleuronectes platessa L.). J. Cons. 32(3) :344-383, 22 figs. S-294 Venugopala Pillai, S. 1968. A note on the morphological irregularities in the Indihn oil-sardine, ^rd(i7velUL longiceps Val. J. Mar. biol. Ass. India 1967, 9(1) :195- 196, fig. S-295 Volodin, V. M. 1960. Effect of temperature on the em- bryonic development of the pike, the blue bream {Abramis ballerus L.) and the white bream (Blicca bjoerkna L.). Trud. Inst. Biol. Vodokhr. 3:231-237. S-296 Warlen, S. M. 1969, Additional records of pugheaded Atlantic menhaden Brevoortia tyrayiniis, Chesapeake Sci. 10(1) :67-68, 2 figs. S-297 Whitley, G. P. 1964. Presidential Address — A survey of Australian Ichthyology. Proc, Linn. Soc. N. S. W. 89 (1) :11-127. S-298 Wunder, W. 1950. Verdoppelung und Verdreifachung der Endcn der Kiemenblattchen beim Karpfen. Zool. Anz. 145:225-230. S-299 1962. Missbildung des Unterkiefers beim Karpfen, Fischwirt. 12 (8) :231-235. S-300 1964. Doppelbildung der Brustflosse und des Schultergurtels auf einer Seite nach einer Schnittver- letzung beim Hecht {Esox lucius L.). Roux Arch. Entw- Mech. Organ. 155:1-8* 4 figs. S-301 1968. Hochriickigkeit beim Aal (A7iguilla an- guilla L.), bedingt durch Wirbelsaulenverkiirzung. Biol. Zbl. 87:323-331, 8 figs. S-302 Zieller, W. 1968. Hippocampus Hippocampus erectus erectus. Drum and Croaker 68(2) :23, 2 figs. — 230 — S-303 Ziemiankowski, B. W. 1954, Ein Fall von Zwitterbildung beim Waxdick {Acipeme?’ qiddenstaedti Brandi) . Z. Fisch. 3 :235-236. S-304 Zorach, T. 1970. Gill cover deformity in eastern johnny darter, Etheostoma olmstedi (Percidae). Chesapeake Sci. 11(1) :65-66. TAXONOMIC INDEX Abramis ballems — 295. Acipenser giildenstaedti — 303. Acrocheilus alutaceus — 239. Albumoides bipunctatus — 222. Alosa psmuloharengu^ — 149, 263. sapidissima — 155, 163. Amia calva — 186. Anchoa mitchilli — 131. Anguilla anguilla — 301. bengalensis — 198. japonica — 192. Anisotremus davidsonii — -190. scapularis — 178. Anoplopoma fimbria — 243. Apistogramma ramirezi — 260. Barbus canis — 241. Basilichthys bonariensis — 159. Blicca bjoercna — 240. bjoerkna — 295. Boops salpa — 122. Botkus ovalis — 270. Brevoortia smithi — 206. tyrannus — 131, 206, 230, 296. Carassius — 260, 264, 268, 280, 282, 298, 299. auratus - — 173. auraiiis gibelio — 207. Carcharhinus Umhatus — 108. Carcharodon car chariot — 164. Catostomus clarkii — 93. cohvmbianus — 239. insignia — 93. maerocheilus — 239. Ceratoptera ehrenbergii — 105. Oianna punctatus — 278, 279. Chimioecetes opilio elongates — 195. Chirocentrus nudus — 202. Chondrostoma nasus — 249. Citharichthys abbotti — 139. Cliipea harengus — 95, 109, 119, 157, 168, 185. pilchardus — 210. — 231 — Coregonus — 167. CotUis aleuticTis — 239. asv^r — 239. confusus — 239. rhotheuft — 239. Cynoglossus lida — 270. semifasciatus — 266. Cynoscion regalis — 131. Cynscion nehulosus (sic) — 262. Cyprinm carpio — 196. Dasyatis sabiiia — 131. Diplodys vidgwns — 285. Drepane punctata — 272. Elassonia okefenok^^ — 119. Eleutheronenia tetradactylmn — 237. Elops saiinis — 131. Esox — 214, 295. lucivs — 100, 203, 204, 300. Etheostoma ohnstedi — 304. Etropiis CTOSsotiis — 131. Fimdulus heteroclitus — 124, 166. Gadella jnaraldi — 126. Gadus morhua — 288. Virens — 133. Galeichthys felis — 131 . Galeorhimis zyopterus — 128. Gambusia af finis — 118. Gerres oyena — 248. Gila roh'usta — 93. Girella trieuspidata — 297. Gobio gobio — 281, Gobionellus hastatus — ■ 135. Gobius microps — 175, Gymmira — 148. micrura — 131. poecilnra — 105. Heterodontus japonicus — 271, Heteropneustes fossilis — 101. Hippocampus Hippocampus erectus erectus — 302. Holanthias chrysostictus — 286. Hyphessobrycon flammeiis — 156. Hyporhamphus unifasciatns — 140. Ictalimis — 221. p'unctatiis ■ — 111. Inopsetta ischyra — 176. Katsuwonus pelamis — 217. Lampetra. lamottei — 213. Lebistes reticidatus — 127, 151. Lepisosteus platystomus — 186. Lepormus — 162. Lim.m melanogaster — 290. — 232 — Lotu lota lacustris — 103. Lycengraidis barbouri — 220. Macrozoarces afneHcamis — 253. Makciira — 143. Mastacembehis armatus — 211. Melanogrammus aeglefimm — 253. Menidia menidia — • 131, 182. Menticirrhns americaniis — 131. Merhiccms escnlentus — 115, merlucciiis hubhsi — 125. productus — 223, Mlcrogobivs gulosus — 135, 137. Micropogon midulatus — 172. Microptervfi dolomieui — 239. Microstomas aehne — 184. Mormong fuscus — 297. Mugil cephalus — 224. Notoptems notopterus — 267. Novadon modestus — 183. Oncorhifnchas gorhuscha — 161, 177. 231. Icisutch — 129, 239. nerka — 161. tshawytscha — 158, 171, 239, 261. Onos mediterraneus — 287. sellai — 287. Oryzias tripes — 275, 276. Osinerus eperlanus — 208. OtoUthiis argenteiLS — 174. Pagroso7nm auratus — 251. Paralabrax nebulifer — 130, 291. ParaUchthys albigutta — 181. dentatus — isi. lethostigma — 131, 136, 138, 227. Perea, fla vescens — 203. fluviatilis — 216, 260. Petrom%fZon marinus — 213. Phochilodns — 123. Piabucina festae — 113. Platichthys flesiLS — 218. Platygobio gracilis — 187. Pleuronectes platessa — 293. Pleivvoniehthys coenosus — 238. PoeciUa veMfera — 188. Pohmemms keptadactylus — 232. Poly od on spathula ■ — 215. Pomatomas saltatrix — 265. Pomoscis anmdaris — 228. Protopterns dolloi — 104. Pseiidopleuronectes americanus — 136. Ptychoceihis oregonensis — ■ 239. —233— Raja binoculaia — 117 . clavata — 179 , 180 , 258 . eglanteria — 131 . richardsoni — 154 , Rastrelliyer kanagurta — 99 . Reinharditius hippo glosaoides — 283 . Remora remora — 197 . Rhinichthys cataractae — 239 . 08 cuVus — 239 . Rhinolejds aspera — 226 . Rhynchobatus djiddensis — 105 . Richardsonius balteatus — 239 , 261 . Roccus saxatilis — 141 , 255 , 277 . Roeboides — 242 . Rutilus rutilus — 96 . Salmo — 189 , 247 . gairdneri — 120 , 239 , 260 . tmitta — 229 , 274 . Salvelinics fontinalis — 239 . malma — 92 . namayctish — 209 . Sarda chiliensis — 217 . Sardina pilchardus — 246 . Sardinella longiceps — 106 , 107 , 165 , 294 . Scardinws erythrophthalmus — 112 . Schizothorax niger — 212 . Scoliodon walbeehmi — 98 . Scolopsis phaeops — 256 . Scomber scombrus — 170 . Scomberomortis maculaitis — 102 . Scophtkalmus maeoticus — 250 . Scyliorhinus caniculus — 199 . Scylliorkimis canicida — 260 . Scyllium stellare — 292 . Sebastes oblongus • — 285 . Sebastodes aleutiantis — 244 . alutus — 244 . crameri — 244 . eloiigatas — 244 . entomelas — 244 , flavidus — 152 , 245 . melanostomiis — 153 . minialus — 244 . paucispinis — 134 , 244 , 245 . pinniger — 244 , 245 . mbrivinctus — 244 . Sebaatolobus macrochir — 191 . Segutilum sydn^yanum — 297 . Solea lascaris na^uta • — 144 . vulgaris — 236 . — 234 — Somnioslis pacificus — 128. Sphyrna lewini ■ — -219. zygaena — 128. Spirinchus — 145. Stellifer Imiceolatus — 131. Stizostedion lucioperca — 252. Strinsia tinea — 126. Symphii7-'us diomedianus — 225. pln.gima, — 131. Tarpon atlanticus — 233. Tautoga onitis ' — 116. Trachurus symmetricu^ — 146. Trachysurns dussumieri — 254. TricMurm Upturns — 273. Trinectes nmctilaius — 131, 136, 138. Urophyds regius — 131. Xiphophonis — 97. helleri — 150, 234. maculatus — 94. INDEX OF ANOMALIES Abnormal coloration — 100, 111, 131, 134, 156, 174, 177, 187, 217, 234, 238, 243, 293. Albinism ~ 94, 101, 130, 136, 153, 186, 191, 196, 198, 219, 221, 226, 236, 254, 260, 293. Ambicoloration — 131, 138, 181, 193, 225, 236, 270, 293. Anal fin — 256, 294. Barbels — 165. Body (mi.se.) — 95, 99, 102, 108, 162, 187, 192, 205, 213, 239, 269. 301. Caudal fin, etc. — 107, 126, 131, 144, 233, 239, 286, 294. Dorsal fin, etc. — • 137, 147, 167, 288. Eye — 115, 141, 209. 228, 241, 252, 277. Fins (misc.) — 108, 110, 131, 147, 173, 194, 204, 229, 260, 264, 282. Gills, etc. — 98, 108, 189, 281, 282, 291, 298, 304. Head (misc.) — 121, 143, 145, 147, 185, 239, 285, 287, 289, 291. Internal organs, fasciae, etc. — 268. Lateral line, etc. — 146, 151, 160, 167, 176, 222. Melanalbinism — 138, 153. Melanism ^ 97, 109, 152, 153, 188, 189, 215, 218, 244, 245, 247, 297. Mouth, jaws, etc. — 131, 135, 274, 285, 299. Pectoral fin, etc. — 104, 105, 148, 200, 240, 300. Pelvic fin, etc. — 132, 178, 220, 239, 240, 278, 280, 281 282, 291. — 235 — Pug-head, etc. — 116, 131, 147, 163, 203, 214, 216, 235, 252, 253, 255, 259, 260, 262, 277, 296. Regeneration — 107, 126, 127, 165, 166, 173, 280. Reversal — 139, 225, 227, 266. Scales, etc. — 135, 136, 187, 281. Sex organs, hermaphroditism, etc. — 92, 96, 106, 118, 119, 123, 124, 125, 142, 149, 160, 165, 167, 168, 180, 199, 207, 208, 211, 212, 223, 224, 231, 232, 237, 246, 248, 263, 267, 279, 284, 290, 292. Teeth, etc, — 128. Triple monsters — 120. Twins, double monsters, etc. — 147, 210, 260, 271, 302, 303. Vertebral — 93, 103, 122, 126, 131, 136, 136, 147, 159, 161, 167, 171, 172, 175, 182, 183, 189, 201, 206, 222, 230, 239, 242, 247, 249, 251, 257, 260, 272, 273, 275, 276, 283, 291, 294, 301. Wounds — 112, 113, 114, 117, 131, 133, 140, 147, 154, 158, 164, 169, 170, 197, 202, 209, 233, 250, 261, 265, 277, 288. Xanthochroism — 138, 184, 190, 297. INDEX OF SOURCES AND ABBREVIATIONS Acta biol. cracov. Zool. — Acta Biologica cracoviensia. Kracow. Advan. Mar. Biol .—Advances in Marine Biology. Academic Press, N. Y. An. Congr, Lat-Amer. Zool. — Anais do Congresso Latino-Ameri- cana de Zoologia. SSo Paulo. Ann. Fac. Sci. Univ. Dakar — Annales de la Faculte des sciences, Universite de Dakar. Ann. Mus. Stor. nat. Genova — Annali del Museo civico di sfcoria naturale. Genova. Ann. Parasit. hum. comp. — Annales de parasitologie humaine et comparee. Paris. Arch. Environ. Health— Archives of Environmental Health. London. Arch. FischWiss. — Archiv fur Fischereiwissenschaft. Hamburg. Arq. Estac. Biol. mar. Univ. Ceara — Arquivos. Eatacao de Bi- ologia Marinha. Universidad do Ceara. Fortaleza, Bol. Soc. Cear. Agron. — Boletim da Sociedade cearense de agron- omia. Ceara. Bull. Bingham oceanogr. Coll. — Bulletin of the Bingham Ocean- ographic Collection. New Haven, Conn, Bull. Cent. Etude Rech, sci., Biarritz. — Bulletin du Centre d’4tudes et de recherches scientifiques. Biarritz. —236— Bull. Mar. Sci. — Bulletin of Marine Science. Miami, Fla. Bull, mens. Soc. linn. Lyon. — Bulletin Mensuel de la Societe Linneenne de Lyon. Lyon. Bull. Misaki Mar. biol. Inst. — Bulletin of the Misaki Marine Biological Institute. Kyoto University. Kyoto. Bull. Pacif. Mar, Fish. Comm. — Bulletin of the Pacific Marine Fisheries Commission. Portland, Ore. Bull. U. S. Nat. Mus, — ^Bulletin of the United States National Museum, Washington, D. C. Caca e Pesca — Caca e Pesca. Sao Paulo. Cienc. e Cult. — Ciencia e Cultura. Revista da Sociedade Brasil- eira para o Progresso da Ciencia. Sao Paulo. Contr. Fish Comm. Ore. — Contributions. Oregon Fish Commis- sion. Portland, Ore. Contr. Sch. Fish. Univ. Wash. — Contributions. School of Fish- eries. University of Washington. Seattle, Wash. Contr. Sci. Los Angeles Cty. Mus. — -Contributions in Science. Los Angeles County Museum. Los Angeles, Calif. Crustaceana — Crustaceana. Leiden. Csl. Rybarst. — Ceskoslovenske Rybarstvi. Prague. Dopov. Akad. Nauk. ukr. RSR- — Dopovidi Akademiyi nauk Uk- rayins’koyi RSR. Kiev. Drum and Croaker — Drum and Croaker. Palos Verdes, Calif. Embryologia, Nagoya — Embryologia. Nagoya University. Nago- ya. Fauna, Oslo — Fauna. Norsk Zoologisk Tidsskrift. Oslo. Fischereiwelt — Fischereiwelt. Hamburg. Fischwirtschaft — Fischwirtschaft. Bremmerhaven. Gerontologia — Gerontologia. Basel, N. Y. Invest, pesq, — Investigacion pesquera. Barcelona. Israel J. ZooL — Israel Journal of Zoology. Tel Aviv. J. Miss. Acad. Sci. — Journal of the Mississippi Academy of Sciences. Jackson, Miss. J. Parasit. — Journal of Parasitology. Lancaster, Pa. J, Zool., London — Journal of Zoology, London. London Nat. — London Naturalist. London. Lucrar. Stat. zool. mar. Agigea — Lucrarile ale Statiei zoologice maritime ’Regele Ferdinand I' della Agigea. Mem. 1st. ital. Idrobiol. de Marchi — Memorie dellTnstituto Ital- iano di Idrobiologia Dott. Marco de Marchi. Milano. — 237 — Nat. Wales — Nature in Wales. Orielton. Notas Estud. Inst. Biol, marit. — Notas e estudos do Instituto de biologia maritima. Lisbon. Notul. nat. Acad. Phil ad. — Notulae Naturae. Academy of Natural Sciences of Philadelphia. Philadelphia, Pa. N. Y. Fish Game J. — New York Fish and Game Journal. Albany, N. Y. Opusc. zool. Inst, zoosyst Univ. budapest — Opuscula Zoologica. Instuti Zoosystematici Universitatis Budapestinensis. Buda- pest. Pacific Sci. — Pacific Science. Honolulu, Hi. Pakist. J. Sci. indust. Res. — ^Pakistan Journal of Science and Industrial Research. Karachi. Physis. B. Aires — ^Revista de la Sociedad argentina de ciencias naturales. Buenos Aires. Proc. biol. Soc. Wash. — Proceedings of the Biological Society of Washington. Washington, D. C. Proc. Calif. Acad. Sci. — Proceedings of the California Academy of Sciences. San Francisco, Calif, Proc. Conf. stheast. Ass. Game Commrs. — Proceedings of the Annual Conference of the Southeastern Association of Game and Fish Commissioners. Columbia, S. C. Proc. int. Congr. Zool. — Proceedings of the International Con- gress of Zoology. London. Proc. Leeds phiL lit. Soc. — Proceedings of the Leeds Philosophi- cal and Literary Society. Leeds. Proc. Mont. Acad. Sci. — Proceedings of the Montana Academy of Sciences. Missoula, Mont. Proc. nat. Acad. Sci. India — ^Proceedings of the National Acad- emy of Sciences of India. Allahabad. Przegl. Zool. — Przeglad Zoologiczny. Warsaw. Piibl. Serv. Piscic. Bras.-Public^es. Service de piscicultura, Bra- sil. Fortaleza. Pubis. Carnegie Instn. — Publications of the Carnegie Institution of Washington. Washington, D. C. Quart. J. Fla. Acad. Sci. — Quarterly Journal of the Florida Academy of Sciences. Tallahassee, Fla. Res. Briefs — ^Research Briefs. Oregon Fish Commission. Port- land, Ore. Res. Bull. Punjab Univ. Sci. — Research Bulletin of the Punjab University of Science. Hoshiarpur. — 238 — Rev. Trav, Inst. Peche. mar it. — Revue des Travaux de Tlnstitut des Pechea. Maritimes. Paris. Rev. Trav. Off. Peche, mar it, — Revue des Travaux de TOffice des Peches Maritimes. Paris, Schr. naturw. Ver. Schlesw. -Holst. — Schriften des Naturwis- senschaftlichen Vereins fiir Schleswig-Holstein. Kiel. Scot. Fish. Bull. — Scottish Fisheries Bulletin. Edinburgh. Skr. Komni. Havunders. — Skrifter udg. of Kommissionen for Havundersogelser. Copenhagen. Texas J. Sci. — Texas Journal of Science. Houston, Tex. Tijdschr. ned. dierk. Ver. — Tijdschrift der Nederlandische Dier- kundige Vereeniging. Leiden. w iJ Trav, Sebast. biol. Sta, — Trudy Sevastopor.skoi biologicheskoi .stantsii Akademiya nauk SSSR. Trop. Fish Hobbyist — Tropical Fish Hobbyist. Jersey City, N. J. Trud. Inst. Biol. Vodokhr. — Trudy Instituta biologii vodokhra- nilishch. Akademiya nauk SSSR. Moskow. Underw. Nat. — Underwater Naturalist. Bulletin of the American Littoral Society. Highlands, N, J. Vet. Rec.' — Veterinary Record. London. Wassman J. Biol. — ^Wassman Journal of Biology. San Francisco, Calif. Zool. Polon. — Zoologica Poloniae. Breslau, Zool. Zh. — Zoologicheskii zhurnal. Moskow. CORRIGENDA The following corrections should be entered in the appro- priate sections of the original bibliography (Gulf Res. Repts. vol. 1, no. 6). Reference Correction Title 447 To read: 40(4) : 564-671 ” 561 Change: "rav” to ray ” 681 Change date to: 1903 ” 925 To read: 27:263-264 ” 953 To read : mycteridoide ” 993 Add: Univ. Paris (A) 244:1-179, 26 figs. ” A 15 To read: (Cuvier) Page 371 To read : Katsuivoiius pelamys — 465. ” 374 vSyngnathidae : add — 194, 195. ” 376 Pug-head, etc.: delete — 555. 385 Collect. & Breed. : add — saishu to siiku — 239 — Gulf Research Reports Volume 3 Issue 2 January 1971 Descriptions of Shrimp Larvae (Family Penaeidae) Off the Mississippi Coast Chebium B. Subrahmanyam Gulf Coast Research Laboratory DOI: 10.18785/grr.0302.06 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Subrahmanyam, C. B. 1971. Descriptions of Shrimp Larvae (Family Penaeidae) Off the Mississippi Coast. Gulf Research Reports 3 (2); 241-258. Retrieved from http:/ / aquila.usm.edu/ gcr/vol3/iss2/ 6 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. DESCRIPTIONS OF SHRIMP LARVAE (FAMILY PENAEIDAE) OFF THE MISSISSIPPI COAST by C. B. Subrahmanyam' INTRODUCTION Muller (1864) showed that the penaeid egg hatches into a nauplius. Some years later studies of the metamorphosis of penaeid shrimps in the Gulf of Mexico were made (Pearson 1939, Heegaard 1963, Dobkin 1961, Cook and Murphy 1965, and Renfro and Cook 1963). The present paper treats the larvae taken in Mississippi and brings together the descriptions of the larvae scattered in the literature. The salient features of various stages of different species of the six genera studied are pointed out with the aid of drawings to facilitate easier iden- tification. Besides the references cited above, the works of Heldt (1938), Gurney (1924, 1942), Heegaard (1966) and Cook (1966) have been consulted for this presentation. The author is grateful to Dr. Gordon Gunter for his helpful criticisms and to Dr. Harold Howse, Gulf Coast Research Laboratory, for his generous help in photography. MATERIALS AND METHODS Plankton was collected simultaneously from the surface, mid-depth, and bottom at 10 m, 18 m, 36 m, 54 m, 72 m, and 90 m depths in the Gulf of Mexico. The nets used were fitted with closing devices and the netting had a mesh of 0.33 mm. After letting the plankton settle, penaeid larvae were picked out of the entire sample and preserved in buffered 5% formalin. Photographs were taken with the aid of a microprojector. The larvae were placed in a depression slide which was mounted on the stage of the. projector. The image of the specimen was directly focusvsed on an 8.3 x 10.2 cm photographic plate in a dark room and processed immediately. The subjects w'ere printed on a high contrast gloss paper (Kodabromide F-5). Magnifi- cations were measured by photographing a stage micrometer un- der the same setting. This method permits greater freedom for focussing and greater resolution of the objects. Pictures were drawn based on these photographs. •Department of Zoologyj Mississippi State University, State College, Mississippi, and Gulf Coa.st Research Laboratory. Ocean Springs, Mississippi. Present address: Dept, of liiology, Florida A&M University, Tallahassee, Florida. — 241 — The six littoral genera encountered in the samples were Penaeus, Parapenaeus, Trachypeneus, Xiphopeneus, Sicyonia, and Solenocera. Some larvae of Gemiadm and Artemisia were taken one day in two years of collecting, and they are described separately (Subrahmanyam and Gunter 1970). THE LARVAE Eggs Penaeus (Fig. 1). The egg measures 0.33 mm in diameter. The egg membrane is transparent. The perivitelline space is narrow and the embryo occupies almost the entire inside of the egg. Trackypenms (Fig. 2). Eggs with embryonic mass and iiauplii inside measure 1.38 mm in diameter. They are larger than Penaeus eggs and the perivitelline space is wdder. The nauplius, how^ever, fills up the egg. These eggs were, taken in thousands on some occasions. Nauplius Penaeus (Fig. 3). Only naplius V of this genus was col- lected. It measured 0.55 mm in body length. The oblong pear shaped body, deeply notched telson lobe.s, and long setae on the appendages are characteristic. These were collected mostly from 36 to 54 meter stations, and could belong to the white or brown shrimp. Trachypeneus (Fig. 4). Only nauplius 1 of this genus was collected. It measures 0.28 mm in body length. The oval body and a protuberance on the dorsal side of the larva posterior to the median eye distinguish this larva. The eggs and nauplii of this genus were collected mostly at 9, 18, and 36 meter station.s. Protozoea Penaeus (Fig. 5). Photozoea I measured 0.90 mm in body length. Frontal organs are present. The formula for the lateral setae on the end pod of antenna II is 2 -f 2 + 1 (Fig. 5A). The second protozoea (Fig. 5B) measures 2.04 mm in length. The rostra] spine is long, veantraliy curved, and measures about one third of the carapace length. Supraorbital spines are present. Protozoea III (Fig. 5C) measures 3.04 mm. The rostrum is longer. The lateral setae on the second antennal endopod retain the same formula as protozoea I. Trachypeneus (Fig. 6). Protozoea I measures 0.91 mm in body length. It is very delicate and transparent (Fig. 6A). Pro- tozoea II measures 1.40 mm in body length. The rostrum is — 243 — 1 'WTM. FIG. 6 — 244 — short, and supraorbital spines are absent (Fig. 6B). Protozoea III measures 1,97 mm in body length, The rostrum is short (Fig. 6C). All three stages are identifiable with the setal formula of the second antennal endopod, 2 b 2, and short rostrum in second and third stages. Xiphopeneiis The protozoeal stages of this genus are identi- cal in morphology and sizes to those of Trachypenevji except for one short terminal setae on the second antennal endopod. ParapeiiaeiLii (Fig. 7). Protozoea I is larger than the other genera. It measures 1.28 mm in length (Fig. 7A). This stage and the following two stages show 2 + 2 1 lateral setae on the second antennal endopod. Protozoea I (Fig. 7B) measures 2.04 mm and is robust. The rostrum extends to the distal seg- ment of first antenna, and two pairs of supraorbital spines are present. The third protozoea (Fig. 7G) measures 3.18 mm in body length. The rostrum is longer than that of comparable stage of Penae'iis, — 246 — Solenocera (Fig 8). Protozoea 1 (Fig. 8A) measures 1.0 mm in length. It has a short rostrum even at this stage. The cara- pace carries forked spines above the eyes, laterally and dorsally at the junction of carapace. The telson lobes are large and the notch is very shallow- The formula for the. lateral setae on the second antennal endopod is 2 H- 2 -j- 3 for all the three stages. The second protozoea (Fig. 8B) measures 1.84 mm in body length. The rostrum is spiny and as long as the first antenna. The carapace is characterized by spiny lobes. The eyes are large. The third protozoea (Fig. 8C) measures 2.66 mm in body length. It is robustly built, and the rostrum is longer than the first antenna. The supraorbital spines are large and robust. The carapace shows accentuated spiny protrusions and it is spiny all over. The salient feature is the presence of lateral spines on all the six abdominal segments. The telson carries long spines. Sicyonia (Fig. 9). The first protozoea measures 0.93 mm in body length. The striking feature is the long first antenna (longer than the second) with three long terminal setae (Fig. 9A). The formula for the lateral setae on the endopod of second antenna is 3 -f- 2 + 1, which is the same for the next two 247 - stages. The notch on the telson is narrower than that of Pen- aetfs and Tr(whypeneus. The second protozoea is characterized by the absence of rostrum (Fig. 9B). It measures 1.42 mm in body length. The first antennae are still the longest appendages. The third protozoea also shows no rostrum (Fig. 9C). This larva measures 2.24 mm in body length. It can be distinguished from the other genera by the three long antennal setae and the nar- row notch on the telson. — 248 — Mysis PeTvae'iis (Fi^. 10). All three mysis stages can be iden- tified by the len^h of the rostrum reaching beyond the eyes, and dorsally one small spine each on the thirds fourth, and fifth abdominal segment. The first mysis measures 3.47 mm in body length and is slender (Fig lOA). The second mysis measures 3.80 mm in length and shows pleopod buds (Fig. lOB). The third mysis is longer measuring 4,36 mm in length, and ha^s one tooth on the dorsal margin of the rostrum (Fig. IOC) Pleopods are two segmented. Trachypeneus (Fig. 11). The mysis of this genus can be distinguished by the length of the rostrum, which just reaches the margin of the eyes. The fourth and fifth abdominal seg- ments bear dorsal spines, of the former being the shorter of the two. The first mysis measures 2.80 mm in body length and FIG. 12 — 249 — is more transparent than the older larvae (Fig. IIA). The second mysis measures 3.62 mm in length and shows pleopod buds (Fig. IIB). The third mysis is not too transparent, meas- ures 4.44 mm in length, and shows two segmented pleopods (Fig. IIC). Xiphop&neiis. The mysis stages of this genus resemble the previous genus in measurements. The only difference is the lack of lateral spines on the fifth abdominal segment. Parapenaeim (Figs. 12 & 13). These myses are characterized by the rostrum extending beyond the eyes and a prominent spine on the third abdominal segment, followed by two shorter spines on the dorsal margins of fourth and fifth segments. The rostrum also bears teeth dor sally, and one tooth is added at each moult. The first mysis is slender, and measures 3.65 mm in length. 250 — —I Q_ FIG. 14 The abdominal segments bear spines ventrally on the sternites of the first to fifth segments. The rOvStriim is decurved with two dorsal teeth (Fig. 12A). The second mysis measures 4.44 mm in length. The rostrum has three spines and the sternal spines on the third to fifth segments have disappeared (Fig. 12B). The third mysis measures 5.55 mm, has five rostral teeth, and two segmented pleopods (Fig. 12C). The characters of these larvae agree with those given by Pearson {op, cit.) . — 251 — Along with these mysis stages, occasionally slightly dif- ferent types of myses were noticed (Fig. 13). They were gen- erally larger and, while sharing the generic characters of the mysis described above, they have a longer rostrum with more teeth. The dorsal spine on the third abdominal segment is tri- angular, being broad at the base. The two short dorsal spines on the fourth and fifth segments are present. The first mysis measures 3.96 mm, the second 5,28 mm and the third mysis 8.00 mm in body length. It is obvious that these mysis are larg- er than those of P. longirosti'is. The rostral teeth numbered one for the first mysis, four for the second, and six for the third mysis (Fig. 13 A, B, C). The fourth mysis was never caught. Sicyonia (Fig 14). The mysis is characterized by a short rostrum (shorter than the eye), absence of dorsal spines on the abdominal segments, and presence of ventro-mediam spines on all the five abdominal segments. The larvae are also more robust. The first mysis measures 2.45 mm (Fig. 14A) and shows the ventro-median spines clearly. The second mysis measures 2.90 mm and shows rudiments of pleopod buds (Fig. 14B). The third mysis measures 3.20 mm in length, and shows small two-segmented pleopods (Fig. 14C). The fourth mysis measures 3.35 mm in length and shows prominent and two seg- mented pleopods. The features of these larvae are in general agreement with those given by Cook and Murphy (1965). Solenocera (Fig, 15). The myses are the easiest to be iden- tified by the spiny nature of the whole body. The rostrum is long, and the carapace as well as the abdomen carry long .spines. The dorsal organ is the salient feature of Solenocera mysis, the function of which is disputed. The first mysis measures 4.42 mm in length and bears ventro-median spines (Fig. 15A), The second mysis measures 6.85 mm in length and bears strong- spines dorsally on the abdominal seginents. The pleopods are beginning to show (Fig. 15B). The third mysis measures 6.96 mm in body length, and bears dorsal abdominal spines and two segmented pleopods (Fig. 15C). These larvae were particularly abundant in waters deeper than 54 meters. Postlarvae Postlarvae of Penaeus, Parapenaeus, Trachype/mus, Sicyon- ia, and Solenocera were collected during the present study. Only the postlarvae of Penaeus and Trachypeneus are described here. These were most commonly taken in the plankton. Pe'naeus (Fig. 16). The postlarvae are distinguished by long and slender bodies, thin rostrum, and long sixth abdominal segment. The post-larvae were identified with the aid of the key worked out by Williams (1959). In Figure 16, the first and the third postlarvae of Penaeus fluviatilis are given. The first post- larva is slender, and measures 4.5 mm in body length. The ros- — 253 — 254 — trum evens with the margin of the eye, and bears one dorsal tooth (Fig. 16A). The third postlarva measures 8.38 mm in length and has three rostral teeth. The rostrum just reaches the margin of the eye (Fig. 16B), Though the postlarvae of brown shrimp were taken, they are not described here. Pink shrimp postlarvae were least abundant of the three species. Trachypeneus (Fig. 17). The postlarva is thick and the sixth abdominal segment is not as long as in Penaeus. The ros- trum does not reach up to the margin of the eye, and it bears .seven dorsal teeth. It measures 8,45 mm in body length, and judging from its size and the number of rostral teeth it is the fourth postlarval stage. Younger postlarvae were not common in the plankton samples. REMARKS The diagnostic characters of different larval stages of var- ious species of the six genera have been pointed out to facilitate easier identification. Plankton samples collected from any level of a water column (of the area sampled) and from any depth invariably contain a mixture of .stages and specie.s, and it is possible to identify these larvae with the help of the draw- ings presented as far as the Gulf of Mexico genera are con- cerned. It appears to be a general feature with crustaceans that their larval stages occur together in any area. The proportions of stages and species, however, exhibit seasonal variations. This has been observed by Gurney (1924, 1942), Pearson (1939^ and Eldred et al. (1965). Gurney (1924) remarks that crustacean larvae have the power of keeping together or collecting at a suitable locality and may not be at the mercy of the currents as much as it is generally supposed. The correspondence be- tween the bathymetric distribution of the larval species and the adults appears to lend support to this sumise. It has been found that the identical stages of any species are not uniform in size, and identification based on the size alone is liable to be misleading. That within an instar the body size of the larvae may differ has been pointed out by Hudinaga (1942) and again by Renfro and Cook (1963). Though growth has been known to occur only at each molting in crustaceans it is interesting that size differences within an instar are notice- able. It is difficult to separate the three species of Penaeus, P. fluviatilis, P, aztecus, and P. duorarum, based on larval morpho- logy or morphometry. The white shrimp and the pink shrimp are relatively shallow water species and the brown shrimp is known to occur in deeper waters (Burkenroad 1939). There- fore, the larvae caught in deeper waters may belong to the brown shrimp, and those in shallower waters may belong to — 255 — either white or pink shrimp, depending on the geographical locality. However, this is complicated by the offshore move- ments of all the species into deeper waters with the tempera- ture decline as has been shown in the case of P. fluviatilis (Weymouth, Lindner and Anderson 1933). The eggs of Penaeus can be distinguished by the narrow peri vitelline space. The two common species of Trachypeneiis in the Gulf of Mexico are T. similis and T. consUictus, and their ranges over- lap (Burkenroad 1939). No descriptions of the larvae of T. similis are available, and it is hard to distinguish the larvae of these two species. Similarly, the protozuea of Xiphopeneus resembles Trachijj)eneus but for one small seta on the second endopod and many times this is lost> making it difficult to separate the protozoeae of the two genera. The mysis of Tra- chypeneics can be easily identified by the lateral spines on the fifth segment, though Cook (1966) says that the rostrum can be used for this purpose. However rostral length, in my exper- ience, is not a dependable character. Pearson (1939) described only two mysis stages of T. constriotus and his second mysis appears to be the third mysis because of two segmented pleo- pods. Also, the lack of lateral spines on the fifth abdominal segment casts a doubt that his larvae could belong to Xiphope- neus, Unfortunately, there is no information on the development of other Trachypeneus species since Pearson's work. The present larvae of Parapenaeus agree with the descrip- tions of Pearson (1939) and Heldt (1938). It has been noticed that the mysis stages may differ slightly in morphology with- in the species. The dorsal spine on the third abdominal seg- ment looks different in some larvae as well as the rostral length and shape (Figs. 12 and 13), This has been pointexl out earlier by Heldt (1938). The most common species in the Gulf of Mexi- co is P. lo7igirostris (Williams 1965). P, americanus is relative- ly a deep water species (Springer and Bullis 1956). Both Sicyonia dorsalis and N. brevirostris occur in depths from inshore to the continental shelf (W’illiams 1965). S. stimp- soni is a shallow water species confined to the inside of 90 m contour (Lunz 1957). During the present investigation S, dor- salis was most commonly taken. The larval stages of 5. hre- virostnds, S, stimpsoni, and S. wheeleri have been described and it is possible to distinguish these species based on the lateral setal formulae (Cook and Murphy 1965). Again, the short seta on the endopod is often lost, and the present larvae could belong to S. brevirostris (1 -|- 2 -|- 3 ) or S. dorsalis ( 1 -|- 2 -p 2 ) . The life history of S. dorsalis has not been described. The three species of Solenocera known to occur in the Gulf of Mexico arc S. vioscai, S, atlantidis, and S. necopina. These species inhabit waters 18 to 329 m deep and S. 7iecopina occurs — 256 — in shallow waters as well (Williams 1965). The mysis can be distinguished from the sergestid mysis by the presence of the dorsal organ. The different species are identified based on the length and shape of the rostrum and the structure of the spines on the carapace (Heegaard 1966). There is practically no in- formation on the Solenocera from the Gulf of Mexico. The most common species on the Louisiana and Mississippi coasts is iS. vioscai (Burkenroad 1936), and the present larvae could belong to this species. The significant point during the present investigation has been the correspondence between the bathymetric distribution of the larval genera and the known ranges of the species of the six genera. Penaev^ larvae were obtained in depths from 10 to 90 m, Trachypeneiis larvae mostly from 10 to 54 m, Xiphopen- ct(s larvae from 10 to 90 m, Ptirapeyiacns larvae mostly from 36 to 90 m, Sicyonia larvae from 10 to 72 m mostly, and Soleno- cera larvae from 18 to 90 m. The adult ranges are: Pink shrimp 0-109 m, white shrimp 0-78 m, brown shrimp 0-180 m; P. longi- rofstns 25-145 m ; T. constrictus 20-37 m ; T. similis 5-55 m ; A'. kroyen 5-36 m ; S. dorsalis 5-85 m ; brevirostris 5-85 m ; S. vioscai 36-72 m; S', atlanfidis 18-329 m; and S. necopina 5-183 m; (Burkenroad 1936, 1939 and Williams 1965). From regular observations on the distribution and seasonal abundance of these larvae, it has been possible to gain an understanding of the breeding areas of the species belonging to the six genera. The life histories of species of Traehypeneus, Xiphoperteus, and SoleMOcera need to be worked out. It is a matter of conjecture whether the larvae of the species of one genus (except Sicijonia) can be distinguished by morphological characters alone, or whether one has to investigate at the biochemical or molecular level. LITERATURE CITED Burkenroad, M. D. 1936. The Aristaeinae, Solenocerinae and pelagic Penaeinae of the Bingham Oceanographic Collec- tion. Materials for revision of the oceanic Penaeidae. Bull. Bingham Oceanogr. Coll, 5(2) .T-151. 1939. Further observations on Penaeidae of the northern Gulf of Mexico. Bull. Bingham Oceanogr. Coll. 6(6) :l-62. Cook, H. L. 1966. A generic key to the protozoean, mysis and postlarval stages of the littoral penaeidae of the north- western Gulf of Mexico. U. S. Fish Wildl. Serv, Fi.sh. Bull. 65(2) :437-447. and M. A. Murphy. 1965a. Early developmental stages of the rock shrimp Sieyonia brevirostris Stimp.son reared in the laboratory. Tulane Stud. Zool. 12(4) : 109- 127. - 257 - Dobkin, S. 1961. Early developmental stages of pink shrimp, Penaeiis duoramm, from Florida waters. U. S. Fish Wildl. Serv. Fish. Bull, 61(190) ;321-349. Eldred, B., J. Williams, G. T. Martin, and E. A. Joyce, Jr. 1965. Seasonal distribution of penaeid larvae and post-larvae of the Tampa Bay Area, Florida. Mar. Lab. Florida, Tech. Ser. 44. 47p. Gurney, R. 1924. Crustacea. Fart JX, Decapod Larvae. Br. An- tarct. Terra Nova Exped. Nat. Hist. Rep. 8(2) : 37-202 1942, Larvae of Decapod Crustacea. Ray Society, London. No. 129. 306p. Heegaard, P. E. 1953. Observations on spawning and larval history of the shrimp Penaeus Hetiferus (Linn). Publ. Inst. Marine Sci, (Univ, Texas) 3:75-105. 1966. Larvae of Decapod Crustacea. The oceanic penaeids Solenocera ~ Cerataspis - Cerastaspid^s. Dana Rep. 67. 147p. Heldt, J. H. 1938. La reproduction chez les crustaces decapodes de la famille des Peneids. Annls Inst. Oceanogr., Monaco. 18(2) :31-206. Hudinaga, M. 1942. Reproduction, development and rearing of Penaeus japonicus Bate. Japanese J. Zool. 10(2) : 305-393. Lunz, G. R. 1957. Notes on the rock shrimp Sicyoma brevirostris (Stimpson) from exploratory trawling off the South Caro- lina Coast, Bears Bluff Lab. Contri. 25. 10 p. Muller, F. 1864. On the metamorphoses of the prawns. Ann Mag. Nat. Hist. Ser. 3, 14: 104-115. Pearson, John C. 1939. The early life histories of some Ameri- can Penaeidae, chiefly the commercial shrimp Penaeus seti- ferus (TJnn.). Bull. U. S. Bur. Fish. 49(30) : 1-73. Renfro, W. C. and H. L. Cook. 1963, Early larval stages of the sea bob. Fish Wildl. Serv. U. S. Fish Bull. 63(1) : 165-178. Springer, S., and H. R. Bullis, Jr. 1956. Collections by the Oregon in the Gulf of Mexico. U. S, Fish Wildl. Serv. Spec. Sclent. Rep. 196. 134 p. Subrahmanyam, C. B. and G. Gunter. 1970. New penaeid shrimp larvae from the Gulf of Mexico (Decapoda, Penaeidea). Crustaceana 19(1) : 94-98. Weymouth, F. W„ M. J. Lindner and W. W. Ander.son. 1933. Preliminary report on the life history of the common shrimp, Penaeus seti feints (Linn.). Bull. U. S. Bur. Fish. 48: 1-25. Williams, A. B. 1959. Spotted and brown shrimp postlarvae (Penaeus) in North Carolina. Bull. Mar. Sci. Gulf & Caribb. 9(3) : 281-290. 1965. Marine decapod crustaceans of the carolinas. U. S. Fish Wildl. Serv. Fish Bull. 65(1) : 1-298. —258— Gulf Research Reports Volume 3 Issue 2 January 1971 Discovery of the Carolina Marsh Clam^ Polymesoda caroliniana (Bosc)^ A Supposed Florida Disjunct Species^ in Everglades National Park^ Florida D.C.Tabb D.R. Moore DOI: 10.18785/grr.0302.08 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Tabb, D. and D. Moore. 1971. Discovery of the Carolina Marsh Clam, Polymesoda caroliniana (Bose); A Supposed Florida Disjunct SpecieS; in Everglades National Park, Florida. Gulf Research Reports 3 (2): 265-281. Retrieved from http:// aquila.usm.edu/gcr/vol3/iss2/ 8 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. DISCOVERY OF THE CAROLINA MARSH CLAM, POLYMESODA CAROLINIANA (BOSC),A SUPPOSED FLORIDA DISJUNCT SPECIES, IN EVERGLADES NATIONAL PARK, FLORIDA' by D. C. Tabb and D. R. Moore INTRODUCTION The presence of disjunct species of animals on either side of the Florida peninsula has been reported by a number of authors. The littorinid mollusk, Littonna irrorata Say, which has a range from Massachusetts to the Rio Grande of Texas, except for south Florida, is one such species (Requaert 1943), The marsh crab, Sesarvia cineveum (Bose), is another example of an animal with a distribution from Virginia to the western Gulf of Campeche except for a break in southern Florida (Rathbun. 1918). Williams (1965) lists 23 species of crustac- eans having interrupted distribution at the Florida peninsula. This report on discovery of a breeding population of the Caro- lina mar.sh clam, Polymesnda carolininna (Bose) in southern Florida supports the contention by Hedgpeth (1953) that at lea.st some, perhaps many, of the disjunct records may be a result of insufficient collecting in south Florida. The Carolina marsh clam has been assumed to be a typical disjunct species .since it was described as .such by van der Schalie (1933). It was not included in Marine Shells of Southwest Florida by Perry (1940) nor in Florida Marine Shells by Vilas and Vilas (1945). Abbott (1954) apparently knew of no southern Florida material, and recent examination of collections of this species in the U. S, National Museum provided no material south of New Smyrna on the east coast or Fort Myers on the west coast of Florida. Gunter and Hall (1963) found a breeding colony in the St Lucie River estuary near Fort Pierce, Florida extend- ing the range nearly 275 km farther south along the Florida east coast but gave no details on the .size of the population. The initial discovery of a single valve of the Carolina marsh clam in extreme southern Florida was made by Tabb and Man- ning (1961) in deltaic muds at the mouth of the East River where it enters Whitewater Bay in Everglades National Park. Since 1962 sufficient discoveries have been made in Everglades National Park to prove the existence of a breeding population occupying two rather different but adjoining habitats over an extensive area of southern coastal mar.sh (Figure 1). Contribution #1396 from the University of Miami, Rosenstiel School of Marine and Atmospheric Science, Miami, Florida. — 265 — SYNONYMY AND DIAGNOSIS When the first specimen ^vas found in Everglades National Park it was necessary to consult several old publications for a description, and to unravel the synonymy. Because of the general scarcity of these publications and relative rarity of the species it is thought desirable to reproduce the most important of these references. Dr. H. A. Rehder, Research Curator of Molliisks, U. S. National Museum, has kindly made the following comments concerning the nomenclature: *'Polyraesoda was used as a ge- neric name by von Martens, Biologia Central! Americana, Moll., p. 540, 1900, and usually by others who worked with it .since 1900. 1 think the group is generically distinct from the Old World cyrenas. However, the fact is that Cyrena will go out, its type being a Corbicula, and the Old World group will be called Geloina Gray.'' Diagnosis of Family CyrpMidae ( = Corbwulidae) after Dali, Wm. H., 1895. p. 540. Anatomy as in Veniellinae , except that the mantle is more open ventrally, the siphons dis- tinctly developed, short, united more or less, us- ually with papillose orifices; dioecious; fluvi- atile or estuarine. Shell porcellanous, with a conspicuous epider- mis, usually with concentric sculpture; valves equal, free, closed, usually with plain margins; area obscure or none ; ligament and resilium ex- ternal, paravincular, opisthodetic; adductor scars subequal, separate from the pedal; pallial line simple or with a small sinus; hinge with anterior and posterior laminae usually double in the right, single in the left valve, distinctly separated from the cardinals; cardinal teeth bifid at the summit, three in each valve when none are obsolete. Lias to Recent fauna. Synonymy after Dali, Wm. H., 1903. p. 1447. Cyrena iPolpnesoda) carolinmia (Bose) Cydas carolmiana Bose, Hist. Nat. des Coq., iii., p. 37, pi. xviii., fig. 4, 1802; Say, Am. Conch., vii., Ixii., 1833. Cyrena caroliniensis Lamarck, An. s. Vert., v., p. 553. — 266 — Cyrena c(iroline7isis Hanley, Rec. Shells, p. 93, pi. xiv., fig. 54, 1842. Cyrena carolmieyms Holmes, Post-Pl. Fos. S. Car., p, 31, pi. vi., fig. 7, 1860. Cyrena flondana Sowerby, Conch, Icon., 1878 ; not of Conrad, 1846. Pleistocene of Simmons Bluff, South Carolina, and of North Creek near Osprey, on the west coast of Florida ; Recent from South Carolina to Florida and westward to the coast of Texas, in streams and brackish water near the sea. Synonymy after van der Schalie, H., 1933. Cyclas caroliniana Bose, 1802, Hist. Nat. Coq., 37, pi. xviii, fig. 4; Chenu, 1845, Biblio, Conch., 3: 27; Dali, 1903, Proc. Biol. Soc. Wash., 16: 6; Walker, 1918, Syn. Fresh-Water Moll. N.A. : 85. Cyrena carolmmisis Bose., Dali, 1903, Trans. Wag. Free Inst. Sci., 3: 1447. Cyrena caroUnumsis Lamarck, 1818, Hist. Nat. des An. sans VerL, Part il, 568; Dubois, 1825, Ep. Lam. Test.: 65; Ravenel, 1834, Cat, Rec. Shells: 4; Conrad, 1853, Proc. Acad. Nat. Sci. Phila., 6 : 246 ; Prime, 1865, Smith, Misc. Coll. 145: 11; Paetol, 1890, Cat. Conch. Samm., (4th Ed.), 3:97. Cyrena carolmensis Bose, Say, 1819, Nich. Encycl., (3rd Ed.), 4: 56; Hanley, 1842, Rec. Shells, p, 93, pi. xiv, fig. 54; DeKay, 1843, Zool. New* York, Y: 226, pi. xxv, fig. 266; Wheatley, 1845, Cat. Shells IJ. S., p. 6; Conrad, 1846, Am. Jour. Sci., 2: 394; Gibbes, 1848, Appen. Geol. S* C., p. xxi; Philippi, 1849, Abild. und Beschreib. Conch., p. 8, pi. ii, fig. 4; Deshayes, 1854, Brit. Mus. Conch. II; Say, 1858, Conch. U. S., p. 56, 226; Dali, 1889, Bull. U. S. Nat. Mus. 37 : 56 ; Simpson, 1889 Naut., 3: 80 ; Johnson, 1890, Natur., 4: 4; Baker, P. C., 1891, Proc. Acad. Nat, Sci. Phila.: 45; Simp- son, 1892, Naut., 6; 40; Hinkley, 1907, Naut., 21: 80; Mazyck, 1913, Cat. Moll. S. C.: 25; Johnson, 1919, Naut., 33: 7. Cyrena caroliniensis Bose, Stark, 1828, Ele- ments Nat. Hist., 2 : 100 ; Hanley, 1842-56, — 267 — Descrip, Cat.: 93; Holmes, 1860, Post-Pl. Fos. So. Car. : 31, pi. vi, fig. 7 ; Fischer, 1887, Man. de Conch.: 1091. Unio carolinianu.^ Bose, Ferussac, 1835, Mag. de Zool., No’s. 59, 60, V:26; Conrad, 1853, Proc. Acad. Nat. Sci. Phila., 6:246. Cyreiia cavolinensis Say, Roemer, 1849, Mol- lusca: 453. Cyrena carolhmisis Lamarck, Nylander, 1921, Naut., 34: 120. DISCUSSION Following the first di.scovery of P. cavolmiana at the mouth of the East River in Everglades National Park (Tabb and Man- ning, op. cit.) no additional material was found there until the I isu.e 1. The Cape Sable region of South Florida showing Paurotis Pond and the North and East River systems where Polynieisoda earo- liniana populations are known to occur. — 268 — period of 4-2o -Marcli 3 962 when laiye numljer.-^ of moril)iincl specimens were found being" washed ashore at Paurotis Pond, a fresh-water lake about 12 miles north of Flamingo on Floi'ida Highway 27 (Figure 1). Fifi’ure '2. Exti rnal and internal aspeet of shells of I'nlfiinefioiJii cn r- oliniava from Paurotis Pond showing- thick, tuirlily n- jIov{^.d valves ’.vith flaky periostracum. The iibnormal condition under which the specimens were collected was a result of a severe, prolonged invasion of wind- driven salt water from Whitewater Bay during a southerly windstorm on March 4 through 10 (Craighead and Holden 1965). This saline invasion occurred at the peak of a severe drought which had lowered the levels of fresh water in the coastal region surrounding Baurotis Pond thus paving the way for replacement by wind-driven salt-water. During the saline in- trusion the salinity increased from 2 ppt to 20 ppt in six days. Many hundreds of the clams, all near the 40.0 mm maxi- mum size for the species given by Abbott {op. cit.) were washed ashore by the strong winds which caused the saltwater invasion. After stranding they were killed by the heat of the sun and then preyed upon by crows, racoons and seagulls from nearby Florida Ba>\ Although the mortality of P. cm'oliniana from these causes was extensive it was apparently not total, because a visit to the pond on the following May 4 produced a small .sample of living adults. At that time the salinity had fallen to about 12 ppt. The survivors were located in 0.5 to 0.8 m of water in soft, fine- grained calcium carbonate mud having the local name of Flamingo marl. Until August 1965, the Paurotis Pond population was the only known concentration of this species in the Park. However, during August and September 1965, and again in March 1966, additional specimens were found in headwater marshes of the North River some 18 km west of Paurotis Pond and about 5 km inland from the northern edge of Whitewater Bay. HABITAT P. carolmimia of Everglades National Park occurs in soft mud, generally 2.5 to 5.0 cm below the surface film of benthic algae and organic debris. All living specimens found by us have been in water less than 1 m deep although dead shell can be found on the bottom of the North River in 1 to 2 m depths. The Paurotis Pond population occurs most abundantly in marginal shallows where the fresh -water needle rush, Eleocharis celhdosa Torr. is abundant, and where the yellow-flowering bladderwort, UtHcuXaria lutea Birdsey and the euryhaline green alga, Batophora oerstedi var. occidentalis (Harvey) Howe, oc- cur side-by-side. The water in this area is characteristically clear and without color imparted by organic material. The clar- ity of the water, the characteristically high pH of 7.8 to 9.0, and the general absence of humus in the mud all combine to produce a brightly colored form of P. carolmian^ (Figure 2) having a high gloss, straw-yellow flaky periostracum and no erosion of the shell at the umbo as reported by van der Schalie. In addi- tion to the above characteristics the shells of the Paurotis Pond population are more massive than specimens from the North River population. — 270 — :e of adult Polumcfioda pper) and North River Figure 4. Single values of Poli/nicsoda carnUniava from North River peat marsh illustrating eroded condition of the shell mater- ial approximately G months after death of the animal. Note pcrio.stracum fragment still adhering to upper specimen. — 272 — In the North River the living clams were found in an en~ vironment like that described by van der Schalie in that they occur in the soft mangrove peat deposits along the edges of the brackish-water creeks. In the same region small specimens may also be collected at some distance back from the creek edges in seasonally flooded marshes where water depth fluctuations of 15 to 60 cm are common due to accumulation of fresh-water runoff during the rainy season. All living specimens in the North River peat had eroded umbos, thinner chalky shells, thick, dark periostracum and some- what longer and flatter shell profile (Figure 3). The peats are slightly acidic and the shells are quickly eroded by solution after death of the animal (Figure 4), The shells dissolve appreciably in 3 to 4 months when left in flooded mangrove leaf litter in the marsh shallows. Solution of the calcified shell material is often far advanced before the periostracum has decomposed. The dominant emergent vegetation in the North River habi- tat is a mixture of black rush, Jiincns roemeriamis Scheele, and stunted red and white mangroves, RhizophoraG mangle L. and LaguncidaHa racemom Gaertn. Van der Schalie subjected T. caroliniann. from Back Creek, a tributary of the Neuse River near Beaufort, North Carolina, to “normal sea water” for 2 weeks. After that period 9 of an original 14 animals used in the experiment were still alive but the “bodies of the suiwiving specimens were so emaciated that it was evident that they had suffered starvation”. Considering that his 14 test animals were collected from waters having sa- linity of 18,63 ppt and placed in “normal sea water” which, presumably was at about 35.00 ppt it is likely that they were also seriously affected by salt. The mortality at Paurotis Pond in Everglades National Park was initiated by salt intrusion which finally led to stranding and predation. Considering the habitat salinity of the breeding populations in Everglades National Park it is likely that the normal salinity range will be about 0.5 to 10.0 ppt with occasional rises to 12.0 to 15.0 ppt. The limited observations we have on reproduction, as indicated by the presence of 2-5 mm young, suggest that this occurs at salinity under 5.0 ppt and probably is most successful in fresh water. Van der Schalie himself took them in fresh water and noted that “Mazyek (1913) reports the salinity probably does not exceed the 3.5 ppt salinity tolerated by wild rice of the region (Palmer 1949).” Table 1 records the salinity, temperature, and dissolved oxygen conditions prevailing at one of the marsh stations in the North River where a large colony was found. Living animals were collected at that station until late March 1966, when salin- ity exceeded 15.0 ppt and water temperature rose to 24.5“ C. — 273 — Table 1: Maximum, minimum and average salinity (ppt.), temperature (C°) and average dissolved oxygen values (ppm) for five day sampling periods in each month measured at North River Station 6, Everglades National Park. SaUnity (ppt) Temperature (CO) Oxygen (ppm) Maxir mum Mini- mum Aver- age Maxi- mum Mini- mum Aver- age 1965 17-20 Aug 20.8 17.7 19.3 32.3 30.0 31,7 3.75 13-17 Sept 0.0 0.0 0.0 29.0 24.8 27.9 0.80 11-15 Oct 5.5 0.0 3.0 28.2 23.9 26.4 2.75 8-12 Nov 10.0 6.2 7.9 25.6 24.2 25.5 5.20 6-1 0 Dec 8,0 5.9 6.5 21.0 17.7 19.7 6.00 1966 3-7 Jan 13,4 9.5 10.9 24.0 21.0 22.6 5.75 28 Feb 13.8 12.5 12.9 18.0 14.4 16.5 6.75 1-4 Mar 15.5 14.6 15.0 24.0 23.5 23.7 4.50 28 Mar* 23.4 21 .0 22.5 24.8 21.0 24.5 5.40 25-29 Apr 26.5 22,0 24.6 25.3 23.0 25.2 4.40 23-7 May 25.0 20.0 22.4 31.5 28.5 30.0 3.80 20-24 June 0.0 0.0 0.0 32.8 29.0 30.5 2.05 18-22 July* 0.0 0.0 0.0 31.0 29.6 30.5 2.60 15-19 Aug 0.0 0.0 0.0 29.7 29.0 29.4 2.00 *Point of apparent total mortality of population at station 6. •‘Reproduction indicated by presence of 4-7 mm young in sediments of channel edges. Successful re-colonization of the station, as evidenced by 2.5 mm young, wrs observed during the following July after the marsh had been re-flooded by fresh water. (5anter and Hall (op. cit.) recorded salinity of 0.15 to 2^.3 ppt where P. Carolw^ iana occurred in the St. Lucie River with the majority of young animals (6 to 18 mm) being found when salinity was below' 1.0 ppt. In a later paper (Gunter and Hall 1965) they recorded 109 specimens in the Caloo.sahatchee Estuary of Florida at salinities ranging from 0.13 to 19.8 parts per thousand. The length range was 7-25 mm. SIZE AT MATURITY Abbott (op. cit.) gives the size of P. carolhviana as 25.5 to 38.0 mm in length and about as high. This is in general agree- ment with measurements of south Florida specimens. A series of 25 adults from Paurotis Pond ranged from 27.0 to 36,0 mm in length, averaging 31.8 mm. The range in height was 26.0 to 33.0 mm with an average of 29.7 mm. Shells of the North River series were noticeably larger. The shell length range was 33.0 to 47.0 mm with an average for the series of 40.3 mm while the height range was between 30.0 and 38.0 mm with an average of 36.2 mm. — 274 — No growth estimates are possible at this time, but the ultimate size of the mature individuals suggests that conditions for growth are somewhat more favorable in the North River habitat than in Paurotis Pond. This might be expected since the North River population is most abundant along the edges of marsh drainage channels where water movement, hence food availability, is most dependable. In Paurotis Pond, the water movement is caused almost exclusively by wind circulation. CONCLUSIONS The Carolina marsh clam, Polyrnesoda carolirdann, (Bose), is not a Florida disjunct species, but instead it occupies a re- stricted habitat in coastal marshes where little collecting has been done until recently. Before drainage of coastal marshes it is probable that the species distribution was continuous along the east Florida coast in the marsh belt adjacent to the coastal lagoons and estuaries. However, as these marshes w^ere drained for development of cities, breaks were made in the distribution. Thus, colonies probably exist today only in extensive rem- nants of the marshes which have nearly natural overland flow of fresh water emptying into coastal bays and estuaries, such as that found in Everglades National Park. The optimum habitat in southern Florida is found in a narrow belt of shallow marshland where the mangrove forests intergrade with fresh-water flora of the interior. The normal depths of water there range between 0.25 and 1.0 m. The salinity range there is 0.0 to 10.00 ppt but may rise to 20.0 ppt or higher during drought or during wind-driven intrusions of sea water. The adults at least can tolerate salinity as high as 26.3 ppt for short periods of time but become adversely affected when salinity rises above 18 to 20 ppt. South Florida populations apparently spawn during the spring and early summer coincident with the onset of the rainy season. Discovery of the population of marsh clams in Everglades National Park provides yet another important reason for pre- serving the traditional volume and seasonal pattern of over- land flow of fresh water into coastal marshes there. — 275 — ACKNOWLEDGEMENTS The investigations that produced the material described herein were carried on during the period 1957 through 1966. They were sponsored in turn by the Florida State Board of Con- servation (1957-1960), the U. S. Public Health Service, Division of Wacer Supply and Pollution Control (Grant Number WP- 00400-01, 02, 03) and the U. S. Department of the Interior, Office of River Basins (Grant Number 14-16-0004-56). We gratefully acknowledge this support. Doctor Moore’s research on unpublished material in the U. S. National Museum was supported by National Science Foundation Grant GB-5055. We are especially indebted to Dr, Harald A. Rehder, Research Curator of Mollusks, U. S. National Museum, for comments on the validity of the generic name Polymesoda. We are also pleased to acknowledge the assistance of the Superintendents and staff of Everglades National Park who encouraged the research and provided vital logistical support. LITERATURE CITED Abbott, R. T. 1954. American seashells. New York: D. van Nos- trand Co., Inc., i-xiii: 1-541- Requaert, J. C, 1943. The genus Littorina in the western North Atlantic. Johnsonia 1(7) : 1-27, Craighead, F. C, and M. Holden. 1965. A preliminary report on the closure of culverts along the Flamingo highway and the effects of changing water levels on wildlife and plants. Report to Office of Superintendent, Everglades National Parks, Homestead, Florida (mimeo). Dali, Wm. H. 1895. Contribution.s to the tertiary fauna of Flor- ida with special reference to the Miocene Silex-beds of Tampa and the Pliocene beds of the Caloosahatchee River. Trans. Wagner Free Inst. Sci., Phila., 3(3) : 48S-570. 1903. Contributions to the tertiary fauna of Florida with special reference to the Miocene Silex-beds of Tampa and the Pliocene beds of the Caloosahatchee River. Trans. Wagner Free Inst. Sci., Phila., 3(6) : i-xiv, 1219-1654. Gunter, G. and G. E. Hall. 1963. Biological investigations of the St. Lucie e,stuary (Florida) in connection with Lake Okee- chobee discharges through the St. Lucie Canal. Gulf Re- search Reports, 1(5): 291-292. 1965. A biological investigation of the Caloosahat- chee Estuary of Florida. Gulf Research Reports, 2(1) : 1-71. — 276 — Hedgpeth, J. W. 1953. An introduction to the zoogeography of the northwestern Gulf of Mexico with references to the in- vertebrate fauna. Publ. Inst. Mar. Sci., Texas, 3(1) : 109- 224. Mazyck, Win. G. 1913. Catalog of mollusca of South Carolina. Contr. Charleston Museum, 2: i-xvi, 1-39. Palmer, E, L. 1949. Fieldbook of natural history. New York: McGraw-Hill Book Co., Ill p. Perry, L. 1940. Marine shells of the southwest coast of Florida. Paleontological Res. Inst., Ithaca, New York, 260 pp. Rathbun, M. J. 1918. The grapsoid grabs of America. Bull. U. S. Nat. Mus., 97: 1-461. 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 and Caribb., 11(4) : 552-649. Van der Schalie, H. 1933. Notes on the brackish water bivalve Polyniesoda carolimana (Bose). Occ. Pap. Mich. Mis. ZooL, 258: 1-8. Vilas, C. N. and N. R. Vilas. 1945. Florida marine shells. C. N. Vilas Publ., Sarasota, Florida, 151 p. Williams, A. G. 1965. Marine decapod crustaceans of the Caro- linas. Fish. Bull., IJ. S. Fish and Wildl. Serv., 65(1) : 1-298, — 277 — Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Gulf Research Reports Volume 3 Issue 2 January 1971 Some Effects of Hurricanes on the Terrestrial Biota^ With Special Reference to Camille Gordon Gunter Gulf Coast Research Laboratory Lionel N. Eleuterius Gulf Coast Research Laboratory DOI: 10.18785/grr.0302.09 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Gunter^ G. and L. N. Eleuterius. 1971. Some Effects of Hurricanes on the Terrestrial Biota^ With Special Reference to Camille. Gulf Research Reports 3 (2): 283-289. Retrieved from http:// aquila.usm.edu/ gcr/vol3/iss2/ 9 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. SOME EFFECTS OF HURRICANES ON THE TERRESTRIAL BIOTA, WITH SPECIAL REFERENCE TO CAMILLE by Gordon Gunter and Lionel N. Eleuterius Gulf Coast Research Laboratory Ocean Springs, Mississippi INTRODUCTION There have been very few articles concerning the effects of hurricanes upon marine and shore organisms. Some effects on fishes have been described by Hubbs (1962) and in that paper he reviewed some of the previous references. Information on animals killed or injured by hurricanes is scarce because potential observers in areas where they strike are generally more concerned with practical personal matters than biological studies right after a bad storm. The senior author has been in or very close to seven West India hurricanes as they came ashore. Each time he was somewhat forewarned and had determined to make some type of quantitative appraisal of killed animals following these storms. However, on no occasion has this been done. Nevertheless, the two writers have collected some fragmentary information worth recording. Some Damages to the Fauna on the Mississippi Coast Hurricane Betsy — 9-10 September 1965 When Betsy passed the Mississippi Coast on its way to dev- astating areas of New Orleans, the center was approximately 50 miles south of Horn Island. Thus the wind blew more or less from east to west along the Ocean Springs-Pascagoula coastal area. Following this storm hundreds of sea balls mostly of the marsh grass Spartina were found on the mainland beach of Mis- sissippi Sound near Gulfport. The water rose to a height of about six feet on the Labora- tory grounds and left a strand of debris along the beach. In areas where there was marsh grass, thousands of little drowned mice, the Eastern Harvest Mouse, Reithrodontomys Jmmulis, lined the shore in a little brown windrow which was sometimes 100 yards long without a break. Also lying on the beach every ten yards or so was a dead raccoon, 'Procyon lotor. There were so 283 — many on the Laboratory grounds that they had to be hauled away. Raccoons are good swimmers and they certainly did not come from the surrounding nearby marshland. Horn Island, which lies eight miles offshore, was either completely or nearly submerged during this storm. The most reasonable assumption is that these coons were drowned in Mississippi Sound, after being washed off Horn Island and their bodies were finally blown onto the mainland shore. Hurricane Camille — 17-18 August 1969 This has been publicized variously as the worst storm that ever struck North America, or as the worst that has come ashore in this country in 143 years. Old, indefinite accounts in- dicate that something like this struck Florida in the 1700’s. It is quite certain that Camille was the most powerful hurricane that has struck a well-populated shore of the United States. The weather planes flying through it clocked the winds at 218 mph and recorded the lowest natural barometric pressure that has ever been read (26.01 inches). The ‘‘Big House,” an old landmark of the Laboratory and of the coast, was splintered and even the brick pillars upon wdiich it stood were washed away. We have no way of quantifying the destruction of animals, except to say that the clean-up agency, the 43rd Battalion, Corps of Engineei’S, U. S. Army, reported removing 28 tons of animals from the beach between Biloxi and Gulfport on August 22-24. Most of these animals were dogs and cats, but some horses and cattle were mixed in. After the storm many dogs \vere home- less and many were systematically shot because they were starv- ing. Following the storm, the writer was waked up by a bird singing lustily just outside his window; this was the only bird seen for about a week. An unknown number of wild animals, birds, dogs and other life including human beings lost their lives in the storm; after about three days, the odor of decaying animals was noticed in the atmosphere and lasted about a week before it gradually went away. The bird population and the squirrel population virtually disappeared but both came back after a few weeks time, mo.st noticeably the jaybirds and a few gray squirrels {Sciunis caro- linensis). The birds disappeared again, probably because they could find nothing to eat. This was certainly true of the squirrels and they were reduced to gnawing the bark off of felled water oaks (Gunter and Elcuterius 1971). When the storm struck, the seeds of various nut trees — chiefly the hickory, black walnut, and thousands of pecans which — 284 — are planted in this area — were just beginning to mature. Many of these trees were blown down and approximately half of the foliage of those remaining was denuded by breakage of the limbs. The same thing was true of oaks and acorns. Additional- ly, the nuts themselves were beaten off of the trees that re- mained standing. Presumably for that rea.son the Eastern Gray wSquirrek which was quite common, had not returned in its for- mer numbers by April 1970. Before the .storm it was quite com- mon to see as many as eight of these at one time in a relatively small area of trees in the senior author’s front yard. After the storm, he saw none for one week and then he saw a lone squirrel. The squirrel population apparently increased in about three weeks to a month after the .storm, then declined again. This observation would bear out the supposition that squirrels mov- ing in from other areas could not find sufficient food and moved out again. The same thing apparently was true of the jaybirds. There was a decided diminution in the number of birds which came to feeder stations during the following winter. For instance, dozens of birds and sometimes a few hundred in one afternoon formerly fed at a home facing the beach just to the side of the Laboratory grounds. The most numerous species, sometimes present in the dozens at a time, was the Savannah Sparrow. During the past winter only three or four have ap- peared at a time. The owner, before Camille, had to keep watch on the Starlings and jaybirds because they disturbed and ran off the others, but has had no trouble since the storm. General ob- servations show that the Brown Thrashers, the jaybirds and the Cardinals are present in very diminished numbers even today (April 1970). These facts have been noticed by other people and recorded, especially in The Dixie Guide by Mr. Clayton Rand who has gone through three bad hurricanes at his home in Gulfport. Mr. Rand has mentioned in his paper several times, the last being February and March 1970, that during former hurricanes there were many snakes and frogs everywhere in the area and that the mosquitoes were quite bad. He has remarked three times in his monthly newspaper that there was a great absence of life following Camille, even of the birds. To the senior writer, however, the most amazing thing has been the disappearance of the ants up until this time (April 1970). The black carpenter ant and the Argentine fire ant and several other smaller species were quite common in his yard. Apparently they all succumbed to the storm, except for a minute yellow species that goes by the name of sugar ant, which has been seen one time. Bread and other foods set out for dogs and cats were formerly covered with ants in a matter of minutes ; but, even this long after the storm, they may remain untouched by ants for days. We do not know the extent of destruction of the Argentine fire ant, but locally they are gone. — 285 — It is to be expected that termites and termite feeding ani- mals and possibly woodpeckers would increase greatly in num- bers due to the thousands and thousands of felled trees and rotting timber, a good bit of which, after having had the top broken off, is still upright. Damages to the Flora on the Mississippi Coast There are very few reports of the effects of hurricanes, typhoons, or cyclones (tornadoes) on coastal vegetation. Sauer (1962) reported the effects of cyclones on the coastal vegetation of a tropical island (Mauritius) in the Indian Ocean. Chamber- lain (1959) and the U. S. Department of Agriculture (1960) reported some of the effects of Hurricane Audrey on the vege- tation of south Louisiana. Previous hurricanes which struck the Mississippi coast inflicted minor damage to the vegetation; one of the worst of these storms known to the junior author occurred in 1947. The ‘*eye’' or center of Hurricane Camille came ashore in the Pass Christian-Bay St. Louis area and the path was well marked by the effects of the storm on vegetation. The most ap- parent and obvious effect wa.s the destruction of the trees. In Jackson County most of the trees blown down were oriented with the tops pointing toward the northwest. In Harrison County near Gulfport, the trees became oriented with the tops pointing toward the west-northwest and in the Pass Christian-Bay St. Louis area, they were oriented in an east-west direction, but some tree tops pointed eastw'ard and some pointed to the west and the trees were nearly parallel in alignment (figs. 1 and 2). The paradoxical alignment wa.s apparently a result of the initial winds from the east, followed after the “eye” passed over the area, by winds from the west. Trees west of Bay St. Louis near Pearl River were oriented with the tops toward the east-north- east and near Slidell, Louisiana, they \vere down in a north- east direction. The intensity of winds from Hurricane Camille could be seen in the number of trees felled, the number increasing as the wind velocity increased toward the path of the “eye.” In fact, without referring to other data, one could determine the .storm path by observing the east-w’est direction in which the trees were blown down and by the gradual increase in the numbers of trees destroyed as the center of the path was approached. Tornadoes or extremely turbulent winds ripped through many areas on the periphery of the hurricane and the paths of their “touch downs” were well documented in the vegetation. In Magnolia State Park, which almost adjoins the Laboratory property, there is one area 60 feet wide and 17 tree lengths long, which the second author attributed to these tornadic gusts. — 286 — The junior author conducted two vegetational surveys to compare the intensity of damage to areas on the periphery of Hurricane Camille with areas nearer the center. In Jackson County, these surveys showed that in one tract, 4% of the trees were blown down and 10% were damaged to the point that survival was in question. The plant community was dominated by Quercm nigra (water oak) with Finns elliotii (slash pine), Canja glnbra (hickory) and Quercu^ rubra (red oak) being the subdominant species. This 40-acre tract in Magnolia State Park was approximately 22 feet above sea level. Destroyed trees in decreasing order were: red oak, slash pine, water oak, and hick- ory. It was noted that the heart wood (xylem) of the red oaks had been weakened by pathogenic attack and were rotted. Less than 10% of the pines destroyed were uprooted; they were twist- ed or broken off at heights ranging from 5 to 20 feet above the ground. The large tap-root characteristic of the pines apparent- ly held the trees up; they were not blown down easily, but could be broken. Other trees blown down in adjacent plant com- munities were Magnolia grandiflora (Magnolia), (Nyssa biflora (black gum), Liquidambar styraciflora (sweet gum), and Lireo- dend'i'um tiiHpera (tulip tree or yellow poplar), Another survey was conducted on 87 acres of forested land north of Pass Christian in Harrison County, bordering the Wolf River and Red Creek Road. Approximately 10 acres here were bottomland forest along the river and adjacent low-lying drainage areas. The rest of the land was approximately 25 feet above sea level and covered with Pimts elliotii (slash), Finns taeda (loblolly) and Pmus palustris (longleaf) in various stages of growth. The owner considered the area a game reserve and left it undisturbed. Results of a sample showed that approxi- mately 70% of the bottomland species were blown down. The species were Magnolia virgimana (sweet bay), Liquidambar sty- raciflora (sweet gum), Taxodium distichum (bald cypress), Acer mbrum (red maple), and the area was dominated by Quer- cus nigra (water oak). ^Mnety per cent of the trees in the low- lying area had diameters greater than 24 inches at breast height and there were between 100 and 150 trees per acre. An estimated total of 201,000 board feet of hardwood timber was lost. Approximately 10,000 slash, loblolly, and longleaf pine trees with diameters greater than 10 inches were present on the higher sites and there were only 300 of these trees that were not damaged, i.e. 97% were destroyed. Many of those standing were not expected to survive due to lack of limbs, miss- ing tops or split trunks. A total of 607,600 board feet of pine was estimated as lost. Many young trees were crushed by the falling trees, and other understory plants and habitats for wildlife were destroyed. At the time of the survey (March 1970), beetles, especially /p,9 avulsus, Ips grandicoUis, and Ips calligraph%i8, had infested many of the downed trees and rot — 287 — had begun. The specific names of the beetles were furnished by Dr. Virgil Smith, entomologist, U. S. Forest Service, Gulf- port, Mississippi. Twisted and split saw logs could not be sal- vaged for use. Paper wood operations were expected to be hin- dered by the tangled mass of trees. Practically all of the pine trees were second growth and ranged from 16 to 68 years old. The water oaks and other hardwoods were much older, ranging from 100 to 125 years. These two tracts simply show by comparison that the most damage to the vegetation was caused by winds occurring near the center of Hurricane Camille’s path. Another observation was the destruction of Querem inr- c/iniana (live oak) along the beach front from Biloxi to Pass Christian. Approximately 25,000 live oaks w^ere growing along the beach before Camille and one-fourth w'ere destroyed by wind and water and one-half w'ere damaged. Those trees nearest the beach were partially inundated and the roots eroded by wave action. The immediate beating action of the wind and the physio- logical “drought” resulting from the salt spray reduced these evergreens to bare branches (figs. 3 and 4) . Many slash and longleaf pines may have been killed as a result of the inundation of low-lying areas near the mouth of the Wolf and Jourdan Rivers. The trees are dead but standing; however, this could be the result of other, internal damage since many trees on the barrier islands were covered by salt water and surived. This observation needs further study. The Corps of Engineers> U. S. Army, estimated that a total of 1.2 million board feet of saw timber and one million cords of pulpwood in Mississippi were lost. On the Mississippi Test Facility in Hancock County, an estimated 6,000 cords of pulp- wood were damaged and only 60% of the downed trees could be salvaged for lumber. It has been reported that a total of 290 million cubic feet of pine alone was lost in South Mississippi (Van Hooser and Hedlund 1969). The barrier islands presented a pattern of destruction sim- ilar to that on the mainland. Petit Bois Island was affected relatively little but there was a gradual increase in damage on the i.slands to the west. Horn Island was heavily eroded on the outside beaches. The marsh vegetation was pushed down and pres.sed to the soil surface by the water as it passed over the island (figs. 5 and 6), Ship Island was cut into three pieces and more than one-third of the vegetation, most of which was her- baceous, was removed. Gat Island was heavily damaged. Large oaks were uprooted by wave action and many pines were broken by the wind. Large sand dunes were leveled, the sand re-distri- buted over much of the adjacent low-lying marsh. Tons of plant materials swept from the liOuisiana marshes and the barrier islands were deposited on the mainland in large windrows. — 288 — Marshlands were affected insit^nificantly because the water covered them early in the hurricane and they were not exposed to the terrific beating of wind and wave that occurred later. Spartifia alterniflora (smooth cord grass) flowered on schedule (September through November). Shrubs found along the periph- ery of marshes, where they formed thickets, acted as baffles and protected trees and, in some cases, homes. Many upland under- story areas were denuded of herbaceous and woody shrubs where they were located near water. The botanical regime of South Mississippi was dis- turbed by Hurricane Camille of August 1969, probably to a greater extent than by any other hurricane in the history of the Mississippi, and the greatest influence on the terrestial vege- tation was the destruction of the trees. LITERATURE CITED Chamberlain, J. L. 1959. Influence of Hurricane Audrey on the coastal marsh of southwestern Louisiana. Coastal Studies Institute, Louisiana State Universitv, Technical Report, lOB, ONR 35608. Gunter, G. and L, Eleuterius. 1971. Bark eating by the com- mon gray squirrel following a hurricane. Amer. Midi. Nat. 85(1) : 235, Hubbs, Clark. 1962. Effects of a hurricane on the fish fauna of a coastal pool and drainage ditch. Tex. Jour. Sci. 14(3) : 289-296. Sauer, J. D. 1962. Effects of recent tropical cyclones on the coastal vegetation of Mauritius. J. Ecol. 50: 275-290. U. S. Dept, of Agr. Soil Conservation Service. 1960. Effects of saline water from Hurricane Audrey on soils and vegeta- tion. Alexandria, La., Special Rept. (Minco), Van Ilooser, Dwane D. and Arnold Hedlund. 1969. 'Timber dam- aged by Hurricane Camille in Mississippi. U. S. Forest Ser- vice Res, Note. SO-96: 1-5. Southern Forest Experiment Sta., New Orleans, La. — 289 — Gulf Research Reports Volume 3 Issue 2 January 1971 The Relative Abundance and Distribution ofPenaeid Shrimp Larvae Off the Mississippi Coast Chebium B. Subrahmanyam Gulf Coast Research Laboratory DOI: 10.18785/grr.0302.10 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Subrahmanyam, C. B. 1971. The Relative Abundance and Distribution ofPenaeid Shrimp Larvae Off the Mississippi Coast. Gulf Research Reports 3 (2): 291-345. Retrieved from http:// aquila.usm.edu/gcr/vol3/iss2/ 10 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. THE RELATIVE ABUNDANCE AND DISTRIBUTION OF PENAEID SHRIMP LARVAE OFF THE MISSISSIPPI COAST by Chebium B. Subrahmanyam Gulf Coast Research Laboratory Ocean Springs, Mississippi and Mississippi State University State College, Mississippi INTRODUCTION Penaeid shrimp go through a complicated metamorphic life cycle involving a change in their habitat during the course of development. Adults inhabit and spawn in highly saline off- shore waters, the larvae are planktonic and the postlarvae mi- grate into low saline coastal bays for their survival and growth. Spawning cycles of several species in the Gulf of Mexico have been studied chiefly by collecting the mature adults. A consider- able volume of work has been done on the biology of the post- larvae, but information on the planktonic larvae is scanty. As- sessment of reproductive cycles of marine animals based on the larval abundance is one of the several methods employed by biologists (Giese 1959), This method is particularly applicable to animals such as penaeid shrimp, which are benthonic. The literature on the development and various other as- pects of the biology" of the penaeid shrimp is becoming volumin- ous. Many investigations have considered the spawning seasons, especially of commercially important species. Since Muller (1864) showed that the penaeid egg hatches into a nauplius, a series of investigations have traced the development of several species, especially those by Gurney (1924, 1927, 1942, 1943), Hudinaga (1942), Menon (1951), Heldt (1938, 1954, 1955), Heegaard (1966) from various parts of the world; Pearson (1939), Heegaard (1953), Dobkin (1961), Renfro and Cook (1963), and Cook and Murphy (T965a), from the Gulf of Mex- ico. Cook (1966) worked out a generic key for the identifica- tion of larvae to the generic level. The commercial importance of penaeid shrimp evoked a great interest in the study of their biology, and a considerable amount of information has accumulated as reviewed by Williams (1965) and Lindner and Cook (1967). A UvSeful bibliography has been prepared by Chin and Alien (1959). The first to un- — 291 — derstand that the penaeid shrimp spawn in the littoral water was Viosca (1920) who stated that Pcnaeus setiferus (Linn.), a syn- onym of P. fluviatilis Say when applied to North American white shrimp, spawns in the Gulf, chiefly on the evidence that mature shrimp are found only in outside waters. The young are said to live in the plankton of the Gulf until a size of 1^/4 inch^ is reached. Now it has been well established that this generaliza'- tion is true. However, the size at which the postlarvae enter the bays is 7 mm (Weymouth, Lindner, and Anderson 1933). Actually some postlarvae are 12 mm or slightly more at this stage. After spending a variable period in the plankton, larvae metamorphose into postlarvae and migrate into coastal inland waters. They grow very rapidly in the low saline environment. This was first discovered by Viosca (1920), and was redis- covered by Gunter (1950), after it was forgotten or ignored for 30 years. Gunter states that the young white shrimp grow 25 to 45 mm per month during warmer months. Williams (1955a) has confirmed this. The most thoroughly investigated species is the white shrimp, Penaeus fluviatilis Say, which has been studied in de- tail by Weymouth et al, (1933), Pearson (1939), Anderson, King and Lindner (1949), Gunter (1950), Anderson (1955), Lindner and Anderson (1956), Christmas and Gunter (1967) and Lindner and Cook (1967). According to these authors, the white shrimp .spawn mainly from spring througli late fall with variable peaks in different geographical areas. The brown .shrimp, P. aztecus Ives, is believed to spawn through an ex- tended period with little variation along its range (Gunter 1950), Kutkuhn 1962, and Williams 1965). The peak spawning seasons of this species are March-April and September-October. The pink shrimp, P. duorarum Burkenroad, has been studied extensively on the Florida coast by Eldred et al. (1961, 1966), Idyll, Jones and Dimitriou (1962) and Iversen and Idyll (I960), It breeds from spring to late summer or late fall according to these authors, but Roessler, Jones and Munro (1967) believe that it spawns year round. The^ other species have not received as much attention as the species of Penaeus. From the available information (Pearson 1939, and Eldred et al. 1965) , it appears that Trackypervens spp. breed from February to NovemW; Parapenae'iis longirostns (Lucas) from April to June or October; Sicyonia spp. from January to December with summer peaks; and Solenocera spp. from February to June or November. These conclusions have been based on studies made on the larvae or the adults at a par- ticular depth or a few depths. JKdilorial note. Vio>5ca always maintained that his measurements were In cm and they were botched by printers. — 292 — Most of the species of penaeid shrimp in the Gulf of Mexico appear to breed when the temperature rises in spring and ex- hibit peaks in spring or summer and in fall. The paramount importance of temperature in controlling the breeding and dis- tribution of marine animals has been emphasized by Orton (1920), Thorson (1946, 1950), Ekman (1953), Gunter (1957), Johnson (1957) and Radovich (1961). Orton's rule states that, “most marine animals under normal conditions begin to breed either at a definite temperature, which is a physiological con- stant for the species, or at a definite temperature change, narne^ ly, at either the maximum or the minimum temperature of the locality.” Rising temperatures induce gonadal development in most temperate organisms, and actual spawning takes place when a certain temperature, which varies with different species, is reached (Gunter 1957). MTiile the occurrence of mature adults and of larvae sheds light on the reproductive cycles of shrimp, the abundance of postlarv^ae in the backwaters offers corroborative evidence. Contributions on this phase of the shrimp life history have been made by Williams (1955 a,b, 1959 and 1969), Gunter (1961 a,b), Renfro (1960, 1961), Loesch (1965), (Jjhristmas, Gunter and Musgrave (1966) and Baxter and Renfro (1967). These authors have discussed the incidence of postlarvae in the bays, which occur in two or three waves, and these waves of abundance correlate with the spawning seasons. It can be seen that the important larval phase of the life cycle has not received much attention. The occurrence of larvae is a definite sign of spawning activity, especially of the ben- thonic animals or sessile animals such as oysters (Korringa 1957). The first study purely on larval distribution was made by Eldred et ai. (1965) who discussed trends in abundance in west Florida waters up to 37.8 m deep, and showed that spawn- ing peaks varied at different depths for various species of six genera. Temple and Fischer (1965) studied the vertical distri- bution of the four larval stages and elucidated their vertical stratification and diurnal changes. The same authors discussed the relative abundance and distribution of Penaeus larvae off Galveston (Temple and Fischer 1967), and showed that the breeding season tended to be more protracted progressively with depth, and that the peak spawning season differed at different depths. Thus, the information on the distribution of larvae of var- ious commercial penaeids of the South Atlantic and Gulf of Mexico is limited to these three studies. Sampling at one water depth and at one particular level in the water column will not yield accurate information on the previous spawning activity of benthonic animals. Also, the distribution of larvae in relation to season, temperature, salinity and depth is of fundamental biological interest. 293 The objectives of the present investigation arc; (a) to de- lineate spawning seasons and the areas of as many species as possible based on larval abundance; (b) to study the spatial and seasonal distribution of penaeid larvae in relation to depth, temperature, salinity and seasons, which will indicate the movements of the spawners; (c) to inquire whether any cor- relation exists between occurrence of larvae and of adults in any area; (d) to examine the relationship between Venaeus postlarval abundance in the Mississippi Sound and larval and postlarval occurrence in the open sea; and (c) to study the vertical seasonal distribution of different stages, and to find out whether different developmental stages exhibit diurnal mi- grations. Larvae of six genera, Penaeus, Paraperuteus, Trachypeneus, Xiphopeneus, Sicyonia, and Solenocera, were encountered and the information on these is presented here. Protozoeal and mysis stages of Gennadas and Artemisia were collected, and these are new records from the Gulf of Mexico. They were reported by Subrahmanyam and Gunter (1970). The study was conducted from November 1966 to December 1968 inclusive. MATERIALS AND METHODS Plankton samples were collected from three depths at six different stations in the Gulf of Mexico, Subject to weather conditions, cruises were made to all or some of the stations every month for the purpose of obtaining a night and a clay series of samples. FIELD PROCEDURE Stations The sampling stations were established to provide 18 m depth intervals. Station I was of particular interest because of its location just off the western end of Horn Island, where the depth was 10 m. The exact locations of the different stations are indicated in Fig. 1 and Table 1. The R. V. Gulf Researcher, a 65-foot (19.8 m) boat owned by the Gulf Coast Research Laboratory was used for the sampling program. Equijrment For salinity estimates water samples were collected with Nansen bottles from the two subsurface depths and with a bucket from the surface. — 294 — Figure 1. Station locations off the Mississippi Gulf Coast. —295 Table 1. Station locations and their depths St. No. Loran SHI 3HO Longitude West Latitude North Depth 47’00" 3001 2'30'’ 9.1 II 1220 3580 88°40'15'' 30002*30” 18.3 II 1220 3580 88^40' 15” :i0O02'30’' 20.1 III 1440 3539 88O27'30'' 29O42'00" 36.6 IV 1618 3494 8801 7'00” 29®24'15" 54.9 V 1657 3480 88°14'00” 29019*00” 73.1 VI 1683 3472 8801 2'05'' 290i7'15” 91.5 VI 1556 3457 88031 '00” 29Ol2'00” 109.8 VI 1562 3449 29012*00” 100.6 The positions of the stations were determined by Loran.and the fathometer NOTE: At timesdue to the drifting of the boat the Station locations differed slightly. Therefore, the altered positions for St. I, Si. II and St. VI are also included in the Table. Temperature profiles at each station were made with two bathythermographs, one that operated up to about 70 m depth, and the other up to about 275 m. Reversing thermometers mounted on the Nansen bottles offered a check on the bathy- thermograph temperature readings. Air temperatures were taken with a dry and wet bulb thermometer. Plankton collections were made with three closing nets devised according to Hardy (1956). Each net measured 50 cm across the mouth, with a cross sectional area of 1964 cm", and wa.s 2 m long up to the bucket, including the canva.s portion around which the belly rope for closing the net was looped. The netting was No. 3 Nylon with 0.33 mm mesh size. The surface net was towed from the stern of the boat. Simultaneously, the other two nets were towed at two subsinTace levels. These two nets were fixed half the station depth apart (e.g., 9 m apart at 18.2 m station) on the same cable, with the bottom net attached 1 m above the sinker. Messengers for closing the nets were fixed on the closing devices. Three minutes were allowed for stabiliza- tion of the wire angle. Then the nets were towed at 600 rpm ( 3 to 5 km/hr) for exactly 20 minutes. At each station a cir- cular course was taken to avoid drifting into deeper or shallow- er waters. The cable angle was measured at the beginning of each tow and attempts were made to keep the angle constant during the tow. Appropriate lengths of cable, read off a pre- pared chart, were let out for sampling at the desired depth.s (cable length^depth x cosecant of wire angle). Later the exact depths were calculated (depth=sine of wire angle x cable length). Since the position of the bottom net was known, and the length of cable sent out corresponded to the depth of the station, the bottom net was usually I m above the bottom. The — 296 — subsurface nets were always fixed with the same distance be- tween them on the cable, and therefore the sampling- depth of the middle net varied a little due to the different cable angles. After the tow was completed a messenger was sent down to close the subsurface nets. At the same time the surface net was hauled aboard. Plankton samples (from the three depths) were stored in separate bottles containing 10% formalin. In my abvsence, sampling was done by trained personnel. The number of samples collected and the other details are given in Table 2. Table 2. Details of the samples collected at 3 depths Year & Month ■ Day St. Number of samples collected Night No. samples St, No, samples Total 1966 Nov. ll-VI 15 — - 15 Dec l-VI 18 - - 18 TOTAL 33 1967 Jan l-VI 18 l-VI 18 36 Feb Mil 9 - - 9 MdF l-VI 18 IMII 6 24 Apr 1,11 5 - - 5 May l-VI 18 l-VI 18 36 June l-VI 18 l-VI 18 36 July l-VI 18 l-VI 18 36 Aug l-VI 18 l-Vl 18 36 Sep 1,11 6 1,11 6 12 Oct 1 3 11,111 6 9 Nov 1,11 6 lll-V 9 15 Dec 1 3 Ml 6 9 TOTAL 263 1968 Jan Mil 9 MM 8 17 Feb 1 3 - - 3 Mar i-III,Vi 11 IV-VI 8 19 Apr 1,11 6 - - 6 May MV 10 MM 9 19 June 1, II, IV-Vl 14 III 3 17 July MV 12 l,ll,V,VI 11 23 Aug l-VI 18 - - 18 Sep Mil 9 III-VI 11 23 Oct l-VI 18 I-Vl 18 36 Nov l-VI 18 l-Vl 18 36 Dec l-VI 18 1-VI 15 33 TOTAL 248 GRAND TOTAL 544 297 — Trawling was done with a 40-foot (12.19 m) balloon trawl with a mesh size of 3.2 cm from knot to knot. The boat speed was 1100 rpm (14 km/hr) for this purpose. The adult shrimp were picked out and preserved in 20% formalin for later iden- tification. LABORATORY PROCEDURE Temperatures at different depths were read off the bathy- thermograms made at each station. Salinity wa.s estimated with a Goldberg refractometer. The salinity at the depth where the middle net was calculated to be was read off the temperature- salinity curves drawn for each station by the procedure of Mc- Lellan (1965). Plankton samples were allowed to settle for at least 48 hours and the settled volumes were recorded. All the penaeid eggs and larvae were picked out. The larvae were identified as to developmental stages and genera using Cook (1966) and other references. The larvae were stored in vials of 5% buffered formalin. Since the numbers of larvae caught might be related to the amounts of plankton strained^ correlation analysis was made between settled sample volumes and numbers of larvae per 500 ml standard volume. The nonsignificant correlation coefficients, 0.019 and 0.127, respectively, for day and night samples ruled uul any such relationship. The numbers of larvae caught ap- parently depended on their general availability in the water column sampled. Hence the numbers of larvae per sample are compared in terms of catch per unit effort (20 min standard tow) . Adult shrimps were identified, measured, and sexed. Since the maturity condition reveals the breeding potential of the species, the different maturity stages of male.s and females were determined by methods set forth before (Subrahmanyam 1965b). RESULTS HYDROGRAPHY The two physical factors examined were temperature and salinity. The salinity ranges are given in Tables 3 and 4, and the temperature ranges in Tables 5 and 6. Salinity The minimum salinity during the study period was 18.5Voo at St. I and 26.8o/oo at St, VI. But the maximum salinities Var- ied between 36.6Voo and 38Voo only. The range of variation decreased seaward, the deeper waters tending to fluctuate over — 298 — Table 3. The ranges of salinity ( *^^00 ) at different stations during 1966-1968, St. Depth Minimum Month Sal. °/t>o Maximum Month Sal. 9^00 Range °/oo t 10 Jul. 68 18.5 May 68 36.6 18.1 II 18 Jul.68 21.8 Nov. 68 37,1 15.3 Ml 36 Mar. 68 24.4 Ocl. 67 37.7 13.3 IV 54 Oct, 68 27.2 Jun. 68 37.2 10.0 V 72 Aug. 68 26.0 Nov. 68 37.7 11.7 VI 90 Oct. 68 26.8 Aug. 67 38.0 11.2 Table 4. The ranges of salinity ( °/oo ) at different depths during 1966-1968. St. Min. Surface Max. Range Min. Middle Max. Range Min. Bottom Max. Range 1 13.1 37.1 24.0 19.0 37.6 18.6 19.9 37,6 17.7 II 18.6 37.1 18.5 22.2 38.9 16.7 23.3 38.9 15.6 III 21.6 37.0 15.4 24.6 38.2 13.6 24.6 39.0 14.4 IV 16.8 36.8 20.0 25.0 38.0 13.0 28.8 38.9 10.1 V 18.6 37.4 18.8 25.6 38.0 12,4 24.9 38.0 13.1 VI 23.2 38.0 14.8 23.3 38.0 14.7 26.6 38.0 11.4 Range 10.1 1.2 6.6 1.3 8.9 1.3 Table 5. Temperature ranges at different stations during 1966-1968. St. Depth (m) Minimuii* Month Temp,°C Maximum Month Temp.°C Range 1 10 Jan, 67 12.3 June 68 30.1 17.8 II 18 Mar, 67 14.2 Aug. 68 29,4 15.2 III 36 Feb, 67 16.2 Aug. 68 30,1 13.9 IV 54 Jan. 68 16.9 June 68 28.5 11.6 V 72 Mar. 68 17.7 Oct. 68 26.4 8.7 VI 90 Mar. 68 17.4 Aup. 68 26.8 9.4 Table 6. Temperature ranges at different depths during 1966-1968. St. Min. Surface Max Range Min, Midwater Max. Range Min. Bottom Max. Range 1 12.2 30.4 18.2 12.2 31.0 1S.8 12.5 29.5 17.0 II 13.6 30.1 16.5 14.4 28.0 13.6 14.4 29.0 14.6 III 13.6 30.8 17.2 16.1 31.5 15.4 16.4 29.0 12.6 IV 15.6 32.0 16.4 17.2 26.5 6.3 17.2 27.0 9.8 V 17.5 30,4 12.9 17.8 25.9 8.1 17.8 25.5 7.7 VI 17.8 30.4 12.6 17,2 28.0 10.8 17.2 21.9 4.7 Range 5.6 0.3 5.6 5.5 4.7 7.6 — 299 — a range of ii.2\/oo as compared 18.lo/uo at St. I. Months of low and high salinities differed among the stations (Table 8). Surface, midwater, and bottom salinities at each station also showed certain trends. The minimum surface salinity ranged from at St. I to 23.2o/oo at St. VI. The mid- water salinities fluctuated from 19.07'’° to 26.6V‘>o- Minimum salinities were higher toward the bottom, and the range of variation decreased from 10.17°° at the surface to 8.97 qo at the bottom. Maximum salinities at all depths of different sta- tions varied only -within 1.37oo (Table 4), No correlation was found between larval abundance and salinity, the correlation coefficients being 0.07 and 0.03, respec- tively, for day and night collections. In general, .salinity fluct- uations did not follow predictable patterns. Temperature Minimum temperature was recorded in winter in the in- shore waters and at St. Ill and IV, and in spring at St. V and VI. When the average temperature is considered, inshore w'aters cooled dow'n faster than the offshore w-aters. For deep waters 16.2 C was the lowest temperature recorded (Table 5) . When the minimum temperature is considered, the St. VI minimum was 5.1 C higher than the St. I minimum. Maximum temperatures varied only over a range of 3.7 C. The range of fluctuations during the period of .study decreased from 17.8 C at St. I to 9.4C at St. VI. When the stations are compared (Table 6) it is seen that the minimum surface temperature Avas higher sea- ward, and the maximum temperature did not vary a great deal. Midwater and bottom minimum temperatures varied up to 4.0 C between St. I and IIL At deeper stations variation wa.s only in a range of 0.6 C. Ho-wever, the range of fluctuations of maxi- mum temperature w^as greater in midwater and bottom, 0.3 C, 5.6 C and 7.6 C at the surface, midwater and bottom re.spective- ly- Vertical temperature profiles for all the stations are de- picted in Fig, 2. Data are from the bathythermographs. In win- ter, isothermal conditions existed at St. IT, IV and VI, and slightly warmer w^aters occurred toward the bottom of the other stations. In spring, temperature did not vary more than 0.6 C from surface to bottom at St. I, II, and III, while at St. IV and V considerable mixing of cold and warm waters was evi- dent. Ninety meter waters (St. V) showed a gradual decrease in temperature toward bottom. In summer, typical thermoclines were found only at St. I and II. At all the other stations a gradual top to bottom decrease was evident. In fall, vertical mixing and isothermal conditions were evident at St. I through VT with some stratification at St. V and VI. — 300 — 1 2 3 4 5 6 STATIONS 1 2 3 4 5 6 Figure 2. Bathythermograms for six stations in different seasons. SEASONAL ABUNDANCE AND HORIZONTAL DISTRIBUTION General Larvae of the six genera, PenamiHy Parapenaeiis, Trachy- pen&us, XipkopeneuSy Solenocera and Sicyonia, were caught in all depths at all the stations, but the relative abundance of in- Table 7. Seasonal abundance of penaeid larvae expressed as average number of larvae per 20 min haul Station I M 1967 III IV V VI 1 II 1968 III IV V VI Spring 64 62 30 58 237 42 25 267 30 47 17 43 Summer 47 719 262 115 95 123 68 97 500 72 134 121 Fall 34 117 185 496 161 — 63 707 214 110 85 25 Winter 3 43 78 366 152 230 3 28 19 76 29 36 Average for two years 1967 •> 1968. Spring 45 165 30 53 127 43 Summer 57 408 371 94 114 122 Fall 49 412 200 303 123 25 Winter 3 36 49 216 91 133 — 301 — dividual genera varied in relation to seasons and depth. Average counts for each station and for the four seasons of 1967 through 1968 are given in Table 7. Large numbers of lai’vae were taken in winter at stations beyond St. Ill, peaks being at 86 m depth in early winter and at 54 or 90 m depths in mid-wiiitcr. In early spring the peak was still at St. IV, but by late spring the peak shifted to St. II. Fair numbers of larvae were caught at all stations during summer, indicating that penaeids were breeding over a wide area. In fall, the peak was still at St. II but increased numbers were taken from deeper stations, for example at St. IV. In winter, larvae were scarce at St. I to III and good num- bers were taken at St. IV, V, and VI. These treiid.s in shifting of the larval peaks become clear if the average counts for the two years are examined (Table 7) . Shrimp appeared to spawn in shallow or deep waters with warm- ing or cooling of the environment. In spring spawning activity seemed to be concentrated at 18 m, in summer at 18 and 36 m, ill fall at 54 m and in winter beyond 36 m. Minor spawning ac- tivity was evident at the other depths. Correlation studies relating larval abundance and absolute in aitu temperatures at various depths and stations failed to show any significant correlation, the correlation coefficients being 0.09 for day and 0.08 for night samples. This is to be ex- pected in view of the fact that spawning activity heightens or even starts in spring in the inshore waters, when temperature starts rising, while in deeper ^vaters it occurs all through the year. Table 8 indicates that shrimp in this area breed betw'een average temperature range of 17 and 29 C. Within this range the spawning activity of the six genera, as indicated by the lar- Table 8. Average seasonal temperatures (°C) at different stations during 1967-1968. station 1 11 iir 1967 IV V VI 1 n 19ffi III IV V VI Spring 21.4 19.5 20.1 20.7 20.4 20.6 22.2 20.8 19.6 20.1 18.0 19.3 Summer 25.3 23.3 24.1 23.9 22.4 22.6 29.5 28.2 28.4 25.7 24.9 24.6 Fall 23.2 23.3 22.6 21.3 21 .6 — 21.0 23.8 24.5 22,9 23.2 22.7 Winter 14.6 15.8 16.9 18.3 19.3 19.1 13.9 16.0 17.1 19.6 21.9 21.6 i-or Two Years 1967 ■ 1968. Spring 21.8 20.2 19.9 20.4 19.2 19,9 Summer 27.4 25.8 26.2 24.8 23.6 23-6 Fall 22.1 23.6 23.6 22.1 22.4 22,7 Winter 14.2 15.9 17.0 19.0 20.6 20.4 — 302 — val abundance, varies in such a manner that specific correlation with in situ temperatures may not show. In other words, larval abundance is not absolutely related to temperature changes be- tween 17 and 29 C. Table 9. Bottom temperatures {°C) at different stations in four seasons during 1967 - 1968. Station I II 1967 III IV V VI 1 II 1968 III IV V VI Spring 20.7 18.3 19.3 19.S 19.5 17.6 21.7 19.3 19.2 19.4 17.8 18.3 Summer 24.0 21.B 21.0 21.3 19.6 19.4 29,1 26.8 27.1 22.7 21.5 19.2 Fall 22.4 23.2 22.8 21.7 19.5 — 20.5 24.4 24.1 21.5 21.3 21.0 Winter 14.6 16.1 18.1 18.6 19.4 18.6 14.7 16.4 17.8 20.4 22.0 21.5 For Two Years 1967 - 1968. Spring 21.2 18.8 19.2 19.4 18.6 18.0 Summer 26.6 24.2 24.1 22.0 20.6 19.3 Fall 21.4 23.8 23.4 21.6 20.4 21.0 Winter 14.6 16.2 18.0 19.5 20.7 20,1 As penaeid shrim.p are benthonic, bottom temperature is important for their spawning. It is evident from Table 9 that intense spawning occurred within the temperature range of 17 to 29 C. In spring, summer and fall, all six genera appear to breed in waters up to 54 m (temp 18.8 to 24.2 C) and in winter to shift their spawning area to deeper waters where the temper- ature remained above 19 C. From the present data, penaeids seem to spawn throughout the year, but they move to deeper waters as the season advances from spring to winter. This does not, however, mean that one species spawns all the time. Pres- ence of larvae in plankton is a good indication of spawning activity even in temperate waters as has been shown for the European oyster (Korringa 1957). Abundance in relation depth Station I (10 m). The trends in abundance and seasonal distri- bution of the larvae are depicted in Fig. 3. Larvae, mostly of four genera, started appearing in fair numbers in May and were present until November. The maxi- mum number taken in one haul was 192 (September 1968, day). Four per cent and 6.3% of all the larvae caught occurred at this .station in 1967 and 1968, respectively. This was a unimodal trend of abundance, larvae being caught between May and No- \ember in good numbers. Bottom temperature rose from 13.3- 15.5C to 21.7-23.1C in April, and dropped in the October-Novem- ber period from 20.8-23.2 to less than 17 C. These periods of rising and falling temperatures produced more numbers of — 303 — ST 1 Figure 3. Seasonal abundance, stage and generic composition of penaeid larvae at Station 1 during 1966 to 1968. larvae. Peaks of abundance were in May to September and in November, i.e., spring-summer and fall peaks. In general, more larvae were caught at night. Trachypeneus was the dominant genus, the number of lar- vae ranging from 2 to 153 per haul. The spawning season started by April and lasted through November. Spring-summer and fall peaks were evident. Eggs were taken in April (276) and May (40,340) of 1968, and in June (283) 1967; nauplii in June; — 304 — protozoeae in all months except October; myses in all months; and postlarvae in July, August, September and November. Second in the order of abundance was Penamis, the number of larvae varying from 1 to 38 per haul. The breeding season started in April and continued until November. Eggs, probably of white shrimp, were taken in April (35) and May ^50) of 1968. Before May only postlarvae of brown shrimp were ob- tained. White shrimp postlarvae were caught from May to November, but in December only brown shrimp postlarvae oc- curred. Protozoeal and mysis stages first appeared in May. Nauplii occurred only in June. On the basis of the stages of larvae, spawning occurred from April to November. Swyonia ranked third in numbers, the maximum number of larvae caught being 34 per haul. Though all the four stages were taken in good numbers, protozoeae were dominant in July and August 1968. The spawning activity appeared to last from March through November. Xiphopen^us occurred mostly as myses and only in five months. The maximum number caught was 20 per haul. Spawn- ing occurred from May to August. Paraperiaeiis is known to be a deep water genus (Cf. Wil- liams 1965). Fair numbers of larvae were taken in May 1967 (78 per haul). Protozoeal and mysis stages were observed at this time, and in July and November also a few of these two stages were caught. To summarize the trends, spawning of all the .species of shrimp appears to begin in April, with rising bottom tempera- tures and continue through summer and fall. Decreasing tem- perature in November seems to induce spawning again. This is chiefly a unimodal trend, because spawning continues, once it starts, without a break within the season. Trachypemus spp. were dominant and Penaeus spp, next in abundance. Sicyonia is fairly common at these depths, and the occurence of Para- penmm is considered unusual. Station U (18 m). The greatest numbers of larvae were ob- tained at this station. The peaks were much pronounced (Fig. 4). The proportion of larvae as percentage of all larvae cap- tured, amounted to 37.8 for 1967 and 42.3 for 1968. Larvae of five genera started appearing in appreciable numbers (over 100 per haul) in May and continued through November. The maximum number obtained was 2543 per haul in October 1968. Peaks were in June and July 1967, and in May, July and Octo- ber 1968, Indications of spawning activity were apparent in January, but pronounced spawning occurred from May through November. This again is a unimodal trend of spawning. The temperature range during this period was between 19.4 (Novem- - 305 — ST. 2 Figure 4. Seasonal abundance, stage and generic composition of penaeid larvae at Station 2 during 19GG to 1968. ber 1968) and 27.7 C (July 1968). A few early larvae were taken in January when the temperatures were 16.1 and 16.9 C in 1967 and 1968 respectively. As at the previous station, Tmchypeneus predominated, maximum number of larvae taken being 2252 per haul (October 1968). Eggs were obtained in July (240) and August (278) of 1967, and in May (1652), October (90), and November (20) of 1968. Nauplii were taken in September 1967 and May 1968. Pro- tozoeae occurred in all months ; myses predominated in summer - 306 - and postlarvae appeared in November (Fig. 4). Spawning ap- peared to have occurred from May through November, and the fall peak was higher than the summer peak. Penaeits ranked next in abundance, maximum number of larvae taken being 184 per haul, a higher number than caught at St. I. Eggs were taken in August (52) of 1967 and in May (51) and November (10) of 1968. Nauplii occurred in July 1968 and in August 1967. Protozoeae appeared from January to November, and all three stages were caught in varying pro- portions during the summer and fall months. Pemens species appeared to breed from January to November, with peak ac- tivity in summer and fall, the fall peak being higher. Po.st- larvae of brown shrimp were common in winter, of brown, pink and white shrimp in summer, and again brown and white shrimp in fall. The next in importance was the genus Sicyonia, with a max- imum larval production of 155 per haul. Protozoeae started ap- pearing in plankton by March and myses were found through- out. Postlarvae appeared in November. Species of this genus appeared to breed throughout the year with pronounced ac- tivity in summer and fall (July and October) at 18 m station. Xiphopeneus appeared in 7 months and only in the mysis stage. Summer (July)^ and late fall (November) were peak breeding months. Maximum number of larvae taken was 53 per haul. Solenocera was the new element taken at this depth. A maximum of 48 larvae per haul was taken. Protozoeae occurred in all the months, especially July, September, October and No- vember. Spawning season appeared to last from January' to November with peaks in summer and late fall. Parapenamis occurred only twice, in December 1966 and July 1967. All the larvae were protozoeae. From the foregoing it is seen that breeding starts earlier than May, even in January at 18 m. Penae 2 is occurs in greater abundance, and Solenocera starts appearing regularly. Minimum temperature at which spawning occurs is 16.1 C, especially for Solenocera. Station III (36 m). Fairly large numbers of larvae were taken in these waters, the largest number being 1456 per haul (Au- gust 1968). Of the total larvae taken during the 2 years 21.2'?^ and 27.1'//' were collected at this station in 1967 and 1968 respectively. The bottom temperature range was 16.4 C (March 1968) to 29 C (August 1968). Spawning activity of one species or the other was evident throughout the year, with peaks in July, August, November and December. Intense activity started much later than it did at St. 1 and II. Heightened spawning in December and January was the interesting feature. The trends in larval abundance are illustrated in Fig. 5. 307 — ST. 3 Figure 5. Seasonal abundance, stage and generic composition of penaeid larvae at Station 3 during 19C6 to 19G8. T rocky penetcs was still the dominant genus, with a maxi- mum density of 1202 larvae per haul (August 1968). Eggs were obtained in June (72) and July (10) of 1967 and May (105) 1968. Protozoeae, as well as myses, occurred in every month, myses being particularly abundant in summer and fall. It ap- peared that the species of this genus had summer and fall peaks in spawning activity, a bimodal trend, with a less inten.se per- iod in between the two seasons. Next in abundance was Solenocera, with an observed maxi- mum density of 172 larvae per haul (September 1968). Pro- — 308 — tozoeae and myses were taken in almost all months. Pronounced spawning occurred in January and in March through December, which amounted to year round spawning with distinct period- icity. Sicyonia ranked third in abundance, with a maximum of 166 larvae per haul (August 1968). Protozoeae and myses oc- curred throughout the period of study, and postlarvae were abundant in August and November. Peak spawning occurred during July through November. Spawning on a smaller scale in winter was also evident. Penaeus contributed to a fair proportion of larvae, with a maximum of 141 larvae per haul. Spawning started in May and continued through December. In January minor spawning ac- tivity was apparent. Protozoeae and myses occurred during summer, fall and winter. A bimodal pattern of breeding inteiis- ity was obvious, with peaks in July-August and October-Decem- ber. Brown shrimp postlarvae were taken from January to March 1967, and in January and June through December 1968. White shrimp postlarvae were abundant in August 1967 and September 1968. Parapenoeus was a stable element at this depth. Proto- zoeal and mysis stages were caught in almost all the months. Maximum number of larvae obtained was 30 per haul in No- vember 1968. Tw'O periods of intense spawming were observed, January-February and October-December, w'hich was indicative of fall and winter spawning. Xiphopeneus occurred sporadically, with a peak in Decem- ber 1966, when 338 larvae per haul were taken. To summarize, breeding activity of different species Is evi- dent throughout the year. This is due to the occurrence of sum- mer-fall spawners, and fall-winter spawners in these waters. Parapenae^Ls, which is a permanent element at this depth, ap- pears to be mainly a fall and winter spawner. Station IV (54 m). The maximum number of larvae taken at this depth was 496 per haul. The total numbers caught amount- ed to 13.5 and 9.9 per cent of all the larvae taken in 1967 and 1968, respectively. Year round spawning activity was evident with peaks in summer, fall and winter. Bottom temperatures ranged from 17.2 C in January 1967 to 23.0 C in October 1968. The fluctuations in abundance of larvae of the six genera are depicted in Fig. 6. The deep water genus, Soleyiocera, was the dominant ele- ment, with a maximum of 212 larvae per haul (January 1967) . Protozoeae and myses occurred in all the months, and myses were particularly abundant during summer. Starting off with — 309 — ST 4 Figure 6. Seasonal abundance, stage and generic conipordtion of penaeid larvae at Station 4 during 196G to 19(58, a January peak, spawning heightened in summer, continued through September, and again reached a peak in November. Year round activity was evident. Parapenaeus was next in importance, the maximum num- ber caught being 193 larvae per haul (January 1967). Proto- zoeae occurred mainly in January, March, June, November and December. Again there was an indication that species of this genus mainly bred in fall and winter, with minor activity in spring and summer. 310 — Penaeus larvae occurred in good numbers, the maximum being 191 per haul (November 1967). Naiiplii were taken in January 1967. Spawning started in January, as evidenced by the occurrence of protozoeae and myses, and peak activity w-as found in August, November and January. Summer, fall and winter spawning was evident. Postlarvae of white shrimp w’ere plentiful in July 1967 and March 1968. Browm shrimp postlar- \'ae appeared in fair numbers in March 1968. SicyorUa larvae were reasonably abundant, the maximum being 159 per haul. Protozoeae occurred chiefly from July through December except in October and November, Summer, fall and wdnter spawning was apparent, with peaks in August, September and November. In these waters, the species of the genus appeared to be mainly fall and winter spawniers. Track ifpcficics showed a marked decline in numbers of larvae, the maximum caught being only 70 per haul (Novem- ber 1967). Protozoeae were less abundant than myses. Spring, summer and winter spawning w'as evident. Xiphopeneus were least abundant, maximum being 16 larvae per haul. Protozoeae were scarce and myses occurred only in 4 months. It is seen from the foregoing that deep water species. Sole- 7iocera and Parapenaetis spawn intensely at this depth. Year round breeding and a bimodal trend of larval abundance are apparent. Station V (72 m). The maximum caught at this depth was 542 larvae per haul (March 1967). Breeding activity was evi- dent in all the months sampled as can be seen from Fig. 7. Of the total larvae captured 9.4 and 8.4% w'ere obtained in samples from this station. The temperature range on the bottom was 17.8 C in March 1968 to 25.5 C in October 1968. Intense breed- ing occurred in January, March, July, August, October and November. Solenocera was the dominant genus, with a maximum dens- ity of 356 larvae per haul (March 1967). Protozoeae were taken in all the months except June, and myses occurred throughout the year. Spawning was pronounced during winter, spring and fall. Parapenaeus was next in the order of abundance, the max- imum number of larvae caught being 177 per haul (March 1967), Protozoeae were observed mainly in January, March, May, August, November and December. Myses occurred in all seasons. Peak numbers were taken in January, March and Au- gust, which indicated winter, spring and fall spawning for the species of this genus. — 311 — ST. 5 Figure 7. Seasonal abundance, stage and generic composition of penaeid larvae at Station 5 during 1966 to 1968, Penaens larvae were taken in fair numbers, maximum being 103 per haul (November 1967). Protozoeae appeared all through except in March and June when postlarvae were dominant. The same was true for myses. Postlarvae of brown shrimp occurred in October and November 1968, and of white shrimp in Au- gust mainly. Spawning was marked in January, July and Au- gust through November. Sicyoiiia larvae were taken in small numbers, maximum being 52 larvae per haul. Protozoeae appeared in May, July- August, and October-November, and myses were present in all — 312 — seasons. Year round spawning with peak activity in January, July, August and October-November was apparent. Xiphopeneus was represented only by myses in 7 months. The maximum number caught was 18 per haul. The species appeared to breed from August to December at this depth. Trachypeneus larvae were taken sporadically, the maximum being 63 per haul (August 1968). Protozoeae were rare com- pared with myses. From the foregoing, the spawning season for all the species appears to be protracted, and breeding occurs even in winter. Solenoce-m species still dominate at this depth. ST 6 Figure 8. Seasonal abundance, stage and generic composition of penaeid larvae at Station 6 during 1966 to 1968. — 313 — station VI (90 m). Data from this station are not complete, but the available information indicated year round bre^inf^ ac- tivity (Fig. 8). Larval abundance was pronounced in January, July 1967, August 1968 and November 1966. Bottom tempera- ture varied between 17.2 (March 1968) and 21.9 C (August 1967). The maximum number of larvae taken was 642 per haul (November 1966). Solenocera was dominant at this station also, with a maxi- mum density of 260 larvae per haul (January 1967). Protozoeae and myses occurred in all the months. Peak abundance was no- ticed in January, July, and October-Novernber. Next in importance was Parapenaeus, the maximum num- ber of larvae taken being 208 per haul (August 1968). Proto- zoeae and myses were taken in all months. Protracted spawn- ing activity, with peaks in January, July-August, and November- December, was evident. Trachypene/us larvae occurred in fair numbers, with a max- imum density of 166 larvae per haul. Protozoeae were taken in all months except January and October, and myses occurred throughout. Peak spawning activity was noticed in June- July and November. Xiphopeneus was observed sporadically, and the maximum number of larvae collected was 159 per haul. Peak numbers oc- curred in November 1966. PeruieiiS larvae occurred in moderate numbers, the maxi- mum taken being 101 per haul (August 1967), and the majority were postlarvae. Protozoeae appeared in all months except Au- gust, and myses appeared throughout the year, Postlarval brown shrimp were taken during November and December and white shrimp in August. Sicyonia was the least abundant genus, with a maximum density of 91 larvae per haul (November 1966), Vei-y few pro- tozoeae were taken and myses occurred in all months. The peak spawning seasons appeared to be August and November. At this station Solenocera was still the dominant genus. Protracted spawning activity with winter breeding is observed at this depth. When the trends in larval abundance at all depths are con- sidered certain patterns become apparent. While spawning ac- tivity starts only in spring at 10-m depth, it starts earlier, even in January, at greater depths. Further, a unimodal pattern of abundance is characteristic of 10-and 18-m depths, and a bi- modal trend is seen in deeper waters. A gradual replacement of species is obvious as station depth changes. Trackypeneus larvae occur abundantly at 10, 18 and 36 m, and Solenocera lar- vae at 54, 72 and 90 m. Penaeus appear in fair numbers at 18 m. — 314 — and on either side of this depth larval numbers decrease. Sicyon- la larvae occur in fair numbers at 10 to 36 m, and the density per haul decreases with increasing depth beyond 36 m, Para- peyiaeus larvae occur rarely in waters shallower than 36 m, but ill 54, 72 and 90 m waters larval abundance is second only to Solenocera, These trends in the horizontal distribution of the larvae show good relationship with the bath;>'^metric distribu- tion of adults of the species of the six genera. t^ENAEOS PAnAPENAEUS PENEUS A:NEUS SICYONIA SOLENOCERA STATIONS Figure U. Spawning loci of the six genera in different seasons, within their bathymetric range, as indicated by the larval maxima. (Dotted line indicates no data) Spawning loci of the species It is to be expected that different species spawn within the range of their bathymetric distribution. Maximal numbers at any specific depth may indicate the center of spawning activity even though larvae can occur at other depths. In Fig. 9 maximal numbers for each genua are plotted in relation to stations, along with the areas where mature adults were captured. This depic- tion brings out certain trends in the shifting of spawning cen- ters with respect to seasons. Penaeiis. In wanner months (April to November) larval max- ima occurred at 10 to 54 m, and mostly at 18 m. In early spring and winter months peak numbers were caught at 54 to 90 m. The shifting of breeding center closer to shore in warm months was apparent. — 315 — Secondly, adults of white, brown and pink shrimp were taken at all or some of the stations, but larval maxima were ob- served only at specific depth in a specific month. The bathymetric distribution of the three species of Periaeus is known to be: white from inner littoral to 78 m, brown from inner littoral to 128 m and pink to 109 m (Burkenroad 1939, Eldred et aX, 1961, Williams 1965, and Saloman, Allen and Cos- tello 1968). The frequency of capture of the three species during the present investigation is given in Table 10. Table 10. Catch frequency of adults of Penaeus species Station 1 II III IV V VI White 8 8 8 1 1 0 Brown 9 13 15 9 9 7 Pink 7 7 1 0 0 0 It is seen from Table 10 that white shrimp concentration was in 10 to 36 m, brown in 10 to 90 m and pink in 10 to 18 m. Probably the summer and fall peaks at 18 m were due to any or all of the three species ; those at 36 m due to white or brown shrimp; and those at 72 m and 90 m in winter due to brown shrimp alone. It is also possible that these species may move into deeper waters in colder months to breed there. It is known that white shrimp migrate into deeper waters in winter and a few larvae of pink shrimp have been taken in 180 to 300 m depths off Florida (Eldred et ah 1965). Also, each species may have ‘preference’ for a particular depth as it has been shown in British species of Leander (Gurney 1924). Para'penaetis, Parapen^us lofigirostris is the most abundant si>ecie3 of the genus in the Gulf of Mexico, occurring in depths of 25 to 145 m (Burkenroad 1939, Williams 1965) , and P. aimri- camis occurs in waters deeper than 200 m (Springer and Bullis 1956). Adults of neither species were caught during the present study. Larval maxima were noticed between 36 m and 90 m stations (Fig. 9). A positive correlation between larval abund- ance and station depth was found for this species. Trachypeneus. Trachypeneus similis was the only species en- countered in trawl catches, but 7’. comtnctus also occurs in the study area (Burkenroad 1939). The bathymetric range of these — 316 — two species is 20 to 37 m for T. similis and 5 to 55 m for T. constrictus (Burkenroad 1939). T. similis were taken at 10 to 36 m. Larval maxima occurred in 18 to 36 m depths. In summer larval concentrations were noticed mostly at 18 m and during other seasons at 36 m, Xiphopenei^s. Xiphopeneus kroyeri is the only species of the genus and it occurs mainly in 5 to 36 m (Williams 1965) . Larval maxima were observed at 10 to 72 m. Generally, peaks were observed at 10 to 18 m in summer and at 72 m in fall Sicyonia. Sicyonia dorsalis, S. stimpsoni and S, brevirostris are the three species of the genus in these waters. In trawls both the first and the third species were taken, but S. dorsalis was more common. Both the species are known to occur in waters 5 to 85 m deep (Williams, 1965). Larval maxima were mainly restricted to 18 to 54 m, and occasional pulses were noticed at 72 and 90 m (Fig. 9). During summer and fall the concentra- tion of larvae was at 18 to 36 m and in November 1966, and December 1968 it was at 90 m. SoleTvocera. Solenocera vioscai, S. atlantidis and N. necopina are known to occur off Mississippi, with a bathymetric distribution of 36-72 m, 18-329 m and 5-183 m, respectively (Williams 1965). Generally larval pulses were noticed in depths beyond 54 m during warmer months, and at 18-36 m during cooler months. A positive correlation between abundance and .station depth was found for this genus. Species of Solenocera are re- ported to be generally oceanic (Burkenroad 1936). Larval abundance in relation to occurrence of adults Most of the statements on the breeding seasons and spawn- ing localities for shrimps are based on the occurrence of mature adults. Therefore, the relationship between the larval distribu- tion and adult concentrations was examined. Table 11 shows that several times, at different stations, mature adults were taken where larvae were absent. Also, larval maxima and adults did not occur in the .same area several times (Fig. 9). Only nauplius and protozoea stages were considered for this correla- tion study, because their motility is negligible. No significant correlation coefficients for the numbers of larvae and mature adults were found. This indicates that mature adults and larvae need not necessarily occur in the same area, and the locations of adult concentrations do not necessarily indicate precise spawning areas. — 317 — Table 11. Numbers of mature adult species and larvae{nauplius and protozoea) caught during 1967-1968. Genus Penaeus Trachypeneus Sicyonta Date St. D/N Larvae Adults Larvae Adults Larvae Adults 1967 Mar. 2 1 D - - — — 0 1 Mar. 2 11 D 0 1 — — — — Mar. 21 III D 0 1 — — _ — Mar. 21 III N 0 42 — — — — Mar. 1 5 VI D 4 3 — — — — Apr. 18 II D 0 1 — May 18 1 N 0 13 18 2 — — May 19 II D 19 46 1 3 - — May 21 VI N 0 21 - — — May 25 III N 0 9 — — — — May 25 V N 1 23 — — — — June 5 1 N 0 46 _ _ _ — June 5 II N 0 12 — _ — June 22 III N 0 14 40 14 _ — June 27 VI N 3 29 — — — — July 6 1 N 0 77 — — — — July 6 II N 8 45 — — — — July 25 IV N 8 10 — — 6 72 July 12 V N - — — 13 26 Aug. 9 V D — 69 — — _ — Aug. 30 IV N 19 101 — _ _ Aug. 29 III D 4 5 _ _ _ Aug. 8 V N — ■— _ 0 44 Aug. 9 VI D 0 12 — — _ _ Sept. 7 I N 0 67 _ _ _ Sept. 7 II N 14 92 — _ _ Oct. 27 II N 6 33 _ 0 4 Oct. 27 III N 34 115 _ _ Nov. 9 1 D 4 51 _ Nov. 14 II D 2 7 _ _ Nov. 1 4 II N 59 103 _ _ 5 1 Nov. 14 IV N 115 3 _ _ 32 7 Dec. 1 3 1 D 0 53 0 13 _ _ Dec. 5 1 N 0 24 — _ _ Dec. 5 II N 0 33 2 110 0 3 1968 Jan. 15 1 N 1 22 0 13 _ _ Jan. 15 II D 0 31 0 16 0 10 Jan. 17 III D 0 45 0 2 _ Jan. 17 III N 0 86 _ _ 0 5 Jan. 18 IV N 7 1 _ Mar. 26 III D 0 9 0 3 0 1 Mar. 26 IV N 0 1 _ 0 5 Mar. 27 V N 0 2 — _ 0 15 Mar. 27 VI N 0 36 _ _ May 28 II N 10 62 10 18 3 5 May 29 1 N 1 22 _ June 19 V D 0 5 __ _ June 18 III N 0 26 10 1 0 2 July 31 1 N 0 85 —318- — — — POSTLARVAL ABUNDANCE IN RELATION TO LARVAL OCCURRENCE Although larval stages of the three species of Penaeus can- not he distinguished from one another, an idea of spawning ac- tivity of a particular species might be obtained if postlarval abundance is studied. For this discussion only the postlan’ae of white and brown shrimp are considered because of their general availability. Average numbers of larvae and postlarvae per haul (for all stations combined) are plotted in Fig. 10. MAIN MAIN 1966 - 1967 1968 Figure 10. Seasonal abundance of the postlarvae of Penaeus fluviatilk and P. aztecus in relation to the larval abundance in 10 to 90 m during 1966 to ]968. The figure shows that the main spawning season for Fen- aevs lasted from April or May to November, with less intense spawning during January to March. During the main spawning season every spawning success was followed by a dip during next month (Fig. 10). Each postlarval peak, either of brown or white shrimp, coincided with dips in larval occurrence. In other words, po.stlarvae were abundant following each larval peak, which is to be expected because it takes about 10 to 12 days for the nauplii to become postlarvae in summer (Johnson and Fielding 1956). Larval and postlarval peaks were observed in the pattern shown in Table 12. From the data presented it appears that brown shrimp spawned more intensely in January, March and October, and white shrimp in April, June and August. This does not, how- ever, imply that the tw’o species spawned in succession. Larval peaks of white were observed in shallow waters, and those of brown shrimp in deeper waters. Further, mature adults of P. fluviatiUs were more frequently caught at 10 and 18 m, while — 319 — Table 12. Comparison of larval and white and brown postlarval peaks Larval peaks Postlarval peaks White Brown 1967 January February M arch April May June July August August September October November December January 1968 January March March April May June July August September October November December those of P, aztectis were taken at 10 to 90 m during warm months and at 36 to 90 m during winter months. P. duorarum was found mostly at 10 to 18 m. Temple and Fischer (1967) arrived at the same conclusion concerning the spawning areas of the three species. VERTICAL DISTRIBUTION Penaeid eggs are demersal (Pearson 1939, Dobkin 1961, and Subrahmanyam 1965a). Thus, if there is no spring or vernal mixing of waters the early stages may be expected to be found closer to the bottom, and older stages towards sur- face. The only available information on the vertical distribu- tion of penaeid larvae has been given by Temple and Fischer (1965). The data on the depth distribution of protoz.oeal, mysis and postlarval stages are illustrated in Fig. 11. Only data for those months in which a complete series of plankton samples were obtained from all the six stations are used for this discussion. Larvae of all the species are treated together. It is clear that all stages were mixed in various propor- tions in samples from the three depths at each station. Proto- zoeae were more abundant during peak breeding months. — 320 — SCALE Q ^ Q ^ o o joo q ao NuMatn r low lam 36rTi vsm 72 m 90m Pz Pt My Pi Pj My 9< Pi My Pr Pj My Pi Pf fyfy P( ■ ■ a _ a 1 a gB|j aai mH; “n z=it ■ 1 i ■ ^1' a y Zita ■ ■ a a a ■ 1 I 1 M a a a D Bi m a a H ■ ■ a 1 a a a ■B. SI B: 1 □ a a a B' a Si 1 ■ □ U M 1 3 a n as. w P a H si, ^■1 O M L. a a a a' m a a a i^l! fi a a a a a a a a a Bl a a a J □ s D M zn a a a a I a a a a a 1 □ Zi 1 3 3 ■ a a a a a a 3 Zi a a - 9 ■ Ol ■ 5 s a a a a a a a a ft ■ a a a a a a L. 3 a a a a a a b a ■1 IZl O M MiVM ■ m ■ i ■ a m m ( i— r&t ss ... fi ■ aa ly^H mm ■■ } Q ■ ZJ 3 B a a ■Bfrli a ■ bIH 3 IB ■ ZZIC [■■■Bj IC & D M O D ZJ a a a a n a a la ' a a a 3 a < ^ ^ N M a 1 a a a 1 a — 71 • =3 3 i □ a ■ a a — r a Li ,B Sol < B ■ a a a 9 a a a IB ■ BHj a 9 I^B a 5SI JLJ sasB aSM ■■ tm \wm 3 m^M ■ : 1 !■ !■ =1B sM !■ \md IbI o ^ N M ti ^ma _ZJU iZ7a a 5 HD 1 a a IB a a IB 1 ■M m iimi a a a a IB 1 1— J N M i 1 — j L m (> J Q B =1 1 3 1 1 3 1 S 0 M ■ a a a 1 ■ la IB IB a IB n IB \ Pi Pi 1 PI My *H Pi My Pi 9i My PI 1 Pa My PI PX My PI j * C.T A ’ Stl ST 2 ST 3 STfl ST. 5 SI 6 Figure 11. Vertical distribution and diurnal variations of protozoea, mysis and postlarvae at different stations during 1966 to 1968. Pz : Protozoea My : Mysis PI : Postlarvae D : Day N : Night S : Surface M : Midwater B : Bottom IStipled bars) (Open bars) (Shaded bars) Though the mid-depths of the six stations are not absolutely comparable, protozoeal and mysis stages showed a general tendency to aggregate at middle levels. — 321 — No statistical correlations between different larval stages, and depth, salinity and temperature were found. Protozoeal stage Protozoeae appeared by May at 10 m and declined by No- vember. In deeper waters they occurred in most months. From December to March they were taken in deeper waters and in- creasing mimbers w'ere taken with increase in depth. Vertically, in winter months, more protozoeae congregated at the surface and mid-w^ater at 18 to 36 m. They were more evenly distributed in deeper waters during the day. At night there was a general tendency for larvae to move upward and to be more abundant in surface layers, than in mid-water. In spring the highest concentration was in the bottom dur- ing day and night except at 54 and 90 m, in which depths they were often found in equal abundance at the surface and bottom. In summer months again they were concentrated on the bottom during the day, and mid-water and bottom at nights in all depths. In fall, the majority were taken in mid-and bottom levels during day, and surface and mid-levels at night. My sis stage Mysis stages were relatively more abundant than other stages. They appeared in inshore w^aters by May and became scarce by December. They W'ere taken at all depths in all sea- sons. In general, myses showed a tendency to congregate in mid- layers, In winter they were taken more at the surface and mid- water during the day, and mid-water and bottom at night, ex- cept at 36 m where they occurred at the surface. On many occas- ions they were abundant at surface even during the day. In spring months during the day they were abundant near the bottom except at 36 and 54 m, where they occurred more often in mid-waters. At night they were near the bottom at 10 m, and in mid-layens in other depths. In summer, they were more abundant at bottom at all sta- tions during the day. At nights they rose to mid-waters and even to the surface at 54 and 72 m. In fall, except at 10 m they were more abundant in mid- water during day. They were well dispersed at 54 and 72 m depth, and occurred either at the surface, midwater or bottom at other depths. ^ 22 — Postlarval stage Postlarvae were taken in small numbers in all depths in all seasons. In general, they occurred more at Stations I to 111 in winter months. They were more randomly distributed in ver- tical depths at each station than the other two stages. Occasion- ally they were taken in greater numbers in surface plankton as in November 1967 (St. VI, day), July 1967 (St. II, night), August 1967 (St. Ill & VI, night) ; in midwaters as in July 1967 (St. II, day) ; or in bottom plankton as in November 1%8 (St. II, night). No definite seasonal trends were observed in vertical distribution. Probably their power of motility bestows on them more freedom of movement compared to earlier stages. From the foregoing it is evident that vertical distribution of protozoeal and mysis stages differs with respect to seasons, depths and day and night. At no time was there a definite stratification according to stage, i.e., protozoeae at the bottom, myses in midwater and postlarvae at surface, exclusively. All stages occurred mixed in the meroplankton with varying pro- portions. In general, depth distributions of protozoeal and mysis stages follow similar trends, w'hich emphasizes the fact that these two stages stay together. Unfortunately, not enough nau- plii were collected for a discussion of their vertical distribution. DiurncU variations The data indicate that night stratification of larvae was not, as a rule, opposite to that during day. On several occasions protozoea and mysis stages were concentrated at the surface during the day, and in bottom plankton at nights. On other oc- casions both stages were abundant in midwater during both day and night. In general, larvae appeared to be evenly distributed vertically at nights, and to show abundance at a particular depth during day (Fig. 11). DISCUSSION HYDROGRAPHY The salinity gradients through depth.s from 10 to 90 m fol- low the expected trends with increasing values seaward, and at each station the increasing gi'adient is from surface to bottom. The fluctuations at each station are complicated by rainfall, land runoff, Mississippi River discharge and currents. How far these seasonal fluctuations affect the breeding seasons is not certain. Temperature patterns described are typical for any open sea environment. While the surface is subjected to heating by solar radiation, subsurface temperatures are influenced by cur- — 323 — rents and advection. The trends of temperature variations shown here agree with those described by Drennan (1968). The minimum and maximum temperatures for any locality are of paramount importance to the breeding activity of marine ani- mals as has been demonstrated by Thorson (1946). In general, the Gulf of Mexico is unique as far as hydro- gi'aphy is concerned. The existence of semi-permanent rotary circulations in the central Gulf and its effects on northern and eastern waters have been shown by Drummond and Austin (1958), Armstrong and Grady (1967) and Armstrong, Grady and Stevenson (1967), The Missis.sippi River starts discharg- ing great amounts of fresh cold waters in March of each year (oyer 10,000 mVsec), and subsides by May or June. Therefore, it is not unusual to find pockets of low salinity waters in March, May and June. It is also evident that the .spring discharge in- fluences the temperature profiles at Stations III to V (Fig. 2). The other factors that bring about hydrographical changes in the Gulf of Mexico in general, and the northeastern Gulf in par- ticular, are subtropical underwater currents, the loop current from^ Yucatan channel through the Florida straits, upwelling in winter, westerly currents from Mobile Bay, and the outflow from Mississippi Sound, and the mixing of different kinds of waters which has been demonstrated by Drennan (1968). Fur- ther, surface divergence brings to surface high-salinity, cool w^aters, and convergence introduces low-salinity, warm waters (Drennan 1968). In view of these factors it is not possible to explain the fluctuations of temperature and salinity off the Mississippi coast in terms of regular patterns. SEASONAL AND HORIZONTAL DISTRIBUTION Among the several methods that are employed to study the reproductive cycles of marine invertebrates a study of the larval abundance yields fairly reliable information. This method has been adopted by several workers on molluscs and other in- vertabratea as reviewed by Korringa (1957) and Giese (1959), and on penaeid shrimp by Eldred et aL (1965) and Temple and Fischer (1967). The spawning periods and area.s have also been delineated by studying the mature adults (Kutkuhn 1962). Both these methods have certain merits and shortcomings. Ripe- ness of the gonads indicates imminent spawning though un- favorable conditions may set back the process of gamete re- lease. Thorson (1916) has shown that critical temperatures for maturation and spawning are different for many Danish bottom invertebrates. If the temperature is not right, ripe ova may be resorbed as has been .showm in oysters by Loosanoff (1969). The spawners may survive the adverse environment and successfully spawn on the return of favorable ambient fac- tors (Tioosanoff and Davis 1963). Therefore, conclusions mainly based on the occurrence of mature adults, without taking into — 324 — consideration the critical temperature requirements, should be made with caution. The development of embryos and larvae are also dependent on critical temperature requirements. Cook and Murphy (1965b) have shown that no brown shrimp larvae underwent complete development below 24 C; that naupli did not survive the molt to protozoea I at 18 C and that growth w^as faster between 27 and 30 C, They obtained the first postlarva after 11 days at 30 C, 12 days at 27 C and 15 days at 24 C. But postlarvae start grow'ing at a temperature betw'een 11 and 18 C, and show' maximal growth rate in the temperature range of 17.5 to 25 C (Zein-Eldin and Aldrich 1965, and Zein-Eldin and Griffith 1966). It is not known whether the optimum temperature for growth of larvae and postlarvae is significantly different. Muk- hacheva (1959) has shown that eggs of Nlegimis gracilis (Gadi- dae) develop only w^hen the temperature is -2.8 to 8C; and eggs of Crassostrea virginica do not develop if the water tempera- ture is below 15 C (Loosanoff and Davis 1963) . There are cer- tain unproved indications that eggs or larvae of several com- mon marine invertebrates on the Gulf coast may overwinter and suddenly effloresce in the spring. It is possible that spawn- ing may occur at 17 C but the eggs and the larvae may not un- dergo complete metamorphosis until the temperature ri.ses above 24 C. On the contrary, they may metamorphose at 17 C if the larvae need the same temperature as the postlarvae for maximal growth. However, the occurrence of protozocae, mj^ses and postlarvae at deep stations even in winter (bottom tem- perature above 18 C) is interesting. Possibly these larval stages may not grow in wdnter, but their presence in a water column may indicate previous spawning. With these reservations it is assumed here that spawning occurs in the temperature range of 17 to 29 C, The larvae may take longer time to grow to post- larval 8tage.s in the cooler season because the length of pelagic life depends on the ambient temperature (Cf. Thorson 1961). The pui*pose of the present investigation is to understand the spawning seasons, and does not focus on growth factors of the larvae. The spawning seasons are discussed here with these reservations in mind. Besides the temperature as a factor, penaeid larvae are subjected to the same ambient factors that affect plankton in general. During the present investigation, as a w'orking hypoth- esis to interpret seasonal larval pluses at different depths, areas of larval concentration w'ere assumed to represent breeding localities. The movements of the spawners are assumed to be indicated by the occurrence of larval aggregations at different stations. The conclusions based on the larval pulses need not necessarily give an accurate idea of the incidents in the open sea environment in view of the arguments presented hereunder, for and against such a hypothesis. — 325 — Some factors that influence the larval distribution are the movements of the organisms themselves, predation, adaptibility of the larvae to the environment, transport by currents, and illumination. Thus, nauplii, protozoeae and myses are capable only of feeble movements with the aid of the first antennae (Ewald 1965) and they may not by their own motility travel great distances. Further, penaeid larvae belong to the category or organisms with relatively short pelagic life, (10 to 12 days), and a great stability of occurrence characterizes such larvae (Thorson 1946). Finally, several fish, Sagitta, and medusae have been observed to feed on penaeid larvae, and this predation may cause scarcity. Currents are of great importance for the transport of pel- agic animals, and in some cases for survival (Davis 1965). Tidal currents particularly influence organisms in inshore waters less than 16 m deep. Many animals adapt their physio- logical rhythms to such tidal currents with the results they are transported landward during flood tide as in Lucifer (Wood- mansee 1966). Thus, tidal currents may transport penaeid lar- vae from 10 m deep waters into coastal bays. Idyll et al. (1962) have shown that currents off the Florida coast are tidal in waters less than 15 m deep, tidal and wind driven at 15 to 33 m depths and density related in deeper waters. Generally spawn- ing grounds are located where strong tides do not exist. Fur- ther, it is also possible that shrimp prefer suitable areas for spawning so that larvae will not be exposed to adverse water currents. Johnson (1939) has shown that Ementa breed in such favorable areas in relation to currents. Surface currents, essentially wind-produced, may carry the larvae along the flow. On the other hand, subsurface currents are density effected. Heavier organisms such as nauplii, protozoeae, myses, and even eggs are unlikely to be carried away by these currents. These larvae show a tendency to stay in a water column, performing only weak vertical movements. Postlarvae, which can swim for- ward, are the exception (Ewald 1965). Therefore, sampling at three levels, as has been done in the present study, will compen- sate for such pelagic transport and may give reliable informa- tion on abundance. Thorson (1946) has shown that a) occurence of swarms in a particular area to the exclusion of adjacent localities would indicate massive current transport, and b) occurence of older and younger larvae in different regions indicates current trans- port. The average fair representation of penaeid larvae in the samples precludes current transport of significant magnitude. Though larval pulses are noticed at certain depths, larvae still occur at other depths. Finally, younger and older stages invar- iably can be collected from any station and any depth. This ap- pears to be a rule for crustacean larvae in general (Gurney 1924, Pearson 1939, Eldred et al. 1965, Temple and Fischer 1965 and 1967). Based on such mixed collections, Gurney con- —326— eluded that crustacean larvae may not be at the mercy of cur- rents as much as is supposed, and Pearson agreed with him. Though currents influence the distribution of the larvae, larval studies can provide a good idea of spawning activity and loca- tions for penaeid shrimp, in view of the arguments presented here. Finally, eddies of gyrating currents (non-tidal) are be- lieved to be effective in supporting a self-sustaining population of specific planktonic forms (Sverdrup, Johnson and Flemming 1946, Davis 1955). Where such eddies exist, plankters may not drift too far away from such gyrations but may be circulating in a specific area. That such eddies exist off the Mississippi coast has been shown by Drennan (1968) and Armstrong et al. (1967). Therefore, it is possible that penaeid larvae stay in a particular area in the offshore waters for some time after the spawning of the adults. However, postlarvae can swim land- ward and can make use of tidal currents to gain entry into coastal bays, with the aid of their endogenous tidal activity rhythms (Hughes 1967a). P.oth the methods of determining spawning seasons and loci have weak points. While adults can move on their own, sub- ject to circadian and feeding rhythms (Hughes 1967b), larvae are exposed mainly to natural mortality, predation, and current transport. Nevertheless, sampling at three levels and at dif- ferent depths will yield reliable information on the spawning activity. During the present investigation a good correspondence was found between the seasons of occurrence of mature adults of Penaeus, Trackypeneu^ and Sicyonia species and of their larvae. Thus, spawning seasons can be delineated based on both factors. However, demarcation of spawning loci based on a single factor may not be accurate. It is likely that a more ac- curate picture of spawning areas can be based on the occur- rence of eggs and larvae if the reservations presented above are borne in mind. Finally, study of the adult or larval concentra- tions at a .specific depth will not yield correct information on the spawning seasons in view of the temperature control of breeding, and of the movements of adults along the increasing temperature gradient. Gene^'al It has been shown that spawning is pronounced when tem- perature rises above 17 C. At 10- and 18-m stations, rise of temperature to above 20 C in May, and fall from above 25 C to 20 C in September induce intense spawning activity. As tem- perature drops in shallow waters shrimps follow a temperature gradient and spawn in deeper waters in winter. Year round breeding is evident if various depths are considered. Orton (1920) states that marine animals are stimulated to breed — 327 — either by a specific temperature (physiological constant) or bty a rising or falling of temperatures in a particular area. The present findings agree with this rule. Thorson (1946) empha- sized that minimum and maximum temperatures are critical for breeding. In the case of shrimps in the Gulf of Mexico the minimum temperature is 17 C and maximum 29 C. Gunter (1957) states, with reference to shallow water species, that all shrimps are spring or summer spawners. Taking the group as a whole, present findings and those of Temple and Fischer (1967) indicate that penaeid shrimps, including deep water species, breed throughout the year in areas where temperature remains within a range of 17 to 29 C. A protracted spawning season, based on larval abundance, has also been reported for Peiiaeus duorm'urn off the Florida coast (Roessler et al. 1967). The European oyster starts spawning when temperature rises above 15 C and continues the activity as long as temper- ature remains above 15 to 16 C (Orton 1920, Korringa 1957). The environment for the shrimp in the Gulf of Mexico appears to lead to an analogous situation. These findings point out that penaeid shrimp have pro- tracted spawning seasons. This may be due to a) great verti- cal distribution of the species, b) different timings of gamete release by younger and older males and females, c) several spawnings of individual females in a season. An extended sea- son implies asynchronous spawning, that is some shrimp are in early stages of maturation, some are getting ready to spawn, some are spawning and others are spent (Giese 1959), Adults caught in the trawls during the present study were in various stages of maturity in any month. Secondly, females of Penaeus fluviatilis are known to spawn up to four times a season (Lind- ner and Cook 1967) ^ Postlarvae migrate into estuaries in two or three waves in summer (Gunter 1950, Tdndner and Anderson 1956). After each spawning female gonads rejuvenate and pro- duce more batches of eggs as has been shown for P. fluviatilis (King 1948), P. indicus (Subrahmanyam 1965b) and four other penaeids (Rao 1968). Lastly, many species have a wide range of distribution (Burkenroad 1934), and younger and older spawners invariably occur mixed in any area. These ob- servations indicate that penaeid shrimp can spawn over a long period of time. Though the breeding season is protracted, distinct pulses of larvae are observed in spring, summer, fall and winter, de- pending on the depth of the water column. Mainly there appear to be summer and fall peaks. Periodicity in breeding is a general phenomenon even under stenothermal conditions such as tropical environments, as has been shown for the brackish water fauna of Madras (Panikkar and Aiyar 1939), Great Barrier Reef in- vertebrates (Stephenson 1934) and P. indicus (Subrahmanyam 1963). — 328 — It is significant that during spring and summer the spawn- ing center is at the 18-m station. This has survival value for the species because postlarvae have easier access to the estuaries. From 10 to 12 days are required for the nauplius to become a postlarva at 25.6 C (Johnson and Fielding 1956). In colder months this may take longer because temperature controls the length of pelagic larval life (Cf. Thorson 1961). Thus, when the spawning center shifts to deeper waters in colder months the postlarvae still have a chance, if growth is retarded, to enter the coastal bays on the return of warm temperatures. They may overwinter offshore and enter the bays in spring as it has been suggested for brown shrimp along Texas coast (Temple and Fischer 1967). Abundance in relation to depth The data indicate that unimodal spawning occurs in waters up to 18 m deep and bimodal activity in deeper waters. The peaks are observed progressively later in the year as depth in- creases. In Penaem the summer peak shifts from 10 m in July to 36 and 54 m in August; the fall peak shifts from 10 m during September to 18 and 36 m during October; and to 54 and 72 m in November. A January peak is seen at the 90-m stations. These indicate movements of spawners. Similarly in Trachypeneus the fall peak shifts from 10 m during September to 36 and 54 m during October and November. Sicyonia shows identical trends. Parapenaeiis and Solenocera, however, do not show such dis- tinct shifts of peaks. Temple and Fischer (1967) also demonstrated such trends in the shifts of larval maxima. They showed that spawning oc- curs even in December at 46-m depth, and that the breeding season is more protracted in deeper water compared to the May to October period at 14 m, Eldred et at, U965) have shown that the intense spawning season commenced a month or two later at 10-25-m depths compared to the season in 3-9 m for Trachype- neus and Sicyonia, Since these authors did not study deeper wat- ers they could not demonstrate year round spawning in depths greater than 36 m, w'hich is a significant point found in the present study. The same authors came to the conclusion that the minimum spawning temperature tor Penaeus dmrarum is 23.9 C, but they later collected larvae at 25-to-36-m depths when the temperature was 19.2 C. It is clear, therefore, that spawn- ing occurs in the temperature range of 17 to 29 C and the spawners move along with the increasing temperature gradient with depth. The spawning seasons delineated by various authors for different species are in agreement with the present findings. Most of the authors, however, studied a particular depth and the occurrence of mature adults there. When the larval abun- — 329 — dance is studied, taking into consideration a wide range of depths, year round spawning activity becomes apparent. Spawn- ing may start early in deeper waters and last longer, while in shallow waters it starts later and ends earlier. Spawning loci of the species The spawning areas of the different species of the six genera show a good correlation to the bathymetric ranges given by Biirkenroad (1934) and Williams (1965). The species with a wide bathymetric range breed as close to the shore as possi- ble during warm seasons and offshore during cooler months. It is interesting that Pdrapenaeiis and Solenocera spawn at 18-to- 36-m depths in the cooler season and at 54-to-90-m depths dur- ing summer. When shallow water species are spawning in the area of their depth range, species of these two deep water genera have moved out to deeper waters. In the cooler season, when the shallow water species move offshore, the deep water spe- cies move into shallower waters. It has been shown that though the species spawn in their entire range of distribution they prefer certain depths in spe- cific seasons. Eldred et al. (1965) were also able to observe such shifts in the spawning loci. They showed that P, duoramm spawuied intensely cither in 3 to 9 m or in 25 to 38 m ; T rachy- peneus in 3 to 9 m; Sicyonia species in 3 to 38 m with distinct seasonal pulses at specific depths; and Parapenaeus chiefly be- yond 25 m. Ingle et al. (1959) pointed out that large females offshore may have less rigid temperature requirements for spawning, but it is more likely that penaeids can spawn year round in deep waters because of small scale offshore tempera- ture fluctuations. Thus, larval maxima indicate spawning loci of the spe- cies, and definite seasonal trends in the occurrence of peaks at specific depths argue against effective current transport. Pres- sure changes at certain depths may also regulate the release of larvae or embryos as has been shown for Spirorbis borealis (Knight-Jones and Morgan 1966). Therefore, it is possible that the maximum number of eggs may be liberated by females at favorable depths. The larvae, in view of their power of keeping together (Gurney 1924), may not drift too far away from such area until they become postlarvae. Although the larval pulses shed light on the movements of the spawning population, adults may not be captured during larval peak abundance. Larval abundance in relation to occurrence of adults No correlations were found between adult numbers and larval abundance. This would mean either that the adults moved away from the area of spawning, or that the larvae 330 — were carried to the sampling areas by currents from some other areas. However, the ecological requirements of adults and larvae are not identical, and spent females may have dif- ferent needs. It is significant that several times adults, but not larvae, were captured in specific areas. Penasns plebejtis and P. esculcMus do not necessarily spawm in their areas of con- centration (Racek 1955). It is more likely that adults can move far and wide with the benefit of their activity controlled by a circadian and a 24-hour feeding rhythm (Hughes 1967b), while larvae have feeble motility. Further, adults w^ere not taken at the 10- and 18-m stations where thousands of eggs were collected (Figs. 3 and 4). Thus, here is additional evidence that determination of spawning loci based on the adults does not always yield the correct picture. postlarval abundance in relation to larval OCCURRENCE Following every larval peak a postlarval peak, either white shrimp or brown shrimp, is noticed in the open sea. White shrimp poatlarvae are abundant in March, May, June, July and September, and intense spawning occurs at 18-m depth during these months, Christmas et aL (1966) have shown that white shrimp postlarvae start appearing in Mississippi Sound in May, reach a peak in June, July or August and decline hy October. Thus, there is good correlation between the two trends. The Sound postlarvae come from broods in the open sea. Postlarvae of brown shrimp first appear in the inside waters in February, and i*each a peak in April, June and Au- gust. The abundance in the open sea bears a positive relation- ship to that in the Sound. However, fair numbers of postlarvae occur in December and January. Since brown shrimps appear Lo breed in deep waters during this period, it is likely that these larvae overwinter offshore and move into the estuaries in February or March. Temple and Fischer (1967) came to a similar conclusion in view of the slightly larger size of the postlarvae during the January to April period. Further, post- larvae bury themselves in mud at temperatures low^er than 17 C and become active only at higher temperatures (Aldrich et aL 1968). It may be possible to predict the shrimp fishery in Mis- sissippi Sound based on a larval index in the open sea. Fol- lowing a spawning success, postlarvae can be expected to enter the Sound within three or four weeks. The average annual production of pink shrimp protozoea in South Florida has been estimated to be 87.0 x 10“ ; the survival rate was 74 to 98"^? per day; 0.05 to 0.14U of the original protozoeal population survived to become postlarvae; and of the postlarvae sur- vived to produce the commercial catch of 5 x 10® individuals in — 331 — 1963 (Roessler et al. 1967), Such calculations can be based on the larval numbers obtained by sophisticated sampling. Also, from a long range study it is possible to predict the recruit- ment seasons for the postlarvae in the estuaries as has been shown by Williams (1969) in North Carolina 'waters. Because of their fast growth rate, a millimeter or more per day in sum- mer (Viosca 1920, Gunter 1950, and Williams 1955), postlarvae can reach commercial size in three months. Therefore, a lar- val peak in open sea should be followed by maximal commercial catches in four or five months, allowing a wide margin for the hazards of dispersal, mortality, predation, unfavorable temperature and other ambient factors that affect larvae in the open sea and postlarvae in the coastal bays. It also appears that from the time of hatching about six or seven months are re- quired for the subadults to return to the sea to become mature adults. This surmise is in agreement v/ith the earlier findings of various authors. An uncertain correspondence between postlar- val abundance and commercial catches has been shown (Christ- mas et al, 1966). On the other hand, Williams (1969) has shown that no correlation existed between the two factors off North Carolina during a period of 10 years. As the evidence is not conclusive, it will be interesting to examine the relationship between larval, postlarval and commercial catch indices. VERTICAL DISTRIBUTION No chronological abundance of stages in vertical depths can be demonstrated, and concentrations of protozoeal and mysis stages can be expected at any level in any season in any depth. Protozoeae and myses have more or less similar, though not identical, patterns of distribution. Postlarvae seem to be dis- tributed at random in vertical depths in all seasons. Larvae of marine invertebrates in general are known to be positively phototactic. The organisms become negatively phototactic as they grow' older (Thorson 1946). It is probable that both pro- tozoeal and mysis stages may a.ssemble at levels where optimum light occurs. It is not understood why they do not migrate to surface, as a rule, at night. Temple and Fischer (1965) state, based on collections from four cruises, that during June, July and September protozoeal and mysis stages occur more abundantly near the bottom, while in November they are more evenly distributed vertically. The present, more extensive data indicate that no such definite patterns occur in the summer and early fall months. Even in fall, greater concentrations can be found in bottom layers. Fur- ther, during winter both stages were taken in maximal abun- dance at the surface, even during the day. Vertical distribution of planktonic animals, including mero- planktera, is controlled by several factors, such as direction and speed of movement of species (Szlaeur 1963), hydrostatic pres- —332— sure (Hardy & Bainbridge 1951, Knight-Jones and Quiisim 1955), and salinity, oxygen, dissolved nutrients, viscosity and density (Russell 1927). It has been shown that animals in the upper part of a population respond more to light, and those in bottom layers more to temperature. The depth at which any group occurs reflects isolume movements in the upper part and isotherm movements in the lower part of the population. Also, random movements about an optimal depth result in vertical spread (Moore 1956). Light is believed to be a major factor in distribution (Cushing 1951). Further, four major types of responses in relation to hydrostatic pressure are known to oc- cur in planktonic animals with respect to vertical distribution, namely (1) orientation to gravity alone, (2) orientation to gravity with the subsidiary effect of light, (3) orientation to light alone and (4) no response to pressure changes. Increased pressure induces positive phototaxis, and decrea.sed pressure, passive sinking (Knight-Jones and Morgan 1966). Larvae can also avoid depth changes by endogenous reversals of phototaxis. Responses to pressure changes also depend upon the physiologi- cal state of the species (Knight-Jones and Morgan 1966). Tem- perature changes also influence vertical distribution. Warming and cooling of water may influence heliotropism, altering it from negative geotropism to positive geotropism; and tempera- ture rise may bring about negative phototropism and vice versa (Russell 1927). During the present study only temperature and salinity were considered^ and since so many factors are involved in regulating vertical spread of larvae, it is difficult to explain the patterns of vertical sea.sonal distribution of protozoeal, mysis and post-larval stages. However, isothermal conditions during winter and fall combined with less illumination at the surface may explain the wider vertical spread of the stages during these periods, even during the day. In summer the larvae are .seen to be more restricted to bottom layers during day and to bottom and midwater at night. Sometimes larvae were absent in the surface waters (Fig. 11), possibly because of more illumination of top layers and negative phototropism induced by temperature rise. Crustacea, including planktonic larvae, are known to per- form diurnal migrations (Russell 1925 and 1928). An excellent review on the subject is given by Bainbridge (1961). The mech- anisms for these migrations appear to be active swimming, ver- tical currents, viscosity of water layers and temperature chang- es. Several factors such as light, gravity, pressure, temperature and phytoplankton are believed to affect vertical diurnal mi- grations. The combined effects of light, temperature and pres- sure changes in a day cycle appear to be the more important (Moore 1955, 1956). — 333 — Although a 24-hr study was not made during the present investigation, there are indications that larvae have a tendency to rise toward the surface at night, or that they are evenly distributed in the vertical column. Second and third protozoeae and myses have been reported to undertake considerable ver- tical movements; they may aggregate at a depth or spread out depending on optimum conditions. It has not been demonstrat- ed that, as a rule, planktonic shrimp larvae congregate in the surface layers during night. However, they may be scarce at the surface frorn midnight to midday, and may rise to surface lay- ers from midday until the following midnight (Roessler et aL 1967). Temple and Fischer (1965) claim that such larvae show a distinct ascent to surface at night. However, their data do not lend themselve.s to such broad po.stulations. Postlarvae ap- pear to behave more in a classic diurnal rhythm of ascent and descent, though not always. The present data indicate that protozoeal and mysis stages do not congregate, as a rule, in surface layers with the advent of night. Random patterns of distributions are more prominent. Since information on the be- havior of penaeid larvae is lacking, interpretation of the diurnal patterns of vertical distributions through seasons is not possible. It is concluded, therefore, that protozoea and mysis stages show random patterns of vertical distribution; show a tenden- cy to be in midwater layers; congregate near the bottom during summer months; show a tendency to rise to the surface in winter months; and show no stratification in a water column in relation to the ontogenic stage. Postlarvae are randomly dis- tributed. Though typical diurnal migrations to surface from bottom and back are not observed, there is a general tendency on the part of the larvae to rise toward surface layers or to be- come more evenly distributed vertically, in response to decreas- ing light. SUMMARY AND CONCIAISIONS 1. An invewSligation was carried out from November 1966 through December 1968, on the relative abundance and sea- sonal and spatial distribution of penaeid shrimp larvae off the Mississippi coast of the Gulf of Mexico. 2. Six stations were established between 29°N and 30“N lat- itude, and between 88M2'W and 88“47'W longitude. The depths of the stations were: St. I, 10.7 m; St. 11, 18.3 m; St. Ill, 36.6 m ; St. IV, 54.9 m ; St. V, 73.1 m and St. VI, 91.6 m. 3. Plankton collections were made with a No. 3 Nylon clos- ing net, that had mesh size of 0.33 ram, length of 2 m and diameter of 50 cm across the mouth. Three simultaneous — 334 — tows of 20 min duration were made at surface, midwater and bottom levels at each station. Attempts were made to obtain a complete series of day and night collections every month. 4. Penaeid larvae were separated from the rest of the plank- ton and identified to stage and genus. They were preserved in 5% buffered formalin (with borax and glycerine). Lar- vae studied represented six genera, namely Pejmeus, Para- periaeus, Trachypeneus, XiphopeneKS, Solenocera and S^'c- yonia. 5. Trends and patterns of salinity and temperature of the area are described and discussed. The fluctuations of these two factors are brought about by Mississippi River dis- charge, eddy systems and other kinds of water movements and mixing. While bottom temperatures fell to 12 C in the inshore waters in winter they remained uniformly above 16 0 in 54 to 90 m throughout the study period, Isothermal conditions existed in winter and fall, while some mixing was evident in spring. In summer, thermal stratification was evident only in 10 to 18 m. 6. Temperature changes were more marked at the 10-m sta- tion and less marked at the 72- and 80-m stations. The range of variation was 17.8 C, between 12..^ and 30.1 G, at Station I, and diminished to 9.4 C, between 17.4 and 26.8 C, at Station VL Surface temperatures fluctuated with a greater range than mid-water and bottom temperatures. The range was 12.2 to 30.4 C, 12.2 to 31.0 C, and 12.5 to 29.5 C at surface, midwater and bottom, respectively, at Station 1 ; and 17,8 to 30.4 C, 17,2 to 28.0 C and 17.2 to 21.9 C re.spectively at the three levels at Station VI, Bottom temperature varied from 12.5 to 26.1 C in 10-m depth, the range decreasing gradually with increasing station depth. The variation was between 16.7 and 20.0 C in 90-m depth. 7. Salinity fluctuated from 18.5 to 36.6Voo in lO-m depth and the range decreased at deeper stations, the variation be- ing between 26.8 and SS.C^/oo at the 90-m station. Surface salinity varied more than mid-water and bottom salinities at all the stations. The ranges for the surface, mid-w^ater and bottom at Station I respectively were 13.1 to 3T.l®/oo, 19.0 to 37.6“/oo and 19.9 to 37.6V and for the three levels at Station VI were 23.2 to 38.0Voo, 23,3 to 38.0V<'o and 26.6 to 38.0VOO. 8. Determinations of spawning seasons and areas were made by considering the abundance of eggs and of naupliu.s, pro- tozoeal and mysis stages of the species of the six genera. — 335 — 9. No correlation was found between the occurrence of ma- ture adults of Penaeus spp., Trachypeneiis spp. and Sicyon- ia spp. and of their larvae in a particular area. Adults were taken in some depths where larvae were scarce and vice versa. 10. In general, spawning of all species of the six genera seem- ed to occur within the bottom temperature range of 17 and 29 C. Intense spawning was associated with rising temperatures in spring and falling temperatures in late fall or winter. As long as the temperature remained above 17 C spawning activity prevailed. A unimodal pattern of spawning w^as observed at 10- and 18-m stations; and a bi- modal pattern at 36-, 64-, 72- and 90-m stations. 11. The spaw'ning season of penaeids studied was protracted with distinct pulses in spring, summer, fall and winter. During spring larval concentrations were observed at the 18-m station, during summer at l8-to-36-m stations, dur- ing fall at 18-to-54-m stations and during winter at 54- to 90-m stations. This indicates that species breed close to shore during warmer months, and move away from in- shore waters as temperature starts falling. 12. Species of Penaeus, Trachypeiwm, Xiphopeneus and Sicyon- ia spawned mainly from April to November, and even in winter in waters deeper than 54 m. Species of Parapenaeus and Solenocera bred intensely during fall, winter and spring. While shallow water species .spawned in all depths of their bathymetric range during warmer months, deep water spe- cies like Parapenaeus and Solenocera spawned in deeper waters. During the cooler season shallow water .species moved offshore and deep water species moved into waters less than 54 ra deep. Then there appeared to be some over- lapping between the inshore and offshore species as far as the breeding areas were concerned. 13. Penaeus larvae occurred in all depths, Trachypeneus main- ly between 10 and 36 m, Solenocera beyond 18 m, Sicyonia in all depths, and Parapenaeus mainly beyond 18 m. The larval distribution showed a relationship to the bathymetric distribution of the adults. 14. When maximal numbers of larvae were considered, definite inshore and offshore movements within the bathymetric range of species, wore obvious. Penaeus spp. spawned in all depths, mainly at 18 m in summer, 36 m in fall and 72 to 90 m in winter. These larval maxima could belong to white and pink shrimp in shallow waters, and to brown shrimp in deep waters. Trachypeneus spp, mainly spawned at 18 to 36 m, Xiphopeneus at 10 to 72 m, Parapenaeus at — 336 — 56 to 90 m, Sicyonia at 18 to 54 m, and Solenocera at 18 to 54 m. Larval maxima, thus, give some indication of spawn- ing loci of species. 15. The relationship between spawning success and postlarval abundance of white and brown shrimp was examined. Dur- ing the main spawning season increase and decrease in lar- val numbers in alternate months was noticed. For e very- corresponding valley in the larval abundance curve there was a postlarval peak, either of Penaeus fluviatilis or F. dztecm. The patterns of occurrence of postlarvae of these two species in the open sea agreed with those observed in Mississippi Sound during a study' made previously in the area. Though it is not possible to distinguish the larvae of the three species of Penmens, some understanding of spawn- ing activity of each species can be derived from postlarval abundance. 16. The vertical distribution of protozoeal, mysis and postlar- val stages of all the genera has been studied. Protozoeal and mysis stages show'ed similar patterns in their vertical spread. During the spring and summer months they were more restricted to sub-surface layers during day, and oc- curred in upper layers at night. In winter months they were found in large numbers in surface layers even during day. In general, they showed a tendency to aggregate in mid-water layers and sometimes at the surface. Postlarvae showed random patterns of vertical distribution. Tempera- ture, light and pressure appeared to be the main factors controlling depth distribution. 17. A stratification, of larvae in vertical profile in relation to ontogenic chronology was not found. Even when there was no vertical mixing of water protozoeac occurred in surface layers, and postlarvae could be found in good numbers near bottom. Eggs were found mainly either near the bottom or in mid-waters. 18. The classic pattern of diel migrations was not shown either by protozoeal or mysis stages. In general, they showed a tendency to ascend to upper layers during night or to spread out evenly. 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