NPS ARCHIVE
1966
MOMMSEN, D.

A STUDY OF MARINE FOULING
IN MONTEREY HARBOR

DURWARD BELMONT MOMMSEN, JR.

trSHARY

NAVAL POSTGRADUAx^. ... a

MONTEREY, CALIF. 9394'

DUDLEY KNOX LIBRARY
NAVAL POSTGRADUATE SCHOOl
MOWTISftEY CA 93943-5101

s -'-ai^:t r.s??-s.r.r^-"-

3'

( ;

A STUDY OF MARINE FOULING
IN MONTEREY HARBOR

by

Durward Belmont Mommsen Jr.
Lieutenant, Uni tecf/States Navy
B.S., University of Wisconsin, 1959

Submitted in partial fulfillrnent
for the degree of

MASTER OF SCIENCE IN OCEANOGRAPHY

from the

UNITED STATES NAVAL POSTGRADUATE SCHOOL
May 1966

ABSTRACT

Observations were made on the marine fouling occur ing on test panels
in Monterey Harbor during the period January 26 to April 21, 1966. Test
pflmiels of various materials were placed at three depths. Observations
were made on plywood panels exposed for four weeks, immersed at two week
intervals, at just below the mean low tide level to determine the change in
rate of attachment of fouling organisms during the test period. Observa-
tions were also made on the amount of fouling occuring on different test
materials at the same depth and on the same test material at different
depths.

The most important short-term fouling organisms in Monterey Harbor
were found to be barnacles, bryozoa, serpulids and hydroids. The number
of barnacles attaching to test panels reached a peak in early April and
then declined. The amount of fouling on the test panels increased with
depth. Wood was determined to be the best surface for collecting and
observing marine fouling organisms.

US ^ t:— t- DUDLEY KNOX LIBRARY

^^- NAVAL POSTGRADUATE SCHOOL

MONTFREY CA 93943-5101

TABLE OF CONTENTS

Section Page

1 . Inlferoduct ton 7

2. Equipment 9

3. Procedures 13

4. The Fouling Organisms 15

5. Factors Affecting the Intensity of Fouling 24

6. Conclusions 42

7. Acknowledgments 43

8. BibI ionraphy 44

LIST OF TABLES

Table Page

1, Fouling Organisms Recorded on Test Panels in

Monterey Harbor 16

2» Results of First Observation on Long-term Panels 26

3. Results of Final Observation on Long-term Panels 27

4. Vertical Distribution of Bryozoan Species 39

LIST OF ILLUSTRATIONS

Figure Page

1. Location of Test Site 8

2. Photograph of Racks 10

3. Relationship of Racks to Sea Surface 11

4. Fouling after 29 Days 28

5. Fouling after 55 Days 29

6. Times of Exposure of Short-term Panels 32
7» Variation of Major Fouling Organisms with Time 33
8. Weekly AAean Temperatures and Salinities 34

1 . Introduction.

The primary objective of the research described in this paper was
to determine the types of marine fouling organisms active in Monterey
Harbor and how their intensity varies during the late winter and early
spring. Numerous studies of this type made throughout the world show
that marine fouling varies greatly with geographical location both In
the types of fouling organisms present and in the intensity of their
foul Ing. \_6J

Several studies of marine fouling have been made along the West
Coast of the United States. These include studies at Frl<Jay Harbor,
Washington, [lj and in California at Oakland [sj , Port Hueneme |_10J ,
La Jolla [2! and San Diego I10J • These studies have shown that each
area has its own characteristic set of fouling organisms and Its own
seasonal variations.

As far as can be determined, no systematic study of marine fouling
has previously been conducted in Monterey Harbor.

A secondary objective of this research was to show how the fouling
In Monterey Harbor varies with depth and type of surface and to observe
the growth and change of a fouling community on a test surface.

The site chosen for the study was at Monterey Municipal Wharf M2
about 1000 yards from the shoreline (see Figure 1). This site was
selected both for its proximity to the marina and for its inaccessibility
to the general public. The depth at the test site was 21 feet at mean
low tide. No direct sunlight reached the test site due to the wha^f over-
head and the pilings on either side. However, due to the fact that the
test site was located nearer one side of the wharf than the other, more
light reached the test site from that direction than from any other.

The observation period was from January 26 to April 21, 1966,

CHART OF
fclOWTEREY HARBOR

Figure 1. Location of Test Site (denoted by arrow)

8

2, Equipment.

Three racks were hung from a platform beneath the wharf. Two types
of racks were used (see figure 2). Each rack held six 8X10 Inch panels
spaced at three Inch Intervals. The wood rack was made of pine and the
metal racks of stainless steel. The wood rack was rigged for floating on
the sea surface so that its test panels would always be at the water's
surface with the upper edge of each panel about two Inches above the
waterllne. Two metal racks were hung by 3/32 Inch stainless steel cables
to depths of one foot andjISr/eet below m<tan Uw tide ( $$6' ifl^urf 3) •

The following kinds of 8X10 inch test panels were used: marine
plywood, fibreglass, glass, and stainless steel. The fibreglass panels
were constructed by using 3/16 inch plywood as a backing with fibreglass
on one side only and both sides of the plywood coated with resin. The
marine plywood panels had no preservatives or other finishes applied.
The surfaces of the glass and stainless steel panels were likewise
unfinished.

Each metal rack was hung by two cables in order to restrict Its
movements. A 1 /4 Inch nylon line was also attached to each for use in
raising and lowering the racks. The floating wood rack was secured to
the platform by one 1/4 inch nylon line and to an adjacent piling by
another similar nylon line with enough slack to account for the full
range of the tide.

The floating rack contained a fibreglass and a plywood panel. It
originally also contained a glass panel, but this was lost (presumably
due to rough wave action) and was never replaced. The fibreglass and
plywood panels were exposed for a period of 54 days from February 14 to
Apri I 9.

The shallow r^ck contained panels of glass, stainless steel

9

10

REFER£i\'CE
(FEET)

+10

-15

-21

A~

RAWGE

OF
TSPE

MEAN HIGH TIDE

SEA SURFACE

f.lEAN LOW TIDE

B0TT0P4

FLOATING
RACK

SHALLOW
RACK

DEEP
RACK

Figure 3. Relationship of Hacks to Sea Surface

11

and plywood exposed for a period of 55 days from February 14 to April 10.
At any particular time this rack also contained two other plywood panels,
one new panel being entered every two weeks and removed four weeks later.

The deep rack contained panels of glass, stainless steel, plywood
and fibreglass, all exposed for a period of 57 days from February 14 to
April 12.

12

3. Procedures.

In order to determine the change in the rate of attachment of the
marine fouling organisms with time new plywood panels were exposed every
two weeks during the test period and removed for examination after four
weeks exposure. The examination of these panels was done in the biological
(Oceanography laboratory at the UiS. Mavil Postgraduate School uilng a binocular
microscope. The panel was kept immersed in a pan of sea water during the
examination. The surface of each side of the panel was scanned system-
atically and the name, size, and location of each organism was recorded
on rectangular coordinate paper. The area covered by such organisms as
hydroids was recorded and an Indication of the density per square inch
also noted.

The set of nine, long-term panels, which were exposed continuously
for eight weeks, were examined after four weeks and again at the end of
the exposure period. The first examination was conducted at the test
site by binocular microscope with the panel immersed in a pan of sea
water. Each panel was returned to its rack immediately after examination
to assure that the organisms suffered no i I I effects. Notes were made
of the fouling organisms present on each panel. An area, 2-1/2 by 4
Inches square, on the plywood panel in the shallow rack was sketched for
comparison with the fouling organisms present in that area at the time
of the final examination.

The final examination at the end of the eight-week period was
conducted in the laboratory at the U.S. Naval Postgraduate School. A
more detailed examination could be conducted at that time since the
organisms did not have to be kept alive.

The surface water temperature at the test site was taken at two or
three day intervals throughout the test period. Starting from March 1

13

the surface water salinity at the test site was also taken. The temper-
ature of the surface water was determined with a standard Navy bucket
thermometer and the salinity with a Kahlsico salinity hydrometer. The
mean temperature and salinity was recorded for each week during the test
period to give an indication of the change in water conditions at the
test site during this period.

14

4. The Fouling Organisms.

It was possible, since the test panels were examined while immersed
in sea water, to observe the fouling organisms in si tu, thus making
identification easier and allowing observation of the ecology of the
fouling cormiunity.

Complete identification of all the fouling organisms was not attempted.
The immaturity of most of the organisms made their Identification difficult.
If not impossible, and correct identification could be made only by an
experienced biologist.

Many of the organisms discussed here are free-living and were not
attached directly to the test panel, but when the panel was lifted from
the sea and placed in a pail of sea water for transportation to the
laboratory they remained with the panel. Therefore, It was assumed that
they were closely associated with the life on the panel.

In some cases, such as the flatworm, the free-living organism prefers
moving along a surface to swimming in the sea. [4^ Some free-living
organisms, such as nudibranchs, feed on the attached organisms, j 8j Others,
such as diatoms, are the food of the attached organisms. Since all of
these free-living organisms have some influence on the attached organisms
they were considered worth studying In a work on marine fouling.

The marine borer, Limnori a I iqnorum, is not properly considered a
fouling organism, but it was found boring into wood panels examined after
the first of April and is worth mentioning. The most found on a single
panel was three. A seasonal variation in the abundance of these organisms
was found at Friday Harbor, but it was present in some numbers all year
round. [lj Since this was also true at Oakland [z] , It Is probably true
In Monterey Harbor.

A listing of the fouling organisms observed may be found in Table 1.

o- 15

TABLE 1

FOULING ORGANISMS RECORDED ON
TEST PANELS IN MONTEREY HARBOR

Plants
Diatoms (unidentified)

Animals

Phylum Protozoa

Forj9(fnini fera (unidentified)
Colonial vorticelllds (unidentified)
Fol I icul ina sp.

Phylum Pori fera (Sponges)

One species (unidentified)

Phylum Coelenterata - Class Hydrozoa
. Obel ilBi qraci I Is

Phylum P latyhe Iminthes (Flatworms)
Leptoplana sp.

Phylum Nemertea (Ribbon Worms)

One species (unidentified)

Phylum Asche Iminthes

Nematodes (unidentified)

Phylum Annelida (Segmented Worms)
Nerei s sp.
Spirorbis sp.
Sp ion ids (unidentified)

Phylum Arthropoda - Class Crustacea
Bal anus qiandula
Bal anus t int Innabulum
Bal anus crenatus
Capre I la sp.
Copepods (unidentified)
Crabs (unidentified)
Tube-building amphipods (unidentified)

16

TABLE 1 (continued)

Phylum Mo I lusca

Snai I (untdent i fled)
Hermissenda crasslcornis
Eubranchus ol I vacea
Corambe paci f ica
Myt 1 1 us edul is
Pododesmus macroschlsma
Clams (unidentified)
Pecten sp.

Phylum Bryozoa

Barentsia qraci I Is
Buqula nerltina
Hippothoa hyal ina
Hippodiplosia inscu Ipta
Membranipora membranacea
Tubul ipora sp.

Phylum Echinodermata

Strongy locentrotus sp.

Phylum Chordata

Two species of tunlcates (unidentified)

•I.'.:"' . ' • ■■ i

6 f 1 7

Plants

Numerous diatoms were observed, but not identified. Amasses of
diatoms became attached to any projections on the test panel with the
hydrolds and erect bryozoa being the most frequent collectors.

No algae' were observed. This Is thought to be the result of the
lack of direct sunlight at the test site. \p]

Animals
Many animals were observed and will be discussed by phyla.

Phylum Protozoa
Several unidentified species of foraminifera were observed. Many
of the panels had collections of bluish green Fol I icul ina that could be
seen with the naked eye as patches of dark specks. All panels observed
during April were covered with microscopic colonial vorticellids that
recoiled when touched with a dissecting needle. They seemed to attach
as readily to the smooth glass panels as to the wood panels.

Phylum Porl fera (Sponges)
One species of sponge was found frequently on the long term panels.
It belonged to the class Oemospongiae, but could not be identified with
the intertidal keys available.

Phylum Coelenterata - Class Hydrozoa
The hydrold, Obe I ia qraci I is, was the most Important fouling organism
on the earlier panels, but as the season progressed only the remains of
the stolons and vertical stalks could be found on the panels. Numerous
nudlbranchs were found on these panels and were apparently the cause of
the hydroid demise. Other species of hydrolds may have been present
earlier In the season, but were not identified.

18

Phylum Platyheltninthes (Flatworms)

The flatworm, Leptoplana, was found on all but two of the panels
and those two panels were those with the least amount of overall fouling.

Flatworms are sensitive to light and avoid it whenever possible. \_Aj
The favorite hiding place of the flatworms on the test panels, which offer
a relatively bare environment, was the inside of empty barnacle shells.
Almost every empty barnacle shell of sufficient size could be observed
to have a flatworm in it. Those flatworms not Inside barnacles were
most frequently seen lying along-side a living barnacle.

The mouth of a flatworm Is about midway along the ventral surface of
the worm and in some cases the flatworm could be seen draped over the
barnacle with the flatworm' s mouth over the opening of the barnacle. In
all of these cases observed the barnacle was dead after the flatworm left
It. No case was actually observed where the flatworm was able to approach
a living barnacle without the barnacle closing up. But flatworms have
been known to feed on barnacles ^Sj , and several cases were observed
where the flatworms did attempt to gain entry to a living barnacle.
Perhaps It is just a matter of patience on the part of the flatworm (and
the observer, if he wants to see It) for the flatworm to catch the barnacle
unaware.

One panel, which had been exposed for one month, had 191 deed or
empty barnacles out of a total of 238. Most of the empty barnacles were
too small to offer hiding to the flatworms, but most of the larger empty
barnacle shells had flatworms Inside.

A few cases on other panels were observed where the barnacle Itself
lay dead outside Its shell while a flatworm was Inside.

Although the flatworms are apparently a factor In reducing the
population of young barnacles, their affect on the barnacle population as

a whole Is probably small. It Is possible that another organism not
observed on the panel, such as a starfish, was responsible for eating the
young barnacles.

Phylum Aschelmlnthes
This phylum Includes the nematodes ^7j , which were numerous on all
the panels observed. Nematodes were invariably found in the masses of
diatoms and debris on the panels.

Phylum Nemertea (Ribbon Worms)
One species of nemertean worm was observed occasionally but not
identified further. These are not considered of great importance In
foul ing. ^6j

Phylum Annelida (Segmented Worms)
A few individuals of Neries were found on the panels. These are
known to bui Id mucoid tubes {6j , but none were observed.

Numerous tube-building spionids were found on the edges and in cracks
in the panels. They appeared to need well protected crevices in order to
build their tubes. The edges of the panels, which contained many holes
and cracks, seemed to provide the optimum surface for this purpose.
The coiled calcareous tubes of Splrorbis were one of the most
frequently observed foulers. These were found on every one of the test
panels. Three different tube designs and both sinistral and dextral
coiling were observed, A few uncoiled serpulid tubes were also found.

Phylum Arthropoda - Class Crustacea
Copepods were numerous on all the test panels, but no attempt was
made to further identify them. Their importance to the fouling community
is questionable.

20

Several young crabs were observed, but not Identified. Most of them
were heavily covered with diatoms and debris and were difficult to distin-
guish from the other debris on the panels. They appeared to be eating
the detritus attached to the hydroid remains.

Two species of tube-building amphlpods became numerous late In the
test period. They seemed able to build their tubes on a smooth surface,
but preferred building in among crowded barnacles. During some years at
San Diego these were found to be the most important summer fouling
organism. [2j They undoubtedly would become more Important In Monterey
Harbor later In the year.

The skeleton shrimp, Caprel la, was frequently observed waving back
and forth on the remains of the hydroid stalks and on barnacle shells.
One was observed attached to a debris-covered crab.

Barnacles were the most significant fouling organism on all but the
first panel observed. Three species of barnacles were found. These were
Bo I anus ql andula, Ba I anus crenatus and Balanus t int innabulum. B. crenatus
was the most frequently observed barnacle on the deep and shallow panels,
but B_^ qiandula were dominant on the floating panels and numerous on the
shallow panels. The most barnacles per panel were of B. crenatus on the
deep panels, but the greatest crowding was found of B. qiandula within a
two Inch band on the floating panels.

B. qiandula Is an intertidal barnacle that prefers periods of
relative dryness. The only areas of the test panels used in this Inves-
tigation that offered such an environment was the splash zone at the
waterline of the floating panels and this is where the maximum concen-
tration of this barnacle occurred. Several were also found on the shallow
panels and one on a deep panel, but only the larger barnacles could be
Identified so their exact number could not be determined.

21

B, crenatus seemed to thrive on the constantly submerged panels and
their concentration appeared to increase with depth, or at least to the
depth at which this study was conducted.

The pink barnacle, Balanus tint innabulum, was found on two panels
in the shallow rack. There were 16 individuals on one side of the stain-
less steel panel and one individual on the side of the glass panel facing
the stainless steel panel. None were found on any of the other test
panels. This distribution is not believed to indicate a preference for
the stainless steel surface, but rather a chance distribution of a few
larvae in the vyater.

Those B^ tint innabulum that were found must have attached in February
since they were already quite well developed by the first examination of
the panels on March 15. The breeding season of B. tint innabulum at
La Jolla does not begin until the water temperature reaches 16 degrees
Centigrade, usually in April, ll'] If there Is a similar temperature
dependence in Monterey Harbor, there would not be a significant number of
this larvae in the water until much later in the year. It Is probable
that panels exposed during the summer would pick up a much larger concen-
tration of these barnacles since they are found frequently on pilings and
rocks in the area. [9^

The largest barnacle found on the shallow panels after four weeks
exposure measured 3.0mm in diameter. After eight weeks exposure the
largest found were 5.0mm for (3^ glandula, 7,0mm for B_^ crenatus, and
9.0mm for B_^ tint innabu ium.

Phylum Mo I lusca

Three species of nudlbranchs were found. These were Hermisseda

crassicornis, Eubranchus ol i vacea and Corambe pad flea. H. crass I corn I a-

22

and E. ollvacea were found on all except the first panel observed and
were very likely the cause of the demise of the hydrords in the later
panels. Only one Individual of C. paclfica was observed and It was found
on the lone colony of the bryozoan, Membranlpora membranacea» observed on
all the test panels. It*s habitat is apparently limited to this partic-
ular species of bryozoan which it closely resembles by protective
coloration. (_7j

Only one species of snail was observed and it was found frequently
on all but the first panel. It was not possible to identify this snail
due to i ts smal I si ze.

Several kinds of pelecypods were observed on the test panels. The
only one actually found attached was the rock oyster, Pododesmus
macrochisma, which was found on the glass, fibreglass and plywood panels
of the deep rack. This species is chiefly subtidal and in spite of its
common name prefers pilings to rocks. \9^ Several very young Myti lus
edul is were observed, but none had yet become attached. They were very
numerous in cracks of the plywood panels exposed for two months. Numerous
unidentified clams and one Pecten were observed.

Phylum Bryozoa

Circular colonies of encrusting bryozoa were numerous on almost all
of the panels observed. They were found least on the floating panels
where they were located only on the most deeply submerged part of the
pane I .

The species of encrusting bryozoa identified were Hippothoa hyalina,

Hippodiplosia insculpta, Membranlpora membranacea and Tubul ipora sp.

The distribution of these bryozoa was interesting and will be discussed

later. Only one colony of A'.emb ran ipora was found, but it was the largest

I i ■ • ■ - ■ ' : ■ ■ . i

23

of all the bryozoan colonies observed, measuring 26rmi in diameter.

Other than the one colony of Membran ipora the largest encrusting
bryozoan colony found was 11.5mm in diameter. The largest colony found
after four weeks exposure was 4,5mm.

Erect bryozoa were frequent on the later panels. The two species
identified were Barentsia qraci I is and Buqula neri tina.

Phylum Echinodermata
A few young individuals of the sea urchin, Strongy IdBi^il't'rbtus, wfer6
found on the panels throughout the test period. These measured about
0.5mm in diameter.

Phylum Chordata
Two species of tunicates were observed, but not identified. These
tunicates were observed on panels exposed for two months and although
they were insignificant in the fouling community at that time, they might
have become more important with a longer exposure time.

24

5. Factors Affecting The Intensity of Fouling.

Six factors were observed to Influence ttie Intensity of organisms
attaching to the test panels. These factors were length of exposure,
season of exposure, type of surface, depth, light and edge effect.

Length of Exposure
In all cases, as can be seen by comparison of Tables 2 and 3, the
intensity of the fouling increased with time. The fouling on a 2-1/2 by
4 inch area of the plywood panel in the shallow rack was sketched after
29 days exposure (see Figure 4) and again after 55 days exposure (see
Figure 5). It Is not difficult to visualize the chronological events
that took place on this area of the panel. Within a few days after
exposure about six barnacle cyprlds landed on the area, attached and
began developing into the adult form of barnacle. A couple days later
two more attached. After about two weeks hydroids began coming Into the
area from the edge of the panel. A serpulid came Into the area and began
secreting its calcareous tube. About the third week eleven new barnacles
became attached. Sometime just after the fourth week a bryozoan colony
began forming and a barnacle was killed In the center of the area. A few
more barnacles attached during the fifth week, but some of the other
barnacles were killed. Three more bryozoans began colonies and more
serpulids were building their tubes on the area. Some of the barnacles
were growing faster than others. Sponges were beginning to appear in the
ar»ea. By the sixth week the hydroids had reached their maximum growth
and were being eaten by nudlbranchs coming through the area. Some
amphipods built their tubes along-side one of the larger barnacles.
Another barnacle was killed and a flatworm took up residence Inside.
More barnacles became attached durlna the seventh week and two more of

25

TABLE 2

RESULTS OF FIRST OBSERVATION ON LONG-TERM PANELS

(Amount of barnacles and serpulids indicated by number of individuals,
bryozoa by colonies, and hydroids by square inches of surface area
covered.)

FLOATING RACK (29 Days exposure)

n

ibreqiass

Wood

Barnacles

131

39

Serpul ids

1

2

Bryozoa

0

0

Hydroids

2

3

SHALLOW RACK (29 Days exposure)

Stainless

Steel

Glass

Barnacles

23

68

Serpul ?ds

15

0

Bryozoa

1

6

Hydroids

2

4

Wood
82
27
3

7

DEEP RACK (29 Days exposure)

Stainless

Steel

Fibreql
41

ass

Glass
200

Wood

Barnacles

10

112

Serpul ids

21

15

8

45

Bryozoa

5

Hydroids

2

0

2

1

/< i

26

TABLE 3

RESULTS OF FINAL OBSERVATION ON LONG-TERAA PANELS

(Amount of barnacles and serpulids Indicated by number of individuals,
bryozoa by colonies, and hydroids by square inches of surface area covered.)

FLOATING RACK (54 Days exposure)

Fibreqiass Wood
Barnacles 1175 1050

Serpulids 2 5

Bryozoa 20 10

Hydroids 5 9

SHALLOW RACK (55 Days exposure)

Stainless

Steel

Glass
551

Wood

Barnacles

96

575

Serpu! ids

40

26

36

Bryozoa

152

173

158

Hydroids

0

0

0

DEEP RACK (57 Days exposure)

Stain 1

ess

Stee

1

Fibreql
5840

ass

Glass
6960

Wood

Barnacles

28

4240

Serpu 1 ids

74

132

55

73

Bryozoa

77

292

173

331

Hydroids

2

0

0

0

27

r

o

O

O

O

0

CO

?^

a
as

<N

u

a

ao
c

i-t

3
O
►4

<u
u

3
bO

L

J

28

r

c

O vi>

0

n

0 0

©'^o

cv

u

"O

o

®

o

Q o

C 0

^C?

0

0 o

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>%

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m
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4J

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•I-l
1-1

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(30

0^

^0 ^

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29

Key to Fi^:" ires 4 and 5.

Q Living barnacle

Dead barnacle

^ Serpulid (Spirorbis)

Hydro id

Bryozoan colony

*^ Erect bryozoan

V

£ponge

:ube -building amphipod

30

the larger barnacles were killed. The hydrolds were by now reduced to
decaying remains. By the eighth week the area appeared as shown in
Figure 5.

There were some indications that with increased exposure time there
would be a new dominant organism on the panels. After two months exposure
the barnacles were definitely the dominant fouling organism, but already
many of the encrusting bryozoan colonies were spreading over the barnacles.
The tunicates or the mussels could also become dominant |_6J , although
there was no indication of this in the present study.

Another effect of an increased length of exposure is that even with
no increase in the number of fouling organisms the amount of fouling will
increase due to the growth of the individual organisms themselves.

Season of Exposure

A series of five plywood panels were exposed in the shallow rack
during the late winter and early spring as shown in Figure 6. Each was
exposed for a period of four weeks. The changes in abundance of the
major fouling organisms attaching during the test period are shown In
Figure 7.

As can be seen, the serpullds and bryozoa on each panel increased
as the season progressed, whereas the hydrolds decreased after being the
dominant fouling organisms in February.

The number of barnacles per panel increased from a low of three in
February to a high of 238 in early April and then dropped to 21 on the
last panel observed in April. This indicates that there was a maximum
of barnacle larvae in the water in late March and early April and that
the number of these larvae decreased greatly during April.

Similar peaks of barnacle attachment have been found in Puget Sound

: i 1 . " ,; ' In ' ,1 ■ . !'■ i '•••- i

31

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32

300

200

100

Figure 7. Variation of Major Fouling Organisms
v;ith Time. (Amount of barnacles and
serpulids indicated hj individuals,
bryozoa by colonies, and hydro ids by
square inches of surface area covered)

33

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34

in May and in San Francisco Bay In April 3 . The peak In Puget Sound
was due to Ba lanus qlandula» whereas the peak in San Francisco Bay was
due to Ba lanus improvlsus»

It would be Interesting to know if the peak In Monterey Harbor
represents the maximum abundance of one species of barnacle and. If so,
whether there is a peak for the other barnace I species in Monterey Harbor.
It was Impossible to distinguish between the young of Balanus glandula
and Balanus crenatus on the shallow panels, but a time series of panels
placed at an intertidal level would pick up predominantly B. glandula
and, at the depth of the deep rack, predominantly B. crenatus and thus
their time of maximum attachments could be determined.

The weekly mean surface temperatures and salinities during the test
period are shown in Figure 8, No apparent correlation with the amount of
fouling can be observed during this time period. Most of the organisms
seem to have increased in abundance during the period of relatively
constant temperature and salinity while the hydrolds decreased before the
temperature began to rise in April, The peak of barnacle abundance also
preceded the rise in water temperature.

*

A nine year study at La Jolla showed a difference in the seasonal
variation of the fouling organisms from year to year 2 • Therefore,
observations over several years would probably be necessary to get an
adequate picture of the seasonal variation in AAonterey Harbor.

Type of Surface
At the time the present study was Initiated it was felt that the use
of several different surfaces would pick up a more complete set of fouling
organisms and also give some insight into the conditions necessary for
the attachment of particular organisms. It was not the purpose of this

35

study to test antifd^ling compounds or surfaces, therefore no antifouling
preparations were applied to the panels.

Glass and wood have been used frequently in other studies to collect
fouling organisms. ["1,2,3,5] Fibreglass and stainless steel were added
to give a wider variety of surfaces.

The results of the fouling observed on the nine longf^ii;m.p|iJfillS -
after eight weeks exposure can be seen in Table 3.

No significant differences can be seen of the amount of fouling on
the fibreglass and plywood panels in the floating rack. A comparison of
the fibreglass and plywood panels in the deep rack shows a slight
preference of Balanus crenatus and Spirorbis for the fibreglass surface.

A comparison of the two sides of the fibreglass panels was not
possible due to the effect of light which will be discussed later.

The glass and plywood panels showed no significant differences in
their fouling at the shallow depth, but at the deeper depth glass
accumulated more barnacles and less bryozoo than did plywood.

Since the glass panel in the floating rack was lost before observa-
tions were made, glass and fibreglass can be compared only in the deep
rack. The glass panel at this depth picked up more barnacles, but the
fibreglass panel picked up the greater number of serpulids and bryozo^.

The stainless steel panels showed a significant resistance to fouling
compared to the other panels. The difference in barnacle fouling between
the stainless steel panel and other panels in the deep rack was especially
striking. However, the stainless steel was comparible to plywood in the
number of serpulids attached and, in the shallow rack, showed comparable
numbers of bryozoan colonies to that of plywood and glass. The stainless
steel panel in the deep rack showed hydroid fouling that was not observed
on the other panels after two months exposure.

36

As far as can be determined, there is nothing in stainless steel
that is toxic to marine organisms and stainless steel is considered to
be in the group of metals which are most likely to foul. \_6'] Therefore,
it must be the character of the stainless steel surface itself that causes
less barnacle fouling than the glass surface yet permits serpullds to
attach as readily to one as to the other. It may be a difference in the
mechanism of attachment of these organisms that affects their ability to
attach to the stainless steel surface.

Glass panels have frequently been used to collect fouling organisms
when the investigator intends to scrape off the organisms for volume
determination. However, for in situ observation and identification of
the organisms, wood is the most desirable panel material. It is much
easier than glass to examine under the binocular microscope and it is
more rugged and inexpensive. Another advantage is that it can also be
used to col lect marine borers.

Depth
Because of the? length of time required to make the final observation
of each of the long-term panels it was not possible to examine them all
on the same day. Instead, the panels in each rack were examined on a
different day. The floating panels were examined after 54 days exposure,
the shallow panels after 55 days exposure and the deep panels after 57
days exposure. Since it appeared that very few of the attached organisms
could have been attached less than three days, it is assumed that a three
day period would not make any significant change in the intensity of the
fouling accumulated over a two month period. Therefore, valid assumptions
can be made about the fouling at various depths using the data in Table 3.
Care must be taken, however, not to make direct comparisons of the number

37

of rndividual foulrng organ tsms found on the panels In the t loitifng' reck
and those of the other racks since only about six inches of the floating
rack panels were below the water line.

The Intensity of Spirorbi s, tube-building amphlpods, and the one
species of sponge observed appeared to increase with depth at the test
site. Additional racks placed at intermediate depths would be necessary
to determine the exact depths of maximum abundance of these organisms.
It may also be that their vertical distribution varies with time depending
on the water circulation.

Balanus qiandula and possibly the hydrolds appeared to be the only
fouling organisms decreasing with depth.

The vertical distribution of the barnacles shows two maxima, one at
the surface due to Ba lanus qiandula and one at depth due to Ba I anus
crenatus. At Friday Harbor the maximum abundance of B. q landula was
found to be at 6.3 feet above mean lower low water [ij , but the depth
of maximum abundance of this barnacle in Monterey Harbor could not be
determined from the three depths considered. This species of barnacle
was rarely found on submerged panels at San Diego. [2]

The vertical distribution of the bryozoa depended on the species
considered (see Table 4). All species were at a minimum on the floating
panels, but Tubul ipora was far more abundant at the deeper depth while
the abundance of Hippothoa hya I ina and Hippodiplosia Insculpta varied
little between the shallow and deep racks.

The rock oyster, Pododesmus, was found only on the deep panels.

Taken as a whole, without regard to type of organism, the amount of
fouling was found to increase with depth.

33

TABLE 4
VERTICAL DISTRIBUTION OF BRYOZOAN SPECIES

Hippothoa hyal ina
Hippodiplosia tnscu Ipta
Tubul rpora sp.

Plywood Panels
F loafing Shal low
1 17

4 63

5 75

21

59

273

39

Light

Almost all fouling organisms are negatively phototropic at the time
of their attachment. [^6] Therefore, if a panel is illuminated more
from one side than from the other, there is a tendency for the fouling
organisms to attach more frequently to the shaded side of the panel.

The location of the test site was such that the most illumination
was from the southeast, causing the east side of the shallow and deep
panels and the south side of the floating panels to be illuminated more.
Other factors, however, reduced this light effect. The depth of the
deep rack was such that light probably had very little effect on the
attachment of fouling organisms. This was borne out by the fact that
the intensity of fouling on both sides of the panels were about equal
at that depth.

The west side of the plywood and stainless steel shallow panels did
usually show an increased amount of fouling over the east side. The 16
Balanus t int innabu lum that were found on the stainless steel panel were
all on the shaded side. An indication that the increased fouling on the
west side was due to light was that the glass panel, which was transparent
to light, had about an equal amount of fouling on each side. The light
effect on all these panels was probably reduced, however, by the panels
being only three inches apart and each shading the panel to the west of
It.

The north side of the floating panels had a much larger number of
barnacles than the south side.

The most important effect of light in this investigation was
undoubtedly the absence of algae due to the lack of direct sunlight at
the test site.

Edge Effect

Most of the fouling organisms recorded showed no preference for any
particular position on the panel. There was, however, a few notable
exceptions.

The few L Jmnor ia observed were boring into the edge of the panels.
This observation was also made in the study at Oakland. |_3j

All of the hydr.oid fouling on the panels began at the edge and
spread inward and the tube-bui Id inn spionicls Ghowod a preference to
build their tubes on the edges of tho panels.

But the most Interesting example of the edge effect was on the
distribution of the encrusting bryozoan, Hippothoa hyal ina. On one panel,
which was exposed for four weeks in the shallow rack, 30 colonies of
H. hyal ina were observed. Of these, 26 were found within one inch of
the edge of the panel and 24 within a half inch of the edge. The half
inch band at the edge of the panel represents less than 22 percent of the
total surface area available for attachment, yet 80 percent of these
colonies were attached there.

This preference for the edge can probably be explained by the fact
that the panels were spaced three inches apart and, with panels on either
side, it made the center of the panel less accessible to the larvae than
the edges. But no such preference for the edge was noted in the case of
Hippodiplosia insculpta. In fact, of the eight colonies of H, Insculpta
observed on the above panel, none were within an inch of the edge. A
similar distribution of these two species of bryozoa was noted on the
other test panels, but no exact records of their positions were kept.

41

6. Conclusions.

The fouling organisms present at the test site during the period
January 26 to April 21, 1966, were those as listed in Table 1.

Factors important in determining the type oiff intensity of the fouling
were length and season of exposure, type of surface, depth, light and
edge effect.

Hydroids were the dominant fouling organism attaching during the
late winter, but barnacles were dominant during the spring. Other
Important fouling organisms were serpulld worms and bryozoft.

The marine borer, Limnor ia I ig'norum, was found on wood panels in April,

A maximum abundance of barnacle larvae was present in Monterey Harbor
in early April 1966 after which the number of larvae decreased.

The amount of fouling In Monterey Harbor Increases with depth.

Plywood Is the best material for collecting and observing marine
fouling and boring organisms. Stainless steel fouls the least of those
materials tested.

No correlation of temperature or salinity with the Intensity of
fouling during the test period could be determined.

Although flatworms are apparently a factor in reducing the population
of young barnacles, it Is felt that their effect on the barnacle
population as a whole is small.

Subjects v/hich can bear further study are the complete annual variation
of Important fouling organisms In Monterey Harbor, the seasonal and vertical
variation of the different barnacle species, a comparison of the fouling
In the marina with that In the outer harbor, the distribution of the
various species of encrusting bryozoa and serpulids, and the effect of
flatworms on a young barnacle population.

42

7. Acknowledgments.

The encouragement and assistance of Dr. Eugene C. Haderlle during
this Investigation Is gratefully acknowledged. Thanks are due to
Cormiander Donald A. Still, U.S. Navy, for his assistance in providing
use of the facilities and much of the equipment.

:,k43

BIBLIOGRAPHY

1. Johnson, M.V/. and R.C. AMIIer. The Seasonal Settlement of Shlpworms,

Barnacles, and Other Wharf-pile Organisms at Friday Harbor, Wash-
ington* Univ. Wash. Publ. Oceanogr. v. 2, No. 1, March 1935: 1-18.
A ten year study using wooden blocks.

2. Coe, W.R, and W.E. Allen. Growth of Sedentary Marine Organisms on

Experimental Blocks and Plates for Nine Successive Years at the
Pier of the Scripps Institution of Oceanography. Bull. Scripps
Inst. Oceanogr. tech, ser. v. 4:4, 1937: 101-136.
A nine year study using cement blocks and glass plates.

3. Graham, H.W. and H. Gay. Season of Attachment and Growth of Sedentary

Marine Organisms at Oakland, California. Ecol. 26:4, October 1945:

375-386.

A fourteen month study using wood panels.

4. Buchsbaum, R. Animals V/i thout Backbones. Univ. of Chicago Press. 1948.

Contains good discussion on flatworms.

5 . Vv'e i ss , C .M » The Seasonal Occurence of Sedentary Marine Organisms in

Biscayne Bay, Florida. Ecol. V. 29:2, April, 1948: 153-172.
A four year study using glass panels.

6. Woods Hole Oceanographic Institution. Marine Fouling and Its

Prevention. U.S. Naval Institute. 1952

A basic text on all phases of marine fouling, includes an extensive

bibliography up through 1952,

7. Light, S.V. rev. by R.I. Smith, F.A. Pitelka, D.P. Abbott and

F.M,. Weesner. Intertidal Invertebrates of the Central California

Coast . Univ. of Calif. Press. 1954.

Necessary for identification of marine organisms in this area.

8. Hedgepeth, J.W. Introduction to Seashore Life. Univ. of Calif. Press.

1962.

Contains discussions of most common marine organisms along

Cal i forni a coast .

9. Ricketts, E.F. and J. Calvin*, rev. by J.W. Hedgepeth. Between Paci fie

Tides. Stanford Univ. PreSs. 1962.

Contains numerous pictures of marine organisms and a section on

whar f-p i I e organ i sms .

10. Drisko, R.W. Protection of /Aooring Buoys Part III Second Rating
Inspection. U.S. Naval Civil Eng. Lab, tech. rep. R-291 , 1964,
Contains lists of fouling organisms collected on test panels at
Port Hueneme and San Diego,

44

INITIAL DISTRIBUTION LIST

No. Copies

1. Defense Documentation Center 20
Cameron Station

Alexandria, Virginia 22314

2. Library 2
U.S. Naval Postgraduate Sctiool

Monterey, California 93940

3. Dept. of Meteorology & Oceanography 1
U.S. Naval Postgraduate School

Monterey, California 93940

4. Prof. Eugene C. Haderlie 1
Dept. of Meteorology & Oceanography

U.S. Naval Postgraduate School
Monterey, California 93940

5. LT Durward B. Mommsen Jr., USN 1
20 E. Humbird St.

Rice Lake, Wisconsin 54868

6. Commanding Officer and Director 1
Naval Electronics Laboratory

Attn: Code 2230

San Diego, California 92152

7. Environmental Sciences Service Administration 2
U.S. Department of Commerce

Washington, D.C.

8. U.S. Naval Oceanograph re Office 1
Attn: Division of Oceanography

Washington, D.C. 20390

9. Superintendent 1
United States Naval Academy

Annapolis, Maryland 21402

10. Office of Naval Research 1
Attn: Biblogy Branch (Code 446)

Department of the Navy
Washington, D.C. 20360

11. Director 1
Woods Hole Oceanographic Institution

Woods Hole, Massachusetts 02543

12. Dr. James S. A^uraoka 1
Materials Division

U.S. Naval Civil Engineering Laboratory
Port Hueneme, California 93041

45

13. Director

Scripps Institution of Oceanography
University of California, San Diego
La Jol la. Cat i fornia

14. Chairman, Department of Oceanograjphy
Oregon State University
Corvallls, Oregon 97331

15. Executive Officer ,^,^^,.
Department of Oceanography
University of Washington
Seattle, Washington 98105

46

Security Classification

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Environmental Sciences Programs
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Monterey, California

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A Study of Marine Fouling in A\onterey Harbor

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5' AUTHOR(S) (Laat name. 11 rat name, initial)

mmSEH, Durward B. Jr.

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May 1966

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Wa sh i n n t o n , ;J . ( ; , 2002 5

13 ABSTRACT

Observations were made on the marine fouling occur ing on test panols in
/.'onterey Harbor during the period January 26 to April 21, 1966. Test pnneif, of
various materials were placed at three depths. Observations were mode on plywood
panels exposed for four weeks, immersed at two v^eek intervals, at just below the
mean low tide level to determine the change in rate of attachment of fouling
organisms during the test period. Observations were also made on the amount of
fouling occuring on different test materials at the same depth and on the same
test material at different depths.

The most important short-term fouling organisms In Monterey Harbor were
found to be barnacles, bryozoa, serpullds and hydroids. The number of barnacles
attaching to test panels reached a peak In early April and then declined. The
amount of fouling on the test panels increased with depth. V/ood was determined
to be the best surface for collecting and observing marine fouling organisms.

DD /.A°N«'5. 1473

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Foul ing
Biology

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thesM6695

A Study of marine fouling in Monterey ha

llllllllllllill

3 2768 002 04690 6

DUDLEY KNOX LIBRARY

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