I
J
SETTLEMENT AND GROWTH OF FOULING ORGANISMS AT ALAMEDA ~~RINA, SAN FRANCISCO BAY, CALIFORNIA
A Thesis Presented to the Graduate Faculty
of
California State University, Ha~vard
In Partial Fulfillment
of the Requirements for the Degree
Masters of Arts in Biological Science
By
Christopher P. Ehrl8r
August, 1976
'u.', . ·{~!t"' · - ,
ACKNOVVLEDGE!\1ENTS
I would like to thank the following people for
assistance and support during this study: Dr. Edward B.
Lyke, Dr. MichaelS. Foster, Dr. James W. Nybakken, Dr.
James M. Erickson and Mr. Jerry Thoss. Without their help,
this project and paper would have taken longer to complete.
Thanks must also go to the officers of Alameda Marina for
allowing this study to be carried out there.
I would also like to thank my wife Betsy, without
whose constant encouragement and personal contributions
this study would probably have not been undertaken and
completed.
' This research was partially funded by the Department
of Biological Science, California State University, Hayward.
I appreciate their support.
' J
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., F.
TABLE OF CONTENTS
Acknowledgements. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . J
Abstract.,·, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Introduction ......... . I I I I I I I I I I I I t I I I I 41 41 I 41 I I I I • I I 41 I 6
Methods and Materials ............................... 9
Results ..... , ........................ I I ••••••••••••• 14
Discussion and Comparison. . . . . . . . . . . . . . . . . . . . . . . . . . .1?
Liter a tu r e C i t e d . . . . . . . . . . . . . . . . . . . ~ . . . . . . . . . . . . . . . . 31
Figures. I I I I I I I I I I II I I I I I f I I I I I I I I ' I I I I I I I I I I I I I I 1 I I I 35
Tables .............................................. 69
'
ABSTRACT
Settling periods and maximum growth of fouling organisms
at Alameda Marina, San Francisco Bay, California, were examined
from January 1, 1975 to April 21, 1976. Plastic plates sus-
pended in a rack were exposed at a constant depth and retrieved
at one, two, six and twelve month periods. Organisms settling
during these periods were identified and size and numbers of
certain species were recorded. Particular seasons of settlement
were inferred fro~ when the species attached to the plates.
Settlement times and growth rates of these organisms at
Alameda Marina were compared with findings of other investiga-
tors. A direct correlation was noted between water temperature
and (1) the total number of attached species, (2) the total
number of attached individuals of six species, and (J) the
growth rate of eight species. In addition, a correlation was
found between salinity and nu~cers and growth for a few species.
The Index of Similarity was used to make a comparison
between the total number of species that attached after one
and six or tv.,relve month periods. 'rhe data indicated that
organisms did not disappear as the community developed, and
settlement was dependent o~ when the larvae or spores were in
the water. This development of the community was interpreted
as a seasonal progression, instead of a true succession.
5
INTRODUCTIOli
Many s"'!:;udies have been undert2.ken on different
aspects of the biology of fouling organisms, plants and
animals that attach to and grow on submerged man-made
objects. There are nearly 2,000 species of fouling organisms
from at least the following groups: Bacteria, Fungi, Algae,
Protozoa, Porifera, Cnidaria, Platyheln1inthes, Nemertea,
Rotifera, Bryozoa, Brachiopoda, Annelida, Arthropoda, Mollusca,
Echinodermata, Tunicata and Pisces (Woods Hole Oceanographic
Institute 1952). In some studies, submerged artificial test
panels have been used to accurately determine the season of
settlement (Coe 1932; Goodbody 1961; Nair 1967) and growth
rates (Nair 1967) of these organisms.
Several factors have been found to affect the settle
ment of these organisms on fouling surfaces. The physico
chemical factors i~clude type, color, texture, orientation,
and depth of the substrate, presence of silt, water current
moving over the substrate, time of year, length of submergence,
water temperature and salinity. The biological factors include
concentration of larvae, growth after attachment and longevity
of the breeding season (Visscher 1928; ~oods Hole Oceanographic
Institute 1952).
Some of these investigations have attempted to deter
mine if the fouling community developed via a true succession
or by a seasonal progression. For true succession to occur
6
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I
7
(1) earlier organisms in the community must be essential to
the attachment of later ones, and (2) organisms must disappear
as the development of the community progresses (Shelford 1930).
Scheer (1945) showed that when bacteria were present on
glass plates, there was increased s2ttlement of hydroids. He
also found that the settlement seQuence did not depend on
when the plates were exposed, and thus development must have
been via true succession. Many investigators (Shelford 1930;
McDougall 1943; Reish 1964; and others) have found that
settlement depends on when the larvae or spores of any organ-
ism are in the water column, and that the presence of one
organisms is not essential for the attachment of another.
To my knowledge, only one study has been carried out
on the fouling organisms of San Francisco Bay, that of Graham
and Gay (1945). They found the community on wood to be domi
nated by Tubularia crocea (Cnidar:.a), Polydora ligni
(Annelida), Corophium insid5osum (Amphipoda), Balanus
improvisus ( Cirripedia) ar,d ~:vtilu~ edulis (Pelecypoda).
The settlement of most of the organis~s in this study appeared
to be related to the changes in water temperature.
The purpose of my study was to answer the following
four questions: (1) What was the season of settlement of
the fouling organisms at Alameda ~arina, San Francisco Bay?
(2) What was the growth rate of certain of these fouling
organisms? (3) Was the season of settlement or growth rate
related to either water temperature or salinity changes?
' '
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8
(4) Did the development of the community take place via a
true succession or by a seasonal progression?
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T I
IVIATERIALS AND l/lliTHODS
The study was carried out from January 1, 1975 until
April 21, 1976 at Alameda Marina, Alameda, California. This
Marina is located on the Oakland Estuary, across from
Government Island (Figure 1) . ·l'he area was chosen because
fouling organisms are abundant and present thraughout the year,
and it was within one mile of Graham and Gay's (1945) study
site.
Experimental fouling surfaces, 10 x 10 em, were con-
structed of 5 mm thick black acrylic sheeting. The plates
were sandblasted to roughen the surface (crevices about
0.1 mm wide and deep), and thus aid in the attachment of
organisms (Pomerat and Weiss 1946). A total of twenty-four
numbered plates were used for the entire Etudy.
Five sets of plates were used, w~th three replicates
per set in the rack (see below) at all times. These five
sets were as follows: (A) plates that were exposed for one
month, (B) and (C) plates that were exposed for two months,
(D) plates that were exposed for six mo~ths, and (E) plates
that were exposed for twelve months. T·wo plate types, (B)
and (C), were needed for t'iVo months exposure so that one
set could be collected at the end of each monthly period.
It should be noted that 'one month' in this study consisted
of exactly four weeks. Table 1 illustrates the chronological
sequence of placement and replacement of the plates.
9
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10
The pla~es were held in a rack constructed of rigid,
white one inch PVC tubing filled with concrete to create a
negative bouyancy (Figure 2). The rack was held together
with waterproof PVC glue and stainless steel hosP clamps.
The rack held fifteen randomly positioned plates oriented
vertically at a constant distance of 5 em from each other.
Stainless steel cable (5 mm diameter) was used to suspend
the ~ack at a constant depth of 76 em from an eyebolt which
was screwed in on the underside of the dock. The other end
of the cable hooked to the rack via a brass swivel which
enabled the rack to turn with water movement (Figure J). A
swivel and cable were also attached to the underside of the
rack for security reasons. This cable was hooked to a second
eyebolt, also attached to the underside of the dock. The
distance between the two eyebolts was approximately one meter.
Each 'month' the appropriate set of 1,2,6 and/or 12
month plates were collected from the rack and clean, ran-
domly selected plates were used to replace the collected
plates. The fouled plates were returned to the laboratory
in a carrying chamber. Photographs were taken of both front
and back of each plate, and within two days, all organisms
were identified and listed, and size and number of certain
species (called quantified species) were recorded. While 1n
the laboratory, the water in the carrying chamber was
aerated, and the temperature was kept within ~ 1°C of the
temperature at the study site.
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11
During the study, representative examples of species
were removed from the plates and fixed in 10% neutral
formaldehyde. The plates were then scraped clean with a
razor blade and placed in a freshwater bath for one week.
The plates were then used again at a later date in the
study.
Water temperature and salinity were monitored at a
depth of 10 em throughout the study. Temperature was determined
by use of a thermometer,,and salinity was determined by use
of a Goldberg T/C Refractomer (AO Instrument Company, Buffalo,
New York; accuracy=~ 1°/oo).
The total number of i~dividuals of many species that
attached to the one and ~No month plates was determined.
Certain species were not quantified, but from the presence
or absence of each species it was possible to determine when
they settled.
In an effort to determine the maximum growth rate of
the quantified species, the mean size of the three largest
individuals of each species on one and two month plates was
calculated. It was assumed that the largest individuals of
each species attached on the day the clean plates were placed
in tr.e water. Size of encrust:.ng animals (bryozoans and
colonial tunicates) was determined with a planime~er and
expressed as total area cove:c·ed (mm2). Areas under 25 mm2
were estimated. Size of upright ar1imals (barnacle~, mussels
and simple tunicates) was determined ty use of a micrometer
12
and expressed in mm. Figure 4 shows the parts of the body of
the erect species that were measured. Simple tunicates were
relaxed before measuring.
The Mann-Whitney test was used to determine if the
total number of attached individuals and their mean size were
statistically similar on both front and back of the one and
two month plates. Siegel's (1956; p.125) formula was used,
and the calculated Z values were compared as in Zar (1974;
p.112). Zar (1974) notes that the critical values of t and Z
are equal for large samples, and for~= 0.05, t and Z = 1.960.
Multiple correlations (Zar 1974) were carried out to
determine if the total number of attached species, or the
numbers or growth of individuals of the quantified species,
had any relationship with either temperature and/or salinity
changes.
A comparison was made between the total number of
species that attached after different lengths of submergence
to determine if the development of the fouling co~~unity took
place via a true succession or by a seasonal. progression.
This comparison was made by use of the Index of Similarity (S):
s = 2c a+b X 100
where a = number of species 1n month A, b = number of species
in month B and c = number of species 1n common to A and B
(Sorenson 1948). A high similarity between overlapping periods
lJ . of long and short submergence would show that organisms do
not drop out as the community develops, and no one organism
was essential for the settlement of another. Thus such a high
similarity would indicate that community development was via
a seasonal progression. A low similarity between all overlapping
periods of long and short submergence would mean that organisms
were dropping out as the co~~unity developed and may indicate
that one organism was essential to the attachment of another
(development takes place via a true succession).
l I I
I I
RES1JLTS
The season of settlement of the fouling organisms at
Alameda Marina is shown in Figure 5. The solid lines denote
settlement on both one and two month plates, while a dotted
line signifies settlement only on two month plates. Only a
diatom film (probably composed of both bacteria and diatoms)
and Melosira sp. attached through0ut the entire study, the
rest of the species settled over only part of the year.
Certain species (ex. Zoothamnium sp., Obelia longissima
did not attach during the sum~er, while many others (ex.
Corophium sp., Mytilus edulis) did not settle during the
fall or winter.
The front and back of the plates were found to be
statistically similar in relation to the total number and
mean growth of all individuals of the quantified species on
the one and two month plates (Table 2). Thus, data from the
front and back of three plates in a set (N = 6) could be
used together, and the total number of settled individuals
and their maximum growth rates could be determined.
Figures 6 to 16 represent the total number of individ
uals and the mean size + 1 S.E. of the three largest individ
uals of the quantified species: the bryozoans Membranipora
membranacea, Cryptosula nallasiana, Sm~ttoidea prolifica,
the barnacle Balanus imnrovisus, the mussel Mvtilus edulis,
and the tunicates Botryllus s_p., Botrvlloides sp., Molgula
manhattensis, Ascidia ceratodes, and Cio:1a intestinalis. Many
14
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15
of the attached colonial t~nicates could not be identified
to genus due to their small size, and were placed in an
additional category, Family Botryllidae. Figure 17 shows the
total number of attached Mercierella eni&natica. No growth
data was collected for this species.
Multiple correlations were calculated to determine
water temperature or salinity changes (Figure 18) had a
significant effect on the total number or average growth of
all attached individuals of the quantified species (Table 3).
The number of attached C. uallasiana, ~· improvisus, Botryllus
sp., Botrylloides sp., Family Botryllidae and~· ceratodes, and
growth of C. pallasiana, B. improvi.sus, Botryllus sp.,
Botrylloides sp., Family Botryllidae, Molgula manhattensis,
Q. intestinalis and A. ceratodes were directly correlated with
water temperature. The relationship with salinity shows so~e
significant positive (C. intestinalis, Eotrylloides sp. and
Family Botryllidae) and negative (~. membranacea and M. edulis)
correlations fer numbers and growth.
Table 4 shows that there is a direct correlation
between the total number of attached species and temperature.
Salinity does not have a statistically significant effect.
Some Index of Similarity (S) values are shown in
Table 5. There is a high similarity between certain 1 and
6 or 12 month periods, such as June 1 month and June 6 month
plates and August 1 month and December 6 or 12 month plates.
Little similarity is seen between different 1 month periods,
such as J~nuary 1 month and August 1 month plates. It should
~ ) ' ' . . . ' .~ • .,, •"' ':.~,,..t,l ~-~·~t) '• ' ,"".ttl ' .. ~.~ l-; I< ;t ,1 ,.';. • ~" _,.' • '~· . ', ••• ~ ·~ • •• ~
16
be noted that in all comparisons between 1 and 6 or 12 month
periods, there was one month of sutmergence in common to
both plate types. In other words, while the August 1 month
plates were in the water, so were the December 6 month plates.
'
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DISCUSSION AND COMPARISON
Algae
Coe (1932) working at La Jolla, California, found
that algae settled year round. The settlement of algae is
usually best near the surface of the water (Pyefinch 1950).
In the present study, a diatom film and Melosira sp. attached
year round, while only during the spring were a few
Enteromorpha sp. and Ulva lobata found attached to the plates
(Figure 5). The docks at Alameda are covered with large
quantities of these algae, and the limited algal attachment
on the plates was probably due to the lack of a minimum
quantity of light at the depth of the rack, caused by shading
from the dock and a nearby boat, by the turbidity of the water,
and by the vertical orientation of the plates.
Protozoa
Coe (1932) and Graham and ~ay (1945) found that
protozoans settle year round. My study shows that protozoans
were always found attached to the plates, but no one species
was present throughout the year (Figure 5). Allen and Wood
(1950) in Australia, and Ganapathi et al (1958) in the
Indian Ocean, found that Zoothamnium sp. settled year round.
At Alameda, it only settled from November to May (Figure 5).
Zoothamnium sp., Folliculina sp. and Stentor sp. did not
attach during the su~~er at Alameda and might be limited by
17
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18
warm water. 'The suctorians and unidentified protozans (all
ciliates) were able to settle during these warmer water
periods. Stentor sp. appears to also be limited by colder
water temperatures, and thus did not settle at either of the
extremes of temperature at Alameda (Figures 5, 18).
Porifera
Nair (1962) working in Norway and Coe (1932) found
that sponges attach during the warmer water periods. Scypha sp.
at Alameda, followed this pattern, probably being limited by
cold water (Figures 5, 18). Kajihara et al (1975) in Japan,
found that Halichondria panoce~ settles from May to August,
while Halichondria bowerbankia at Alameda, attached for a
longer period of time, April to December (Figure 5). Fell
(1970) found that Haliclona eshasis has two periods of repro
duction at the Berkeley Yacht Harbor, San Francisco Bay, spring
and fall. Settlement of Haliclona sp. at Alameda appears to
follow the same pattern (assuming season of settlement re
flects period of reproduction), with the fall period lasting
longer than the spring period (Figure 5).
Cnidaria
Visscher (1928) working on the East Coast of the
United States, found that hydroids settled from January
to April, while Coe (1932) found that Obelia dichotom~
attached from August to May. Obelia longissima at Alameda,
settled from November to June (Figure 5).
'
Syncoryne sp. and the unidentified hydroid only
settled in the cool water periods of 1976, having not been
19
seen in 1975 (Figure 5) . The unidentified hydroid consisted
of small, less than 1 mm tall, single upright polyps, inter-
connected by a stolon-like structure. A hydromedus:l was con-
tained inside each polyp. The hydromedusae were small, less
than 1 mm across, and had four short tentacles. No feeding
polyps were seen.
Platyhelminthes
Egg cases from an unidentified flatworm were found
on many plates (Figure 5). The adult flatworms were white in
color, with two dark anterior eyespots. Four to six young
were found in each egg case.
Annelida
Mercierella enigrnatica settled from April to August
at Alameda (Figure 17), while Kajihara et al (1975) found it
attached in Japan from Nay to November. No aduJts of this
species were seen at or near Alameda Marina, but large popula-
tions live in Lake Merritt, a brackish lake in Oakland that
connects with the Oakland Sstuary via a canal. The individuals
on the plates might have been recruited from Lake Merritt.
Polydora ligni lives in a tube which it constructs
out of silt and debris (Graham and Gay 1945). It might be that
not enough of this type of material was found on the 1 month
. ' ' '
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plates for tube construction, individuals thus only being
found on two month plates (Figure 5).
Bryozoa
Membranipora tenuis settled from April tc November
20
in North Carolina (Maturo 1959). At Alameda, d· membranacea
attached from February to June, with peak settlement from
April to late NT·J.y (Figure 6) . It is not k.nown why this species
did not attach again in the second year.
~· membranacea appears to have about the same growth
rate (Figure 6) as M· pilosa in Woods Hole (Parker 1924), but
much slower than Membranipora sp. in India (Paul 1942).
Cryptosula pallasiana has two settlement periods in
North Carolina, April to June and October to November (Maturo
1959), but in Norway, it settles continuously from April to
December (Nair 1962). At Alameda, it attached from February to
August and from October to November (Fig1Jre 7).
Settlement of Smittoidea nrolifica is during the
warmer water periods, with peak settlement from mid-June to
mid-July (Figure 8).
Settle~ent of Bu~ula californica in Japan took place
from May to August (Kajihara et al 1975), in North Carolina,
it attached from April to December (Maturo 1959) . Maturo
(1959) also found that this species began to settle when the
water temperature rose to 15°C. At Alameda, this species did
not settle until the temperature reached 19°C (Figures 5, 18).
Coe (19J2) and Maturo (1959) found that Eugula neritina
21
began to attach when the water temperature rose to 15 - 16°C
{April) and continued until the end of fall (November, December).
It did not settle until the temperature reached 20°C (July)
at Alameda (Figures 5, 18). It continued until
December.
Tricellaria occidentalis has not been listed as a
fouling organism by either the Woods Hole Oceanographic
Institute (1952) or Ryland (1965), yet it is the dominant
erect bryozoan in the fouling community at Alameda (Figure 5).
It is limited by the colder water temperatures during the
winter at Alameda.
Settlement of Bowerbankia gracilis appears to be
limited by high summer water temperatures (Figures 5, 18).
Settlement of Alcyonidium ~olvoum, Parrella elongata and
Electra crustulenta was rare and limited to spring and summer
(Figure 5) •
The unidentified bryozoans (Figure 5), both erect and
encrusting, were small (1 and 2 zooid) and probably young
individuals of the dominant species.
Arthropoda
Graham and Gay (1945) found that Balanus irnnrovisus
attached from March (temperature 15°C) to Octooer. At Alameda,
it started to settle in i'i!arc!-1 ( FioTure --'
9) at a temperature of
11°C (a possible explanation for this difference will be
discussed later). The growth of this barnacle at Alameda
(Figure 9) is within the range that Graham and Gay (1945)
22
found, an average growth of 4.4 rnrr. in 30 days.
The amphipod Corophium insidiosum began to settle
when the temperature reached 15°C at Oakland (Graham and Gay
1945). At Alameda, Corophium sp. (Figure 5) began to attach
at a temperature of 11 to 12°C (see below for a possible
explanation) .
Mollusca
Settlement of Mvtilus edulis is from June to August
in Long Island Sound (Engle and Lcosanoff 1944) and Maine
(Fuller 1946) and from March to May at Oakland (Graham and
Gay 1945). At Alameda, settlement appears to take place from
March until June and again in August and October (Figure 10).
Mytilus edulis exhibits a crawling behavior (Harger 1968)
and it 1s possible that the large N· edulis found on the
plates of June 18, August 13. October 10, 1975 and March 24,
1976 might have crawled onto the plates. If so, settlement
at Alameda takes place from March to June.
The growth of this species, minus the very large
individuals, ranges from 4 to 9 mm per month. A similar range
has been found in other stt<dies (Graham and Gay 1945; Fuller
1946; Reish 1964).
Settlemeni of Ostrea lurida at Alameda, did not begin
until the water temperature reached its maximum, 20°C (Figures
5, 18). Coe (1932) found that this species began to attach at
LaJolla, California, after the temperature had reached only
16°C, while McDougall ( 1943) found that .Q_strea virginica
'
in North Car~lina, did not begin to spawn until the water
reached 20°C.
Entroprocta
Maturo (1959) found that Barentsia laxa in North
Carolina settled from July (water temperature 28°C) to
October. At Alameda, Barentsia sp. did not attach until the
temperature had dropped to 16°C (Figures 5, 18).
Ascidians
Millar (1958) in Scotland, found that Botryllus
2J
schlosseri began to attach when the water temperature was
8°C (April). At Alameda, ~otryllus sp. does not settle until
the temperature reached 11°C (Figures 11, 18). The growth
rate of Botrvllus sp. at Alameda was within the ranges for
both B. schlosseri (Parker 1924) and B. gouldii (Grave 19JJ).
The growth rate of this sp~cies was much less on the July
plates than on the June or August plates (Figure 11). It
might be that on the July plates, individuals did not start
to settle on the first day the plates were placed in the
water, and thus did not have the entire 'month' period in
which to grow.
The difference between the settlement of Botrylloides •
sp. on the 1 and 2 month plates (Figure 12) might be due to
the inability of identifying small (young) individuals. They
have to attain a certain size (age) in order to be identified.
Thus, more and larger individuals were seen after two months
24
than one.
There was usually fewer Family Botryllidae individuals
on the two month than one month plates (Figure 13). This
might be due to the ability of identifying larger colonies,
and reclassifying them into one of the two genera of colonial
tunicate.
McDougall (19L~J) found that high summer temperatures
tended to stop reproduction in ~.1olgula manhattensis. This is
a possible explanation for the absence of this species on
the September one month plates (Figure 14).
Ciona intestinal~s attached from April to November
in Norway (Gulliksen 1972) and from May to October in Alamitos
Bay, California (Reish 1964). At Alameda, this species did
not settle until July of 1975, yet in 1976, it started to
attach in early March (Figure 15). This species was not
found attached to the docks of this Marina until July, 1975,
and thus may have been introduced to this Mar~na at that time.
Attachment of Ascidia ceratodes (Figure 16) and
Styela clava (Figure 5) appears to be limited to warmer
water periods (Figure 18). Settlement and growth of A.
ceratodes decreases as the temperature decreases.
Graham and Gay's (1945). study and results differed in
a number of respects from the present study. T~ey used 16 in2
(100 cm2 ) wooden panels suspended vertically at a constant
depth just below the water's surface. It has been found
(Aleem 1957) that wood and plastic have about the same suit-
ability for attachment and growth of organisms.
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25
Ectocarpus sp., Vaucheria sp., Eteone lighti, Eteone
californica and Tubularia crocea attached in 1945, but not in
the present study. I have found no specimens of the algae or
annelids and only one T. crocea attac~ed to the docks at
Alameda.
Polvdora sp., Corophium sp. and Balanus l!I!.P.rovisus
were found in both studies, but in 1945, the numbers of these
three that attached were statistically much higher than in
1975-76.
No bryozoans or ascidians attached to the plates or
were seen on nearby docks in 1945, yet they now dominate the
community at Alameda. Obelia lon£issima and Ostrea lurida
were also no~ present in 1945.
The reason for the differences 1n the two studies is
not known, but may be due to a number of factors. Graham
(personal comrr.unication) noted that there was considerable
pollution from a sanitary sewer in the area of their study.
The decomposition of this sewage might have decreased the
dissolved oxygen content in the water to a level which would
support only relatively few types of organisms. In 1945, the
California State Department of Public ]{ealth ordered an end
to the discharge of raw sewage into San Francisco Bay waters
(San Francisco Bay Conservation and Development Commission
1969b), and in recent years, extensive improvements in the
treatment of industrial and municipal wastes have greatly
reduced the amount of pollutior1 in the Bay (San Francisco Bay
26
Conservation and Development Commission 1969a).
Patrick, Hohn and ~allace (1954) found low diatom
density in polluted river water, with large numbers of indi
viduals of each species (low diversity), while in unpolluted
water there were more species, but less individuals of each
species (high diversity). If this also happens for macroscopic
organisms, it could explain some of the differences seen
between the two studies now under comparison. In the more
polluted case, 1945, there was a large number of individuals
of a few species, while in 1975-76, there was less pollution,
and fewer individuals of a large number of species.
It is also possible that many organisms had not been
introduced into the Oakland Estuary by 1945, and thus the
differences seen between the two studies are due to the
introduction of new species and interspecific competition
for available niches.
Variations occur during the year in both the number of
attached individuals and growth rate of fouling organisms, and
they have been found to be regulated by water temperature
(Orton 1920; Coe and Allen 1937; Nicol 1960). In the present
study, temperature was correlated with the total number of
attached species, the total number of attached individuals of
six species and the growth rate of eight species.
It is known that spawning ir1 many marine organisms is
triggered by a certain temperature, which varies with species
(Vernberg and Vernberg 1972). Within any one species, the
breeding season will vary in different parts of its range
~ - . ~ ' < ~ ' • - .- ,. - /
' ' • • ' ' • 'I ... ·' ':~ ' ~ • ' .. ~ ;)t•~:.i+.J.-i'"':• ' ' '~_...,!: <I' ~ .,."'-""" *;' • • '-( : i' " ... ~ • ' '• • • ' ( ' ,'_.
27
.. depending on the temperature variation at different latitudes
(Crisp 1957). This is the probable reason why certain species
in my study started to settle at a different temperature than
was indicated by other investigators. It is not certain why
two species (Balanu~ improvisus and Coronhium sp.) started to
attach at different temperatures at Oakland (Graham and Gay
1945) and Alameda. It is possible that the increased amount
of pollution in 1945 put an added stress on these organisms,
the adult and/or larval stages, and thus they did not begin
to settle until a slightly higher temperature.
Sastry (196J, 1968) found that scallops in Massachu-
setts start spawning when the temperature increases, while
more southern scallops spawn only as the temperature rises.
It appears in my study that all species begin to settle as
the temperature is increasing.
Nair (1967) found that salinity variations played a
maJor role in settlement and growth of the major fouling
organisms in Cochin Harbor, India. Orton (1920) found that
salinity had no affect on the breeding of many marine organ
isms. I found that salinity and the number or growth of
attached individuals were only correlated for a few species.
The presence and grow~h of the attached species might
also be affected by certain biological factors. Predation
could have affected the number of attached individuals. Coe
(1932) found that ''even during the season when young barnacles
are daily attaching themselves to the blocks, the rate of
. . ~ . ' ' . . " - • ~ • '•lilt r,~.,_t \~r·-, J,to'> ,'' <' -~.,:t .. -. .,/~"; 4- ' .-.' -,. ' •j ·~
28
mortality rna~ exceed the increment owing to new arrivals,
with a possible decrease in the population following an early
maximum''. This could also happen to other young organisms.
Flatworms, caprellid amphipods, nudibranchs and fish, which
were seen on the plates or in close proximity to them, might
have eaten and thus decreased the number of attached individuals.
Competition for food and space could also limit the
number of individuals and their growth rate. Coe (1932) found
that there was a definite competition for food among newly
attached individuals. The amount of food, if limited, can
greatly affect the growth rate of organisms (Coe and Allen
1937; MacGinitie and MacGinitie 1968). Possible competition
for food was not examined in this study.
Competition for space can also affect marine organ
isms. Connell (1961) found that the lower limits of Chthamalus
stellatus in the rocky intertidal is limited by competition
for space with Balanus balanoides. In my study, overgrowing
by colonial organisms was only noticed twice, but in each
instance the bottom organism was dead. This overgrowing could
affect the number or size of individuals.
The monopolization of limited resources has been
found to affect community develop~ent. There will start to be
interspecific competition (interference) for the limited
resource as the number of individuals and species (diversity)
increases. As the competitively successful species become
dominant, the less successful will drop out of the community,
29
and the dive'rsity will decrease (Grig;; and Maragos 1974). In
the present study, competition for space was never intense
enough, even on the twelve month plates, so that there was
a decline in the number of attached species. A comparison of
the climax community on the docks and that on the twelve month
plates shows that the number of species on the plates might
decline as development continues.
Grigg and Maragos (1974) while working on coral diver
sity in Hawaii, found that during the succession of a biolog
ically accomodated community, the diversity would be expected
to increase steadily, reaching a peak value at or near the
climax. Also, competition and preda t_~on would "provide regu
lation and therefore confer stability to the community".
Physically controlled communities usualJ.y show a diversity
peak at an intermediate stage. The development of the fouling
com:rnunity at Alameda fits in between these two extremes,
showing characteristics of both biologically accomodated
and physically controlled communities.
Odum (19?1) states that succession lS composed of "an
orderly process of community development that involves changes
in species structure and community process with time''. Scheer
(1945) at Newport Harbor, California, found that the develop
mental sequence of organisms on experimental panels leading
to a climax co~munity was not dependent on the time of year.
This does not happen at Alameda. Interpretation of the Index of
Similarity values shows that earlier organisms were not
30
essential for settlement of later ones, organisms did not
disappear as the development of the co!nnmni ty took place, and
settlement was dependent on when the larvae or spores are
present in the water. Thus, development of the community was
via a seasonal progression and not a true succession. These
were also the findings of Coe (1932) and Coe and Allen (1937)
at La Jolla, California, Weiss (1948) in Biscayne Bay, Florida,
Kawahara (1962, 1963, 1965) in Japan, and others.
In conclusion, it is hoped that this study will aid
others in understanding certain aspects of the biology of
some of the organisms in San Francisco Bay. Additional studies
of this type must be carried otl.t to determine more about the
life histories of individual species, the year-to-year fluc
tuations in the species composition, the seasonal variation
in growth under different environmental situations, and
interactions between different populations. Only then can any
far-reaching conclusions be drawn.
LITERATURE CITED
Aleem, A.A. 1957. Succession of marine fouling organisms on test panels immersed in deen water at La Jolla, Calif;rnia. Hydrobiologica,-~: 40-58.
Allen, F.E. and E.J.F. Wood 1950. Investigations on underwater fouling. II. The biology of fouling in Australia. Result of a year's research. Aust. J. Mar. Freshwater Res., 1= 92-105.
Coe, W.R. 19J2. Season of attachment and rate of growth of sedentary marine organisms at the pier of the Scripps Institution of Oceanography, La Jolla, California. Scripps Inst. Oceanography, Bull. Tech. Series, }: J7-87.
Coe, W.R. and W.S. Allen 19J7. Growth of marine organisms on experimental blocks and plates for nine years at the pier of the Scripps Institution of Oceanography. · Scripps Inst. Oceanography, Bull. Tech. Series, 4: 101-1J6.
Connell, J.H. 1961. The influence of interspecific competition and other factors on the distribution of the barnacle Chthamalus stellatus. Ecol., 42: 710-72J.
Crisp, D.J. 1957. Effects of low temperature on the breeding of marine animals. Nature (London), 122.: 11J8-·11J?.
Engle, J .B. and V .L. I!oo~anoff 1944. On seasons of attach,'71.ent of the larvae of Mvtilus edulis. Ecol., gj_: 4JJ-440.
Fell, P.E. 1970. The natural history of Haliclona eshasis de Laubenfels, a siliceous sponge of California. Pacific Science, 24: J81-J86.
Fuller, J. 1946. Season of attachment and growth of sedentary marine oY'ganisms at Lamoine, Maine. Ecol., gz: 150-158.
Ganapathi, P.N., M.V. Lakshmana Rao and R. Nagabhushnam 1958. Biology of fouling in Visakhapatnam Harbour. Anhra. Univ. Mem. in Oceano., _62: 19J-209.
Goodbody, I. 1961. Continuous breeding in three species of tropical ascidians. Proc. Zool. Soc. Lond., l}Q: 40J-409.
Graham, H.t'J. and H. Gay 1945. Season of attachment and growth of sedentary marine organisms at Oakland, California. Ecol., 26: J75-JS6.
Jl
32
Grave, B.H. 1~33. Rate of growth, age at sexual maturity, and duration of life of certain sessile organisms at Woods Hole, Massachusetts. Biol. Bull. , .§2: 37 5-386.
Grigg, R.W. and J.E. Maragos 1974. Recolonization of hermatypic corals on submerged lava flows in Hawaii. Ecol., 22: 387-395.
Gulliksen, B. 1972. Spawning, larval settlement, growth, and distribution of Ciona intestinalis L. (Tunicata) in Borgenfjorden, North-Trondelag, Norway. Sarsia, 21.: 83-96.
Harger, J.R.E. 1968. The role of behavioral traits in influencing the distribution of two species of sea mussel, Mytilus edulis and Mytilus californianus. Veliger, 11: 45-49.
Kajihara, T., R. Hirano and K.Chiba 1975. Marine fouling animals in the Bay of Hamana-ko, Japan. Veliger, 18: 361-366.
Kawahara, T. 1962. Studies on the marine fouling communities: I. Development of a fouling community. Rep. Fac. Fish. Prefect. Univ. Mie., 4: 27-41.
Kawahara, T. 1963. Studies on the marine fouling communities: II. Differences in development of the test block communities with reference to the chronological differences of their initiation. Rep. Fac. Fish. Prefect. Univ. Mie., ~: 391-418.
Kawahara, r·., 1965. Studies on the marine fouling communities: III. Seasonal changes in the initial development of test block communities. Rep. Fac. Fish. Prefect. Univ. Mie., 2: 319-364.
MacGinitie, G.E. and N. MacGinitie 1968. Natural history of marine animals. Second edition. McGraw-Hill Book Co., New York, 523 pp.
Maturo, F.J.S. 1959. Seasonal distribution and settling rates of estuarine bryozoa. Ecol., 40: 116-127.
McDougall, K.D. 1943. Sessile marine invertebrates of Beaufort, North Carolina. Ecol. Monographs, l}: 323-374.
Millar, R.H. 1958. The breeding season of some littoral ascidians in Scottish waters. J. Mar. Biol. Ass. U.K., J..1: 649-652.
Nair, N.B. 1962. Ecology of marine fouling and wood-boring organisms of Western Norway. Sarsia, 8: 1-88.
JJ
Nair, N.B. 1967. The settlement and growth of major fouling organisms in Cochin Harbor. Hydrobiologia, }Q: 503-512.
Nicol, J.A.C. 1960. The biology of marine animals. Interscience Publishers, Inc., New York, 707 pp.
Odum, E.P. 1971. Fundamentals of ecology. Third edition. W.B. Saunders Co., 574 pp.
Orton, J.H. 1920. Sea temperature, breeding and distribution in marine animals. J. Mar. Biol. Ass. U.K., 1£: 339-366.
Parker, G.H. 1924. The growth of marine animals on submerged metals. Biol. Bull., ~: 124-142.
Patrick, R., M. Hahn, and J. Wallace 1954. A new method of determining the pattern of the diatom flora. Academy of Nat. Sci. of Phil. : Notulae Natural, ill·
Paul, M.D. 1942. Studies on the growth and breeding of certain sedentary organisms in the Madras Harbour. Proc. Indian Acad. Sci., 12: 1-42.
Pomerat, C.M. and C.M. Weiss 1946. The influence of texture and composition of surface on the attachment of sedentary marine organisms. Biol. Bull., 21: 57-65.
Pyefinch, K. 1950. Notes on the ecology of ship fouling organisms. J. An. Ecol., 12.: 29-J5.
Reish, D. 1964. Studies on the Mytilus edulis community in Alamitos Bay, California. I. Development and destruction of the community. Veliger, Q: 124-131.
Ryland, J.S. 1965. Catalogue of main marine fouling organisms. Volume 2. Polyzoa. Organization for Economic Co-operation and Development, France,. 82 pp.
San Francisco Bay Conservation and Development Commission 1969a. San Francisco Bay Plan. 4J pp.
San Francisco Bay Conservation and Development Commission 1969b. San Francisco Bay Plan. Supplement. 5'?2 pp.
Sastry, A.N. 1963. Reproduction of the bay scallop, Aequinecten irradians Lamarck. Influence of temperature on maturation and spawning. Biol.. Bull., 12S: 146-1.53.
34
Sastry, A.N. 1968. The relationship among food, temperature and gonad development of the bay scallop, Aequipecten irradians Lamarck. Physiol. Zool., 41: 44-53.
Scheer, B.T. 1945. The development of marine fouling communities. Biol. Bull., ~: 103-121.
Shelford, V.E. 1930. Geographic extent and succession 1n Pacific North American intertidal (Balanus) communities. Pub. Puget Sd. Mar. Biol. Stn., 1.: 217-222.
Siegel, S. 1956. Nonparametric statistics for the behavioral sciences. McGraw-Hill Book Co., New York, 312 pp.
Sorenson, T. 1948. A method of establishing groups of equal amplitude in plant sociology based on similarity of species content. K. Danske. Vidensk. Selsk., Biologiske Skrifter, 2: 1-34.
Vernberg, W.B. and F.J. Vernberg 1972. Environmental physiology of marine animals. Springer-Verlag, Inc, 346 pp.
Visscher, J.P. 1928. Natur2 and extent of fouling of ships' bottoms. Bull. Bur. Fisheries, ~: 193-252.
Weiss, C.M. 1948. The seasonal occurrence of sedentary marine organisms in Biscayne Bay, Florida. Ecol., ~: 153-172.
Woods Hole Oceanographic Institute 1952. Marine Fouling and its Prevention. United States Naval Institute, 388 pp.
Zar, J.H. 1974. Biostatistical Analysis. Prentice-Hall, Inc., 620 pp.
35
Figure 1. Map of San Francisco Bay. Parallel straight
lines Sj-mbolize water. Insert shows Alameda
Marina (A), Oakland Estuary (B) and Govern
ment Island (C). At point D, Latitude is
)8°00' N and Longitude is 120°00'W. Total
scale equals 4 miles.
Figure 2. Rack with fifteen plates in place. Scale equals 15 ern.
PVC tubing
a) Restraints are attached to the rack with stainless steel bolts and keep the plates from falling out of the rack.
J8
Figure J. Suspension of rack, side view. Scale equals 15 em.
Stainless steel cable
Restraint
39
Figure 4. Measurement of upright species. Scales represent
parts of body rnea~ured. Measurements expressed in
mrn in text.
L;.o
Ascidia ceratodes
Ciona intesti~alis
Molgula manhattensis
Balanus improvisus
Mytilus edulis
41
Figure 5. Settlement times of the fouling organisms at
Alameda Marina. Solid line indicates settlement
on 1 and 2 month plates; dotted line, settlement
only on 2 month plates.
Diatom film Melosira sp. Entermorpha sp. Ulva lobata
Zoothamniwn sp. Folliculina sp. Stentor sp. Suctorians Unidentified protozoans
Halichondria bowerbankia Haliclona sp. Scypha sp.
Obelia longissima Syncoryne sp. Unidentified hydroid
Flatworm egg cases
Polydora sp. Mercierella_ enigmatica
Tricellaria occidentalis Bugula californica Bugula neritina l1!embrani pora membranacea Cryptosula pallisia~a Smittoidea prolifica Bowerbankia gracilis Alcyonidiwn polyown Farrella elongata Electra crustulenta Unidentified bryozoans
Corophitun sp. Balanus improvisus Balanus crenatus 'i3alai1uS s p .
!:!ytilus edulis Osuea lurida
Barentsia sp.
Botryllus sp. Botrylloides sp. Family Botryllidae i.fol~ula manhattensis Ascidia ceratodes Styela clava Ciona inteStinalis
42
Collectian dotes
1975 1976
.-1 ,-; w ,o "' 0 w ""
,, "' co "" ~ ..-;
(\4 rl .-1 .-1 ,_ ' " ---- ('J ('~ ~ ('J
" --, " ' '- ---- 0 .-1 ~ ~ " " " " ~' -D t'- tO C'· r~ ,.-j r-1 , .. ,., (·~ ..-, '-1
----·······
-------·······
--------- .... - .. -·. . . . . . . .......
------····-
··---------------- " ........
-----------··----· .. ·---------··-------
-------- .. ·--
4J
Figure 6. Numbers and growth of Nlembranipora membranacea with
season. For Figures 6 to 16, the top graph indicates
the total number of individuals and the bottom graph
shows the mean size + 1 S.E. of the three largest
individuals that settled on three 1 and three 2
month plates (total plate area for each month equals
600 cm2). Solid line represents 1 month plates;
dashed line, 2 month plates. Arrow point indicates
that error bar extends up above scale.
160
150
140
lJO
120
110
100
s.. 90 Cl> p E :::l 80 z:
...... C1l 70 .., 0
E-< 60
50
40
JO
20
10
0
eoo
700
600 (\/
! 500
~ 400 .... {/)
s:: )00 C1l Q)
:.:: 200
100
0
I I I I
I 1-
,, II I 1 I I I I I I I I I I I \ I I I \ I \ I I I I I I I I I l I I I I I I
l ! \ \ \
\ \ \
A
i
\
A /f\
\
I \ I I I I \ I \
\
I \ I l \ / \~' \
\ \
i 1 \ I \ I I I I I \
~ I -t--- \_ -·-~~--~--~=r--~--~=---~~~~---~~~. --~
NU +:"\./\ Q-,~ OJ'-0 ,_.. ,_.. ~ ~ ~ ~ ~ ~ ~ ~ 0 .... N N N N ,_.. ,_.. >-• ,_.. ~~ a- a- ~ .... OJ a- u 0 OJ \.1\
19? 5 Collection dates
..... N ~ u
..... N ~ u
44
1976
45
Figure 7. Numbers and growth of Cryptosula pallasiana with
season. For explanation, see legend Figure 6.
25 1\
20 I \
1-< I \ Ql I I p E 15 \ I \ =' z \ I \ r-i 10 \ I \
111 \ +> / 0
E-1 5 I I
/ 0 -·
400
)50
I JOO
C\J 250 ,-J T E I
E
Ql 200 t-1 ~
" {/} 150
r:: cO " C1l 100 " ::E '\T
50 l } " \ _...r-....~
0 '[-- ---- -----~ N \.,.) +:- \.;'\ 0\ --J co \0 t-" t-" 1-" t-" t-" N \.,.) +:-
.......... .......... .......... .......... .......... .......... .......... .......... .......... 0 1-" N N .......... "'-. .......... "'-. N N N N N ~ 1-" 1-" 1-" .......... .......... "'-. .......... N N N N \Q 0\ ~ \.,.) ~ co 0\ \.,.) 0 co \.;'\ lu.l \.,.) co \.;'\ +:- 1-"
1-"
1975 1976
Collection dates
47
Figure 8. Numbers and growth of Smittoidea prolifica with
season. For explanation, see legend Figure 6.
60
50
40
20
10
0
so
70
;; 6o
~ ..... 50
Q)
~
•ri 40 til
s:: ~ JO
;:;::
20
10
D I ~
.......... N '\C)
( j
N w ~
.......... .......... .......... N N N 0'- 0'- w
I /
/
I /
I
I
1\ I \
I \ I \
I \
I I
I \ I \
\ \ \ \
\--·- -·- -·-
I
\I I I I ....... I '
A \
\ \
I \ -... . 1----.--- --~--~
~ 0'- --J CD -..() ,___.
~
.......... .......... .......... .......... c 1-' N ~ ~ I-' ~ .......... .......... I-' CD 0'- w 0 CD V\
1975 Collection dates
48
------, ' ~ 1-' I-' N w ~ N N .......... .......... .......... ..........
.......... .......... N N N N u w CD V\ ~ ~
~
1976
49
Figure 9. Numbers and growth of Balanus improvisus with season.
For explanation, see legend Figure 6.
J " ~ '" ' .., ,; "' > .,, __ 1, ,, 0 • ' \; ' ! •• -1~ ·} ·~" < ·--~ " ~~~':( -1>. ' ',· - ' ' • '., - .... ; ~ •
~ ~ • ~ .} :'\ " "- >- : - \ \,. ' • ; ~ ,(, .o') ,• • ' t~ I' " 4 <'
70
60
50
I-< Q) 40
..0 e ;J :z ~
~ JO 0 8
20
10
0
20
~ 15 Q)
~ 10 [/)
@ 5 Q)
::;;:
I I I I I I
/\ I \ I \
I
II I I I \
I I I I I I I
1975
\ I I I I I I I \
' ' \ \
\
\ \
Collection dates
...... ....... ....... >~ N N
......... ......... ......... '-" \...) \...)
......
1976
50
I
I I
I
I I
51 ..
Figure 10. Numbers and growth of Mytilus edulis with season.
For explanation, see legend Figure 6.
10 r..
,-4Q)
5 ro.o ...., e 0 ::l E-<Z
0
1
L~=== )0
25
e 20 e
Q)
15 ~
~
Ul
c 10 ro Q)
~ 5 ./
0 ./
.... N '._.) ~ V\ 0\ -..J ClJ '-() ,_. ,_. .......... .......... .......... .......... .......... .......... .......... .......... .......... 0 ,_. N N N N N ....... .... ..... ....... .......... .......... \Q 0\ (1'\ \....) .... r:n 0\ \....) 0 (0 VI
1975
Collection dates
,..... N
.......... \....)
], If I
I I I I I I \ I I I I I \
52
--~--!----._\ ,_. ,_. N I...J ~
N ..........
.......... .......... .......... .......... N N N I'J
\....) ()) V\ +- ,_. ......
1976
53
Figure 11. Numbers and growth of Botryllus sp. with season.
For explanation, see legend Fi~Jre 6. Arrow
points indicate that error bars extend up
above scale.
)5
)0
25
20
15
10
5
0
1700
1600
1500
1400
1)00
1200
1100
~1000
~
Q)
N
900
;:;j Boo c ~ 700 :E
600
500
400
)00
200
100
0
,...... / '\ ...... / \
'-/ \
' \ \
\
l l 11 'i I I' 'I . \
. il· \ I I I \ 1 I
\ I I I /
1 I
\ / \. T I I \I
I
I I 1
\ \
!( I / 11\
I I 1
I I
\ ..,.., . / \
\ \
\
' '
11 \
\ ~I I
I [ I \.i. t// \ I/ l '
! I I I I I I
\.!\ a.. .......... .......... N ,_. ..... co
f \ 1 " ...... ..... 0 .....
.......... .......... OJ V\
...... N
~
1975 Collection dates
'
I I
1976
I I
I
54
55
Figure 12. Numbers and growth of Botrylloides sp. with season.
For explanation, see legend Figure 6.
25
s.. 20 Cl> .0 e 15 :l z. ...-1 10 as ..... 0·
5 E-o
0
900
800
700
...... 6oo C\1
! 500 Cl> 1'1 400 oM
en s:: JOO ro (I)
::: 200
100
0
____ , / \
I \ I \
I \ ,I
/ \
/ .
~--~~--------~~~~-/_/_/_~~~----------~'\--\~''~--~----~
(]'\ "'-l co ........... ........... ........... ..... ..... ..... co (]'\ \...}
1975 Collection dates
\
._.. N \...l ........... ........... ........... N i\) N co V\ +="
1976
/ /
57
Figure 1.3. Numbers and growth of Family Botryllidae with
season. For explanation, see legend Figure 6.
• "' ~ •• ' «-...."' '"" ., " __, .. "~..-,~"" ~ ' ~
; ~· ' <'" '•4' •' • 'I I •:·~~ ~. ~ I • ' <" 4 •, [ • • ) "• •' ,t ' / ' ' ~ ~ I ';
\
\
0
)5,
)0
C\1 25 e l T I
I e 20
Q.) I \ T I ~
''{ -I 15 I If) I c rl (II 10 Q) /----v ::;;;: / 1
5 ///.
0 - ,.:.. iv --(,., 0-. ~ Co u ~
........ ........ ........ ........ ........ ........ ........ ........ N N 1\) 1\) N .... .... .... -o a-- a-- u .... OJ a-- u
-D ,.:.. ,.:.. ........ 0 .... .... ........ ........ 0 OJ '-"
1975 Collection dates
\ \ \ \ \ \ \
.... N
........ u
\ \
\
-----.---.... --- ... .... N N ........ ........ ........ N N u Q:l '-" ....
I I I I I I
I I I I I I I I I I
I I
J
---- ... -·-l:-u
'--... ........ N N ..,. ....
1976
58
59
Figure 14. Numbers and growth of Molgula rnanhattensis with
season. For explanation, see legend Figure 6.
' A • ~, • ,. "- - • -,, ·~' • "• ' \ ' < t -;. ,.""' ,r •, '; :
' ' •, :. • lo ~ ' "- • • I 1
•:_, ~~"<,>' 1 '\ ' 'f • .., ~ ,.,., ,' ~ ( • " • •
1
' " t • > f '~ '
~ 50 /I
I I
I 1
I I
40 I \
I I
'"' l I ~ I .c I e I =' I z:. JO
I I ,...;
I I ro \ +> I 0
E-< I I 20 \
I I \
I \
10 I I '
~ ' ' I ' I " ............ --' ' ,.,.......
;...--
0 "'""' --· 25 1
~ 20
- ' ',·--L ~ 15 c-1
•.-i Ul 10 !: Cll ~ 5 ~
0 ~ N w +=" V\ a-. --.J OJ "' ~
,.... ~ ~ ~ N w -
" " " " " " " " " 0 ~ N N " " " "'-N N N N N ~ ~ ,.... ~ " " " " N N N N -a a-. a-. w ~ OJ a-. w 0 co V\ w w co V\ +:- ~
1975 ~ 1976 Collection dates
,
) L
Figure 15. Numbers and growth of Ciona intestinalis with
season. For explanation, see legend Figure 6.
62
90 ~ ,,
80
I\ I' 70 \\
6o I I I I I
s. I 11 50 I
,, ,/:)
I' 6 ,, ;:1
\1
z I .-1 I tU
I +' 40
\1
0 I ~
I I
1\ JO
r .\ l I I
20 I
10 f ;A} __ . .--
0
60
50
~ 40 l I ' T T
~ )0 / 1--L /'1 .... rn I 'l, ~ 20 y Ill ::E 10 '\.
0 ... 1'\) w .e- VI a- ....., ,., '-JJ .... .... ... ... N 'vJ ~ ........ ........ ........ ........ ........ ........ ........ ........ ........ 0 ... N N ........ ........ ........ N N N N ~J ... ... ... ... ........ ........ ........ ........ N N N N '-JJ a.. a- w ... co 0.. w 0 CJ VI w w co VI +=" .... ....
1975 1976 Collection d::J.tes
' ·· - ,. •.· ...
• . ""' ~ ,. I ~~ { w<(:-'
63
Figure 16. Numbers and growth of Ascidia ceratodes with
season. For explanation, see legend Figure 6.
~
20
~ 15 ..0 e i 10
0
50
40
e e -30
Q)
N
"" {/)
~
~ 20 ::;::
10
0 ....... N \...) .z ........ ........ ........ N N N N \Q 0"- 0"- \..;.)
/ /
\ \ \ \ I
r I I /
/ /
V\ 0"- -...J co \Q
........ ........ ........ ........ ........ N ....... ....... ....... ....... ....... co 0"- \...) 0
1975 Collection
/I \ I \ I \ I \
....... 0
........ co
dates
;\ / \
I \
\
--I, ....... ....... ....... ....... N N
........ ........ ........ \.1\ \...) \...)
.......
' ....... ........ N co
64
I
I I
I
--------~
\
I \ I \ I \ r I \
I \
I I I
I I I
N \...) +=" ........ ........ ........ N N N \.1\ +:- .......
1976
Figure 17. Number of Mercierella eni@1atica with season.
Total number of attached individuals that settled
on three 1 and three 2 month plates (total plate
area for each month equals 600 cm2). Solid line
represents 1 month plates; dashed line, 2 month
plates.
r... 15 (])
~ 10 :I z
5
0
I !
t_ .....
-........ N \C)
N w ~
-........ -........ -........ N N N 0"- 0"- w
' ..--"-........ , ~······ ..... ... '
1..1\ 0"- -.;) (1) '-0 -........ -........ -........ -........ -........ N ..... ..... ..... .... ..... (1) 0"- w 0
1975 Collection
- ,, ' · .: > .· ,· . ·,·_ ·:~'- · . '_ ~ _ •. cr..:p...,', "··. · .
66
'- -~~ ..... ..... ..... - ..... N w ~ 0 ..... N N -........ -........ -........ -........ -........ -........ -........ -........ N N N N (1) 1..1\ w w (1) 1..1\ ~ ..... ......
1976 dates
' " ~)-, ... ""' ~ ; ~
;, ... ·' .,-~:·. ~! . ·:t---
67
Figure 18. Salinity and water temperature at Alameda Marina.
•
68
4/21
J/24 \,() c-..
2/25 0'\ ~
1/28
12/31
12/J
11/5 (fl
10/8 (I)
+> ro 'tl
9/10 ~ 0
8/13 ...... +> (..)
7/16 "' (I)
c-.. ,.....f 0'\ ,.....f ~ 0
6/18 0
5/21
4/23
J/26
2/26
1/29
1/1 N 0 a) \,() ~ N 0 a) N N ~ -rl -rl -rl -rl
OaJ'-0 ~ N 0 a:> '-0 C'"\ N N N N N -ri -ri
(I)
• ~ ::::1
+> ro ~ 0 Q,l 0 I
p.. E Cll
E-<
Table l. Schedule of plate placement and replacement.
MONTH DATE
l month plates (A)
2 month plates ( 8)
2 month plates (c)
6 month plates (D)
12 month plates (E)
l l 2 J 4 5 l 29 26 26 23 21
6 7 8 9 10 ll 18 16 13 10 8 5
12 12 l J Jl 28
2 J 4 25 24 21
P ._ R ~ R .,. R .,. R .,. R .,. R .,. R • R_.
P---------____.,.. R ---------___..,. R ------------1~
p R--------------~
P Placement of plates
R - Replacement of plates
70
Table 2. ...
Comparison, using Mann-Whitney test, between total number and mean growth of the individual quantified specie~ found on front versus back of plates, during the entire study. 51-one month plates (J per month, 17 months) and 48-two month plates (3 per month, 16 months) were used.
Z VALUES Z VALUES MONTHS OF FOR FOR
ORGANISM SUBMERGENCE NUMBERS a GROWTH a
Mercierella 1b 0.))1 NO DATA eniEQgatica 2c 0.478 NO DATA
Membrani:Qora 1 0.046 0.163 membranacea 2 0.259 0.239
Smittoidea 1 0.049 0.030 prolifica 2 0.573 0.523
Cryptosula 1 1. 389 1.301 :Qallasiana 2 1.121 0.274
Balanus 1 0.295 0.008 im12rovisus 2 0.598 0.76?
Mytilus 1 0.272 0.257 edulis 2 1.130 0.422
Botryllus sp. 1 O.J67 0.519 2 0.304 0.998
Botrylloides sp. 1 0.849 0.5J5 2 0.348 0.664
Family 1 0.472 1.265 Botryllidae 2 0.450 0.127
Mol@la 1 0.500 0.703 manhattans is '2 0.384 0.1J2
Ciona 1 0.205 0.115 intestinalis 2 0.109 0.515
As~idia 1 0.240 0.518 cera to des 2 1.046 1/124
a) Z values were calculated by the method of Siegel (1956). b) critical value (~=0.05, D.F.=51) = 1.960 (see Zar 1974,p.112) c) critical value (~=0.05, D.F.=48) = 1.960 (see Zar 1974,p.112) No significant difference is seen in the above values.
Table 3. Multiple correlationsr total number and average growth of each quantified species on 3-one and 3-two month plates versus temperature and salinity (average during period of submergence). There was 17-one and 16-two month periods.
~
CORRELATION COEFFICIENTS CORRELATION COEFFICIENTS MONTHS OF OF NUJVIBER VERSUS OF GROWTH VERSUS
ORGANISM SUBMERGENCE TEMPERATURE SALINITY TEMPERATURE SALINITY
IVlercierella 1a 0.421 0.033 NO GROWTH DATA eniRmatica_ 2b 0.470 -0.302 NO GROWTH DATA
* Membrani:Qora 1 -0.050 -0.'?67* 0.180 -0.370* membranacea 2 -0 .184 -0.827 0.108 -0.657
* 0.076 * Cry"Qtosula 1 0.483* 0.493* -0.018 :Qallasiana 2 0._566 0.259 0._586 -0.050
Smittoidea 1 0.)43 0.034 0.)43 0.034 _prolifica 2 0 ,1}18 -0.139 0.466 -0 .192
* * Balanus 1 0.567* 0.029 0.628* -0.231 im:Qrovisus 2 0.499 -0.214 0.498 -0.436
Mytilus 1 0.138 -0.617 * 0 ,l.J-60 -0 .140 edulis 2 -0.059 -0.293 -0.102 -0.159
* * Botryllus sp. 1 0.583* -0 .115 0.616* -0.039 2 0. 835 0.044 0.497 -0.337
* * Botrylloides sp. 1 0.750* 0.394 0.647* 0.247* 2 0.661 0.462 0.825 0.498
* * * Family 1 0.658* 0.482* 0. 61~8* -0.171 Botryllidae 2 0.549 0.594 0.783 0.124
'
-..J ........
Table 3. (cont.)
CORRELATION COEFFICIENTS CORRELATION COEFFICIENTS MONTHS OF OF NUMBER VERSUS OF GROWTH VERSUS
~
ORGANISM SUBMERGENCE TEMPERATURE SALINITY TEMPERATURE SALINITY
-0.054 * -0.063 Molgula 1 0.477 0.499* manhattensis 2 0.396 -0 .188 0.758 0.029
* * Ciona 1 0.312 0.205 0.536* 0.548* intestinalis 2 0.382 0.317 0.526 0.548
* * Ascidia 1 0.803* 0.435 0.682 0.284 ceratodes 2 0.522 0.460 0.259 0.419
* - significant difference a) critical value of r0.05(2),15 == 0.482 (from Zar 1974) b) critical value of r0.05(2) ,14 = 0.497 (from Zar 1974)
Table 4. Multiple correlationsr total number of attached species on )-one and )-two month plates versus temperature and salinity (average during period of submergence) over the entire study. There was 17-one and 16-two month periods.
* a) b)
MONTHS OF SUBMERGENCE
- significant difference
critical value of r0.05(2) ,15 critical value of r0.05(2),14
=
=
CORRELATION COEFFICIENTS OF NUMBERS VERSUS
TEMPERATURE SALINITY
0.901 0.8)4
0.482 (from
0.497 (from
* *
Zar
Zar
0.199 0.)01
1974)
1974)
Table 5. Index of Similarity (S) expressed in percent. All collections referred to were made in 1975.
S _ 2 x number of species in common to both months x 100 - number of species in month A plus number of species
Jan (1) 100.0
June (1)
Aug ( 1)
Dec ( 1 )
June ( 6)
Dec (6)
Dec (12)
(1) = 1 month submergence (6) = 6 months submergence (12)=12 months submergence
in month B
19.0 9.1 66.7
100.0 64.9 41.7
100.0 46.6
100.0
20.0 8.7 8.7
80.0 57 ·9 68.4
50.0 8?.2 ?6.9
29.6 46.7 46.7
100.0 54.1 69.4
100.0 85.0
100.0
MONTH : refers to the month in which the plates were collected and analysed. For example, June (1) plates placed May 21 and collected June 18.
