Introduction
Because of the photosynthetic capacity of phytoplankton,
all animals in the marine environment are ultimately dependent
on them for sustenance. It is therefore of primary importance
to determine the effectsof water quality on their survival
and abundance.
The location of Point Pinos, where the following study
was carried out, proved favorable for such an analysis because
phytoplankton in Monterey Bay have been studied extensively.
(Bolin & Abbott, 1963) Annual cycles of increases and decreases
in phytoplankton numbers are fairly well understood. The
different resident species have been followed through their
anal cycles and their blooming behavior has been recorded.
Effects of upwelling and resultant high quantities of nutrients
on phytoplankton abundance have been observed. Periods of
high and low diversity in plankton populations during the
different marine seasons has been determined. Thus, a large
body of data have been collected regarding phytoplankton in
Monterey bay which could be compared with possibly ahnormal
data collected at Point Pinos.
It is known (Raymont, 1963, and Goldman, 1969) that in
areas subject to high concentrations of inorganic and
organic waste material, phytoplankton growth is promoted and
abnormal blooms result. Often particular species survive better
than others under such conditions and the natural assortment
of phytoplankton species is disrupted. Although natural
conditions may be altered, there may or may not be harmfulseffects.
If the bloom becomes very thick, increasing water turbidity, it
can reduce light reaching bottom algae, thereby affecting their
Introduction
cont d.
photosynthetic capability. The dissolved oxygen concentration
in the area of the outfall may be adversely affected during
phytoplankton blooms. At night when the phytoplankton use
rather than produce oxygen, they may deplete the supply available
to other organisms which could normally live in the same
vicinity. In addition, if the phytoplankton produce oxygen
near the sunlit surface, and consume oxygen on the bottom
(phytoplankton move downwards in the night) the oxygen balance
will be upset. When the dissolved oxygen concentration is
reduced organic wastes cannot be oxidized and will accumulate
on the sea bottom in harmful amounts (Marine Advisors, 1956,
and Prager, 1969).
Materials and Methods
Part 1
A series of phytoplankton samples were collected at 8
stations (Figure 1) around Point Pinos once a week for 4 weeks.
On each sampling day, collections were made at 6:00 am, 12:00
noon, and 6:00 pm. Sampling was completed within ig hours.
Samples were collected from shore with a + meter fine mesh
phytoplankton net. 4 buckets of water (32 liters) were
poured throughthe net and milked into small bottles.
Offshore samples were collected on "The Tage" on 4 days.
When possible samples were collected from 5 stations. (Figure 2)
3 off Point Pinos, one off Lovers Point and one off Hopkins
Marine Station near the bell buoy. Due to unfavorable weather
conditions on one of the days, it was impossible to reach more
than 2 stations. Offshore samples were obtained by dropping
a weighted + meter phytoplankton net over the side of "The Tage
on a 25 foot line. It was dropped and pulled in 3 times at
each station. The net was not towed while the boat was moving
but dropped vertically while the boat was stopped. However,
due to the movement of the water, the tow was not always
completely vertical.
Samples were counted within 3 days of collection using an
Untermohl tube (Doty modification) and an inverted microscope.
The concentrated samples had to be diluted sufficiently in
order to count them. From the bottle (32 ml) into which the
sample was collected, a subsample of 5 ml was removed and
diluted with millipore-filtered sea water. The degree of
dilution depended on the concentration of sample. Most
samples, because of their density, had to be diluted 1:16.
9
Materials and Methods
Part I cont'd.
Phytoplankton in a portion (2.5 ml or the volume of the Untermohl
ml
tube which varied between 2.3-2.8) of the diluted sample were
counted. Organisms were allowed to settle in the Untermohl
tubes for  hour. A differential count was made of the
different genera present. Each cell in multi-celled organisms
such as Eucampia or Chaetoceros were counted as one individual.
Each sample took roughly 45 minutes to count. Approximately
30 different genera were counted, and the number of cells of
each genera present in one liter of sea water sampled was
calculated. Data from a representative day for all 3 sampling
times, appear in Tables 1, 2, and 3. Totals for all collection
days appear in Tables 4 and 5.
Part II
Samples of phytoplankton collected at Poing Pinos were
added to nutrient culture media (containing nitrates,
phosphates, silicates, trace metals, vitamins, and tris buffer)
in Erlenmeyer flasks and allowed to grow in the greenhouse at
"natural" sea water temperature (10-15° 0) and with natural
lighting. Each culture flask was swirled 30 times once a
day. A thick healthy culture grew in approximately two weeks.
This phytoplankton stock was divided into 250 ml
Erlenmeyer flasks to which sewage was added in various concentration
Two series of tests were run, one with Monterey sewage and
another with chlorinated Pacific Grove sewage.
The following amounts of sewage and control medium were
added to 100 ml aliquots of phytoplankton stock culture:
Materials and Methods
Part II cont'd.
Series
all diluted
100% Monterey sewage effluent
100 ml
in culture
100 ml 50% Monterey sewage effluent
media
100 ml 10% Monterey sewage effluent
100 ml millipore-filtered oceanic sea water
100 ml nutrient culture media
Series
II
100 ml 100% Pacific Grove sewage (chlorinated)
Pacific Grove chlorinated sewage diluted in
100 ml 50%
millipore-filtered sea water
100 ml 50% Pacific Grove chlorinated sewage diluted
in nutrient culture media.
100 ml 10% Pacific Grove chlorinated sewage diluted
in filtered sea water.
100 ml 10% Pacific Grove chlorinated sewage diluted
in nutrient culture media
100 ml millipore-filtered oceanic sea water
100 ml nutrient culture media
All sewage dilutions were brought up to the same salinity
as sea water with "Instant Ocean" sea salts.
Duplicate cultures were made of each of the above
dilutions. Cultures were grown in the greenhouse at sea water
temperature and each flask was swirled 20 times each day.
Cells in each culture were examined every two days for
approximately 2 weeks. A differential count was made of the
different genera present. A total of approximately 500 cells
was counted from each culture at each examination time and
percentageswof live and dead cells of each species present
were calculated.
Nutrient Culture Media
Each liter of media contains:
500 uM/1
Nitrate
50 uM/1
Phosphate
Silicate
50 uM/1
1 ml of the following trace metal mixture
0.30 mg ZnS04-H20
25 mg CuSO4-5H20
30 mg CoSO4-7H20
0.20 mg MnSO4-H20
0.50 g Fecl3.6H20
0.25 mg NaMo04.2H90
g Na2EDTA 2H20
5.0
and adjusted to a pH of 7.5 with dilute NaoH
0.10 mg Vitamin B12
1.0 ug Biotin
10.0 ug Thiamine
200 mg Tris Buffer
Use millipore-filtered oceanic sea water for media
Results
Part I
The data collected in the field do not show recurrent and
striking characteristics of the different stations which might
be a result of the presence of the outfall. However, the stations
(Figure 3) on the outfall (south and southeast) side of Point
Pinos (stations 1-5) averaged higher numbers of phytoplankton
than the stations on the opposite side of the point. In addition.
the stations (figure 3) offshore had far fewer individuals than
those close to shore at Point Pinos.
During the sampling period at Point Pinos a peak bloom
(83,000 cells/liter water, see Figure 4) of diatoms appeared
during the second week which decreased to a very small number
(7,000 cells/liter water) of individuals by the fourth week.
The predominant genus in this bloom was Eucampia, (25,000 cells/
liter water), while two other diatoms, Asterionella, (21,000 cells/
liter water) and Chaetoceros (16,000 cells/liter water) were
also numerous. (Figure 4) Offshore sampling was begun as the
first bloom tapered off. By the fifth week, offshore data
(Figure 5) show another minor bloom where the predominant
genus was Chaetoceros.
The samples included both diatoms and dinoflagellates,
but the blooms were of diatoms. In between the blooms, the
percentage of dinoflagellates in the samples increased.
The most recurrent and distinct characteristic of the
phytoplankton collections was the great abundance of plankton in
the morning samples (Figure 6) relative to the noon and evening
ones. It is typical of phytoplankton to exist near the surface
in the morning and then move downwards during the day.
Results
Part I cont'd.
It is apparent here that if one wished to accurately follow
day by day changes in the phytoplankton populations it would
he necessary to take uniform samples at the same time each day.
Part II
Series I
In the first set of phytoplankton cultures, grown in
Monterey sewage effluent, there were 3 species of diatoms
at the start of the experiment: Navicula, Nitzchia closterium
and Fragilaria. These species were the only ones that
survived in the experimental culture conditions in the green
house out of approximately 30 genera in the original samples
from which they came.
In the cultures containing each of the 3 dilutions of
Monterey sewage the percent of Navicula in the culture (Figure 7)
increased repidly for the first few days and remained at a
relatively high level throughout the experiment. In pure
sea water (Figure 7, lowest line) Navicula decreased on the
average, whereas in nutrient culture media it increased for
10 days and then drastically decreased.
The percent of Nitzschia closterium (Figure 8) in the
cultures dropped immediately in 50% and 100% sewage but
increased slightly in 10 sewage. The results from cultures
containing sea water and culture media were opposite from
those of Navicula. In sea water Nitzschia increased
immediately and in culture media it rose slightly at first
and then bloomed on the 1Oth day. In general, Navicula
Results
Part IIcont'd.
appears to survive in Monterey sewage while Nitzschia does
not.
On the 2nd day of the culture period Fragil aria decreased
in number to almost no individuals in every flask, including
4 controls, and never increased significantly again.
Series II
The second set (Figure 9) of cultures, grown in Pacific
Grove chlorinated sewage, showed similar results for Nitzschia
closterium but Navicula did not survive as well in Pacific
Grove sewage as it did in Monterey sewage.
Navicula decreased in all concentrations of sewage, but
most rapidly in 100%. Its behavior in sea water and nutrient
media cultures was essentially thegsame as in Series I.
In 100% and 50% sewage, Nitzschia as expressed by its
proportion to all phytoplankton decreased immediately and
in 10% it decreased slowly. In sea water it increased at
first and then fell slowly and in culture media it remained
relatively constant.
Fragilaria was scarce in all the Series II cultures
at the beginning of the experiment and remained that way
throughout.
Note: The results for the duplicate cultures run for each
dilution were very similar and values are averaged in figures
7-9. In Series II, results of the dilutions of 50% P.G.
sewage in 1) Sea water and 2) Culture Medium, were also very
close, and values for these are averaged in Figures 9 and 10.
The same was done with the 10% sewage cultures in Series II.
76
10
Discussion
Sewage effluent could possibly affect phytoplankton in
a number of ways depending on the kinds and concentrations of
the constituents of sewage. Sewage from a particular area
could contain poisonous or toxic substances (Marine Advisors,
La Jolla, 1956) which may be harmful to some species whereas
a different quality of sewage might enhance phytoplankton
growth.
It is not possible to conclude from the results obtained
in this study that the phytoplankton at Point Pinos are
abnormally affected by the effluent produced from the sewage
outfall. The higher number of plankton found at the 5 stations
on the outfall side of Point Pinos as opposed to the opposite
side suggests that a higher concentration of nutrients such as
nitrates and phosphates from the outfall may be causing the
increase. Station 1, a hook-shaped embayment directly south
of the outfall, and popularly called "Coliform Cove" may
physically trap phytoplankton and nutrients since this cove
faces the prevailing southwest winds. The further decrease in
numbers of phytoplankton collected offshore suggest an even
smaller concentration of nutrients present offshore. It is
often common however for there to be a higher number of
phytoplankton close to shore due to nutrients from shore runoff.
Whether the large abundance of phytoplankton at Point Pinos is
a result of fertilization by natural runoff or from the sewage
cannot be determined from the results of this study due to
lack of shore stations in a comparable area far from the
outfall.
11
Discussion
cont'd.
The kinds of genera found during the study were all
genera common to Monterey Bay at that time of year. There is
no reason to suspect that the Pacific Grove outfall causes
abnormal blooms of one species or another. The bloom observed
at the end of April consisting mainly of the diatoms Eucampia,
Asterionella and Chaetoceros, and the bloom of Chaetoceros
in May would not be unexpected. Chaetoceros has been recorded
(Bolin and Abbott, 1963) to bloom almost continually during
most of the year in Monterey Bay. During the upwelling season
(February-September) when nutrients are brought from deeper
depths to the surface, Eucampia and Asterionella are known to
bloom. Dinoflagellates on the other hand were always fewer
in number than the diatoms but occurred in larger relative
numbers as diatoms were decreasing.
The results from the laboratory cultures grown in this
study suggest that sewage may be both unfavorable and favorable
to phytoplankton. Growth of Navicula was promoted in Monterey
sewage. It was apparently able to take advantage of excess
nutrients in Monterey sewage. In Pacific Grove sewage on the
other hand, the percentage of Navicula in the culture decreased.
The difference between Navicula's behavior in Monterey and
Pacific Grove sewage may have been due to the excessive amount
ofchlorine added to Pacific Grove sewage after treatment, or
perhaps other toxic components of Pacific Grove sewage.
Nitzschia closterium is commonly regarded as a particularly
hardy species and able to withstand extreme conditions. In
this study however, unlike Navicula, it did not increase when
cultured in sewage. In 100% and 50% dilutions of both Monterey
12
Discussion
cont d.
and Pacific Grove sewage it disappeared in two days in every
culture and in 10% sewage it increased very little. These
results imply that in the field sewage would have varied
effects on different species of phytoplankton.
From the cultures in sea water and nutrient culture
medium, the two organisms appear to behave differently in the
presence of different nutrient supplies. It appears that
Nitzschis closterium could survive better than Navicula under
conditions of fewer nutrients as seen in the large percentage
of Nitzschia closterium in the pure sea water cultures and
the large increase of Nitzschia when Navicula suddenly decreased
in the Ist series of cultures. These results suggest that
genera could benefit differentially in different concentrations
of nutrients in the field. Certain species (Navicula for example)
could bloom when nutrients are plentiful and others (Nitzschia
closterium) when they are scarce. It has been said (Patrick.
1948) that the supply of nutrients is so closely correlated
with the abundance of diatoms that one could forecast succession
of diatom blooms from the type of nutrient supply.
13
Summary
The distribution of phytoplankton at Point Pinos was
studied by periodic sampling at 13 stations on and offshore.
Due to constant variability in phytoplankton distribution and
numbers hoth hour by hour and day by day, it was necessary to
take a large number of samples. Inshore samples were collected
once a week for four weeks. Three collections were made on
each sampling day at 6:00 am, 12 noon, and 6:00 pm. 32 liters
of water were sampled at each inshore station at each sampling
time. Offshore samples were vertical tows which sampled
approximately 1100 liters at each station, the net being dropped
3 times at each station. Offshore collections were also taken
once a week for 4 weeks but at one time of day only. Samples
were examined in 1-3 days after collection. A differential
count was made of each species present in each sample.
Counts showed that numbers of phytoplankton on the outfall
side of Point Pinos were always larger on the average than
numbers on the opposite side. In addition, offshore samples
had far fewer individuals than shore samples. These results
suggest that the phytoplankton nearest the outfall may benefit
from an excess of inorganic nutrients in the sewage, but this
cannot be conèluded from the data.
Mixed cultures of two species of diatoms, Nitzschia
closterium and Navicula were grown in different dilutions of
sewage from Monterey and Pacific Grove. The two species
behaved differently. Growth of Nitzschia
closterium was
inhibted by both kinds of sewage. Navicula grew well in
Monterey sewage but very poprly in Pacific Grove sewage.
0
Summary
cont d.
Nutrients in the sewage probably tend to promote growth while
chlorine or other toxic substances might act as inhibiting
factors.
Acknowledgements
I would like to give special thanks to Dr. Isabella
A. Abbott for the helpful advice she gave me throughout
this study. I would also like to thank Craig Blencowe,
Thomas Rotkis, and Gerald Kost for their assistance in
the field.
This work was supported in part by the National
Science Foundation Undergraduate Research Program Grant
Number GY7288.
Bibliography
Bolin, R.L., and Abbott, D.P., 1963, Studies on the Marine
Climate and Phytoplankton of the Central Coastal Area
of California, 1954-1960. California Cooperative
Oceanic Fisheries Investigations Reports. 9:23-44.
Goldman, Charles Remington, Primary Productivity in Aquatic
Environments, 1-464 University of Callfornia Press,
Berkeley, 1969.
Marine Advisors, La Jolla Calif., 1956, Sewage in Santa
Monica Bay; A Critical Review of the Oceanographic
Studies, Prepared for Californians Against Pollution.
Moberg, Erik G., The Interrelation Between Diatoms, Their
Chemical Environment and Upwelling Water in the Sea
off the Coast of Southern California, in Reish, D.J.
Biolog
of the Oceans, ix-x, 1-236, Dickenson Publishing
Co., inc. Belmont, California. 1969, 215-221.
Patrick, R., 1948, Factors Affecting the Distribution of
Diatoms, The Botanical Review, 14 (8):173-524.
Prager, F.C., 1969, Using Plankton in Marine Pollution Studies,
Maritimes, Univ. of Rhode Island, 13,(4) 4-5.
Raynont, J.E.G.,
Plankton and Productivity in the
963
Oceans, vii-xi, 1-688, Pergamun Press, London.
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no.cells per liter
of water sampled
100,000
90
80000
10000
60,000
50000
40000
30000
20.000
10000
FIGURE 3
A COMPARISON OF PHYTOPLANKTON NUMBERS OF 3 AREAS
STATIONS 1-5
HSTATIONS 6-8
STATIONS 13-17
no. cells per lite
of water sampled
(ave.of 8 stations
and 3 times of day)
80,000
60,000
40000 4
20000
FIGURE 4
PT.PINOS SHORE SAMPLES
VARIATION IN PHYTOPLANKTON NUMBERS
total: 30 genera of diatoms
and dinoflagellates
„Eucampia, Asterionella
and Chaetoceros
• • • ° Eucampia
— — — Asterionella
— ———— Chaetoceros



2S-2 9
April 30
May 1:
April 24, 1970
May 8
FIGURE 5
no. cells perlite
OFFSHORE SAMPLES
of water sampled
lave.of 5 stations)
VARIATION IN PHYTOPLANKTON NUMBERS
total: 30genera of
diatoms & dinof lagellates
Eucampia, Asterionella
—
& Chaetoceros
(Eucampia
8000
— — — Asterionelja
- - - - - Chaetoceros
6000
4000
2000

.
.
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May 1,1970
May 13
May 20
May 27
20

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100
80
60 +
40
20
10

12
100% SEWAGE
50% SEWAGE
10% SEWAGE
SEA WATER
NUTRIENT MEDIA
14
50
FIGURE 7
SERIES 1 MONTEREY SEWAGE
NAVICULA
of total
cells
counted
100
80 +
60
40
20
100 PERCENT SEWAGE
50 PERCENT SEWAGE
10 PERCENT SEWAGE
SEA WATER
NUTRIENT MEDIA
FIGURE 8
SERIES 1 MONTEREY SEWAGE
NITZSCHIA CLOSTERIUM
of tota!
cells
counted
100
80 7
60
40
20
FIGURE 9
SERIES 2 PACIFIC GROVE SEWAGE
NAVICULA
NITZSCHIA CLOSTERIUM
100 PERCENT SEWAGE
50 PERCENT SEWAGE
IO PERCENT SEWAGE
SEA WATER
NUTRIENT MEDIA