Green Tide Monitoring Survey for 1986
Results
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Draft Report on
GREEN TIDE MONITORING SURVEY FOR 1986
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Region II
26 Federal Plaza, Room 900
New York, NY 10278
Prepared by
SCIENCE APPLICATIONS INTERNATIONAL CORPORATION
8600 Westpark Drive
McLean, VA 22102
Under Contract to
BATTELLE
Ocean Sciences and Technology Department
397 Washington Street
Duxbury, MA 02332
June 23, 1987
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TABLE OF CONTENTS
1.0 INTRODUCTION.
1.1 BACKGROUND. 1
1.2 PURPOSE OF 1986 GREEN TIDE SURVEY. 2
2.0 SAMPLING PROGRAM. 2
2.1 GEOGRAPHIC AREA. 2
2.2 SAMPLING LOCATIONS AND SCHEDULES. 2
2.2.1 Nearshore Coastal Area. 2
2.2.2 Great Egg Harbor Area. 5
2.3 MONITORING PARAMETERS. 6
2.3.1 Field Measurements. 6
2.3.2 Chemical Measurements. 7
2.3.3 Biological Measurements. 7
2.4 CALCULATION OF NUTRIENT LOADS. 9
3.0 RESULTS. 10
3.1 SUMMARY OF ALL DATA. 10
3.2 INITIAL INVESTIGATIONS. 10
3.2.1 Means of Parameters over All Stations and Dates. 10
3.2.2 Correlation among Parameters. 10
3.2.3 ANOVA Analysis of Parameters. 13
3.3 VARIATION OVER SPACE. 13
3.3.1 Nearshore Coastal Area. 15
3.3.2 Great Egg Harbor. 20
3.4 VARIATION OVER TIME. 23
3.4.1 Nearshore Coastal Area. 23
Gyrodinium and Phytoplankton Abundance. 30
3.4.2 Great Egg Harbor. 35
Seasonal. 35
Tidal. 42
3.5 NUTRIENT INPUTS TO NEARSHORE COASTAL AREA. 42
4.0 DISCUSSION. 48
4.1 GENERAL BEHAVIOR OF NEARSHORE SYSTEM. 48
4.2 SIGNIFICANCE OF NUTRIENT INPUTS. 49
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LIST OF FIGURES
Figure 1. Locations of Sampling Stations.
a. North. 3
b. Middle. 4
Figure 2. Variation of Parameters over Space.
a. Nearshore Coastal Area.
i. Temperature, Chlorophyll, and Dissolved Oxygen. 16
ii. Total Nitrogen, Total Phosphorus, and Total Nitrogen
to Total Phosphorus Ratio. 17
iii. Inorganic Nitrogen, Inorganic Phosphorus, and
Inorganic Nitrogen to Inorganic Phosphorus Ratio. 18
b. Great Egg Harbor.
i. Temperature, Salinity, Total Nitrogen, and Inorganic
Nitrogen. 21
ii. Total Phosphorus, Inorganic Phosphorus, Chlorophyll,
and Dissolved Oxygen. 22
Figure 3. Variation of Parameters over Time.
a. Wind Speed and Direction Measured at Sandy Hook and
Atlantic City. 25
b. Nearshore Coastal Area.
i. Temperature, Chlorophyll, and Dissolved Oxygen. 26
ii. Total Nitrogen, Total Phosphorus, and Total Nitrogen to
Total Phosphorus Ratio. 27
iii. Inorganic Nitrogen, Inorganic Phosphorus, and
Inorganic Nitrogen to Inorganic Phosphorus Ratio. 28
iv. Macroplankton cell counts. 29
c. Great Egg Harbor (Seasonal).
i. Temperature, Salinity, and Total Nitrogen. 39
ii. Inorganic Nitrogen, Total Phosphorus, and Inorganic
Phosphorus. 40
iii. Chlorophyll and Dissolved Oxygen. 41
d. Great Egg Harbor (Tidal).
i. Temperature, Salinity, Total Nitrogen, and Inorganic
Nitrogen. 43
ii. Total Phosphorus, Inorganic Phosphorus, Chlorophyll,
and Dissolved Oxygen. 44
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List of Tables
Table 1. Analytical Procedures for Chemical Analyses. 8
Table 2. Means of Parameters over all Stations and Dates. 11
Tables. Correlations Between Parameters. 12
Table 4. Percent of Variance in Data Explained by Location and Time
Sampled. 14
Table 5. Correspondence between Sampling Week and Date, Summer,
1986. 24
Table 6. Abundance of Gyrodinium aureolum.
a. Nearshore Coastal Area (2 pages). 31
b. Great Egg Harbor. 33
c. Ocean City outfall Area. 34
Table 7. Abundance of Nanoplankton.
a. Nearshore Coastal Area. 36
b. Great Egg Harbor. 37
c. Ocean City outfall Area. 38
Table 8. Drainage Areas and Water Flows from Great Egg Harbor
Watershed. 45
Table 9. Nutrient Concentrations and Nutrient Loads.
a. Great Egg Harbor. 46
b Ocean City Sewage Treatment Plant. 47
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1.0 INTRODUCTION
1.1 BACKGROUND.
In the summers of 1984 and 1985, phytoplankton blooms occurred in nearshore New Jersey
coastal waters. These blooms lasted from late July to late August in 1984, and from early August to early
September in 1985. They caused obvious bright green color to develop in the water, and symptoms of
respiratory distress were possibly associated with their occurrence. Many public beaches were closed
during the blooms. Since the major use of the southern New Jersey coast is recreation, the blooms
posed a threat to local economies and became a focus of activity of three government agencies.
The U.S. Environmental Protection Agency (Region II) (EPA), the New Jersey Department of
Environmental Protection (NJDEP), and National Oceanic and Atmospheric Administration's National
Marine Fisheries Service (NMFS) have convened an Interagency Committee to investigate the causal
factors related to the occurrence of the "green tides" off the New Jersey coast. In the first year of
operation, an Environmental Inventory of relevant physical, chemical and biological data was prepared for
the New York Bight Apex and nearshore New Jersey coastal waters. In addition, NJDEP mounted an
extensive weekly sampling effort over the area where green tides had been significant. The algal blooms
that occurred in both 1984 and 1985 did not develop in 1986 presumably because of the weather
patterns that existed between July and September -- the period over which previous blooms occurred.
Thus it was not possible to examine the direct causes of development of green tide, nor was it possible to
isolate the causative organism for further study.
Nevertheless, significant progress has been made in understanding the conditions that lead to
near-shore algal blooms. Previous work in the New York Bight relating to near-shore anoxia has indicated
that reduced movement of marine waters during warmer months contribute significantly to both algal
production and reduced oxygen levels. The "Environmental Inventory" suggested that reduced transport
could also be a significant factor in green tide development. Analysis of additional data has lent support to
these suggestions.
This report presents a summary and analysis of the data obtained by the NJDEP during the
summer of 1986. It determines the spatial and temporal variations of various factors that affect algal bloom
development, and discusses these variations in terms of their significance to potential bloom
development. Because no significant numbers of the organism responsible for green tide, Gvrodinium
aureolum. were found, little new insight is provided here on causative mechanisms. However, the factors
that contribute to phytoplankton growth in general are discussed in relation to sources of nutrients to the
nearshore area and the water masses that affect their significance.
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1.2 Purpose of 1986 Green Tide Survey.
The purpose of the 1986 survey was to provide baseline information on hydrographic, water
chemistry, and phytoplankton parameters in the nearshore coastal and inlet waters that could prove useful
for understanding dynamic processes contributing to blooms of Gyrodinium. It was also expected that the
geographical and temporal variations in parameters usually important in controlling algal production could
lead to insights on sources of nutrients that could increase the probability of southern New Jersey coastal
algal blooms.
2.0 THE SAMPLING PROGRAM
2.1 GEOGRAPHIC AREA.
Scaled drawings of the study areas are presented in Figures 1(a) and 1(b). The area of interest is a
stretch of coastline extending approximately 18 statute miles from Absecon Inlet in the north to Corson
Inlet in the south. Included in this length of coastline are the municipalities of Atlantic City in the north at
the mouth of Absecon Bay and Ocean City approximately 10 miles further south.
Three inlets are near this coastal area. Absecon Inlet, to the north of the study area, is small, but
perhaps significant in nutrient interactions. Great Egg Harbor is a major inlet located near Ocean City, and
serves as a source of nutrient input to nearshore coastal waters. Corson's Inlet, to the south of the study
area, is similar in size and importance to Absecon Inlet.
Two sewage treatment facilities discharge treated effluent into the coastal waters between
Absecon Inlet and Corson Inlet. The Atlantic City sewage treatment outfall [designated as AC STP in
Figure 1 (a)] releases effluent approximately 1.5 miles offshore and 3 miles south of the entrance to
Absecon Bay. The Ocean City sewage treatment outfall [designated as CMC STP in Figure 1(b)] is
located approximately 12 miles further south, and discharges effluent approximately 1 mile offshore.
2.2 SAMPLING LOCATIONS AND SCHEDULES.
2.2.1 Nearshore Coastal Area.
The primary study area for the nearshore survey during 1986 extended from the mouth of
Absecon Inlet in the north to the mouth of Corson Inlet in the south [Figures 1(a) and (b)].
Nine transects were chosen for sample collections along this distance, with each transect being 2
statute miles from its nearest neighbor. Transects were numbered sequentially from 1 through 9 in a north
to south direction (i.e., Absecon Inlet toward Corson Inlet). Each transect was oriented perpendicular to
the coastline, and routine sampling along a transect occurred at points 0.25, 0.5 and 1.0 statute miles from
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STATUTE MILES
V, 0
PI
'3
ATLANTIC CITY
ABSECON BAY
P2
'3
$1
LAKES BAY
GREEN TIDE PERPENDICULARS
».. 17 I TI
PERP. 7 I TOP
POSITION
P6
/3
P6
VENTNOR CITY^^S/ 1
MARGATE CITY
GREAT EGG
HARBOR INLET
OCEAN CITY
GEN
Figure 1(a). Location of Northern Sampling Stations.
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STATUTE MILES
X 0
OC1
r«
3
2
OC4
OCI
£
K
OCI
OCI
an on
oc*
CHEAT EGO HAMBOM
Figure 1(b). Location of Southern Sampling Stations.
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the beach at mean low water. These sampling locations were numbered 1 through 3, with station 1 being
are shown in Figures 1(a) and (b).
Sampling depths at each station on the transects were dictated by the total depth of each station.
Typical depths on transect lines (as inferred from hydrographic charts of the study area) were the
following: station 1 (5-15 feet), station 2 (12-18 feet) and station 3 (20-28 feet). Samples were collected at
only the top depth (i.e., 1 meter below the air-water interface) at station 1 on each transect. At stations 2
and 3, samples were collected at three depths - 1 meter below the water's surface, 1 meter above the
sediment-water interface, and an intermediate depth. Samples collected 1 meter below the water's
surface were designated as "top" or "T," those at 1 meter above the sediments as "bottom" or "B," and
those at mid-depth as "middle" or "M".
Attempts to sample the coastal transect stations were made at weekly intervals from early June
through mid-September 1986. Weather conditions prevented sampling, primarily in the southern area in
the latter part of the summer. Complete sets of hydrographic, chemical and biological measurements were
made at the "top" depths of each coastal transect station (i.e., all 9 transects, at 3 stations per transect).
Only biological measurements (i.e., chlorophyll and phytoplankton species counts and identifications)
were measured in "middle" depth water samples. Only hydrographic and chemical variables (e.g.,
temperature, salinity, dissolved oxygen, nitrogen and phosphorus) were measured in "bottom" water
samples. Other analyses were done during this period (e.g., pH, iron, Kjeldahl nitrogen), but these are
not reported here, as they did not contribute to the understanding of the coastal processes affecting algal
production.
Because of the weekly sampling program, each sampling week was tabled with a number. These
numbers ran from Week 0 (in which only chlorophyll and phytoplankton abundance was measured) to
Week 15. These Week numbers are used for ease of reference throughout this report.
Samples were also taken around the Ocean City sewage treatment plant outfall for phytoplankton
counts. Stations indicated in Figure 1(b) were sampled once during June, twice during July and August,
and once during September.
2.2.2 Great Egg Harbor.
Samples for chemical and biological analysis were taken along two transects near the mouth of
Great Egg Harbor Inlet. Sampling transect GEN was located in the northern arm of the inlet [Figure 1(a)]
and contained two stations on the left and right sides of the channel [stations GENL (NL) and GENR (NR),
respectively]. The second transect, GES [Figure 1(a)J, was located on the southern arm of the inlet mouth
and contained three stations at the left, middle and right of the channel [stations GESL (SL), GESM (SM),
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and GESR (SR), respectively]. These stations were sampled 1 meter below the water's surface. In
general, samples were taken during the final 2 hours of ebb tide cycles or shortly after the low tide.
Samples were collected at approximately weekly intervals from early June through mid-
September. The sequence of weekly sampling numbers is also used to report on this data.
On three occasions -- 2 July, 31 July and 26 August 1986 -- samples were collected at each of the
five Great Egg Harbor stations at approximately 3 hour intervals for a total of 12 hours. On two of the three
occasions (2 and 31 July) this sampling schedule started before low tide and ended after the following
high tide.
2.3 MONITORING PARAMETERS.
All samples for the nearshore coastal area and Great Egg Harbor were taken and analyzed under
the direction of personnel at the New Jersey Department of Environmental Protection (Project Officer:
David Rosenblatt).
2.3.1 Field Measurements.
Variables that were routinely collected and recorded or analyzed during field sampling included
the following:
• general weather condition (i.e., 0 = cloudless, 1 = cloudy, 2 =overcast, 4 = fog or haze, 5 = drizzle
and 6=rain)
• precipitation (in inches) for the most recent three day period (including the current sampling day)
• direction and speed (mph) of ambient wind
• average daily direction and speed (mph) of wind at the Atlantic City airport for the day
• tidal cycle at time of sampling (i.e., time relative to high or low tide)
• water velocities (feet/sec) at 0.2 and 0.8 fractions of the total station depth (for Great Egg Harbor
Inlet data set only)
• water temperature in °C (YSI Model 57 dissolved oxygen meter)
• dissolved oxygen in mg/liter in water samples (YSI Model 57 dissolved oxygen meter)
• pH
Of these parameters, only dissolved oxygen and temperature are used for characterizing the
nearshore coastal area. Other data are useful for a day-by-day analysis, a level of detail not possible in this
report.
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2.3.2 Chemical Measurements.
Water samples were collected to determine a suite of chemicals of significance in algal production.
Samples collected were analyzed under the auspices of the NJDEP. The procedures used for sample
analysis are summarized in Table 1.
Values for all nitrogen and phosphorus concentrations are reported in (imoles/liter of seawater.
Nitrogen and phosphorus were determined as or are defined as the following: inorganic nitrogen is the
sum of ammonium, nitrate, and nitrite; organic nitrogen is calculated as Kjeldahl nitrogen minus
ammonium.; total nitrogen is Kjeldahl nitrogen plus nitrate and nitrite.
Samples for nitrogen and phosphorus measurement were whole water samples. Since they were
not filtered, reported concentrations are estimates of the sum of paniculate and dissolved forms of the
respective chemical.
2.3.3 Biological Measurements.
Biological parameters monitored during the green tide survey included chlorophyll pigments and
cell counts and identification for macroplankton (large-celled phytoplankton) species. Nanoplankton
(small-celled phytoplankton) cell numbers were estimated in one of four density ranges. Personnel at the
NJDEP Biological Services Laboratory were responsible for these measurements.
Chlorophyll pigments were collected and extracted from water samples according to procedures
outlined in USEPA (1973). Water samples were filtered through 0.45 urn membrane filters and extracted
in a 90% acetone/MgCOs solution. Concentrations of chlorophyll a were determined by
spectrophotometric methods. UNESCO trichromatic equations were used to calculate concentrations of
chlorophyll a from optical density readings. These concentrations are identified as "chlorophyll" in this
report.
For total phytoplankton cell counts and species identification, whole water samples were put in
brown glass jars and placed on ice in coolers at the time of field collections. Cell counts and identification
were done on these samples with Sedgwick-Rafter (S-R) and Palmer-Maloney (P-M) nanoplankton
counting chambers (APHA, 1980). The majority of field samples were counted live within 24 hours of the
time of collection. Use of live samples was preferred because fragile cells (particularly Gvrodinium
aureolum) are grossly distorted with preservation. However, if counting and identification could not be
done within 24 hours of collection, samples were preserved with LugoPs solution and counted by S-R and
P-M techniques.
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Table 1. Analytical Procedures for Chemical Analyses*
Variable
Ammonium
Nitrate, nitrite
Kjeldahl nitrogen
Inorganic phosphorus
Total phosphorus
Salinity
Field Preservation
phenol
dry ice freeze
H2SO4,4°C
dry ice freeze
400
Salinometer
Analysis Method Number
Whitledge autoanalyzer
Whitledge autoanalyzer
EPA Method 351.2
Whitledge autoanalyzer
EPA Method 365.4
Reference
Whitledge et al., 1981
Whitledge etal., 1981
USEPA, 1983
Whitledge et al., 1981
USEPA, 1983
* All data in this report are based on the methods listed in this table. The following equivalencies are used:
Total Nitrogen = Kjeldahl nitrogen plus nitrate and nitrite
Inorganic Nitrogen = ammonium plus nitrate plus nitrite
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2.4 CALCULATION OF NUTRIENT LOADS.
There are three major sources of nutrients to nearshore coastal waters: ocean currents that bring
nutrient rich oceanic waters from the New York Bight Apex, freshwater inflow from the extensive inlet
system adjacent to the coast, and sewage treatment plant effluents. Although the oceanic currents are
probably responsible for the greatest mass of inputs, they cannot be easily quantified, and calculations of
their contribution would be speculation without extensive additional data. Data on freshwater inputs of
nitrogen, however, were adequate for the calculation of monthly nitrogen and phosphorus loadings over
the summer of 1986.
Provisional data on stream flow for 1986 for the Great Egg Harbor River and the Tuckahoe River
gauging stations were obtained from William Bauersfield of the New Jersey District U.S. Geological
Survey. These measured flows derive from approximately 20 percent of the total drainage area of Great
Egg Harbor Bay (Durand, ). Runoff from the ungauged portion of the basin was calculated using area
weighted runoff coefficients. The total flow was calculated by summing the average flows from the two
gauging stations for the months of June, July, and August, dividing by the sum of the drainage areas for
which the flows were measured, and multiplying the result by the total area of the Great Egg Harbor Basin.
Mean nutrient concentrations were calculated for each of the four sampling periods for the five
Great Egg Harbor stations for those days when such sampling was done. The mean concentrations for
the sampling period at which the salinity was lowest (nearest high tide) were subtracted from the mean
concentration for the sampling period at which the salinity was highest (nearest low tide). These
differences were multiplied by the lower salinity divided by the difference in salinity (the ratio of freshwater
flow to total flow in the inlet due to tidal and freshwater flows). The result was multiplied by the product of
freshwater flow and the molecular weight of the chemical (to convert from moles to kilograms) to obtain a
total mass loading.
Using the monitoring data obtained from the Cape May County Sewerage Authority, mean
concentrations of nutrients in the sewage treatment plant effluent in the area of the coastal monitoring
stations were calculated for the months of June, July, and August. These concentrations were multiplied
by mean flows for each month (obtained from D. Rosenblatt, NJDEP) to obtain mean mass loadings from
the plant.
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3.0 RESULTS
3.1 SUMMARY OF ALL DATA.
The information gathered during this study represents the largest body of data gathered on any
single water body in the nearshore coastal environment. Because other studies have not been done on
this scale, it is difficult to use the scientific literature to assist in the interpretation of results. This is
particularly apparent when the relative influence of oceanic and freshwater inputs are discussed.
All data collected during the 1986 Green Tide Survey have been tabulated and combined into
three final data sets. These are included as appendices to this report: Appendix A (the coastal transect or
COAST set), Appendix B (the Great Egg Harbor Inlet or EGG set), and Appendix C (the complete
phytoplankton species count and identification list for all sets). This section of the report extracts,
summarizes and evaluates information from these data that may have relevance to the standing stocks of
phytoplankton.
3.2 INITIAL INVESTIGATIONS.
3.2.1 Means of Parameters for All Stations and Dates.
In an effort to determine the total range of values encountered for each variable, means, standard
deviations, maxima and minima, and coefficients of variation were determined for all stations and times for
the nearshore coastal area and Great Egg Harbor. The results are summarized in Table 2.
These means fall within the general range of values found in most coastal systems.
The coefficients of variation, a measure of the variation of data around the mean, expressed as a
percentage of the mean, indicated that salinity varied little even when an estuarine (lower salinity)
environment is included. This means that the nearshore system, despite freshwater inputs, is essentially
marine in nature.
Macroplankton cell numbers, inorganic nitrogen, inorganic phosphorus, total phosphorus, and
chlorophyll showed the greatest variation. These parameters are those that are most closely related to
algal blooms, and their wide variations indicate that the nearshore system is likely to have large differences
in values of these parameters over time.
3.2.2 Correlation among Parameters.
The statistical correlation among parameters in the combined data for the nearshore coastal zone
and Great Egg Harbor was calculated to determine the overall relationship between parameters.. The
variable-variable correlation coefficients are presented in Table 3. Correlation coefficients range between
10
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Table 2. Means of Parameters over All Stations and Dates*.
variable n mean standard minimum maximum c.v.
deviation value value
temperature
salinity
total nitrogen
inorganic nitrogen
total phosphorus
inorganic phosphorus
dissolved oxygen
chlorophyll
macroplankton
* Includes data from the nearshore coastal area and Great Egg Harbor.
n = number of samples
c.v. = coefficient of variation
789
556
620
626
807
599
738
703
457
20.4
31.7
33.3
3.3
2.2
0.5
7.0
7.4
1090
3.5
0.7
15.0
4.3
1.5
0.4
1.1
4.9
1526
12.0
28.7
4.1
0.3
0.3
0.04
2.6
0.35
50
27.5
34.3
158.6
58.6
25.5
3.7
9.8
30.3
13220
17
2
44
130
70
90
16
66
140
11
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Table 3. Correlations Between Parameters*.
Inorganic Inorganic Macro- Dissolved
Temperature Salinity Total N N Total P P Chlorophyll plankton Oxvaen
Temperature
Salinity
Total N
Inorganic N
Total P
Inorganic P
Chlorophyll
Macroplankton
Dissolved Oxygen
1.00
-0.79
0.28
0.11
0.42
0.00
0.59
-0.26
-0.39
-0.79
1.00
-0.38
-0.33
-0.50
-0.06
-0.54
0.29
0.41
0.28
-0.38
1.00
0.32
0.34
0.04
0.40
-0.11
-0.29
±_^
0.11
-0.33
0.32
1.00
0.43
0.08
-0.01
-0.19
-0.44
0.42
-0.50
0.34
0.43
1.00
0.27
0.40
-0.24
-0.47
0.00
-0.06
0.04
0.08
0.27
1.00
0.14
-0.04
-0.13
0.58
-0.54
0.40
-0.01
0.40
0.14
1.00
-0.10
-0.34
-0.26
0.29
-0.11
-0.19
-0.24
-0.04
-0.10
1.00
0.32
-0.39
0.41
-0.29
-0.44
-0.47
-0.13
-0.34
0.32
1.00
12
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"-1" and "1." A "1" means that as the first parameter increases, the second increases linearly (a plot of
variable one versus variable two would yield a straight line with a positive slope). A "-1" means that as the
first parameter increases, the second decreases linearly (a plot of variable one versus variable two would
yield a straight line with a negative slope). A "0" means there is no linear relationship between the two
parameters (a plot of variable one versus variable two would yield a scatter diagram through which a straight
line could not be drawn).
Relatively high correlation coefficients were observed between a number of variables. For
example, salinity and temperature had a high negative correlation, which implies that water masses
typically had high salinity and low temperature (and vice versa).
Chlorophyll had a high correlation with salinity and temperature. This suggests that chlorophyll
levels were coupled to water masses in the study area. Chlorophyll levels were weakly associated with all
other parameters. This does not mean that chlorophyll and these other parameters were not related,
simply that the relationship between chlorophyll and the other parameters, if one existed, was not a linear
relationship.
In contrast to the correlations mentioned above, macroplankton cell counts showed essentially
no correlation with chlorophyll. This result implies that large phytoplankton cells were not responsible for
the majority of the chlorophyll concentrations during at least part of the summer.
3.2.3 ANOVA Analysis of Parameters.
Attempts were made to look for statistical differences in parameter values between individual
stations of the nearshore coastal area and Great Egg Harbor. Nested ANOVA procedures were used to
determine whether the variation in each parameter was caused by location within the sampling areas or by
date. ANOVA results are summarized in Table 4.
With few exceptions, the portion of the total variance for each parameter due to differences in
sampling time (date) was consistently greater than that accounted for by differences in station location.
These differences are described in the Section 3.4.
3.3 VARIATION OVER SPACE.
The variation in parameters over space allows an analysis of whether changes in concentrations
are associated with known inputs or other geographic phenomena. The following subsections desribe
these changes for the nearshore coastal area and Great Egg Harbor.
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Table 4. Percent of Variance in Data Explained by Sampling
Location and Time Sampled.
Variable: date station
temperature 91.5 0.0
salinity 63.6 0.0
total nitrogen 27.3 7.6
inorganic nitrogen 25.0 0.0
total phosphorus 37.6 0.0
inorganic phosphorus 19.4 0.0
chlorophyll 74.1 4.0
macroplankton 21.0 79.0
dissolved oxygen 47.7 0.0
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3.3.1 Nearshore Coastal Area.
Figure 2(a) contains a series of bar graphs which represent means for major chemical and
biological parameters by transect, by station, and by depth.
Means for each transect were calculated using those sampling weeks when each station and
transect was sampled. With only one missing value for that period, the value of the missing point was
estimated by interpolation between adjacent stations and transects. Top depth means were based on a
minimum of 108 values (up to 216 values), and bottom depth means were based on a minimum of 72
values.
Over the sampling period, temperature in surface waters [Figure 2(a)(i)] gradually increased from
north to south, but not significantly so. The southernmost transect was less than 1 degree warmer than
the northernmost transect. Similarly, bottom waters increased in temperature from north to south, but at a
slighly higher rate. The difference between top and bottom temperatures decreased from north to south.
This means that on average, water in the northern part of the sampling area were more likely to maintain
this vertical difference under the influence of winds and other factors causing mixing.
Surface temperatures were about the same in the surf zone (station 1) as they were at 0.5 and 1
miles from shore (stations 2 and 3, respectively). Bottom temperatures declined with distance from shore
(there are no samples for the nearshore station), and indicate the possible influence of colder, deeper,
New York Bight water.
Chlorophyll [Figure 2(a)(i)] did not vary significantly in a north-south direction over the period of
the study although there appeared to be slightly higher concentrations in the southern part of the
sampling area. The highest means were found in transects 9 (highest), 5 (next highest), and 8 (the lowest
of the three highest values).
As is typical of large water bodies, chlorophyll levels were highest in the nearshore zone where
light pentrated the full depth of the water column, temperatures were higher, and nutrient concentrations
were also higher. Higher concentrations are also typically found deeper than surface waters, and the
nearshore New Jersey coastal area had a similar pattern. However, depth differences in concentration
were not as marked for the survey area as they generally are in deeper coastal waters.
Dissolved oxygen [Figure 2(a)(i)] showed a similar pattern to chlorophyll in surface waters. Since
algal production releases oxygen, this relationship is reasonable for surface waters. Bottom waters,
however, had a very different pattern. Two distinct groups of transects are apparent: a northern group
(transects 1 - 5) and a southern group (transects 6 - 9). The southern pattern may be due to the influence
15
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24
Temperature (°C)
I Top H Bottom
9_
6_
3_
0
9.6_
8.4_
7.2_
6.0_
4.8_
3.6_
2.4_
1.2_
0.0
4567
Transect
Chlorophyll (u.g/1)
• Top S Middle
1 2 3
Station
456
Transect
Dissolved Oxygen (mg/1)
• Top E3 Bottom
1 23456789
Figure 2(a)(i). Spatial Uariation in Nearshore Coastal flrea.
16
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draft
48_
42_
36_
30_
24
6_
0
3.2
2.8_
2.4
2.0
1.6
1.2
0.8
0.4
0.0
20.0
17.5
15.0
12.5_
10.0
7.5
5.0_
2.5
0.0
Total Nitrogen (umoles/1)
I Top S Bottom
5456789
Transect
Total Phosphorus (^moles/1)
• Top S Bottom
1 2 3
Station
23456789 123
Transect Station
Total Nitrogen/Total Phosphorus
• Top S Bottom
1 23456789
Transect
1 2 3
Station
Figure 2(a)(ii). Spatial Uariation in Nearshore Coastal Rrea.
17
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draft
3.2
2.8
2.4_
2.0_
1.6
1.2
0.8
0.4
0.0
0.8
0.7_
0.6_
0.5
0.4_
0.3_
0.2.
0.1.
0.0
Inorganic Nitrogen (umoles/1)
• Top S Bottom
234567
Transect
1 2 3
Station
Inorganic Phosphorus (jimoles/1)
• Top S Bottom
1 23456789
Transect
1 2 3
Station
Inorganic Nitrogen/Inorganic Phosphorus
op H Bottom
123456789 123
Transect Station
Figure 2(a)(iii). Spatial Uariation in Nearshore Coastal flrea.
18
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draft
of highly oxygenated water from Great Egg Harbor entering the coastal zone. Its greater influence on
deeper water is unexplained, as Great Egg Harbor water, being warmer and of lower salinity than the
coastal water, should have floated, and thus should only have affected surface waters. The decline in this
influence with distance from transect 5, however, lends support to the argument that the oxygen pattern
could be due to Great Egg Harbor.
Dissolved oxygen increased in surface waters with distance from shore, but not significantly. It
decreased in bottom waters with distance from shore, typical of nearshore coastal environments.
Total nitrogen in surface waters [Figure 2(a)(ii)] varied slightly, with an apparenly higer
concentration in the northern part of the sampling area than the southern. A noticeable increase in total
nitrogen occurred at transect 6 in bottom waters, probably due to mixing with Great Egg Harbor Inlet water
which in general had higher nitrogen content than coastal waters. This pattern of increase in
concentration of bottom waters coincides with the increase shown by dissolved oxygen.
Total nitrogen was generally higher in bottom waters than surface waters. It declined slightly with
distance from shore, but not consistently.
Total phosphorus concentrations in surface waters [Figure 2(a)(ii)] declined from transect 1 to 5,
then increased in transects 6 and 7, and then dropped to levels similar to transect 5. There is no
explanation for this pattern, as it was not similar to any other parameters. Bottom concentrations of total
phosphorus generally followed those of surface waters, but showed less vertical difference in transects 5
(none) and 6 (slight). The higher concentrations in bottom waters in transects 5 and 6 may have been due
to the Great Egg Harbor influence.
Total phosphorus declined in concentration from onshore to offshore in surface waters and was
higher in bottom waters than surface waters. However, there was little variation in the concentration of
phosphorus in bottom waters with distance from the shortine.
The ratio of total nitrogen to total phosphorus is indicative of the suitability of an environment for
algal growth. Typically, living marine cells have a ratio of 16 parts nitrogen to 1 part phosphorus.
Significant deviations from this ratio indicate either nitrogen or phosphorus starvation and indicate which
nutrient is likely to limit phytoplankton production, if any. The mean values across the study area were
about 16 to 1, the expected value if the majority of nitrogen and phosphorus were contained in algal cells.
(Since inorganic nitrogen is a small fraction of total nitrogen, the majority of nitrogen is organic nitrogen
created by biological activity.)
Inorganic nitrogen [Figure 2(a)(iii)] had three peaks in concentration in the north - south direction --
19
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transect 1, transect 5, and transect 9. These peaks were more obvious in surface waters than bottom
waters, although a similar pattern existed in each. The northernmost concentration cannot be explained,
as the concentrations above transect 1 are not known. It could be due to inputs from farther up the coast
or Absecon Inlet. The other peaks are probably due to inputs from Great Egg Harbor (transect 5) and
either the Ocean City sewage treatment plant or Corsons Inlet (transect 9).
Inorganic nitrogen declined from shore to offshore, and was higher in bottom waters than in
surface waters. This would normally be the case for nitrogen-limited waters where algal production near
the surface removed nitrogen more quickly than at deeper depths. Benthic regeneration of nitrogen
could also account for the higher inorganic nitrogen levels in deeper waters.
Inorganic phosphorus [Figure 2(a)(iii)] was at low levels throughout the sampling area, and was at a
concentration close to the detection limit for the methods used. The high concentrations that occurred in
bottom waters at transects 1 and 9 are consistent with inputs from sewage treatment plants, but transect 1
is not the transect nearest to the Atlantic City outfall, and high concentrations at transect 9 could also be
due to Corsons Inlet. The increase in concentration in bottom waters at transect 6 is probably due to Great
Egg Harbor. Except for the higher surface concentrations at transects 1 and 9, inorganic phosphorus had
slightly lower concentrations in deeper waters.
The inorganic nitrogen to inorganic phosphorus ratio is a measure of the availability of nutrients for
phytoplankton growth. Algae require nutrients in a 16 to 1 ratio. When the ratio is significantly less than
this number, nitrogen is likely to be the limiting nutrient. The ratios of 5 to 1 indicated in Figure 2(a)(iii)
show nitrogen limitation typical of coastal marine environments.
3.3.2 Great Egg Harbor.
The data presented in Figures 2(b)(i) and (ii) are means calculated for all data for Egg Harbor
except for the three sampling periods not at low tide for the three dates when four sampling periods
occurred on the same day. The stations NL and NR were on the north arm of the inlet, SL, SM, and SR
were on the south arm.
Temperature, salinity, and total nitrogen did not vary across these sampling stations. Inorganic
nitrogen, total phosphorus, inorganic phosphorus, and chlorophyll all showed strong gradations across
stations. In general, where chlorophyll was lowest, inorganic nutrients were highest, a pattern consistent
with the use of inorganic nutrients by phytoplankton. Since the waters of Great Egg Harbor are quieter
than those of the nearshore coastal environment, it is likely that these differences are due to strong algal
growth in the Harbor that is not typical of the coastal environment.
20
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Temperature (°C)
Salinity (°/00)
NL NR SL SM SR
Station
Total N (jjmoles/1)
NL NR SL SM SR
Station
NL NR SL SM SR
Station
Inorg N (jimoles/1)
NL NR SL SM SR
Station
Figure 2(b)(i). Spatial Uariation in Great Egg Harbor.
21
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Total P (^moles/1)
Inorg P (jimoles/1)
NL NR SL SM SR
Station
Chlorophyll (jig/1)
NL NR SL SM SR
Station
NL NR SL SM SR
Station
DO (mg/1)
NL NR SL SM SR
Station
Figure 2(b)(ii). Spatial Uariation in Great Egg Harbor.
22
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3.4 VARIATIONS OVER TIME
3.4.1 Nearshore Coastal Area.
All data for variation over time are presented according to sampling week. There were 16 sampling
weeks, numbered from 0 (when chlorophyll and phytoplankton only were sampled) to week 15. The
relationship between sampling week and the date of the beginning of each week is presented in Table 5.
The variations over time in the coastal area are due to a number of influences. The primary
influences are winds, tides, ocean currents, solar heating, and freshwater inputs. However, the
essentially marine nature of the nearshore environment indicated that the predominant influence was
probably caused by circulation patterns in the New York Bight Apex. These influences are best
characterized, in the absence of data on wider-scale circulation, by patterns of winds. Figure 3(a) indicates
the wind speed and direction measured at Sandy Hook and Atlantic City over the period of the study.
While the absolute directions and speeds of winds differed between Sandy Hook and Atlantic City, the
patterns of changes were similar. These patterns are what drive the greater New York Bight circulation.
The winds appeared to have three distinct patterns:
1. A period of highly variable direction and velocity during the first part of the summer, lasting
until about Week 6.
2. Between between Week 6 and Week 10, winds were generally lighter, and when stronger,
were from the same direction (northerly, with one exception at the end of July).
3. After Week 10, a pattern similar to that at the beginning of summer occurred.
These differences in wind patterns were reflected in changes in the nearshore coastal system. These
changes are outlined below.
Temporal trends in a number of the chemical variables were evaluated by plotting mean values for
the given variable averaged over all transects, stations, and depths for each weekly sampling period [the
line in Figure 3(b)] and for each week for which data was complete (the bar graphs).
Temperature [Figure 3(b)(i)J remained low, decreasing slightly into the second week of July (Week
5). In Week 6, temperature increased dramatically. Temperature increased steadily through Week 9, then
decreased sharply, and maintained about the same level for the remainder of the study.
The trends in temperature indicate that the pattern of water movement and the dominant source
of nearshore coastal waters changed twice during the sampling period. Comparison of the temperature
and wind data collected at the National Marine Fisheries Service's Sandy Hook Laboratory during this
period [Figure 3(a)] indicate that trends in the the general water mass movements appeared to be coupled
23
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draft
Table 5. Correspondence between Sampling Week and Date, Summer, 1986.
Sampling Week Week Beginning
0 June 2
1 June 9
2 June 16
3 June 23
4 June 30
5 July 7
6 July 14
7 July 21
8 July 28
9 August 4
10 August 11
11 August 18
12 August 25
13 September 1
14 Septembers
15 September 15
24
-------
Sandy Hook
30 -
20 :
10 ^
10 :
20 -
30 :
•I ,....,....,.
6 II 16 21 26
JUN 1986
II 16 2
JUL 1986
• I •
26
31
•I !••••! |
11 16 21 26 31)
II
16
21
RUG 1986
Atlantic City
Figure 3(a). Wind Speed and Direction at Sandy Hook and Atlantic City.
25
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draft
Temperature (°C)
• Top E3 Bottom
\ 1 1 1 1 r
23456789
Sampling Week
10 11 12 13 14 15
Chlorophyll (iig/1)
• Top S Middle
2 3 4 5 6 7 8 9 10 11 12 13 14
Sampling Week
Dissolved Oxygen (mg/1)
• Top S Bottom
15
0 1 2 3 4 56 7 8 9 10 11 12 13 14 15
Figure 3(b)(i). Temporal Uariation in Nearshore Coastal Rrea.
26
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Total Nitrogen (umoles/1)
• Top H Bottom
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Total Phosphorus (^moles/1)
op S Bottom
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Total Nitrogen/Total Phosphorus
• Top H Bottom
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Figure 3(b)(ii). Temporal Uariation in Nearshore Coastal Rrea.
27
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Inorganic Nitrogen (iimoles/1)
• Top S Bottom
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Inorganic Phosphorus (jimoles/1)
• Top S Bottom
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Inorganic Nitrogen/Inorganic Phosphorus
• Top H Bottom
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Figure 3(b)(iii). Temporal Variation in Nearshore Coastal Rrea.
28
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2400
2100_
1800_
1500_
1200_
900
600
300
0
Cells/ml
• Top S Middle
4567
Transect
Cells/ml
• Top S Middle
I
ill
IKL
1 2 3
Station
i i i i r i i i i i i i i i i
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Sampling Week
15
Figure 3(b)(iu). Macroplankton Rbundance in Nearshore Coastal Rrea.
29
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draft
with ambient wind patterns.
Based on the temperature data, the coastal environment appeared to be affected more by
offshore, colder waters early and late in the summer, while in the period during late July and early August,
the high temperatures would indicate strong local influences from inlets and solar heating. During this
time there were corresponding changes in chemical concentrations of the nearshore coastal water.
Chlorophyll [Figure 3(b)(i)] remained at relatively stable low levels during the early part of the
summer, but increased in Week 5. A maximum was reached in Week 9, and then concentrations declined
somewhat. This pattern correlated with that observed for winds, and presumably reflects increased
phytoplankton productivity when nutrient inputs from sources such as Great Egg Harbor and/or sewage
treatment point sources had greater influence on coastal waters.
Data on dissolved oxygen [Figure 3(b)(i)] were too sparse to determine real trends. The lower
oxygen concentrations observed when full sets of data were not available would appear to be an artifact of
the data rather than real. There is no explanation for these patterns.
Total nitrogen and total phosphorus [Figure 3(b)(ii)] showed patterns similar to that of temperature
until late in August. After Week 12, when temperature had started to decline, total nutrient concentrations
remained high or increased. The lower temperatures indicate greater mixing with the New York Bight, so
the higher nutrients may also have come from areas outside the study area.
Inorganic nitrogen and phosphorus [Figure 3(b)(iii)] were almost mirror images of each other --
when inorganic nitrogen was high, inorganic phosphorus was low. Major changes occurred during Week
6 when temperature also changed dramatically. However, except for two weeks during the last part of
August, inorganic nitrogen to inorganic phosphorus ratios were well below that required to actively sustain
phytoplankton growth. The changes in the relative concentrations of inorganic nitrogen and inorganic
phosphorus around Week 6 probably reflect the greater inorganic nitrogen input from local sources over
that available from the New York Bight. Late in the summer, however, when phosphorus concentrations
were very low, chlorophyll concentrations were still elevated, indicating that there was sufficient
phosphorus to sustain growth.
Gyrodlnlum and Phytoplankton Abundance.
The presence of Gyrodinium aureolum during the period of the 1986 field survey was sporadic
throughout the coastal study area, and cells were never detected at levels anywhere near "green tide"
conditions (i.e., >10000 cells/ml; Table 6). The highest numbers found were only an indication that
Gyrodinium was present in local waters. These numbers were found between Weeks 6 and 9, the time
30
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Table 6(a). Abundance of Gyrodinium aureolum in Nearshore Coastal Area.
Transect 123 456789
Station 123 123 123 123 123 123 122 1£3 123
Depth
WeekO T
IVI •• •• •• •• •• •• •• •• • .
Weekl T 60
M . . . . . . . . . . . . . . . .
Week 2 T 60 115 115 60
M . . . . 60 . . .60 .60 .... 115 . .
Week 3 T ... 228 60 ...
M . . . . . . .60 .60 . . . .
WGGK 41 ••• ••• ••• ••• ••• ••• . * . . . . •••
IVI •• •• •• •• •• •• •• •• • ,
Weeks T 60 ...
M . . . . 60 . . . . . .
Week 6 T . 300 60
M . . . . 100 300 . . . .
Week? T ... 60 200 100 400
M . . . . . . . . . . 300 . . 100
WeekB T 60 50 60 50 60 ...
M .50 . . .60 60 . . . . . .60 . .
Week9 T ... . 50 50 150 200 100 100 . 60 . 60 . . . 60 ... 60
M . . . . 50 . . . . . . . . . . 60
31
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draft
Table 6(a). Abundance of Gyrodinium aureolum in Nearshore Coastal Area (continued).
Transect 123 456789
Station J.23. ±21 ±23. 123 123 123 123 123 123
Depth
Week 10 T 60
M . . . . . . . . . . . . . . . . .
Week 12 T
M . . . . . . . . . . . . . . .
Week 13 T .... 60 ... 60
M . . . . . . . 50 50 . . . . .
Week 15 T
M . . . . . . . . . . . . . . .
Key:
. = not detected
n = cells/ml
32
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Table 6(b). Abundance of Gvrodinium aureolum in Great Egg Harbor.
Station NL NS SL SM SR
WeekO .
Weekl 60
Week 2 .
Weeks .
Week 4 .
Weeks .
Week 6 .
Week? .60
Weeks 60 .60
Week 9 .
Week 11 .
Week 12 .
Week 13 .
Week 15 .
Key:
. = not detected
n = cells/ml
33
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Table 6(c). Abundance of Gyrodinium aureolum around
Ocean City Sewage Treatment Plant Outfall.
Station OC1 OC2 OC3 OC4 OC5 OC6 OC7 OC8
15 May .......
Week 2 . .60
Week6 150 . . .150 . .150
WeekS .60 . .60 . .50
Week 10 . . . . . . .50
Week 15 .........
2 October .......
KEY:
. = not detected
n = cells/ml
34
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when the inlet influence was greatest. Gvrodinium was found infrequently in Great Egg Harbor, and
occassionally, in low numbers, around the sewage treatment plant outfalls.
In contrast to the trend for chlorophyll, macroplankton cells were most abundant in the early and
late summer, and reduced in mid-summer when chlorophyll levels were at a maximum [Figure 3(b)(iv)].
Since these cell counts represent only large-celled phytoplankton, the lower numbers over the summer is
misleading. Nanoplankton, very small plankton cells, dominated the late summer season. Estimates of
the abundance of nanoplankton are presented in Table 7. This table indicates that nanoplankton
dominated between late July and early September. This means that the overall species composition of
the phytoplankton changed from large phytoplankton cells to smaller cells and back again during the study
period.
3.4.2 Great Egg Harbor.
Seasonal Variations.
The seasonal variation of parameters in Great Egg Harbor was similar to that for the coastal
environment in some ways, but different in others. Temperature in Great Egg Harbor [Figure 3(c)(i)] was
never as cold as it was in the coastal area, and the changes in temperature were never as abrupt. This is
because Great Egg Harbor is a system that behaves more like a shallow lake, with water temperatures
following air temperatures more closely than the coastal environment.
Salinity [Figure 3(c)(i)] did not change as much as would be expected in an estuarine environment
- the salinity was always within 1 or 2 parts per thousand of the coastal environment. This indicates that
mixing of Great Egg Harbor with ocean waters was extensive by the time freshwater reached the sampling
stations. Temperature differences indicate that this mixing occurs well into the Great Egg Harbor system.
The other parameters are interrelated and are discussed together [Figures 3(c)(i), (ii), and (iii)].
Total nitrogen and phosphorus, inorganic nitrogen and phosphorus, and chlorophyll were routinely low
until the 8th sampling week (the last week in July). At this time, there was an increase in inorganic
phosphorus (from an unknown source), and the following week showed a dramatic increase in chlorophyll,
a reduction in inorganic nitrogen, and an increase in total nitrogen. The extremely high chlorophyll levels
seen in the first week of August (Week 9, approaching 30 u.g/1) are bloom concentrations. However, the
blooms were nanoplankton, not Gyrodinium. and the effects of the bloom were not as obvious as those
had been for Gyrodinium in the previous two summers. The changes in nutrients were expected given
the magnitude of the phytoplankton growth in this period. Chlorophyll gradually declined for the
remainder of the season, but never reached the low levels seen into the latter part of July. Total
phosphorus increased to even higher levels in the following weeks (probably in the phytoplankton), but
35
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Table 7(a). Abundance of Nanoplankton in Nearshore Coastal Area.
Transect 1 23456789
Station 123 123 123 123 123 123 123 123 123
Depth
WeekO
Week 1
Week 3
Week 4
Week 5
Week 6
Week?
Weeks
Week 9
Week 10
Waalr 19
WccK if.
Week 13
Week 15
T
M
T
M
T
M
T
M
T
M
T
M
T
M
T
M
T
M
T
M
T
M
T
M
. a a ... ... ... ...
a a . . . .
. .
a a
.a
. .
a .
a .ba
b . . . a .
..a aa. .a. ... a.. aab .b. bba b.b
a. .. .. .. ba b. bb ab
aab b.b a. a .aa bba baa bab aba bbb
. b ba ab aa aa aa ab bb bb
abb bcc bbc cb. bbc bab bbb bbb aab
bb bb bb bb ab bb ab ba bb
bab .be bab abb abb -b- -b- bb- bab
bb bb aa a. ab -- -- -- aa
aaa aab bbb bbb bbb bab bbb bbb bbb
aa aa aa ab ba .a aa ab bb
aaa baa ... ..a ... .a. .aa a. a a.
aa aa .a ba .. .a .. .a
KEY:
. = < 10,000 cells/ml
a = 10,000-100,000 cells/ml
b = 100,000 - 500,000 cells/ml
c = >500,000 cells/ml
- = data not available
36
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draft
Table 7(b). Abundance of Nanoplankton in Great Egg Harbor.
Station NL NR SL SM SR
WeekO .....
Weekl .....
Week 2 . .
VV GG K O • • • • •
Week 4 . . • .
WeekS .....
Week6 .....
Week? b . a a a
WeekS a-b a-b a-b b a
Week 9 c . c c
Week 11 b b b b b
Week 12 a-c a-c a-c a-b a-b
Week 13 a b a a a
Week 15 a a a a a
KEY:
. = <10,000 cells/ml
a= 10,000-100,000 cells/ml
b= 100,000-500,000 cells/ml
c = >500,000 cells/ml
37
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Table 7(c). Abundance of Nanoplankton around
Ocean City Sewage Treatment Plant Outfall.
Station
15 May
Week 2
WeekG
Weeks
Week 10
Week 14
2 October
OC1 OC2 OC3 OC4 OC5 OC6 OC7 OC8
KEY:
. =<10,000 cells/ml
a = 10,000 -100,000 cells/ml
b = 100,000 - 500,000 cells/ml
c = >500,000 cells/ml
38
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Temperature (°C)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Salinity (°/00)
01 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Sampling Week
Total Nitrogen (jimoles/1)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Figure 3(c)(i). Temporal Uariation in Great Egg Harbor.
39
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Inorganic Nitrogen (umoles/1)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Total Phosphorus (umoles/1)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Inorganic Phosphorus (umoles/1)
0 1 23 4 5 6 7 8 9 10 11 12 13 14 15
Figure 3(c)(ii). Temporal Uariation in Great Egg Harbor.
40
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Chlorophyll (jig/1)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Dissolved Oxygen (mg/1)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Figure 3(c)(iii). Temporal Uariation in Great Egg Harbor.
41
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inorganic phosphorus declined slightly. Both total and inorganic nitrogen remained at high levels up to
the middle of September when sampling ceased.
Tidal Variations.
On three dates (i.e., 2 July, 31 July and 26 August), each station in Great Egg Harbor Inlet was
sampled four times to evaluate tidal influences on parameters. Although the sampling routine rarely
extended for more than 12 hours, the resulting information indicates that certain variables changed
substantially as a function of tidal cycles. Means of all stations for periods showing maximum
concentrations and minimum concentrations are presented in Figure 3(d). Maximum concentrations
coincided with low tide, the time when Great Egg Harbor waters are most in evidence at the sampling
stations.
The differences in parameters reflect the average differences in concentrations between Great
Egg Harbor and the nearshore coastal area. Temperature was consistently higher on low tide, indicating
that Great Egg Harbor is generally warmer than the ocean during this time period. Salinity differed slightly
over the tidal cycle, but never more than about 1.5 parts per thousand. This indicates that tidal flushing
was several times more significant than freshwater flow in the inlet.
All nutrients, chlorophyll, and dissolved oxygen were consistently higher in Great Egg Harbor than
the coastal environment, indicating that with strong tidal mixing with nearshore waters, Great Egg Harbor
would be an input of these parameters to coastal waters. The spatial distribution of nitrogen, phosphorus,
chlorophyll, and dissolved oxygen in the nearshore coastal environment indicate inputs of these materials
at transect 5 or 6, the transects on either side of of Great Egg Harbor.
3.5 NUTRIENT INPUTS.
The total nutrient input to the nearshore coastal area is not able to be estimated because the
major source of nutrients is the ocean. Shifts in currents, upwelling, and downwelling each affect the
ocean's nutrient contribution. Without much more detailed analysis of the available and additional data,
estimates of loads from the ocean cannot be determined. Only the relativities of known inputs (Great Egg
Harbor and the Ocean City Sewage Treatment Plant) are estimated here.
Table 8 lists the drainage area and flow data used for calculations of the nutrient loads from Great
Egg Harbor. Table 9(a) presents the mean concentrations of nutrients and total nutrient loads for Great
Egg Harbor. Table 9(b) contains the mean concentrations of nutrients and total nutrient loads for the
Ocean City sewage treatment plant.
A comparison of the loads calculated in Table 9 shows that the total nitrogen input from Great Egg
42
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32_
28_
24_
20
8_
4_
0
48_
42_
36_
30_
24
6_
0
Temperature (°C)
• High Tide Slow Tide
7/02
8/26
7/31
Date
Total N (jimoles/1)
• High Tide Slow Tide
7/02
7/31
Date
8/26
32_
28
24_
20
16
12_
8
4
0
Salinity (°/00)
•low Tide SHigh Tide
7/02 7/31 8/26
Date
Inorg N (umoles/1)
• High Tide Slow Tide
i
7/02
8/26
Figure 3(d)(i). Tidal Uariation in Great Egg Harbor.
43
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4.0_
3.5_
3.0_
2.5_
2.0
0.5_
0.0
8_
6_
4_
2_
0
Total P (umoles/l)
• High Tide S Low Tide
7/02 7/31 8/26
Date
Chlorophyll (ug/1)
• High Tide Slow Tide
7/02
7/31
Date
8/26
1.28_
1.12
0.96_
0.80
0.64
0.48
0.32
0.16
0.00
9.6
8.4
7.2_
6.0_
4.8
3.6
2.4_
1.2
0.0
Inorg P (umoles/l)
I High Tide Slow Tide
1
V///////////////A
1
1
•
I
7/02
8/26
7/31
Date
DO (mg/l)
High Tide Slow Tide
7/02
7/31
Date
8/26
Figure 3(d)(ii). Tidal Uariation in Great Egg Harbor.
44
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Table 8. Drainage Areas and Water Flows for Great Egg Harbor Watershed.
(a) Drainage Areas.
Drainage Area
Great Egg
Harbor River
0141100
(km2)
147.89-/1
Tuckahoe River
0411300
(km2)
79.7 /1
Great Egg
Harbor Bav
(km2)
1150-/2
_/1 From U.S. Geological Survey guaging station records
_/2 From Durand, 197_?
(b) Water Flows.
June, 1986
July, 1986
August, 1986
Great Egg
Harbor River
(cfs)_/1
45.1
40.7
33.5
Tuckahoe
River
(cfs)_/1
17.7
20.2
19.3
Total
Flow
(cfs)
317.1
307.5
266.6
Great Egg
Harbor Basin
(m3/s)
8.98
8.71
7.55
Geometric Mean
39.5
19.0
296.2
8.39
_/1 Provisional data from the U.S. Geological Survey
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Table 9(a). Nutrient Concentrations and Nutrient Loads from Great Egg Harbor.
July 2,1986
July 31,1986
High Tide
Low Tide
Difference
Total to net
High Tide
Low Tide
Difference
Total to net
Salinity
32.34
31.33
1.01
Ratio
31.02
(0,00)
31.39
30.82
0.57
Ratio
54.07
High Tide
Low Tide
Difference
Load
High Tide
Low Tide
Difference
Load
Total
Nitrogen
(^moles/I)
27.17
37.06
9.89
(kg/d)
3132
(^moles/I)
26.63
37.89
11.26
(kg/d)
6214
Inorganic
Nitrogen
(M.moles/1)
2.37
6.21
3.84
(kg/d)
1218
((imoles/l)
1.99
3.88
1.89
(kg/d)
1042
Total
Phosphorus
(nmoles/l)
1.29
2.39
1.10
(kg/d)
770
(^moles/I)
1.81
3.87
2.06
(kg/d)
2519
Inorganic
Phosphorus
(|imoles/l)
0.12
0.63
0.51
(kg/d)
358
(jimoles/l)
0.14
1.82
1.68
(kg/d)
2057
(^moles/I) (nmoles/l)
((imoles/l) ((imoles/l)
August 26,1986
High Tide
Low Tide
Difference
Total to net
29.93
31.16
1.23
Ratio
24.33
High Tide
Low Tide
Difference
Load
61.14
39.62
21.51
(kg/d)
5326
5.35
3.94
1.42
(kg/d)
352
3.03
2.26
0.77
(kg/d)
422
0.48
0.09
0.38
(kg/d)
208
Geometric Mean
Total to net
Ratio
34.43
Load
(kg/d)
4698
(kg/d)
764
(kg/d)
936
(kg/d)
535
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draft
Table 9(b). Nutrient Concentrations and Nutrient Loads
from the Ocean City Sewage Treatment Plant.
June, 1986
July, 1986
August, 1986
Geometric Mean
Flow
(m3/s)
0.136
(m3/s)
0.219
(m3/s)
0.259
(m3/s)
0.198
Total
Nitrogen
(p.moles/1)
1931
(kg/d)
315
Qimoles/l)
1200
(kg/d)
318
(^moles/I)
1807
(kg/d)
561
(^.moles/I)
1612
(kg/d)
383
Inorganic
Nitrogen
((imoles/l)
1810
(kg/d)
296
(|imoles/l)
1120
(kg/d)
297
(jimoles/l)
1736
(kg/d)
539
(^.moles/I)
1521
(kg/d)
362
Total
Phosphorus
(limoles/l)
90
(kg/d)
33
(^moles/I)
5*
(kg/d)
11*
((imoles/l)
11*
(kg/d)
7*
(umoles/l)
90
(kg/d)
33
Inorganic
Phosphorus
(|imoles/l)
80
(kg/d)
29
(H.moles/l)
1*
(kg/d)
1*
(^.moles/I)
1*
(kg/d)
<1*
(jimoles/l)
80
(kg/d)
29
* This number is lower than expected results by one or more orders of magnitude
and is not used in calculations.
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Harbor was over ten times that of the Ocean City Sewage Treatment Plant. Even when the large
proportion of inorganic nitrogen from the sewage treatment plant discharge is considered, the inorganic
nitrogen contribution of Great Egg Harbor was twice that of the treatment plant. Both total phosphorus
and inorganic phosphorus loads from Great Egg Harbor were more than ten times those of the Ocean City
outfall.
4.0 DISCUSSION
4.1 General Behavior of the Nearshore System over the Summer of 1986.
The nearshore coastal environment is extremely dynamic and is driven primarily by the winds and
currents of the New York Bight. On a daily basis, temperatures and nutrients can change substantially.
These shifts are related primarily to shifts in water movements of the New York Bight.
This phenomenon can be seen by comparing the seasonal temperature distribution of the coastal
area with the seasonal temperature distribution in Great Egg Harbor. Great Egg Harbor shows much more
uniform changes in temperature, probably related to solar heating of this shallow bay and the influence of
air temperatures. From early June to mid July, for example, temperatures in Great Egg Harbor either
remained steady or increased slightly, while those of the coastal area decreased. This was a time when
solar heating and increasing air temperatures should have caused an increase in water temperatures of
the entire area. The fact that temperatures declined in the nearshore area indicated that offshore water
was being brought to the nearshore area.
Data are too sparse to determine what happened mid to late summer. It is partially speculation that
the dramatic increase in temperatures in the near shore environment was due to the isolation of nearshore
coastal water from the other water of the Bight. However, the greater similarity between the Great Egg
Harbor temperature and nutrient concentrations and those of the coastal environment suggest that such
an isolation occurred. The timing of changes in nutrients and temperatures also correlated with a
decrease in average wind speeds. Except for the three periods (July 22, July 31, and August 12 and 13),
the winds were consistently from the same direction between July 15 (sampling week 5) and August 18
(the last day of sampling week 10). It is over this time period that temperatures rose dramatically,
chlorophyll concentrations increased, and nutrient concentrations changed. This month-long period led
to conditions that were conducive to algal blooms.
With the arrival of the hurricane on August 18, weather patterns changed dramatically.
Apparently, New York Bight water moved into and out of the nearshore area several times after this time.
This water exchange prevented major blooms from occurring, even though the New York Bight water was
also nutrient and chlorophyll rich. Without the stagnant conditions in the nearshore area, blooms or
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potential blooms were dispersed to other parts of the Bight.
4.2 SIGNIFICANCE OF NUTRIENT INPUTS.
The pattern of water stagnation along the nearshore coast is an apparently recurring
phenomenon in summer. The conditions seen in 1986 which were conducive to algal blooms apparently
occurred in the summers of 1985 and 1984. These conditions apparently led to the green tides of those
two summers.
The dominant influence on nutrient concentrations in the nearshore area appears to be Great Egg
Harbor. The total loads of nutrients are ten times that of the Ocean City Sewage Treatment Plant. Other
inlets (Corson's and Absecon) may also be contributing substantial inputs, but so are the Atlantic City
Sewage Treatment Plant and other treatment plants. The sum of these nutrient inputs during periods
when nearshore waters are not exchanged with New York Bight water create the conditions for blooms.
Whenever light winds are found in summer over a period of two weeks or more, and these light winds are
not broken by more than one day of heavier winds, algal blooms are likely to recur.
5.0 REFERENCES
APHA (American Public Health Association). 1980. Standard Methods for the Examination of Water and
Wastewater. Fifteenth Edition. APHA-AWWA- WPCF, Washington, DC. 1134p.
USEPA. 1973. Biological Field and Laboratory Methods for Measuring the Quality at Surface Waters and
Effluents. EPA-670/4-73-001. Environmental Monitoring Series. (Weber, C.I., ed.)
USEPA. 1983. Methods for Chemical Analysis of Water and Wastes. EPA- 600/4-79-020. U.S.
Environmental Protection Agency, Cincinnati, OH.
Whitledge, T., S.C. Malloy, C.J. Patton and C.D. Wirick. 1981. Automated Nutrient Analyses in Seawater.
Brookhaven National Laboratory BNL-51398, U.S. Department of Energy. Upton, New York.
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