Green Tide Monitoring Survey for 1986 Results ------- 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 ------- 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 ------- 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 ------- 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 ------- draft 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. ------- draft 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 ------- 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. ------- 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. ------- draft 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), ------- draft 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. ------- draft 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. ------- draft 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 ------- draft 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. ------- draft 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 ------- draft 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 ------- draft 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 ------- draft "-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. 13 ------- draft 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 14 ------- draft 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 ------- draft 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 ------- 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 ------- 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 ------- 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 ------- draft 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 ------- draft 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 ------- draft 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 ------- draft 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 ------- 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 ------- 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 ------- draft 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 ------- draft 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 ------- draft 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 ------- 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 ------- draft 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 ------- 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 ------- draft 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 ------- draft 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 ------- draft 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 ------- draft 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 ------- 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 ------- draft 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 ------- draft 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 ------- draft 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 ------- draft 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 ------- draft 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 ------- draft 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 ------- draft 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 ------- draft 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 45 ------- 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 ------- 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. 47 ------- draft 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 48 ------- draft 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. 49 ------- |