Size, Abundance, Biodiversity and Distribution of Ichthyoplankton Found in Barnegat Bay from May 2012 to October 2013

Estuaries are a vital part of the marine ecosystem, as they are home to many near-shore larval marine fish, commonly known as ichthyoplankton. Often referred to as nurseries, these estuaries have high productivity and promote biodiversity (Beck et al.). They also provide warm, shallow, wave-protected waters that are high in nutrients and have large vegetated areas (Beck et al.). The success of a species of marine fishes is greatly dependent on its survival rate during the larval stage; this life stage usually takes place in an estuary (Yoklavich et al.). Estuaries often have high economic value, as they are home to many game fish and birds.

Currently, more than half the population of the U.S. lives along the shore, with large numbers near coastal estuaries (Kennish). These coastal homes produce large amounts of pollutant and nutrient runoff, which can be detrimental to marine life sanctuaries (Kennish). For several decades, large amounts of nutrients, including nitrates and phosphates from runoff, have contributed to the increasingly poor water quality, loss of biodiversity and overall deterioration of the ecosystem (Kennish). This large increase in nutrients is often from fertilizer and pesticide runoff. Because of the increasing amount of impervious ground surfaces, pollutants that ordinarily would soak into the ground have nowhere to go but into the water. The algal blooms that occur in the bay as a result of these excess nutrients lead to a shortage of dissolved oxygen. This shortage can kill larval fish.

Barnegat Bay in New Jersey in an extremely valuable economic resource; it contributes $2 billion to $4 billion annually to the state of New Jersey by providing fish and wildlife, recreation, a water supply and jobs (“State of the Bay Report 2011”). Barnegat Bay is home to many organisms that breed seasonally as well as many permanent marine residents. However, Barnegat Bay, once a dynamic breeding ground teeming with marine life like many other estuaries, is now heavily polluted. The pollution is driving out and killing off much of the wildlife and creating a serious environmental problem (Johnston).

In recent years there have been intensive efforts to restore the overall health of the Barnegat Bay estuary system (Kennish). After the publication of the “State of the Bay Report 2011,” Gov. Chris Christie approved $16 million toward the restoration of the bay and named it a matter of statewide environmental and economic importance. The report documented “the lowest biomass levels ever in the estuary” and presented numerous threatened and endangered species that are under serious threat unless the bay is cleaned up (“State of the Bay Report 2011”). The U.S. Department of Wildlife Protection has funded 25 projects toward the preservation and restoration of the Barnegat Bay watershed. 

Barnegat Bay is considered a nationally significant estuary. The federal government has funded the Barnegat Bay Partnership, which, in conjunction with state programs, is designed to restore the overall health, biodiversity and economic value of the bay. The Barnegat Bay Partnership’s main goal is to improve water quality and restore lost habitat (“State of the Bay Report 2011”).

Ichthyoplankton are an important biological component of any marine ecosystem. They can be useful in indicating the overall health and productivity of the bay. The success of these juvenile fish has a strong correlation with the population of adult fish stocks. Studying juvenile fishes is both more practical and economical than taking an adult fish stock assessment, which is why ichthyoplankton are often studied rather than adult fishes. Ichthyoplankton are also important because they are a necessary source of food for higher trophic levels, which in turn provide food and jobs for humans.

Annually, approximately 5.9 million fishing trips are made into the Barnegat Bay watershed, which results in a profit of $57.9 million each year. This means that studying the health of the juvenile fish in the bay can be used to indicate the health of the adult fish populations and, eventually, profit for the marine fishing industry. Without an accurate prediction of the adult fish stock, the health of the bay cannot be accurately determined.

For as long as I can remember, water has been an important part of my life. The house I have lived in for most of my life backs up to a freshwater lake, and I spent my childhood swimming, fishing and boating in this lake. I can remember my family spending long days on the local beach, and I was always intrigued by the birds, dune grasses and other organisms found here. In eighth grade I made the decision to apply to a magnet school, the Marine Academy of Science and Technology, which is located in the Sandy Hook Gateway National Recreational Area. For the past four years, my school has provided me with numerous opportunities to help with the preservation of the environment. This, in turn, has given me a deeper appreciation for the natural world. When I was a junior, I heard about an opportunity to work at Monmouth University and participate in an intensive water study of Barnegat Bay, with which I soon became involved. I worked with a team of undergraduate students to collect larval fish (ichthyoplankton). Back at the lab, I counted, identified and measured each sample.

The ichthyoplankton of Barnegat Bay have not been well studied. The purpose of this research is to establish a good understanding of the ichthyoplankton size, abundance and biodiversity based on abiotic factors, location and time of year in Barnegat Bay, and make correlations with other measures of water quality such as dissolved oxygen, salinity and pH. This study will add to the overall knowledge of the ichthyoplankton in the bay, as well as focus on finding an efficient method for data collection.

After collecting this data, a model of the most significant factors affecting these juvenile fishes will be made. This model will provide a very accurate method for predicting the total expected fish population in any area at any given time. Creating a model will preserve the future of these ichthyoplankton while allowing the study of ichthyoplankton to continue.

 

Study Site

Barnegat Bay, NJ watershed. Labels indicate the five sampling locations.

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Barnegat Bay is located half a mile inland from the Atlantic Ocean, and runs from the south end of Point Pleasant to the southern part of Beach Haven. It is approximately 70 miles south of New York City. The bay covers a total area of 64.5 square miles and holds a volume of 238 cubic meters. Barnegat Bay is a shallow, poorly flushed, highly eutrophic estuary bordered by highly developed watershed areas. The bay has a long retention rate, with recirculation of ocean water only every three months. Barnegat Bay is a shallow, lagoon-like estuary, with an average depth of three to 23 feet, which provides ample sunlight necessary for survival. There are two natural inlets to the ocean, Barnegat Bay Inlet and Little Egg Harbor Inlet, along with smaller, less predominant inlets.

 

Hypothesis

The factors that will have the most effect on the size, abundance, distribution and biodiversity of the ichthyoplankton will be location and time of year. The data results will also depend greatly on the species found in the particular area. Other factors considered will include: the size of the mesh on the nets, salinity, temperature, dissolved oxygen and turbidity. It is expected that Site BB05a, the one closest to the oceanic inlet, will have the highest biodiversity and species abundance. Likewise, due to an outflow of treated water, Site BB07a, the site nearest the Oyster Creek Nuclear Generating Station, will have the lowest biomass and biodiversity. Site BB12, located at the bottom of the bay, will have a large abundance due to the pristine quality of the water, as the shoreline here is the least populated of all the sites. There will be a similar seasonal variation in the species of fish at all of the sites, correlated to species of fish found in the coastal ocean region. The size of the fish will be directly related to the amount of time they have spent in the bay.

 

Method

Grace prepares the nets for sampling.

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Of the 15 sites in the New Jersey Department of Environmental Protection’s Water Quality Monitoring Project in the Barnegat Bay Watershed, five sites were chosen for intensive ichthyoplankton sampling based on important man-made and geological structures. Over 19 months, samplings occurred biweekly, May through October, and monthly from November through April. Due to the large area of Barnegat Bay, the sampling periods were broken into two consecutive days, the northern stations (BB02 and BB05a) on the first day and the southern stations (BB07a, BB10 and BB12) on the second day. A yearly, intensive, 24-hour sampling also occurred, during which samples were taken every four hours at one location to study diurnal vertical migration.

The two bongo nets used to collect samples.

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Collection of the ichthyoplankton required two sets of horizontal surface bongo nets, one with a 500-micron net and one with a 200-micron net, made by Sea Gear. The nets had 20-inch diameters and  were made of stainless steel. The nets were approximately eight feet long and were attached to a collection container. A calibrated gear mechanical digital flow meter was mounted in the center of each net.

Grace measure water clarity using a Secchi disk.

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Prior to each trawl, temperature, salinity, dissolved oxygen and pH were measured using a calibrated YSI. Water clarity was determined by using a white, 20-centimeter Secchi disk, which was recorded to the nearest half-foot. Water depth was recorded at each station using the vessel’s depth finder. Data was recorded on a Water Quality Data Sheet, along with time, location, tidal stage, weather, sea surface conditions, observations and flow count.

The nets were put into the water connected to a 50-foot tow rope. The boat traveled into the current at two knots for a duration of four minutes. The start and end time of each sampling period was recorded. Once brought on board, the nets were carefully rinsed into the collection containers. The collections were removed from the nets and poured into pre-marked jars, labeled with date, time, location and net used.

The samples were then put into ice and brought back to the Monmouth University Urban Coast Institute Lab for preservation. Before chemicals were added to the samples, they were carefully inspected for ichthyoplankton, which were removed with forceps and placed into 95% ethanol for later identification and measurement. The rest of the sample was then put into 10% buffered formalin and put aside for later fractioning.

Ichthyoplankton were identified to the lowest taxonomic level practicable using ichthyoplankton keys and references, including Johnson and Allen (2005), Newell and Newell (1973), Smith and Johnson (1996), Todd et al. (1996), and Young et al. (2006). Then, using AxioVision software, the ichthyoplankton were photographed and measured and the data was recorded. Once time allowed, the data were then copied to an electronic spreadsheet.

 

Results

In total, 1,830 fish larvae were caught and identified. Eighteen species were identified, but six of those species accounted for 96.5% of all fish larvae identified. The species in greatest abundance were: Atlantic silverside, winter flounder, northern pipefish, bay anchovy, lined seahorse and northern pipefish. Atlantic silversides were the most common species and accounted for 55.7% of all the fish larvae (Table 1). The winter flounder, although very abundant, were only found during one month, so they will not be as discussed in depth.

 

Table 1: Total Ichthyoplankon Caught in Barnegat Bay from May 2012 to November 2013

Common Name Scientific Name Number

Atlantic Silverside

Winter Flounder

northern Pipefish

Bay Anchovy

Lined Seahorse

Striped Anchovy

Atlantic Menhaden

Sand Eels

Atlantic Croaker

Feather Blenny

Northern Pufferfish

Atlantic Neddlefish

Black Sea Bass

Summer Flounder

American Eel

Tautog

Striped Mullet

Window Pane

Unknown*

Menidia menidia

Psuedopeuronectes

Sygathus fuscus

Anchoa mitchilli

Hippocampus eretus

Anchoa hepsetus

Brevoortia tyrannus

Ammodytes sp.

Micropogonias undulatus

Hypoblennius hentz

Sphoeroides maculatus

Strongylura marina

Centropristis striata

Paralichthys dentatus

Anguila rostrata

Taugtogola

Mugil cephalus

Scophthalis

 

1019

470

115

88

40

34

9

9

7

4

3

2

2

1

1

1

1

1

23

Total   1,830

Six most common species caught and their measurements. 1) Lined Seahorse (Hippocampus erectus); 2) Northern Pipefish (Sygnathus fuscus); 3) Striped Anchovy (Anchova mitchilli); 4 ) Atlantic Silversides (Menidia menidia); Bay Anchovy (Anchova hepsetus); 6) Winter Flounder (Pseudopleuronectes americanus)

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As well as being the most abundant, Atlantic silversides had the largest catch per unit effort (CPUE) of any species, with an average of 1.54 CPUE for 500 microns and 1.61 CPUE for 200 microns. This was statistically different than the CPUE for all other species (p < 0.05) (Figure 3-1). Net size had a negligible effect on the CPUE. The size of the net used resulted in approximately the same CPUE for each of the main species, as well as the overall CPUE. The size of the ichthyoplankton caught was not correlated with the size of the net used, and therefore it can be assumed that net size had no effect on CPUE or the size of the fish caught (Figure 3-2).

Figure 3-1 (left): Catch-per-Unit-of-Effort (CPUE) based on size of net used. Figure  3-2 (right): Average size in mm based on size of net used.

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In the lower parts of the bay, Stations BB07a, BB10 and BB12 had biodiversities that were almost twice as large as the biodiversity in the northern stations, BB02 and BB05a (Figure 4). The highest biodiversity occurred at station BB12, with a biodiversity of 1.86; this was very similar to station BB07a, where h’ was equal to 1.81. Station BB10 was slightly lower, with a biodiversity of 1.55. The lowest biodiversity occurred at station BB05a, where h’ was equal to 0.52. Station BB02 had a biodiversity of 0.72.

Figure 4: Shannon Weiner Species Diversity by Location in Barnegat Bay from May, 2012 to November, 2013.

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The biodiversity was not consistent between sampling periods. The late spring through late summer months had much higher biodiversity. The biodiversity level reached its peak in late June 2013, when h’ was equal to 1.45; this is much higher than one year previous, when the biodiversity was zero because only one species of fish was caught. Another peak occurred in late November 2012, when the biodiversity was equal to 1.23. One thing that was very consistent was that the biodiversity level rose from mid-May to late November in both years. The biodiversity seemed to be much higher in 2013 than in 2012. In 2012, the average biodiversity was 0.42, while in 2013 it was 0.66 (Figure 5). 

Figure 5: Shannon Weiner Species Diversity by Location in Barnegat Bay from May, 2012 to November, 2013.

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Many of the ichthyoplankton caught were found at Station BB05a, which had an average CPUE of 0.81 fish per one cubic meter. Station BB07 has the smallest CPUE, of 0.06 fish per one cubic meter. The spring and summer months had the most abundant CPUE. Although some ichthyoplankton were seen in the winter months, they were not as relevant to the study. The most abundant month was mid- May 2012, which had a CPUE of 4.29 fish per cubic meter of water; the second-highest month was in early April 2013, with 1.06 ichthyoplankton per one cubic meter of water (Figure 6).

Figure 6: Overall Catch-per-Unit-of-Effort (CPUE) for each month at each location.

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The northern pipefish was predominantly found in the spring and summer of 2013, with the largest abundance occurring in mid-July 2013, with a CPUE of 0.10 fish per cubic meter of water. The pipefish were mainly found at Station BB05a, with a CPUE of 0.24 fish per cubic meter of water, and Station BB12, with a CPUE of 0.18 ichthyoplankton per cubic meter of water. Fewer pipefish were found at other stations in the bay, with the fewest being found at Station BB10, which had a CPUE of 0.04 fish per cubic meter of water (Figure 7-1).

Figures 7-1 - 7-6: BB02 (dark blue) BB05 (red), BB07 (green), BB10 (purple) BB12 (light blue) Catch-per-Unit of Effort (CPUE) per 1 cubic meter of water based on Location and Sampling Event in Barnegat Bay, NJ from May 2012 to November 2013. 1) Northern Pipefish (Sygnathus fuscus); 2) Bay Anchovy (Anchova hepsetus); 3) Striped Anchovy (Anchova mitchilli); 4 ) Winter Flounder (Pseudopleuronectes americanus); 5) Lined Seahorse (Hippocampus erectus); 6) Atlantic Silversides (Menidia menidia)

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Bay and striped anchovies were found mainly in the late spring and early summer of 2013 at the lower stations of the bay. They were regularly found in the same sampling periods and locations as each other, although bay anchovy were slightly more frequent (Figure 7-2 and Figure 7-3).

Winter flounder were only found in April 2013, but in this month they were very abundant. Slightly more were caught in mid-April, when there was a CPUE of 0.49 winter flounder per cubic meter of water, than in late April, when the CPUE was 0.20 winter flounder per cubic meter of water. The winter flounder were found very evenly across all locations during that month (Figure 7-4).

The lined seahorses were found in greater abundance the farther south one traveled; Station BB02, the farthest north, had no seahorses. Station BB12 had the greatest abundance of seahorses, with an average CPUE of 0.03 seahorses per 1 cubic meter of water. The stations in between had increasingly large CPUEs. The seahorses were found mostly between late May and late August 2013 (Figure 7-5).

Atlantic silversides were found regularly throughout the bay and throughout the year but were often found in the late spring of 2012, with an extremely high average CPUE of 36.27. The rest of the spring of 2012 also had large numbers of Atlantic silversides. The average CPUE across all dates and locations of the Atlantic silversides was 1.54; that is almost 63 times the CPUE of the next most-abundant fish (Figure 7-6).

In 2012, the silversides caught in the spring were all in the range of 2-10 mm, with a peak at 4–6 mm. Then one season later, in the summer of 2012, the silversides caught were in the range of 6–22 mm, with a peak at 8–10 mm. In 2013, the spring and summer months tended to follow the same pattern of sizes, from 0–16 mm with peaks around 6–8 mm (Figure 8-1).

Figures 8-1 - 8-5: Frequency Distribution of Ichthyoplankton in Barnegat Bay, NJ from May 2012 to November, 2013.  1) Atlantic Silversides (Menidia menidia); 2) Bay Anchovy (Anchova hepsetus); 3) Striped Anchovy (Anchova mitchilli); 4) Northern Pipefish (Sygnathus fuscus); 5) Lined Seahorse (Hippocampus erectus);  Note: Winter Flounder (Pseudopleuronectes americanus) are not shown as they are found only one month a year.

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The bay anchovy were mainly seen in the summer of 2013, with sizes ranging from 2–28 mm, with the greatest abundance at 6–8 mm. Then, in the fall of 2013, the size class of ichthyoplankton moved to 14–48 mm, with a peak at 20–22 mm (Figure 8-2).

The striped anchovy were only caught in the spring and summer of 2013. A clear shift was visible in the sizes of the fish caught. In the spring, the sizes ranged from 4–14 mm, and in the summer the sizes ranged from 10–22 mm (Figure 8-3).

Northern pipefish were found predominantly in the spring and summer months. In the spring of 2012, there was a very even size-class distribution between 0–20 mm. In the spring of 2013, the sizes ranged from 0–35 mm and had the greatest abundance between 10–15 mm. In the summer of 2013, the sizes ranged from 0–30 mm, with the most abundant frequency at 5–10 mm (Figure 8-4).

The lined seahorse was mainly caught in the spring and summer of 2013. In the spring of 2013 the sizes of seahorses ranged from 2–20 mm, with a peak at 8–10 mm. In the summer of 2013, the sizes ranged from 2–14 mm, with a peak at 4–6 mm (Figure 8-5).

Location seemed to have negligible effect on the size of the larval fish caught. The bay anchovy seemed to be the largest in the northernmost part of the bay, at Station BB02, with an average size of 29.7 mm. The size of the fish declined the further south one traveled; Station BB10 had the smallest bay anchovy, with an average size of 7.41 mm. The northern pipefish were slightly larger in the southern two stations. The size of the Atlantic silversides and lined seahorse did not correlate to location (Figure 9).

Figure 9: A comparison of ichthyoplankton size by location and species.

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Discussion

A total of 1,830 individual ichthyoplankton from 18 species were caught across the five sampling locations from May 2012 to November 2013. This is a total average of 21.29 ichthyoplankton caught per 100 cubic meters of water.

As discussed above, two different net sizes were used to sample for ichthyoplankton. Net size did not have a significant effect on the CPUE of the ichthyoplankton (p > 0.05), or the average size of the ichthyoplankton caught (p > 0.05) (Figure 3).

Overall biodiversity was greatest in the southern part of the bay near Stations BB07a, BB10 and BB12 (Figure 4). It is likely that the biodiversity at Station BB07a was the highest because it is equidistant from the Little Egg Harbor Inlet, located at Station BB12, and the Barnegat Bay Inlet, located at Station BB05a. Because there is no direct ocean waterway to Station BB07a, any ichthyoplankton found here would have either spawned here or migrated from one of the other locations. Also, many of the rarer species found breed in more protected areas, meaning they travel farther from the inlets before spawning. These rarer species greatly add to the overall biodiversity of the area. The last factor affecting biodiversity at Station BB07a is the Oyster Creek Nuclear Power Plant. This plant uses bay water to cool its systems and releases warmer water back into the bay. Ichthyoplankton may gravitate toward the warmer water, either by migration after spawning or by selection as a breeding ground (Taft).

The southernmost stations, BB10 and BB12, are in the most pristine portions of the bay, where there is much less interaction with human development. According to the Barnegat Bay Partnership, these southernmost stations are the most sheltered from nutrient runoff and pollutants. This adds greatly to the overall biodiversity, as the less durable species have a much stronger chance of survival.

Station BB02 had a very low biodiversity because it is located very far from any inflow from the ocean and is the most heavily polluted (“State of the Bay Report 2011”).

Station BB05a had the lowest biodiversity of all, due to the huge numbers of Atlantic silversides seen here. There were approximately 700 silversides found at Station BB05a, which drove the biodiversity down. Removing the silversides from the equation yields a biodiversity comparable to Station BB10. This suggests that many species, especially the Atlantic silversides, enter the bay through the inlet, spawn and then their offspring stay near the inlet entrance for their entire juvenile lives. Another possibility is that due to the high inflow from the ocean, Station BB05a is the most saline; this could be favorable for many juvenile fishes (Figure 10).

In both 2012 and 2013, the spring and summer months had higher biodiversity than the rest of the year. This is the main spawning season for many Atlantic Ocean fishes, and this likely caused many more fish to come into the bay to find shelter for spawning. This is also why the overall CPUE was much higher during the spring and summer months than during the winter and fall months.

Season had a significant effect on overall CPUE (p < 0.05); the spring and summer months had a much higher catch per unit effort. All the stations were similar in total CPUE except for Station BB05a. This was likely due to the overwhelming number of Atlantic silversides found here. Location also had a significant effect (p < 0.05), but not as large as the seasonal effect. Station BB05a had the largest CPUE due to the large inflow from the inlet and the high salinity in this area.

The most common species found in this study was the Atlantic silverside, at a total of 55.7% of all the species caught. They were mainly found in the spring months and very frequently at Station BB05a. Atlantic silversides commonly spawn in mid-spring, which is why such a great abundance was found in this time period. It is likely that the adult silversides entered the bay through the inlet and laid all of their eggs close to Station BB05a (Figure 8-1 and 7-5). The sampling done at BB05a in May 2012 and May 2013 showed an extremely large abundance of Atlantic silversides, but they were very small when caught. In the summers of 2012 and 2013 (Figure 8-1 and 7-5), fewer were found in total, as many of the silversides were beginning to migrate and were being taken by predators, but they were all larger and slightly more dispersed throughout the bay. In 2013, a similar pattern of spring births and summer migration and growth could be seen, but this time at Stations BB05a and BB12. In both years, the silversides had mostly migrated out to sea by the fall, but the few that remained were very large. Date and location were not statistically different (p > 0.05).

The northern pipefish were predominantly seen at Stations BB05a and BB12, which are the locations closest to the two inlets in the bay. They were also mainly found in the spring and summer months. Northern pipefish have a very long spawning season, from March to August. The data shows that the size classes for the spring and summer of 2012 and 2013 were very similar. This either means that spawning occurred consistently throughout these months, and the pipefish exited the bay shortly after they were born, or that pipefish are very slow growers, and the difference in size between spring and summer is negligible. The pipefish were found most abundantly from late May to late July 2013. Season and location were both statistically significant for the northern pipefish (p < 0.05). Stations BB02 and BB07a were statistically similar to each other. From this it can be inferred that the pipefish do not migrate very far in the bay; the adult pipefish lay their eggs, and that is where the juveniles stay until they are able to migrate back to the sea. Station BB12 had a large abundance of northern pipefish, likely due to the immense amount of seagrass found there (Lathrop et al.). According to a paper written by Ryer and Orth in 1987 about the Chesapeake Bay, northern pipefish spend much of their time hiding in seagrass, which they use as protection while finding food and spawning. This is why many pipefish were found at station BB12.

Two species of anchovies were identified during this study: the striped anchovy and the bay anchovy. For each species, each location was significantly different from one another (p < 0.05). For the striped anchovy, the season was significantly different (p < 0.05), but for the bay anchovy, the season was not significantly different (p > 0.05). Both of these species were mainly found in 2013 at Stations BB10 and BB12, suggesting that they entered the bay through the Little Egg Harbor Inlet. The bay anchovy have a longer spawning season, from spring through late summer (Ryer et al.). The striped anchovy’s spawning season peaks in the spring (Johnston et al.). The bay anchovy found in the spring of 2013 ranged from 8 mm to 22 mm, and in the summer the bay anchovy were between 4 mm and 22 mm; this suggests two spawning seasons, one in the spring and one in the summer, at Stations BB10 and BB12. The striped anchovy in the spring of 2013 ranged from 4 mm to 14 mm and in the summer ranged from 8 mm to 22 mm. The striped anchovy stayed near Station BB12 for the whole spring and summer, but there was a definite growth in size (Figure 8-3 and 7-3). A study done about the bay anchovy in New Jersey compared the juvenile anchovies to the adult anchovies; the results of this study showed that there were significant annual differences in number of anchovies found in the bay (Vouglitois et al.).

The winter flounder were only found in mid- and late April 2013. They were found regularly across all stations but were gone from the bay completely by May 2013. The season was significant (p < 0.05), but the location was not (p > 0.05). A study of winter flounder in the Sandy Hook Bay looked in depth at seasonal migration patterns and found similar results to those found in Barnegat Bay (Stoner et al.).

The last major species found was the lined seahorse. It was found only in the southern stations and greatly declined farther north. This pattern suggests that the seahorse is very pollution-intolerant and more suited to the southern parts of the bay, away from pollution (“State of the Bay Report 2011”). Many studies, including one on genotoxic effects, track seahorse populations because of their sensitivity to changing toxicity levels. Because of this, one would expect to see seahorses in the more pristine areas of the bay (Santos et al.). Also, Station BB12 had the highest concentration of seagrasses, meaning the seahorses can find more shelter in these areas (Lathrop et al.). The seahorses breed regularly throughout the spring and summer. In the spring and the summer, their sizes ranged from 2 mm to 14 mm, meaning that the seahorses spawned regularly throughout these months. In the spring months, the seahorses were found almost entirely at Station BB12; in the summer they traveled slightly more northward but never reached Station BB02. Their location was very significant (p < 0.05).

From all the data collected, it was determined that temperature, salinity, dissolved oxygen, water clarity, pH and water depth were the most important factors in determining the overall catch per unit effort. From this information, a regression model was made to determine the predicted catch per unit effort, based on abiotic factors (see Figure 10).

Figure 10

Figure 10


Many other people have made similar models to find the CPUE in various estuaries and reservoirs. In almost every regression model made, the same three factors were relevant: temperature, salinity and dissolved oxygen. In Barnegat Bay, due to the overall shallowness of the bay, water clarity and water depth were important factors, whereas in other estuaries they are not as important (Claramunt).

With the model created, overall CPUE can be calculated for any given date and location by testing the abiotic factors. This approach would prevent having to kill ichthyoplankton to study them as bio-indicators for pollution. This would not only save time, but also would give the ichthyoplankton a chance to survive and become adult fish.

One of the main ways to study the health of a bay is to look at the total number of species living there. In estuaries, the juvenile fish are the most important indicator of health of the area. By knowing the overall CPUE of ichthyoplankton in the bay, the state of New Jersey can determine the health of the bay much easier and more efficiently.

With an easier way to determine bay health, the cleanup process of the bay can be greatly expedited. It is extremely important that the bay be cleaned up as quickly as possible, as it is home to many big game and wildlife. This wildlife is not only important to the ecosystem, but it is an important source of income for the state of New Jersey. This study is an ongoing research effort; in the future the model will be tested for accuracy and completeness.

 

Conclusion

Although this was just a baseline study, the year and a half worth of data already shows an increase in the total catch, biodiversity and size class of the larval fish caught. This could be because the pollutants that used to infest the bay are now beginning to filter out of the bay, and fewer pollutants are being added. With such a positive response seen in just the first year, there is hope that the bay will continue to become healthier in the future. This is great news for the Barnegat Bay: a more abundant larval fish population means that in the future there will be more adult fish. A larger fish stock will bring more revenue to the state of New Jersey, and Barnegat Bay will continue to be one of the most environmentally and economically important bays on the East Coast.

 

Works Cited

Beck, Michael W., et al. “The Identification, Conservation, and Management of Estuarine and Marine Nurseries for Fish and Invertebrates: A Better Understanding of the Habitats that Serve as Nurseries for Marine Species and the Factors that Create Site-Specific Variability in Nursery Quality Will Improve Conservation and Management of These Areas.” Bioscience 51.8 (2001): 633-641. 

Claramunt, Randall M., and David H. Wahl. “The Effects of Abiotic and Biotic Factors in Determining Larval Fish Growth Rates: A Comparison Across Species and Reservoirs.” Transactions of the American Fisheries Society 129.3 (2000): 835-851.

Johnston, R., M. Sheaves, and B. Molony. “Are Distributions of Fishes in Tropical Estuaries Influenced by Turbidity over Small Spatial Scales?” Journal of Fish Biology 71.3 (2007): 657-671.

Kennish, Michael J. Barnegat Bay–Little Egg Harbor Estuary: Ecosystem Condition and Recommendations. Rutgers University Institute of Marine and Coastal Sciences, 2007.

Lathrop, Richard G., Renee M. Styles, Sybil P. Seitzinger, and John A. Bognar. “Use of GIS Mapping and Modeling Approaches to Examine the Spatial Distribution of Seagrasses in Barnegat Bay, New Jersey.” Estuaries 24.6 (2001): 904-916.

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