|
An Exploration of Salt Panne Ecology and Biodiversity in Relation to Size, Depth, and Salinity
Lauren Apakian, Temple University
Salt pannes are bodies of water located in the salt marsh. Though they may be intermittently tidally fed, they have no permanent water source. Salinity and depth fluctuates with high tides and precipitation, and depth and size vary greatly from one panne to another. This project explored the ecological differences between salt pannes in relation to size, depth, and salinity. Six pannes of different sizes (range = 12 to 142 m²) and depths (range = 7 to 40 cm) were monitored in the vicinity of the Wetlands Institute. Each panne was assessed for an array of water quality parameters such as salinity, specific conductivity, dissolved oxygen, and temperature. Pannes were also surveyed for fish, crab, and terrapin populations. Salinity and specific conductivity varied among pannes, ranging from 31 ppt to 41 ppt and 53 mS/cm to 64 mS/cm respectively. Dissolved oxygen (range = 63 to 115% saturation) and water temperature (28 to 31°C) did not vary among pannes. Shallow pannes contained fewer organisms, while deep pannes sustained more life. Pannes with the highest salinities sustained a large fish population, but fewer crabs and no terrapins. Six out of seven terrapins captured during this study were from a large, deep panne, while only one was captured in a smaller panne.
Determining Preferred Nesting Substrate of
Northern Diamondback Terrapin
Alison Ball, The College of New Jersey
Loss and degradation of natural nesting habitat on barrier islands is a significant conservation concern for northern diamondback terrapins (Malaclemys terrapin terrapin) in southern New Jersey. This experiment was designed to determine whether terrapins have a preference toward certain nesting substrates. The results from this experiment may be used to facilitate the construction of artificial nest sites to increase habitat for terrapins. Egg-bearing females were placed in a 488 × 190 cm plot surrounded by 38 cm high plastic fencing divided into equal-sized sections of beach sand, dredge material, garden mulch, and stones. These substrates are now common in areas adjacent to the salt marsh as a result of urbanization. Each terrapin was observed for up to one hour, and nesting behavior was recorded in five-minute intervals. Of 15 successful nests, the terrapins chose sand (n = 6), dredge (n = 5), mulch (n = 4). None of the terrapins was observed to nest in gravel. While chi-squared analysis suggested that nesting was random, this is likely a function of the small sample size. A power test, which doubled the sample size, suggested a preference toward beach sand. Based on this preference, any future efforts that aim to enhance diamondback terrapin nesting habitats should focus on protecting natural barrier island sand dunes. Furthermore, preliminary results suggest that beach sand is the ideal substrate to utilize in the construction of artificial nesting habitats.
Aerial Photography Analysis of Cape May County Wetlands
Shawn Bulifant, West Chester University
With current sea level rise projections predicting as much as a 1-meter rise in sea level, coastal wetlands will be experiencing many changes in the future. The scope of the project was to use ortho aerial photography from multiple years to better understand the changes in the wetlands environment. The project used aerial photography from 1995, 2002, and 2007 that have already been corrected for accuracy. These photos were then cataloged and converted to a geodatabase using ArcMap. Layers were made for each year for both the salt/freshwater boundary and salt pannes around the Wetlands Institute. The main goal of mapping the fresh/saltwater boundary was to see if there was any shift in the fresh and saltwater plant communities due to sea level rise. The criterion for determining the salt/freshwater boundary was the edge between Spartina marsh grasses and freshwater species such as the invasive reed Phragmities australis. The layer was made by tracing this edge in plant communities throughout a transect for each year. The layers for each three years were then laid on top of a base map to see if any shifts in plant communities occurred. The transect for all three years started on the north side of North Wildwood Blvd. and ended at the south side of an old railroad bed north of Corson’s Inlet. Salt pannes are non-tidal pools of water found within saltwater wetlands. Layers of salt pannes were produced for three different years to document changes in size. Salt pannes were digitized in ArcMap and made into layers.
Quantifying Parasitic Trematodes to Census the
Diamondback Terrapin in Southern New Jersey
Chelsea Fischer, Virginia Tech
The complex life cycle of the trematode Pleurogonius malaclemys relies on the eastern mud snail (Ilyanassa obsoleta) and the diamondback terrapin (Malaclemys terrapin). This parasitic flatworm will mature and reproduce only in the intestines of the diamondback terrapin. The abundance of this parasite in an area may give insight into the effectiveness of conservation efforts of its definitive host. Encysted trematodes were counted on snail opercula and measurements were taken for shell and aperture lengths. Cyst frequency of P. malaclemys was calculated for mud snails collected at the Wetlands Institute dock and two locations near causeways with known terrapin road mortality. Forty-two percent of mud snails collected from the Wetlands Institute dock were infected with the parasite. Based on the trematode lifecycle, it was hypothesized that snails from areas with higher terrapin road mortality would have more cysts; however, data from 2012 suggest otherwise. Although the Avalon Boulevard site had more roadkills (169), only 15 percent of the eastern mud snails were infected. Snails collected along Stone Harbor Boulevard had a higher (42%) parasitemia but fewer roadkills (134). Further investigation into the trematode lifespan, local roadkill values, and parasite abundance over a longer term could provide explanation. Eventual correlation between the parasite and its definitive host may still be possible.
Distribution and Survival of Hatchling Northern Diamondback Terrapins (Malaclemys terrapin terrapin) in Storm Drains
Jennifer Jankowiak, Binghamton University
While conservation efforts for diamondback terrapin (Malaclemys terrapin) have focused on reducing mortality of adults and juveniles, it is now apparent that large numbers of hatchling terrapins become trapped in storm drains each year. To understand this problem, 107 storm drains were monitored in Wildwood Crest, New Jersey (WWC) since 2008, and 182 storm drains were monitored in Sea Isle City, New Jersey (SIC) since 2010. Drains were inspected regularly during fall and spring activity seasons, and all hatchling terrapins (live or dead) were removed by dip net. A total of 4,182 hatchlings have been collected since 2008. Seasonal differences in storm drain rescues were observed at both sites. A greater number of hatchlings were found in spring (WWC = 3026; SIC = 842) than in fall (WWC = 212; SIC = 102). No correlation between rain events and terrapin rescues was observed, suggesting that hatchlings walk into drains rather than being washed in. A sample of rescued terrapins (N = 455) was measured to assess growth since hatching. Plastrons of terrapins from storm drains were 2–3 percent larger than those of newly hatched terrapins (N = 30), suggesting a period for growth between hatching and falling into the drains. To date, 135 terrapins have been found dead in storm drains or have died shortly after rescue. Potential causes of death include drowning, low temperatures, or poor water quality. Conservation plans for diamondback terrapins in urban areas must include storm drain surveys to prevent significant and avoidable loss of hatchlings.
An Evaluation of the Wetlands Institute’s
Diamondback Terrapin Head Start Program
Alison Mooradian, Vassar College
Head start programs for threatened species provide protection during early life stages before release, giving the juveniles a greater chance of survival than those hatched in the wild. However, head start programs are controversial due to their high cost and low return. In order to assess the success of the Wetlands Institute’s diamondback terrapin head start program, I evaluated four components: anomaly frequencies and relative growth rates of laboratory-hatched vs. naturally hatched terrapins, the number of recaptured head-started terrapins, and program cost. I analyzed 15 years of mark, release, and recapture data, as well as hatchling data from the Stockton College turtle farm. Anomaly frequencies did not differ between the laboratory-hatched and naturally hatched populations. On average, the naturally hatched terrapins had 1.4 percent longer carapace lengths and 1.1 percent longer plastron lengths than the laboratory-hatched terrapins. However, relative growth rates calculated suggest that head-started terrapins grow 0.5–1.0 percent faster than the natural population. Thirty-five head-started terrapins have been recaptured over the past 15 years, which is 1.8 percent of the 1,886 head-started terrapins released since 1997. I calculated that the approximate 2011 program cost was $93,500 for 137 head-started terrapins released into the wild, making the cost per head-started terrapin $680. While the program is expensive, it also raises public awareness and support, both of which are valuable but hard to quantify. However, in order to truly determine whether or not the program is successful, a comprehensive census of the head start terrapin population is needed.
Examining the Effectiveness of Barrier Fencing for Diamondback Terrapins on Nummy Island
in Southern New Jersey
Ashley Potter, Michigan State University
Loss and degradation of nesting habitat on barrier islands in southern New Jersey leads female diamondback terrapins (Malaclemys terrapin) to nest alongside roadways adjacent to the salt marsh. Along the Atlantic Coast of the Cape May Peninsula, the result is several hundred roadkills annually. To reduce losses, various types of barrier fencing have been installed by staff and volunteers from the Wetlands Institute and nearby communities. I examined the effectiveness of six-inch-diameter corrugated plastic drainage pipe as a terrapin barrier following its installation in late May 2012, along approximately 1/3 of Nummy Island’s roadway. Nummy Island is in an undeveloped salt marsh with a history of frequent roadkills due to a roadway through the middle connecting the southern end of Stone Harbor to North Wildwood. I conducted road patrols and documented saves and roadkills at 7:00 and 11:00 a.m. and 3:00 p.m. daily. In addition, I searched for predated and abandoned nests on a weekly interval. I found no statistical differences between fenced and non-fenced areas of Nummy Island when comparing the frequency of saves, roadkills, and abandoned nests. Predated nests, however, were more abundant in the non-fenced area as compared with the fenced area. Within the fenced area alone, I observed no statistical differences in the frequency of predated or abandoned nests between the marsh and road sides of the fencing. My study suggests that the barrier fencing was not effective in the first two months following installation on Nummy Island. Further research may determine if barrier function improves over time.
Does Shade from the Wetlands Institute Dock Decrease the Diversity, Size, or Abundance of Shellfish Living Beneath it?
Hannah Pretz, The Richard Stockton College of New Jersey
Shellfish, (oysters, mussels, clams, and snails) are common residents of the salt marsh and are ecologically important because, as filter feeders, they clean the water of bacteria and plankton and in some cases stabilize creek banks. A 35-m long dock at The Wetlands Institute projects into an area designated as important shellfish habitat. To understand the impact of the dock on shellfish populations, the number of adult quahog clams (Mercenaria mercenaria) and ribbed mussels (Geukensia demissa) were counted in 0.25 m² quadrats. For the quahog clam population estimate, quadrats (n = 35) were placed in a 12 m × 18 m grid in the intertidal zone beneath and on either side of the dock. Ribbed mussels were counted in quadrats (n = 30) placed in areas of low marsh near the shoreline. Over all, clam density was very low, ranging from only 0.0 to 4.0 clams per square meter of intertidal habitat with the highest density of clams beside the dock rather than beneath it. Ribbed mussel density in the low marsh was 32 mussels per square meter. The loss of 21 m² of low marsh habitat where the dock meets the shoreline likely resulted in the loss of more than 600 mussels. These data suggest that the dock has a negative, but extremely local, impact on ribbed mussels and a negligible impact on quahog clams. Impacts on shellfish may be offset by the broader impacts of research and educational activities associated with the dock that help preserve salt marsh habitat.
Using Plastic Models to Understand the Movement of Hatchling Diamondback Terrapins Trapped in Storm Drains
Jessica Radich, The Richard Stockton College of New Jersey
Although barrier islands of southern New Jersey are extensively bulkheaded, there are areas where diamondback terrapins (Malaclemys terrapin) can access the islands and attempt to nest. These islands have been extensively urbanized and females that successfully navigate the streets lay their eggs in yards, parks, and recreation fields. Months later, hatchlings emerge from these nests and migrate toward water, encountering many obstacles, one of which is storm drains. Hatchlings may fall through the openings of storm drains and become trapped. Storm drains are connected by a network of pipes leading to an outfall where water flows to the salt marsh. I constructed plastic models of the same size, shape and mass as hatchling terrapins to understand how hatchlings might move after entering a storm drain. I deployed 68 models in five storm drains in a network and relocated them after rain events. There are five possible fates for a hatchling that falls into a storm drain; remain in that drain, flow up through the top of the storm drain and back onto land, flow to another drain, flow out into the marsh through the outfall, or disappear entirely. Of the 68 models, 5 stayed in the same drain, 4 flowed to another drain, 21 washed onto land, 13 were washed into the outfall, and 25 disappeared entirely. The fate of a terrapin trapped in a storm drain depends on the location of the drain it falls into. Hatchlings trapped in the drain nearest the outfall had the highest probability of being washed into the salt marsh.
Testing Turtle Fences: Determining Effectiveness of Diamondback Terrapin Barriers on the Atlantic Coast of Southern New Jersey
Hannah Reses, University of Michigan
Nesting season (late-May through mid-July) is a perilous time for diamondback terrapins (Malaclemys terrapin) along the Atlantic Coast of southern New Jersey. Coastal development has deprived terrapins of nesting habitat (sand dunes) on barrier beach islands, forcing many to nest on embankments of causeways that cross salt marshes. Hundreds of adult females are killed by motor vehicles on roads each year in Cape May County. Wetlands Institute staff and community volunteers have attempted to combat this problem by installing terrapin barrier fences made from corrugated plastic tubing. Effective barrier fences restrict nesting females to the marsh side of the barrier. During the summers of 2011 and 2012, I monitored nesting habitat on both the marsh and road sides of fences on sections of two causeways, Stone Harbor Boulevard and the Margate Boulevard. I located predated and abandoned nests to determine areas of concentrated nesting activity. Corrugated tubing was 93 percent effective in restricting terrapins to the marsh side of the barrier; however, terrapins did occasionally reach the road side through gaps beneath the tubing or through access points. To understand how gap height influences barrier effectiveness, I built a 5-m oval arena with corrugated tubing. I placed terrapins individually into the arena and raised a section of tubing to various heights and observed the number of terrapins that escaped within 10 minutes. As gap height increased, the percentage of terrapins that escaped from the arena increased. Corrugated tubing fences are effective in keeping the terrapins off the roads when gaps beneath the barrier are minimal.
Benthic-Dwelling Macroinvertebrate Diversity and Salinity Tolerance in a Tidally Influenced Creek in Coastal Southern New Jersey
Sarah-Anne Rohlfing, The Richard Stockton College of New Jersey
Water quality in freshwater streams may be inferred by resident macroinvertebrates. However, in coastal areas most streams are fresh at their source, but a connection to tidal waters results in significant influence by salt water. Rapid Bioassessment Protocols (RBP) based on benthic macroinvertebrates do not account for tidal influence and salinity. To better understand how salinity affects macroinvertebrate species diversity, RPB surveys (N = 8) were conducted over a 650-meter segment of Crooked Creek, a tidally influenced stream in Cape May Courthouse, New Jersey. At each survey point, water quality parameters (salinity, dissolved oxygen, and temperature) were measured with a YSI 600-XLM multi-parameter water monitoring probe. Species composition varied among sites. Seven macroinvertebrate species were found at the uppermost site (freshwater) of the study area while only four species are found at the most downstream (tidally-influenced) site in the study area. In the uppermost site, lung snails (Gastropoda, Pulmonata) were the dominant species (58%), whereas in the most downstream site scuds (Gammarus sp.) were dominant (83%). Both taxa are indicators of poor water quality. My sampling suggests that scuds are more tolerant of salinity fluctuations than lung snails.
Identifying Terrapin Roadkill Hotspots with
Geographic Information Systems
Ian Van Halem, West Chester University
Since 1991, the Costal Conservation Research Program has documented the number and location of more than 10,000 road-killed diamondback terrapins (Malaclemys terrapin) on a 38-mile transect of roads adjacent to salt marsh in Cape May County. Terrapin mortality can be reduced by locating clusters or hotspots of these roadkills and understanding why they are occurring. Roadkill locations (N = 419) from 2012 were analyzed for speed limit, proximity to the marsh, bulkheading, and barrier fencing. Causeways were identified as roadkill hotspots because they combine several of these factors. Road segments with a speed limit of 50 MPH make up 8 miles (21% of transect), but had 269 roadkills (64% of total). Road segments (causeways) within 15 m of the marsh make up 8.2 miles or 22 percent of the transect, but had 288 roadkills (68% of total). Road mortality was lower on the barrier island roadways because they are farther from the marsh and have lower speed limits, and access to the island is limited by extensive bulk-heading. Road segments near bulkheaded shorelines make up 8 miles or 21 percent of the transect but had 17 roadkills (4% of total). Barrier fencing reduces roadkills on causeways. Fenced areas had 30 roadkills/mile while unfenced causeway segments had 38 roadkills/mile. While fencing reduces roadkill, also creates small hotspots where gaps (e.g., driveways and access points) funnel terrapins onto the road. Reducing speed limits, building additional fences, and minimizing gaps will reduce the number of roadkills on causeways.
|
