Abstracts of Papers
Comparative Analysis of Malaclemys terrapin terrapin
C. Bachman1,2 and D. Kays1,3
The diet of Malaclemys terrapin terrapin at two different New Jersey study sites, one in the Hackensack Meadowlands and one on the Cape May Peninsula, was analyzed. These sites differ in salinity, water temperature, and documented sources of pollution. The study was carried out by collecting and examining fecal samples from terrapins at both sites, and by examining the contents of gastrointestinal tracts of road-killed females collected on the Cape May Peninsula. Fifteen different species of fish, arthropod or mollusk remains were identified, showing that these terrapin populations feed on a much wider variety of species than is generally indicated in literature. There was a substantial amount of crossover of species found at both sites; however, each site had unique species, and the most common prey species were different at each site. These results support that terrapins are opportunistic eaters, and that they do not depend on only a few prey items for survival, but are able to eat many different species. It was also apparent in the data from the Hackensack Meadowlands that mostly larger terrapins were eating blue crab, showing that terrapin size is a factor in prey selection. (Poster presentation}
Estimating Survival Times for Diamondback Terrapins,
Patrick J. Baker1,2, Amy Thomson3, Itzick Vatnick3, and Roger C. Wood2,4
Turtles undergo the longest aquatic dives of any air-breathing vertebrate. Despite this remarkable ability, incidental drowning occurs when a turtle entrapped in fishing gear cannot reach the surface. Mortality in crab pots is a major threat to populations of the diamondback terrapin, Malaclemys terrapin (Latreille), a turtle that inhabits brackish waters along the Atlantic coast of the USA. We integrated laboratory and field observations to estimate survival time for a terrapin submerged in a crab pot. In the laboratory, voluntary dive time (8.4 ± 5.7 min) was compared to a calculated aerobic dive limit derived from mass-specific lung volume and metabolic rates. By this estimate, an active 200 g terrapin has sufficient oxygen stores to sustain aerobic metabolism for ~ 16 min at 20°C. In the field, average time of submergence for crab pots set in shallow tide creeks over a 4-day period was 58 ± 54 min for diurnal high tides and 314 ± 61 min for nocturnal high tides. Accordingly terrapins captured in crab pots during the day had lower plasma lactate concentrations those caught at night. Both groups returned to baseline levels within 12 h. Our data suggest that voluntary dives are terminated before the diving lactate threshold has been reached. However, terrapins that are trapped in crab pots can be submerged for several hours at high tide and must rely extensively on their ability to sustain anaerobic metabolism. Without access to air, entrapped terrapins will become acidotic within a few hours and die.
Saved from the Sewers: Rescuing Hatchling Diamondback Terrapins
J.M. Grottola1, K. Toft1, and R.C. Wood2
Prior to intensive human development of the New Jersey coast, the traditional nesting sites for diamondback terrapin (Malaclemys terrapin terrapin) were sand dunes on barrier beach islands. These dunes were, for the most part, obliterated long ago. However, where access to the salt marsh side of these islands is still unrestricted, terrapins continue to come ashore during the nesting season to nest in people's yards. Storm drains in these island communities are a significant hazard for terrapin hatchlings when they emerge from their nests and attempt to return to the salt marsh. Terrapin hatchlings fall into these drains and become trapped in water which potentially contains toxic chemicals and pathogens. Many drown. Since 1999, students from Lower Cape May Regional High School have been involved in the rescue, care, and release of these otherwise doomed hatchlings. Students have been monitoring storm drains and rescuing terrapins with dip nets in a 20 block area adjacent to the salt marsh in Wildwood Crest and Lower Township, New Jersey. Over 2,500 hatchlings have been rescued so far, with roughly 90% of them successfully released. Storm drains are a potentially significant source of terrapin mortality that has not previously been reported.
Preliminary Results of a Headstarting Project for Northern Diamondback Terrapins
Headstarting of turtles tends to be controversial. Concern has been expressed about whether this kind of activity has value as a conservation tool. We think it does, at least for the population of northern diamondback terrapins (Malaclemys terrapin terrapin) that we have been monitoring over the past twenty years in southern New Jersey. Since 1997, researchers at the Wetlands Institute have been microchipping headstarted terrapins prior to their release. Analysis of recapture data indicates that some of the headstarted terrapins are surviving and returning to nest at the Wetlands Institute, where they were originally released. These preliminary findings are of interest for two reasons: (1) headstarted terrapins are surviving long enough to contribute to the population gene pool, and (2) these headstarters are clearly exhibiting nest site fidelity. We are still in an early stage of this long-term study. Increasingly large numbers of headstarted terrapins are being released into our population every year. As we continue to monitor the population we anticipate being able to develop a clearer understanding of the extent to which our headstarting project is succeeding. (Poster presentation)
Terrapin Barrier Fences along the Atlantic Coast of Southern New Jersey
D.J. McLaughlin and R.C. Wood
Every year during their nesting season (typically late Maymid July), hundreds of adult female northern diamondback terrapins (Malaclemys terrapin terrapin) are killed on roads crossing or adjacent to salt marshes along the southern New Jersey coast. To mitigate this problem, researchers at the Wetlands Institute have conducted experiments to find out whether roadside fencing might be an effective means of preventing nest-seeking female terrapins from wandering onto heavily-trafficked summertime roads. Our research has demonstrated that terrapin barrier fences significantly reduce the number of terrapin road kills. Their widespread use in appropriate places can save hundreds of terrapin lives every nesting season. We have experimented with several different terrapin barrier designs: silt fencing, plastic mesh fencing, concrete blocks made from dredge disposal material, corrugated plastic tubing, and chicken wire attached to roadside guardrails. Citizen conservationists may chose to implement any of these barrier designs with the help of Institute staff. We continue to investigate new barrier designs.
Mercury in Mangrove Terrapins from the Florida Keys
Christina F. Mohrman1,2, Charles H. Jagoe1, and Roger C. Wood3,4
Because of their life history habits and role as a top predator in salt marsh and mangrove ecosystems, terrapins may serve as an important indicator species for contamination of estuarine ecosystems. Previous work has documented metal and organic pollutant burdens and effects in terrapins from sites along the Atlantic coast; however, little or no data is available for most terrapin subspecies. We collected non-lethal blood and scute samples from mangrove terrapins (Malaclemys terrapin rhizophorarum) from two locations in the Florida Keys National Wildlife Refuge and analyzed them for total mercury. Collection locations are small, uninhabited mangrove islands between Key West and the Marquesas. Scute mercury concentrations ranged from approximately 50-350 ppb dry weight. Blood concentrations were much lower. Blood mercury levels represent recent exposure while scute concentrations represent a longer-term, integrative record of mercury accumulation. Mercury concentrations generally increased with turtle size and weight, although relationships were not significant. This may be due to the relatively narrow size range of the captured turtles. For comparative purposes, we are also sampling Mississippi diamondback terrapins (Malaclemys terrapin pileata), which occur from the Florida panhandle to western Louisiana. Like mangrove terrapins, there is no data on the mercury burden of this subspecies. (Poster presentation)
The Influence of Air Temperature, Precipitation, and Tide
Cathrena Samodurov1,2, M. Krachey2, and R.C. Wood1
The significance of environmental influences on the nesting activity of a diamondback terrapin population was examined by analyzing the correlation of air temperature, precipitation, and tide with the activity with nesting females. Over a ten-year period (20002009) researchers patrolled forty miles of roads crossing or adjacent to salt marshes every nesting season. All terrapin road kills were documented. Using the number of kills found as an indicator for the overall activity of nesting terrapins and comparing environmental conditions to the number of kills found indicates in what way nesting behavior is influenced by environmental factors. Data suggest that terrapins avoid nesting on days when extreme air temperatures (both high and low) occur. Precipitation appears to play no significant role in the nesting activity of the terrapin population. But there is a correlation between nesting activity and tide height of the creeks running through the marsh. Terrapins are most active one to two hours before and after both high and low tides instead of only at high tides as previously suggested in the literature. (Poster presentation)
Roadkill Rollercoaster: Twenty Years of Monitoring
R.C. Wood and D.J. McLaughlin
Before human development of New Jerseys coastal barrier beach islands, terrapins nested on barrier island sand dunes. However, most of this natural habitat has been leveled to create nearly continuous resort communities along the Jersey shore. Consequently, female terrapins have had to find a suitable alternative location to lay their eggs. Today, most of the readily available nesting sites for terrapins in southern New Jersey are the shoulders of heavily trafficked roads crossing and adjacent to salt marshes. The result is that hundreds of nesting females are killed by motor vehicles each year. During the terrapin nesting season, Wetlands Institute staff and student researchers monitor 41 miles of salt marsh road (located on the Atlantic coast of the Cape May peninsula, southernmost New Jersey) for nesting female terrapins. The objectives are to record the number of terrapin road mortalities, remove potentially viable eggs from female terrapins run over by vehicles, and save nest-seeking terrapins attempting to cross the road. On average, 400 to 600 gravid female terrapins are killed by motorists every year just within this transect. Over the 20 years that researchers from the Wetlands Institute have been monitoring terrapin road kills, nearly 10,000 terrapin deaths have been documented.
Predation on Northern Diamondback Terrapins (Malaclemys terrapin terrapin) by Bald Eagles
R.C. Wood1, 2 and Larissa Smith3
Between 1999 and 2002, and again in 2010, skeletal remains were collected from a total of 20 different bald eagle (Haliaeetus leucocephala) nests scattered throughout New Jersey. Fourteen of these nests were located in the southern part of the state. Of these, seven adjacent rivers, lakes, or swamps contained shells of Sternothaerus odoratus (the stinkpot or musk turtle), a strictly freshwater species of very small adult size (maximum know carapace length = 13.7 cm). Four of the other seven nests (all located adjacent to salt marshes along the Delaware Bay and Atlantic Ocean coasts) contained only northern diamondback terrapins and musk turtles, and one had shells of both terrapins and juvenile snapping turtles (Chelydra serpentina). Nearly half of the terrapin shells (N = 45) represent males (N = 21). Seven females could be identified, while the remaining shell material represents very small terrapins too disarticulated to determine sex with confidence. Measurable terrapin shells ranged in size from 9.2 to 17.1 cm in carapace length (though only two exceeded 12.9 cm in length). Bald eagles are clearly exercising strong size selection when preying upon terrapin populations. (Poster presentation)