Description

An introduction to Terrapins

Diamondback terrapins are magnificent and unusual turtles in many ways—they live in salt water but are not sea turtles, they are restricted to the Atlantic coasts of the United States, and they play key roles in their ecosystems.  From the 18th through the 20th centuries they were hunted and eaten in huge numbers, sometimes as the unpopular food of the poor and other times as haut cuisine.  Nowadays, Terrapins are legally protected in every state they are found, but this has not stopped their populations from declining from the Gulf Coast of Texas, to Cape Cod, Massachusetts.

Research on this decline is already being conducted at numerous parts of the terrapin range, especially in the southeast (Maryland, Georgia, and Florida).  In these areas conservation issues are fairly well known: terrapin population declines are largely attributable to road mortality (Avissar 2006) and incidental catch in crab fisheries (Butler and Heinrich 2007, Dorcas et al. 2007, Roosenburg, W. M. 2004).  Neither of these factors appears to have a large affect on Jamaica Bay terrapins, which my students and I have been studying since 1999, yet our findings show that terrapin nesting populations there have declined 40% in the last decade alone (Figure 1).

Why are terrapins important? 

Terrapins are considered a keystone species in both estuarine and nearby coastal ecosystems, which means their impact on these environments are greater than their relative abundance. Thus conservation of this species is critical to the maintenance of natural nutrient and energy pathways. Terrapins significantly reduce the populations of the crustaceans, crabs, mollusks and other invertebrates they eat (Tucker et al. 1995), which can have widespread effects on the ecosystem. For example, terrapins dramatically reduce the abundance of periwinkles snails (Levesque and Fauth 1999, who in turn are important predators of salt marsh cordgrass (Silliman and Bertness 2002).

On the other side of the food chain, terrapin eggs and emerging hatchlings are eaten by a variety of predators, which moves enormous quantities of nutrients and calories from water to land. In a single year on one small Jamaica Bay beach, raccoons ate 300,000 Kcal worth of terrapin eggs (Feinberg and Burke 2003).  Eggs that are missed by vertebrate predators provide plant roots important nutrient for growth in an otherwise nutrient-poor environment (Stegmann et al. 1988, Feinberg and Burke 2003, Burke, unpublished).

Location

The research will be conducted in Jamaica Bay, a 2509 acre bay in the southwest corner of Long Island that lies within the boroughs of Brooklyn and Queens, New York.  Much of Jamaica Bay is owned by the National Park Service as part of Gateway National Recreation Area. The Jamaica Bay terrapin population is particularly important because of its high public visibility; it is the largest terrapin population in New York, and it is essential to the ecological recovery of Jamaica Bay.

Two of the main environmental issues at Jamaica Bay are the high rates of marsh loss and pollution, both of which are associated with John F. Kennedy International Airport.  Construction of the airport began in 1942 and eventually covered 1821 acres of salt marsh. Currently the airport is a major source of Jamaica Bay pollution, including noise pollution, glycols and other chemicals used to de-ice planes, and VOCs and NO released into the air during landings, takeoffs, and taxiing. Other important sources of pollution includes sewage treatment plant outflow and old industrial pollution.

Tracking technology

The money raised on iAMscientist will be used to collect information needed to choose the technology needed to track the terrapins. Animal tracking in the sense used here refers to digital electronic devices attached to animals so that they can be located while they move naturally in their habitats. These systems typically include radio telemetry, sonic tags, and archival tags; recently there has been an explosion of new devices incorporating miniature GPS units.  Each of these options is expensive and requires a significant startup investment.  To choose among these options, I need more information about terrapin surfacing behavior.  The technology I need for this are DST milli-L temperature/depth tags, small (5g) devices that record and store depth and temperature readings at regular time intervals for up to three years.  I plan to attach these tags to twenty terrapins when they come on land to nest at my lab’s study site in Jamaica Bay.  I will recover tags when terrapins return to nest in 2014, and more of them in 2015. The tags are highly accurate and can store 682,000 depth/temperature measurements.  This allows frequent depth readings and great depth resolution.

Project outcome and impact of result

The lasting benefits of this project will be improved conservation efforts on the behalf of terrapins, through increased knowledge of their habits. While my lab has documented years of poor population recruitment (Feinberg and Burke 2003, Giambanco 2003, Ner and Burke 2008, Muldoon 2010), thus far we have been unsuccessful in tracking terrapins outside the nesting beaches.  This greatly limits our conservation efforts. We hope the technology bought from this project will help expand our understanding. Also, we have recently started a collaborative project with JFK wildlife biologists, and together we hope to learn more about terrapin declines.