Anthropogenic impacts on the reproductive ecology of the diamondback terrapin, Malaclemys terrapin

John P. Wnek

doi:10.17918/etd-3325

Diamondback terrapins, Malaclemys terrapin, inhabit estuaries along the east and Gulf coasts of North America. One such estuary, Barnegat Bay, New Jersey, is considered one of the most anthropogenically altered estuaries in the United States. Barnegat Bay's marsh and shoreline habitats have been filled with anthropogenically impacted substrate dredged from the bay floor, called dredged sediment. Terrapins use anthropogenically impacted areas for nesting that can negatively impact hatching success of terrapins. The introduction of non-native plants and structures (i.e., fences) shadefinest sites, reducing nest temperature which affects the incubation duration and gender of terrapin embryos. This study investigated population sizes, hatching success, incubation duration of terrapin embryos in nests in different soil treatments including dredged substrate; and nests exposed to shade at North Sedge Island, Barnegat Bay. Microhabitat nest factors including: temperature, soil conductivity (SC), water potential, and gas composition in different soil types were studied. Our results indicated that freshlydredged substrate had the lowest water potential (MPa) and highest soil conductivity (mS/cm) than all other soil treatments with a100% embryo mortality with no embryonic development past the first stage of development. Nest temperatures at North Sedge Island were at the pivotal incubation temperature in non-shaded treatments and were below the pivotal temperature with 50% shade. Shading of nests caused significantly longer incubation durations and delayed emergence for terrapin embryos compared to non-shaded nests. Terrapin population estimates at N. Sedge Island indicated that 430 + 23 female terrapins utilize the island for nesting, and the earliest reproductive age of females on the island was six years. Increased body size and earlier age of maturity at N. Sedge Island may be a result of the area being located within a marine conservation zone, which has a large expanse of marsh, limited commercial operations, and ample estuarine food resources. This study showed that nest site conditions (i.e., soil texture, shading) are important for the success of diamondback terrapin populations. Effective management practices including the analysis of dredged substrate and washing it prior to its utilization to enhance or restore wildlife habitat are recommended based on the results of this study.

Anthropogenic impacts on the reproductive ecology of the diamondback terrapin, Malaclemys terrapin

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Anthropogenic impacts on the reproductive ecology of the diamondback terrapin, Malaclemys terrapin

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