The diamondback terrapin (Malaclemys terrapin), a long-lived turtle species of the eastern coast of the United States, is a charismatic and distinctive species known for being the only emydid turtle that strictly presides in coastal brackish waters. The status of the diamondback terrapin varies locally but many populations face declines due to environmental stressors. Jamaica Bay, an urban estuary located in southern New York City, is home to at least two female diamondback terrapin populations that nest seasonally on Ruler’s Bar Hassock and John F. Kennedy Airport (JFK). Jamaica Bay terrapin populations inhabit a highly urbanized environment with a long history of pollution and habitat degradation. Yearly monitoring has led to a greater understanding of their behavioral and reproductive characteristics, but little is known about their population vital rates including survival, a key parameter in long-lived species. Our objectives here were to 1) estimate survival and detection rate of female diamondback terrapins across years and between the two adjacent populations, and 2) test the impact of water quality, hurricanes, and injuries on survival to understand the primary threats to female terrapin populations. We analyzed long-term mark-recapture data using the Cormack-Jolly-Seber and Multistate models to estimate survival rates.
Results/Conclusions
Initially, apparent survival for Ruler’s Bar female terrapins was high at 0.92 but declined over a 15-year period, while survival for JFK females was constant at 0.92. Water quality, represented by mean nitrogen levels, did not affect female terrapin survival in either population while models including the effect of Hurricane Sandy (2012) indicated a decline in survival to 0.85 for two years following the storm in Ruler’s Bar. Survival estimates for injury states were constant at 0.92 for individuals with no injuries and 0.88 for major injuries. The results support a distinction in survival patterns between the populations as well as the apparent impact of severe storms and major injuries. Ruler’s Bar experiences high nest mortality due to raccoon predation suggesting a greater reliance on adult female survival to sustain the population. Declining survival and even slight reductions in survival of reproductive females can have the largest proportional impact on growth in terrapin populations. These survival determinations are crucial to understanding the status of the breeding female populations in Jamaica Bay and can aid in the development of local conservation strategies.