Assessing Risks from Harbor Dredging to the Northernmost Population of Diamondback Terrapins Using Acoustic Telemetry
The northern diamondback terrapin (Malaclemys terrapin terrapin) is a saltmarsh-dependent turtle that occupies coastal habitats throughout much of the Atlantic coast of North America. We used a novel application of acoustic telemetry to quantify both mobility and occupancy of terrapins within a dredged harbor and surrounding habitats, and used these metrics to quantify relative risk to individuals posed by harbor dredging. Terrapins showed strong fidelity to brumating areas within subdrainages, but extensive movements between these zones during the active period. Activity was greatest in late spring and early summer, declining to near zero by December. Occupancy of the dredge zone was also greatest during spring and summer and declined throughout the autumn months to an annual minimum during winter. Taken together, these data indicate that risks from harbor dredging are minimized during the autumn and early winter months.
KeywordsTerrapin Telemetry Dredging Brumation Hibernation Movement Modeling Risk Assessment
Many people and organizations made important contributions to this project. Special thanks to Bob Prescott and the staff of the Massachusetts Audubon’s Wellfleet Bay Wildlife Sanctuary; Dr. Barbara Brennessel of Wheaton College; and Michael Flanagan and the staff of the Town of Wellfleet Harbormaster’s Office. These individuals and groups provided key resources and guidance, without which the project would have been impossible. We also thank agency staff for providing guidance and insights into the management context for the study, including Eve Schluter, Kevin Mooney, and the staff of the Massachusetts Department of Conservation and Recreation and the Natural Heritage and Endangered Species Program, as well as Todd Randall and Craig Martin (US Army Corps of Engineers). This project was funded by a grant from the Massachusetts Department of Conservation and Recreation Waterways Grant (Project # P11-2660-G01 (3803-G)), the University of Massachusetts Amherst, Department of Environmental Conservation, the Diamondback Terrapin Working Group, and Zoar Outdoor (Charlemont, MA). A.J. Danylchuk is supported by the National Institute of Food & Agriculture, U.S. Department of Agriculture, the Massachusetts Agricultural Experiment Station and Department of Environmental Conservation. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
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