Assessing Risks from Harbor Dredging to the Northernmost Population
of Diamondback Terrapins Using Acoustic Telemetry
T. Castro-Santos1,2
& M. Bolus2 & A. J. Danylchuk2
Received: 2 August 2017 /Revised: 28 September 2018 /Accepted: 1 November 2018
# This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright
protection 2018
Abstract
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.
Keywords Terrapin . Telemetry . Dredging . Brumation . Hibernation .Movement . Modeling . Risk . Assessment
Introduction
Coastal and estuarine environments accommodate a range of
human activities, including fisheries, aquaculture, recreation,
and transportation. These activities are supported by infrastruc-
ture, the maintenance of which can affect sensitive species that
inhabit these zones (Culloch et al. 2016;MoserandRoss 1995).
One such activity is harbor dredging. Harbors are typically
located in sheltered waterways, often with additional armoring
to protect anchorages and ports. This sheltered quality creates
an opportunity for sediments to accumulate, and harbors