Date of Award

Spring 2008

Document Type

Legacy Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

College

College of Science

First Advisor

Robert F. Young

Second Advisor

Ansley Wren

Third Advisor

Christopher E. Hill

Abstract

Behavioural budgets, travelling velocities, and energetic expenditures of bottlenose dolphins, Tursiops truncatus, were compared between estuarine (salt marsh creeks) and oceanic (near-coastal) habitats. We hypothesized that the travel velocities and their associated energetic expenditures would be less in the estuarine habitat. Surveys were conducted at North Inlet/Winyah Bay National Estuarine Research Reserve, Cape Romain National Wildlife Refuge, and the near coastal waters between Murrells Inlet and North Inlet, SC during April to December 2006 and May to October 2007. Behavioural data were collected during group focal follows and travelling speeds were estimated during energetic surveys, which recorded the position and timing of each surfacing and accounted for creek/ocean current speeds. The behavioural budgets of the two sub-ecotypes differed in the time allocated to, but not in the ranking order, of each behavioural category. Individuals in the oceanic sub-ecotype travelled with a significantly higher mean velocity, swimming 1.28 times faster and expending 2.26 times more energy while travelling than their estuarine counterparts. The 95% confidence interval for mean swimming velocity for travelling oceanic dolphins overlapped with the published range for the minimum cost of transport velocity for bottlenose dolphins, but the 95% confidence interval for estuarine dolphins was below this range. Thus, estuarine dolphins do not minimize energy expenditures per unit distance travelled, suggesting they are in a prey-rich environment with little need to maximize efficiency of travel between prey patches. Differences in the behavioural and energetic demands of estuarine and oceanic dolphins will influence the predatory impact of dolphins and the carrying capacities of their respective habitats.

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