Date of Award

Spring 2006

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

Keith R. Walters

Third Advisor

M. Scott Harris

Abstract

Previous studies have investigated bottlenose dolphin distribution relative to vegetated versus non-vegetated benthic habitats but none have examined habitat usage patterns relative to subtle differences in non-vegetated sedimentary bottom types. The purpose of this study is to determine if there is a relationship between areas of dolphin distribution and sedimentary bottom types in a non-vegetated, soft sediment environment. The study area, Winyah Bay, South Carolina (USA), is a ... partially mixed estuary and has a heterogeneous bottom substrate profile, including the presence of various sediment types, ranging from 0-100% sand (as determined through sidescan sonar and sediment grabs). Transect surveys were conducted approximately biweekly from May through October in 2004 and May through August in 2005. Dolphin location, group size, and behavior were recorded and correlated with bottom type, depth, and salinity. Combined years had an average group size and standard deviation of 8.4±7.2, and ranged from 2-28 individuals. Both total and feeding individual bottlenose dolphins in Winyah Bay showed distributions that were significantly different than random in relation to substrate, salinity, and depth. Bottlenose dolphin distribution and feeding behavior occurred more than expected in areas of shallow depth (2.1-4m), higher salinity ranges (15-34psu), and over sand with trace mud sediments. Areas where all preferred salinity, substrate, and depth ranges co-occurred represented 4% of the total bay area, however 17% of individual sightings occurred in these areas and individual observed distribution values were six times greater than expected values. Where one or more preferred ranges occurred, individual bottlenose dolphin only occurred more than expected in areas characterized by the preferred salinity range. This indicates an interacting distributional influence between substrate, salinity, and depth, such that, bottlenose dolphins in Winyah Bay appear to select habitat based first on salinity, and then on depth and substrate.

Download

Share

COinS