Date of Award

Fall 12-15-2012

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Marine Science

College

College of Science

First Advisor

Robert F. Young

Abstract/Description

When studying estuarine environments that are directly fed by the ocean tides, the impact of the changing tide is vital in studying the migration and travel behaviors of organisms within those environments. This study was aimed at determining the influence of the daily tidal currents on movement with or against the tides by Atlantic bottlenose dolphins (Tursiops truncatus). Data collection occurred from March to October 2012, at three study sites: the ACE River Basin National Wildlife Refuge, the Hilton Head estuary, and the Cape Romain National Wildlife Refuge. Photo identification transect surveys were conducted to observe resident Atlantic bottlenose dolphins (Tursiops truncatus) in coastal South Carolina estuarine systems. Travel direction was analyzed using Chi square tests for significance with respect to the overall data set, study site, presence of calves in the group, size of the group and tidal stage. Travel direction was found to be significant (p<0.05) within events where travelling was observed, with most movement occurring against the tide. For data where travelling was observed, travel direction was also found to be significantly against the tide (p<0.05) for two of the six tidal stages; tidal stages were defined as high ebb, mid ebb, low ebb, low flood, mid flood, and high flood. No significant results were found in accordance with the other factors. Studies have shown that many dolphin prey species move concurrent to the tidal changes, and so the dolphins may have a strategy of feeding while swimming against the current.

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