Semester of Graduation

Spring

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

I coupled fine-scale environmental data with observed behavior and group composition data to examine overall distribution within the bay system and to characterize the habitat associated with foraging and the presence of calves. Semi-isolated populations of bottlenose dolphins (Tursiops truncatus) along Louisiana’s coast are undergoing increased risks from boat traffic, oil spills, land subsidence, and planned water diversions (CPRA 2017). Characterizing the habitat use of bottlenose dolphins in Terrebonne and Timbalier bays, Louisiana, is important given the likely high site fidelity, small home ranges, and low exchange of individuals with nearby coastal populations (Lane et al. 2015, McDonald et al. 2017, Wells et al. 2017). Small, semi-isolated populations with associated low genetic diversity are especially vulnerable given that recolonizing to a healthy population level could take several hundred years, if even possible (Sellas et al. 2005, Nichols et al. 2007). Knowledge of dolphins’ responses to crises, including oil spills and hurricanes, is limited (Miller et al. 2013, Nixon et al. 2016). The highest risk is to reproductive-age females and calves, given that the future viability of the population depends on the success of these two age classes (Matkin et al. 2008). Seasonal differences in environmental conditions may indirectly influence bottlenose dolphins by directly influencing the distribution and movements of their prey. The foraging requirements of dolphins determine their distribution, thus extra care to protect the entire range of habitat utilized to fill their needs is crucial (Cockcroft & Ross 1990). In my study, groups with calves occupied a different environmental space when not foraging compared to all other groups (i.e., adults only foraging and not foraging, calves foraging). This presumable shift to nursery conditions protects calves. Conserving this low salinity and high turbidity area is critical to ensure the population’s success.

Committee Chair

Baltz, Donald

Available for download on Sunday, January 16, 2022

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