Investigating Long-term Changes in Distribution and Behavior of Coastal Bottlenose Dolphins (Tursiops truncatus) in Biscayne Bay, South Florida

Authors

Jessica Lynne CardeFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Biology

First Advisor's Name

Jeremy Kiszka

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Michael Heithaus

Second Advisor's Committee Title

Committee Member

Third Advisor's Name

Jenny Litz

Third Advisor's Committee Title

Committee Member

Fourth Advisor's Name

Kevin Boswell

Fourth Advisor's Committee Title

Committee Member

Fifth Advisor's Name

Jennifer Rehage

Fifth Advisor's Committee Title

Committee Member

Keywords

Bottlenose dolphins, Tursiops truncatus, Biscayne Bay, habitat degradation, habitat loss, home range, social structure, stable isotopes, seagrass

Date of Defense

8-30-2023

Abstract

Little is known about the long-term effects of environmental changes on coastal cetacean populations. This question is significant in the light of coastal marine habitat loss, pollution, and climate change. My dissertation focused on investigating the home range, social structure, habitat preferences, and trophic interactions of coastal the bottlenose dolphins (Tursiops truncatus), in Biscayne Bay (South Florida), a heavily impacted subtropical lagoon that has experienced significant habitat degradation over the past decades. My research was organized around four main objectives. My first objective was to analyze home range patterns to determine community structure, and to assess changes in home range dynamics from 1999-2019. I identified two distinct communities: one occurring in the northern portion of the bay, highly impacted by coastal habitat degradation. The other community occurs in the southern part of the bay, where individuals have larger home ranges. Both communities experienced home range contractions over time. My second objective was to describe the social structure and assess how social dynamics changed over time from 1990-2020. I found a dense, interconnected social network that has significantly strengthened over time. The strongest associations occurred between individuals of the same community and sex, with individuals of the southern community exhibiting the strongest associations. For my third objective, I investigated the primary drivers of dolphin distribution relative to environmental changes from 1999-2019. Depth was the primary driver for dolphin distribution, and foraging habitat preference shifted away from seagrass-dominated areas as seagrass coverage declined. For my final objective, I assessed the spatiotemporal variation in trophic interactions for each community using stable isotope analysis and found that individuals from the heavily impacted northern community prefer to forage on pelagic mesopredators, while southern individuals prefer to forage on seagrass-associated prey. Overall, my research sheds light on the community structure, home range patterns, social structure, and habitat use of this population, and highlights the ways in which they have been adapting to habitat loss and degradation.

Identifier

FIDC112025

ORCID

https://orcid.org/0009-0007-9933-5415

Recommended Citation

Carde, Jessica Lynne, "Investigating Long-term Changes in Distribution and Behavior of Coastal Bottlenose Dolphins (Tursiops truncatus) in Biscayne Bay, South Florida" (2023). FIU Electronic Theses and Dissertations. 5409.
https://digitalcommons.fiu.edu/etd/5409