Habitat Use by Bottlenose Dolphins in the Indian River Lagoon

The objective of this research was to examine bottlenose dolphin (Tursiops truncatus) habitat use in the Indian River Lagoon (IRL) based on monthly relocation of photo-identified individuals, prey availability and environmental factors from 2003-2015. We focused on the variation of spatial and temporal abiotic and biotic factors and their influence on bottlenose dolphin habitat use patterns. Harbor Branch Oceanographic Institute (HBOI) conducted monthly photo-identification surveys along the length of the IRL and GPS locations of photographed dolphins were collected at the time of surveying. Stratified random samples of prey and environmental variables were collected monthly by the Florida Fish and Wildlife Conservation Commission (FWC) as part of the Fisheries-Independent Monitoring (FIM) program. Kernel density estimation was used to determine the magnitude-per-unit area of dolphins across a continuous raster surface of the IRL by wet and dry seasons each year, the values of which were used as a response variable in Classification and regression tree (CART) analyses with FIM fish community and environmental factors as predictors. Understanding how dolphins respond to environmental factors over time in the IRL could be used to predict future responses in estuaries and prioritize conservation and restoration actions.