Trophic Interactions, Habitat Use, and Pollution Loads of Bottlenose Dolphins (Tursiops Truncatus) in the Florida Coastal Everglades, Florida, USA, 2013-2019

Cetaceans can feed at upper trophic levels and occur from freshwater to open-ocean ecosystems. Due to their abundance, mobility, and high metabolic rates, they have the potential to affect the structure and function of ecosystems through both top-down and bottom-up pathways. To better understand what ecological roles they may play in a system, it is important to understand patterns and drivers of their abundance, habitat use, and trophic interactions. I investigated the trophic interactions and pollutant exposure of common bottlenose dolphins (Tursiops truncatus) of the Florida Coastal Everglades. Based on bulk stable isotope analysis of tissue samples collected using biopsy sampling, it appears that despite their high mobility, bottlenose dolphins restrict their foraging within the habitats where they were sampled. Trophic position and foraging locations affected exposure to pollutants, with high levels of mercury found in dolphins estimated to forage at higher trophic levels and feeding within an inland bay. Mercury levels also varied with age and sex. Dolphins and their prey both contained substantial mercury levels and dolphins’ health could be impacted by this exposure, but the selenium levels we measured might counteract these negative effects.