Doctor of Philosophy (PhD)
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Trophic interactions, bioaccumulation, Everglades, marine mammals, passive acoustic monitoring, hurricane, stable isotopes
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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, pollutant exposure, and factors influencing habitat use 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 to 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. Bottlenose dolphin use of the Shark River estuary, which extends from the Gulf of Mexico to the marshes of Shark River slough, was estimated using passive acoustic monitoring. Dolphins were detected at stations in rivers on more than 75% of days in both wet and dry seasons and occurred in an upstream bay on most days. Average durations of dolphin detections when they were present varied with an interaction of season, year, and location. While there was not an obvious relationship between fish density measured by DIDSON sonar and dolphin detections, detections of dolphins at most stations were associated with variation in temperature and/or salinity. The passage of a major hurricane also influenced dolphin use of the study area, with considerable increases in the use of upstream areas in the weeks following the hurricane. Overall, the result of my dissertation will help to predict how dolphin respond to environmental variability and help inform Everglades restoration and management.
Paz, Valeria A., "Investigating Trophic Interactions, Habitat Use, and Pollution Loads of Bottlenose Dolphins (Tursiops Truncatus) in the Florida Coastal Everglades" (2022). FIU Electronic Theses and Dissertations. 5014.
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