Examining the Environmental Variables Preceding Stranding by Common Bottlenose Dolphins in the Cooper and Back Rivers, Charleston, South Carolina
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Cheever, Andrew
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Abstract
Bottlenose dolphins (<I>Tursiops truncatus</i>) are one of the most recognized marine animals in the world as a result of this species' ubiquitous distribution throughout estuarine and coastal waters that overlap with human communities, and their prevalence in global aquaria and various media sources. This species is also well-known for its role as a sentinel organism, granting researchers invaluable insights into marine ecosystem function and health. The Charleston Estuarine System Stock (CESS) is a relatively well-studied population of bottlenose dolphins that has been the subject of scientific inquiry for decades. Despite the long-term research performed on the CESS, it is currently unclear how environmental parameters influence this stock's distribution and fine-scale ranging patterns. Foremost among these parameters are salinity, temperature, and prey availability, which can have direct and indirect effects on dolphin foraging, distribution, and overall health. The current study evaluated these environmental parameters to identify potential correlations with stranding data in the low-salinity waters of the Cooper and Back Rivers. The study shows that the stress bottlenose dolphins suffer from exposure to freshwater occurs between 15 and 30 days before the animal perishes, as this time frame accounted for the most variability in both temperature and salinity. Prey species analysis proved less indicative of stranding in this study.
This research will contribute to the growing body of knowledge regarding the interplay between bottlenose dolphins and biotic and abiotic environmental conditions. Further, the findings of this investigation may prove useful to wildlife managers hoping to mitigate and/or efficiently respond to freshwater strandings. This is critical on a population-level to better understand broad-scale impacts of dolphin mortality in low salinity conditions, a challenge facing all estuarine stocks of bottlenose dolphins. It is also significant on an individual-level, as contributing to that body of knowledge can help to increase the likelihood of survival for dolphins that are rescued and relocated from low salinity conditions.