Bottlenose Dolphins - Dani Silva

Bottlenose dolphins are managed by the National Marine Fisheries Services based on stock assessments. The SC/GA bottlenose dolphin coastal stock is defined as dolphins in coastal waters up to 100 m deep from the NC/SC border to the GA/FL border and it overlaps with the Southern Migratory stock in the winter; however the distribution, the seasonal movements, and the interactions with estuarine stocks and other coastal stocks are not well understood (Waring et al., 2010). Its abundance was estimated based on aerial surveys from the summer of 2002 and 2004 (Warning et al., 2010), though local abundance estimates are few and sparse (Young pers. comm.). Studies have shown a seasonal influx of dolphins to South Carolina coastal waters, especially in the fall and winter (Gubbins, 2002; McFee et al., 2006; Speakman et al., 2006; Young, unpublished data), during which coastal and estuarine groups were observed interacting (Laska et al., 2011; Speakman et al., 2010). Furthermore, long-term stranding data shows different stranding patterns in SC, dividing the state in two areas; from Little River to Murrells Inlet strandings peak in the fall, on the other hand from Murrells Inlet to the Savannah River, strandings have a bimodal peak in the spring and in the fall (McFee et a., 2006, SCMMSN unpublished data) suggesting that dolphins north of Murrells Inlet belong to a different stock. Therefore understanding the seasonal trends in abundance and identifying the local population is crucial to conservation and management plans. My objective is to use mark-recapture photo-ID studies to investigate the seasonal migration patterns of coastal dolphins off Long Bay, SC. Using mark-recapture, I hope to investigate seasonal abundance, temporal and spatial distribution of bottlenose dolphins, as well as identify migratory patterns, and identify the stock structure off Long Bay,SC.

Dolphins are the perfect example to explore evolution and genetics. The evolution of cetaceans is well represented in the fossil record. Genetics is currently being used to differentiate bottlenose dolphin stocks. Cell structure and function can be compared between taxa. Here are specific examples encompassing two of the academic standards for tenth grade: 1) the flow of energy within and between living systems; and 2) the interrelationship of organisms with their biotic and abiotic environment. For the first academic standard, we could investigate the changes in the food chain that allow for an influx of dolphins to South Carolina in the fall. Are prey items more abundant in the fall? Is the prey migrating and thus dolphins are following their prey? To investigate energy flow within living systems, we could investigate the allocation of energy in bottlenose dolphins between summer and winter. For example, in the winter we would expect more energy allocation towards blubber tissue as oppose to the allocation of energy to somatic tissue in the summer. One approach would be to check if there are differences in prey preference between summer and winter months.

 
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