29 research outputs found
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Genetic structure of common bottlenose dolphins (Tursiops truncatus) inhabiting adjacent South Florida estuaries – Biscayne Bay and Florida Bay
Coastal common bottlenose dolphins show a variety of migration and residency patterns adding to the difficulty of defining stocks for management purposes. Genetic structure plays an important role in identifying population stocks of dolphins. This study examines genetic differentiation in common bottlenose dolphins both between two social groups occurring in Biscayne Bay, Florida and between Biscayne Bay and an adjacent group of dolphins in Florida Bay. Skin biopsy samples were sequenced at the mitochondrial DNA (mtDNA) control region and genotyped at microsatellite loci. Significant genetic differentiation was found between bottlenose dolphins in Biscayne Bay and Florida Bay (mtDNA FST = 0.139, p ≤ 0.001; microsatellite FST = 0.042, p ≤ 0.001) supporting independent management stock status for these two populations. Within Biscayne Bay, evidence of weak but significant population differentiation was found between the two social groups using microsatellite markers (FST = 0.0149, p ≤ 0.009); however, differentiation was not evident from the mtDNA-based estimates of FST and φST. The lack of differentiation at mtDNA coupled with field observations indicating overlapping home ranges for these two groups suggests ongoing, though perhaps low, levels of interbreeding. These data are insufficient to warrant splitting the Biscayne Bay management stock at this time
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Fine-scale spatial variation of persistent organic pollutants in bottlenose dolphins (Tursiops truncatus) in Biscayne Bay, Florida
Vulnerability to climate change of United States marine mammal stocks in the western North Atlantic, Gulf of Mexico, and Caribbean.
Climate change and climate variability are affecting marine mammal species and these impacts are projected to continue in the coming decades. Vulnerability assessments provide a framework for evaluating climate impacts over a broad range of species using currently available information. We conducted a trait-based climate vulnerability assessment using expert elicitation for 108 marine mammal stocks and stock groups in the western North Atlantic, Gulf of Mexico, and Caribbean Sea. Our approach combined the exposure (projected change in environmental conditions) and sensitivity (ability to tolerate and adapt to changing conditions) of marine mammal stocks to estimate vulnerability to climate change, and categorize stocks with a vulnerability index. The climate vulnerability score was very high for 44% (n = 47) of these stocks, high for 29% (n = 31), moderate for 20% (n = 22), and low for 7% (n = 8). The majority of stocks (n = 78; 72%) scored very high exposure, whereas 24% (n = 26) scored high, and 4% (n = 4) scored moderate. The sensitivity score was very high for 33% (n = 36) of these stocks, high for 18% (n = 19), moderate for 34% (n = 37), and low for 15% (n = 16). Vulnerability results were summarized for stocks in five taxonomic groups: pinnipeds (n = 4; 25% high, 75% moderate), mysticetes (n = 7; 29% very high, 57% high, 14% moderate), ziphiids (n = 8; 13% very high, 50% high, 38% moderate), delphinids (n = 84; 52% very high, 23% high, 15% moderate, 10% low), and other odontocetes (n = 5; 60% high, 40% moderate). Factors including temperature, ocean pH, and dissolved oxygen were the primary drivers of high climate exposure, with effects mediated through prey and habitat parameters. We quantified sources of uncertainty by bootstrapping vulnerability scores, conducting leave-one-out analyses of individual attributes and individual scorers, and through scoring data quality for each attribute. These results provide information for researchers, managers, and the public on marine mammal responses to climate change to enhance the development of more effective marine mammal management, restoration, and conservation activities that address current and future environmental variation and biological responses due to climate change
Stock profiles and narratives.
Detailed scoring results profile and descriptions of the climate impacts on each stock, including key drivers of vulnerability, exposure, and sensitivity; data quality and gaps; and background information on the stock. (PDF)</p
Raw attribute and factor scores.
Expert scores for each exposure factor and sensitivity attribute aggregated by stock. (CSV)</p