Brevetoxin exposure in bottlenose dolphins (Tursiops truncatus) associated with Karenia brevis blooms in Sarasota Bay, Florida
Bottlenose dolphins (Tursiops truncatus) face a variety of threats, including risk of exposure to brevetoxins produced by blooms of the harmful alga Karenia brevis. This study investigated brevetoxin exposure in a population of dolphins inhabiting Sarasota Bay, Florida, USA (27°N, 82°W), utilizing tissues from dolphins recovered between 1994 and 2003. Brevetoxin levels detected by ELISA in tissues, gastric samples and excreta from dolphin carcasses (n = 19) associated with K. brevis blooms were compared with with levels in carcasses (n = 16) associated with background K. brevis conditions. In the K. brevis-exposed set, 84% of dolphin carcasses recovered during K. brevis blooms had detectable brevetoxin levels, with values ranging between 7 and 2,896 ng PbTx-3 eq g−1. Over 50% of dolphin carcasses recovered during non-bloom conditions also tested positive by ELISA for brevetoxins, with concentrations ranging from 6 to 44 ng PbTx-3 eq g−1. Control samples from the east coast of Florida were negative by the ELISA. Results from this study establish baseline brevetoxin body burdens in a dolphin population frequently exposed to K. brevis blooms, and data indicate that dolphin carcasses not associated with large-scale mortality events can contain levels of brevetoxins comparable to carcasses stranding during such events.
KeywordsStomach Content Exposed Group Bottlenose Dolphin Florida Panhandle Dolphin Population
The authors would like to thank Gary Kirkpatrick, Val Palubok, Trish Blum, Nelio Barros, Shana Hamel, Dana Wetzel, Phil Mercurio, Carl Luer and Cathy Walsh of Mote Marine Laboratory, and Mary Silver and Dan Costa of the University of California at Santa Cruz, for helpful discussions, sample collection, logistical support, and/or laboratory assistance. This project was supported by the Disney Wildlife Conservation Fund, Long Marine Laboratory, National Marine Fisheries Service, Harbor Branch Oceanographic Institution Protect Wild Dolphins Program, Florida Fish and Wildlife Conservation Commission and the Chicago Zoological Society. This research was authorized by National Marine Fisheries Service under permit No. 522-1785. All work performed in this study complied with current laws of the USA.
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