Sarasota Dolphin Research Program

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Sarasota dolphins: Now with 50% more HAB!
By Spencer Fire, PhD, NOAA Marine Biotoxins Program

Spencer Fire, now working with NOAA, returns to the site of his academic roots, collecting water samples to look for organisms associated with harmful algal blooms.

Harmful algal blooms (HABs) and their associated toxins are the most common cause of marine mammal unusual mortality events (UMEs) in U.S. coastal waters, especially in the Gulf of Mexico. More UMEs occur in this region than in any other region of the U.S. HABs such as Florida’s well-known Karenia brevis red tides can produce large amounts of brevetoxins which compromise bottlenose dolphin health and contaminate their food webs. Although it is clear that K. brevis blooms and brevetoxins have negative impacts on these animals, it is becoming apparent that HABs formed by other marine algae also affect Florida dolphin populations. Pseudo-nitzschia spp. is a group of marine algae that produce the neurotoxin domoic acid and has caused several Pacific coast UMEs, but has not been a concern in Florida waters until recently. During the May 2008 Sarasota dolphin health assessment, a novel bloom of Pseudo-nitzschia was reported, and domoic acid was detected in the majority of dolphins sampled and in five species of prey fish. During the May 2009 health assessment, domoic acid was again detected in dolphins and prey fish, however, no Pseudo-nitzschia bloom had been reported since the previous year. Analysis of archived SDRP dolphin health assessment samples has detected the presence of both toxins in live dolphins dating back to 2000. Although the levels detected are very low in comparison to UME levels, the effects of long-term exposure to multiple HAB toxins are unknown. We thank SDRP staff and associates for their continued enthusiastic support of our research efforts.