Marine Biotoxin Exposure in an Endangered Fish: A Shortnose Sturgeon Mortality Event Coincident with a New England Red Tide
Abstract
Saxitoxin (STX)-producing blooms of the toxic dinoflagellate genus Alexandrium have been responsible for devastating ecosystem-wide impacts in coastal waters of the northeastern USA.1,3 In the summer of 2009, a severe Alexandrium bloom in New England coastal waters co-occurred with a shortnose sturgeon Acipenser brevirostrum mortality event in Sagadahoc Bay, Maine, USA. Thirteen individuals of this endangered fish species were found dead on 10 July 2009, and this die-off was associated with extremely high Alexandrium cell densities, record-breaking toxin burdens (> 80 000 ng g-1) in shellfish, and closures of shellfish beds affecting nearly the entire Maine coastline. STX-like activity was detected in sturgeon (n = 3) stomach contents and liver and gill tissues via neuroblastoma assay and receptor-binding assay at concentrations ranging between 37 and 2300 ng STX-eq. g-1 (STX equivalents per gram sample). Stomach content analyses of the 3 necropsied sturgeon carcasses showed a large number of amethyst gem clams (Gemma gemma). Liquid chromatography-mass spectrometry confirmed the presence of STX and related congeners in sturgeon stomach contents, at concentrations between 311 and 743 ng g-1. The present study marks the first reported detection of STXs in shortnose sturgeon, and provides evidence of trophic transfer of Alexandrium toxins as a potential cause of mortality in this event, as well as a threat to the health of this endangered population of fish.2
Acknowledgements
The authors thank Tod Leighfield, Jessica Lewis, Fran Van Dolah, Greg Doucette and Steve Morton of the NOAA Marine Biotoxins Program, Don Anderson of Woods Hole Oceanographic Institution, staff of the NOAA Shortnose Sturgeon Recovery Program, U.S. Geological Survey and U.S. Fish and Wildlife Service for assistance with this project.
* Presenting author
Literature Cited
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2. Fire SE, Pruden J, Couture D, Wang Z, Bottein MYD, Haynes BL, Knott T, Bouchard D, Lichtenwalner A, Wippelhauser G. 2012. Saxitoxin exposure in an endangered fish: association of a shortnose sturgeon mortality event with a harmful algal bloom. Mar Ecol Prog Ser. 460:145–153.
3. Landsberg JH. 2002. The effects of harmful algal blooms on aquatic organisms. Rev Fish Sci. 10: 113–390.