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TWO YEARS OF ALEXANDRIUM CYST MAPPING IN THE SURFACE SEDIMENTS OF HOOD CANAL, WA, FOLLOWING AN UNPRECEDENTED BLOOM

In September and October 2014, an unprecedented bloom of Alexandrium occurred in Dabob and Quilcene Bays, Hood Canal, WA, USA. This area, and southward through Hood Canal, was historically biotoxin free. At the peak of the event, toxin levels in shellfish reached 12,688 μg STX equiv. per 100 g shellfish tissue – more than 150 times the regulatory limit for human consumption. Because Alexandrium species produce resting cysts that can overwinter on the seafloor and germinate the following season, providing the inoculum for more blooms, emergency response cyst mapping was conducted throughout Hood Canal in January 2015 to determine if the area had been “seeded” with Alexandrium cysts. Prior limited cyst mapping efforts from 2011-2013 found zero or very low (5-10 cysts per cc wet sediment) concentrations of cysts throughout Hood Canal. In January 2015, up to 120 and 180 cysts per cc wet sediment were observed in Quilcene Bay and Dabob Bay, respectively, indicating that a new Alexandrium seed bed formed in the area following the 2014 bloom. In 2015, increased vigilance and monitoring by the Washington State Department of Health and the SoundToxins Program provided early warning of a toxic bloom of Alexandrium in April. This toxic event spread throughout Hood Canal over the 2015 summer, resulting in shellfish harvesting closures in this area for the first time. In a follow-up survey conducted in January 2016, cysts were also found in the surface sediments of southern Hood Canal for the first time. Surface sediment Alexandrium cyst distribution and shellfish toxin results from 2016 will be presented and compared with the past two years of cyst distribution data.

Authors

Greengrove, C. L., University of Washington Tacoma, USA, cgreen@u.washington.edu

Masura, J. E., University of Washington Tacoma, USA, jmasura@uw.edu

Moore, S. K., University Corporation for Atmospheric Research, USA, stephanie.moore@noaa.gov

Details

Oral presentation

Session #:021
Date: 03/02/2017
Time: 12:45
Location: 323 B

Presentation is given by student: No