Contract Title: Contract for Red Tide Cyst Mapping with Woods Hole Oceanographic Institution
Grantee: Woods Hole Oceanographic Institution
Award Period: November 18, 2009-September 30, 2012
This project was part of a joint Maine, Massachusetts, and New Hampshire effort in which each state dedicated a portion of their federal disaster funds to support scientists from the Woods Hole Oceanographic Institution (WHOI) to map out the size and location of the Alexandrium cyst bed in the western Gulf of Maine in the fall of 2009 and 2010. WHOI also performed a statistical analysis of the sampling data to possibly modify future sampling efforts. Project end date was September 30, 2012.
A multi-investigator, multi-disciplinary, NOAA-funded research program (GOMTOX) studied the dynamics of Alexandrium fundyense in the Gulf of Maine (GOM) and Bay of Fundy (BOF). The primary objectives associated with this project were the collection of surface sediments during cyst cruises to enumerate benthic cysts of Alexandrium, the statistical analysis of data from cyst cruises, and the prediction of future Alexandrium distribution and abundance. The R/V Oceanus cruise (OC458) sampled sediments from more than 100 stations in the GOM and BOF over an 11-day period (October 15-25, 2009). The R/V Endeavor cruise (EN486) sampled sediment from more than 100 stations in the region over an 11-day period (October 13-23, 2010).
The 2009 survey found cyst concentrations (0-1cm) in the region were the highest ever measured. There was also expansion of the cyst bed to the south with a continuous population of benthic cysts (>1000 cysts cm-3) from Penobscot Bay to the offshore waters east of Cape Ann, Massachusetts and Stellwagen Bank. However, the 2010 survey found that the southern extension of the population that was observed in 2009 had mostly disappeared, and there was only a modest amount of cysts present. A figure representing this data can be found in the final report. The data from these cruises were utilized in both seasonal outlooks of the potential for the yearly red tide bloom seasons and in short-term red tide bloom intensity models throughout the seasons called “Nowcasts,” which were provided weekly to shellfish managers.
A statistical model was created using data from 78 stations during 2007, 2008, and 2009 in order to predict cyst abundance. GOMTOX noted that although this model appears to capture a large fraction of the observed interannual variability, it is still an approximation that provides overpredictions and underpredictions. Comparisons between the observed cyst distribution and modeled cyst distribution for all stations and for the 78 stations from 2004 to 2009 showed good correspondence, giving GOMTOX confidence that the statistical approach using the Alexandrium population dynamics model can be used to reduce the sampling schedule. This reduced set of cyst observations, along with the statistical model, could be used for estimating the regional distribution in future forecasts.
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