May 2010

A large scale cyst mapping survey conducted in late 2009 revealed very high abundance of Alexandrium resting cysts in the Gulf of Maine (see map). The cysts were not only more numerous, but also extended further to the southwest then has been observed in the past. As we have done in 2008 and 2009, we used this new cyst map as the basis of a forecast using the Alexandrium population dynamics model. Using weather and oceanographic conditions from each of the 6 preceding years (2004 - 2009) an ensemble forecast was obtained that indicated that with all of these diverse weather patterns, a major regional Alexandrium bloom would have occurred. Accordingly, a seasonal forecast for 2010 was issued calling for a significant regional event.

As of this writing (May 21), the regional bloom remains relatively limited in scale, as evidenced by data from the first GOMTOX cruise and state shellfish toxicity measurements. A few areas in western Maine have been closed, but most of the rest of the coasts of Maine, New Hampshire and Massachusetts remain open. It would appear that despite the very high abundance of Alexandrium cysts, conditions have not been optimal for growth and delivery of cells to shore. In the latter context, weather patterns for the last month have generally had upwelling favorable winds. Typically it takes several northeast storms during this interval to cause a significant coastal outbreak.

It is still early in the bloom season, so its too soon to say much about what may happen going forward. When the season is over, we will be examining the weather patterns and hydrography carefully to see if we can discern why this bloom has started slowly despite a large potential inoculum and environmental conditions (at least on land) that have led to early blooming of many flowers, trees and other plants.

As this year's bloom develops, information and observations will be posted here. Summaries from our GOMTOX research cruises may be found under the "2010 Field Observations" section.

Last updated: April 4, 2011