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2006 Bloom Season

Significant regional-scale Alexandrium catenella blooms occurred in both 2005 and 2006.  The 2005 event was longer, extended further to the south and had higher cell concentrations and shellfish toxicities.

Although analysis is ongoing, we see two major differences that might explain the differences in bloom magnitude and the extent of toxicity in 2005 versus 2006. The first, is a difference in the A. catenella cysts found in Gulf of Maine sediments. Cysts were approximately twice as abundant prior to the 2005 bloom (cyst map, left panel) than they were in 2006 (cyst map, right panel), which would lead to fewer vegetative cells in the water column.  In addition, wind patterns in 2006 were initially very similar to those observed in 2005 but differed in mid to late May.  In particular, 2005 had northeast storms in late May, whereas in 2006 the winds during that time of the month were predominantly from the southwest.  The latter winds would tend to move surface waters and the associated Alexandrium cells out of Massachusetts Bay and into offshore waters.  This inference has been confirmed with computer models.

Conditions in 2005 and 2006 and similarities with a massive 1972 New England red tide lead us to hypothesize that we have entered an era that will have frequent red tides and high levels of toxicity in the western Gulf of Maine and southern New England for the next decade or more.

2006 Status Reports

Gulf of Maine cyst abundance prior to 2005 bloom (left) and prior to 2006 bloom (right). (units=cysts/cm3) (D. Anderson/WHOI)

Mussel harvesting closure areas along the New England coast during 2006. Compiled from information provided by the Massachusetts Division of Marine Fisheries, the New Hampshire Department of Environmental Services, and the Maine Department of Marine Resources.

(WHOI / D. Anderson laboratory)

The Anderson laboratory uses epifluorescence microscopy using "molecular probes" to positively identify and enumerate Alexandrium fundyense. For more information about this process, please see the following publication:
Anderson, D.M., D.M. Kulis, B.A. Keafer, K.E. Gribble, R. Marin, and C.A. Scholin. 2005. Identification and enumeration of Alexandrium spp. from the Gulf of Maine using molecular probes. Deep-Sea Res. II 52(19-21): 2467-2490. (Tom Kleindinst, WHOI)