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2016 Bloom Forecast

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2015 Alexandrium fundyense cyst map

Gulf of Maine Red Tide Forecast Suggests Small Bloom for 2016

Researchers at the Woods Hole Oceanographic Institution (WHOI) and North Carolina State University, funded by the National Centers for Coastal Ocean Research Prevention, Control and Mitigation of Harmful Algal Blooms (PCMHAB) program, are forecasting that the red tide in the Gulf of Maine (GOM) will be the smallest observed over the last eleven years.  That is the interval during which surveys of the abundance of dormant cysts of Alexandrium fundyense, the red tide causative organism, have been made across the Gulf of Maine.

Alexandrium fundyense produces a toxin that can accumulate in shellfish. Human consumers of toxin-contaminated shellfish can experience paralytic shellfish poisoning (PSP), a serious and sometimes fatal illness.  To protect human health, state agencies conduct rigorous monitoring and ban harvesting of toxic shellfish. Advance warning of toxic harmful algal bloom (HAB) events enables proactive responses to protect coastal economies, making the region more resilient to red tide outbreaks.

Alexandrium fundyense has a seed-like cyst stage in its life history that lies dormant in bottom sediments for much of the year, germinating in the spring to produce the swimming cells that divide and grow more numerous in surface waters.  These cells can be consumed by filter-feeding shellfish that can accumulate the toxin to dangerous levels.  The research team has found that the size of a bloom in the spring and summer of a given year is strongly correlated to the number of cysts counted in bottom sediments the preceding winter.  Cyst abundances measured in late 2015 are the lowest recorded since the surveys began in 2004, leading to the 2016 forecast for a small bloom.  However, oceanographic conditions can also affect Alexandrium blooms and shellfish toxicity so continued monitoring is necessary.

The 2016 forecast is the ninth seasonal GOM red tide forecast the WHOI-led team has issued and is part of a larger effort to expand a NOAA harmful algal bloom operational forecasting system (HABOFS) to New England.

During the 2016 bloom, WHOI with funding from NOAA and NSF, will maintain three robotic HAB sensors called Environmental Sample Processors (ESPs) at locations along the Maine coast throughout the spring and early summer.  These will measure the abundance of Alexandrium cells in the water.   NOAA will deploy a toxin sensor on one of the ESPs.  States also monitor Alexandrium cells and shellfish toxicity along the shore.

The magnitude and severity of Alexandrium blooms, and, thus, the need for shellfish harvesting closures to protect human health varies considerably from year to year and between decades.  Shellfish toxicity was severe and widespread from 1978 to 1988 and again between 2003 to 2009, but has been declining since then.  We still do not understand what causes the decadal variations in cysts, blooms and shellfish toxicity, so continued research is necessary.


            Dennis McGillicuddy,, 508-289-2683
            Don Anderson,, 508-289-2351
            Ruoying He,, 919-513-0249    

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Last updated: April 7, 2016

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