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Biologists Predict Moderate Red Tide Season

Biologists Predict Moderate Red Tide Season

April 12, 2012

WoodsHole1 — Harmful algal blooms (HABs) in the Gulf of Maine are caused by the dinoflagellate Alexandrium fundyense. In the early spring, this organism leaves the seafloor sediment as dormant cysts germinate or "hatch," swims toward the surface, and divides again and again to form a “bloom” or red tide. As the bloom ages, new cysts are formed that fall to the ocean bottom where they remain until they germinate the next year to restart the process. (Illustration by Jack Cook, courtesy Woods Hole Oceanographic Institution)

The Woods Hole Oceanographic Institution is reporting that NOAA-funded scientists working in the Gulf of Maine to study the toxic algae that causes red tide are predicting that New England will experience a “moderate” regional red tide bloom this spring and summer (2012).

WoodsHole2 — Map of the Gulf of Maine reveals the concentration of Alexandrium cysts buried in seafloor sediments, as detected by a WHOI-led survey in the fall of 2011. The cyst distribution map is used with computer models that simulate different scenarios of weather and oceanographic conditions in an "ensemble forecast" of the timing and extent of cyst germination and subsequent cell growth to form a regional bloom in 2012. (Courtesy of Don Anderson et al., Woods Hole Oceanographic Institution)

The algae pose no direct threat to humans; however, the toxins they produce can accumulate in filter-feeding organisms such as mussels and clams, which can cause paralytic shellfish poisoning (PSP) in humans who consume them.

Under a newly developed rating system, a moderate bloom could cause the closure of shellfish beds along an estimated 126 to 250 miles of coastline.

The 2012 outlook is based on the quantities of the algae Alexandrium fundyense in its dormant (cyst) state detected in Gulf of Maine sediments last fall. These data are combined with computer simulations that model a complex range of meteorological and oceanographic conditions—winds, sunlight, rainfall, tides, and currents—that impact the size of the bloom.

Woods Hole Oceanographic Institution

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