Low to moderate red tide bloom forecast for the Gulf of Maine in 2022

NOAA’s National Centers for Coastal Ocean Science (NCCOS) researchers expect a weak to moderate red tide for the Gulf of Maine this spring and summer, continuing the pattern of smaller blooms seen in the region over the past few weeks. last years.

The Gulf of Maine red tide is caused by Catenal Alexandrium algae, which produce a toxin that can accumulate in shellfish and cause serious illness, even death, in people who eat contaminated shellfish. NCCOS and partners produce an annual red tide forecast for the Gulf of Maine that helps state shellfish managers assess the severity of the season’s harmful algal blooms before they occur, reducing the possibility of recalls and misunderstandings that may lead to a reduction in seafood consumption.

The forecast is based on data collected on Alexandrium, when it exists as seed-like cysts in ocean sediments before developing into swimming cells in the spring that can produce a red tide. Scientists can estimate the size of red tides in spring and summer by counting the number of cysts in bottom sediments the previous fall or winter.

In February 2022 aboard the NOAA Ship Henry B. Bigelow, researchers from NCCOS and the Woods Hole Oceanographic Institution collected the data needed to map the presence of red tide cysts in the Gulf (Figure 1) and to project the size of the red tide in 2022. The abundance of cysts ranked 16 out of 18 years of sampling, representing the third lowest abundance of cysts ever recorded. NOAA will provide coastal stakeholders with weekly updates of the modeled extent, trajectory, and intensity of the bloom throughout the spring and summer, as well as guidance to states monitoring for harmful toxicity algae and molluscs along the coast.

Figure 1. Concentration of Alexandrium cysts in bottom sediments of the Gulf of Maine (cells/cm²), collected in February 2022. Credit: NOAA/NCCOS.

The scale and severity of Alexandrium blooms and the subsequent need to shut down shellfish harvesting to protect human health vary widely from year to year and decade to decade. Shellfish toxicity was severe and widespread from 1978 to 1988 and again from 2003 to 2009, but has since declined. The causes of the decadal variations are the subject of ongoing research.

This marks the fifteenth year that NOAA and its partners have released the seasonal forecasts, which enable proactive responses to protect coastal economies, making the region more resilient to red tide outbreaks. To learn more, visit the forecast webpage.

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