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Background

Millions of microscopic plants (phytoplankton) thrive in nearly every drop of coastal seawater. In the presence of sunlight and sufficient nutrients, these plants photosynthesize and multiply, creating a “bloom.” Most species of algae or phytoplankton are not harmful and serve as the energy producers at the base of the food web, but some of these species produce potent toxins or have other detrimental environmental effects. While these have commonly been known as “Red Tides” scientists now prefer the term “Harmful Algal Bloom” (HAB). The term HAB is more accurate because not all toxic blooms produce visible water discoloration, while some non-harmful blooms can result in red or brown waters.

A HAB refers to any bloom phenomenon that causes negative impacts to people, fisheries, aquaculture, or ecosystems. Toxins from harmful algae accumulate in the shellfish and fish that consume them, and organisms that eat these contaminated seafoods can become sick. These toxic HABs can harm zooplankton, marine mammals, birds, fish, and even humans. Some non-toxic blooms can deplete oxygen from the water, causing anoxic conditions that lead to fish kills.

There are several species of harmful algae found in the Northeast United States, some of these blooms are well understood while others are emerging threats. The most well-studied HAB events are the seasonal blooms of Alexandrium catenella, the toxic dinoflagellate that causes paralytic shellfish poisoning (PSP). These blooms have occurred in New England on an annual basis since 1972. Toxic blooms of Pseudo-nitzschia, which produce domoic acid and cause amnesic shellfish poisoning, are a more recent phenomenon in New England waters. Other emerging HAB threats include Dinophysis, Margalefidinium, and Karenia mikimotoi.

State agencies are responsible for tracking HAB events and enacting fisheries closures when seafood consumption becomes unsafe. Scientists at Woods Hole Oceanographic Institution have been studying HABs for decades, and seasonal data collection is shared with managers and state officials responsible for making public health decisions. While rigorous monitoring and management have been implemented for PSP, scientists and managers must continue to work together closely to study emerging species and syndromes. WHOI researchers have received funding from NOAA’s National Center for Coastal Ocean Science to create an advanced multi-institutional observational network, (Link) HABON-NE, which will dramatically improve HAB surveillance in the region. Data collected through HABON-NE will be openly available, and will contribute to both early warning as well as future bloom forecasting.

See the timeline below for examples of notable HAB events in the Northeast United States:

Cool Timeline

2017
2017

Dinophysis – Massachusetts

Dinophysis blooms in the Nauset Estuary on Cape Cod cause the first DSP closure in Massachusetts.
2016
2016

Pseudo-nitzschia – Maine, Massachusetts, Rhode Island

Domoic acid levels exceed regulatory limits for the first time in New England.
2016

Dinophysis – Maine

The first fishery closure in New England due to Dinophysis occurs in Maine.
2012
2012

Pseudo-nitzschia – Maine

A precautionary closure is enacted in Eastern Maine in reponse to eleveated presence of Pseudo-nitzschia.
2008
2008

Alexandrium – Maine, New Hampshire, Massachusetts

The HAB forecasting system for the Gulf of Maine predicts the significant region-wide Alexandrium bloom in 2008, which was associated with widespread toxicity in shellfish from Maine to Cape Cod.
2005
2005

Margalefidinium – Massachusetts

First recorded bloom of Margalefidinium polykrikoides in Buzzards Bay. This bloom occurred in September and reached concentrations of 7.6 million cells per liter. This phenomenon is ongoing, as blooms have been recorded in every subsequent year.
2005

Alexandrium – Maine, New Hampshire, Massachusetts

A significant and extended Alexandrium bloom forced the closure of shellfish harvesting from the Bay of Fundy to Martha’s Vineyard for several months and caused an estimated $50 million in losses to the Massachusetts shellfish industry alone.
1980
1980

Margalefidinium – Rhode Island

In the 1980’s, Margalefidinium polykrikoides is first recorded in the Northeast in Narragansett Bay.
1972
1972

Alexandrium – Maine, New Hampshire, Massachusetts

Alexandrium catenella bloom spreads into New Hampshire and Massachusetts for the first time.
1958
1958

Alexandrium – Maine

First paralytic shellfish poisoning closure event in Maine.