HABS Marine Biotoxin Monitoring

Rhode Island’s coastal waters are occasionally impacted by harmful algae blooms (HAB) that have the potential to produce biotoxins that can sicken humans if they consume fish or shellfish contaminated by HAB toxins.

Shellfish are filter feeders and can accumulate biotoxins produced by these microscopic harmful algae to levels that can be poisonous. Cooking does not eliminate these toxins and consumption of contaminated shellfish can cause nausea, vomiting, diarrhea, pain, and other serious health problems.

In August 2017, Rhode Island Department of Environmental Management (RIDEM) and RI Department of Health (RIDOH) finalized revisions to the RI Harmful Algae Bloom and Shellfish Biotoxin Monitoring and Contingency Plan. The plan outlines the state’s routine HAB phytoplankton monitoring plan as well as more intensified monitoring of phytoplankton and shellfish should HAB abundance exceed action thresholds and/or evidence of toxin production is found. It also details contingency actions including emergency closures should conditions warrant.

Emergency closures are announced through local media outlets and on RIDEM’s 24- hour shellfish hotline at 401-222-2900.

All shellfish harvested from waters identified as closed due to harmful algae blooms must not be eaten regardless of being raw or cooked. Rhode Island has taken steps to ensure the safety and high quality of shellfish harvested from RI’s waters. RIDEM encourages all to be informed of the risks associated with marine biotoxins and simple steps to protect you and your family.

Subscribe the Shellfish Area Closure Listserve

Harmful algae blooms (HAB) are naturally occurring – the cause of which is unknown. These blooms occur when colonies of algae—simple plants that live in the sea and freshwater—grow out of control. Sometimes these algae

blooms can become so intense that the blooms can cause harm to fish and shellfish and the mammals (including humans) that eat them. RIDEM regularly monitors local marine waters for the presence and level of various

species of phytoplankton. RIDEM and RIDOH analyze water and shellfish samples from local waters for the presence and abundance of phytoplankton that are known to cause public health issues. Species of concern in RI waters are Pseudo-nitzchia, Dinophysis, and Alexandrium. View RIDEM’s HAB Monitoring and Contingency Plan.

The Phytoplankton Pseudo-nitzchia produces domoic acid which can be harmful to birds and marine life and is responsible for causing amnesic shellfish poisoning (ASP) in humans. Symptoms of ASP include short- and long-term memory loss along with other serious health effects. Other blooms of harmful algae that RIDEM monitors for such as Alexandrium (commonly referred to as “Red Tide”) produce a saxitoxin that causes

paralytic shellfish poisoning (PSP) and blooms occur regularly in the waters of Maine and Massachusetts but blooms have yet to occur in RI waters. Symptoms of PSP are numbness or tingling of the face, arms and legs,

headaches, dizziness, nausea in mild cases and muscle paralysis and respiratory failure in more severe cases. The third phytoplankton that RIDEM routinely monitors for is Dinophysis. This phytoplankton produces

okadaic acid and can cause Diarrhetic Shellfish Poisoning (DSP). DSP produces stomach and intestinal symptoms such as vomiting, severe diarrhea, nausea, abdominal cramps and fevers.

RI experienced blooms of Pseudo-nitzchia in October of 2016 and again in March of 2017, which for the first time resulted in enactment of emergency shellfish closures in Narragansett Bay when evidence of domoic acid production was found. To date, Alexandrium and Dinophysis blooms have yet to occur in RI waters. Waters in other New England states experience HABs sometimes on an annual basis (Maine – Red Tide (PSP) or Pseudo-Nitzchia (ASP)) or as we did as an infrequent occurrence in Massachusetts and New Hampshire. As occurred in Rhode Island, areas of those state’s waters are closed to shellfishing during these blooms.

Depends. Phytoplankton are microscopic organisms that are not visible to the “naked eye”. The phytoplankton Pseudo-nitzchia is not visible from the water surface. Other plankton blooms can cause discoloration of the water if the bloom is intense enough as is the case with Alexandrium thus the commonly referred to name “Red Tide”. However, not all reddish-brown discolorations are associated with Alexandrium blooms. In late summer of 2016, RI experienced a bloom of Cochlodinium that turned the water a rust-red color thus its commonly referred name, “Rust Tide”. A Cochlodinium bloom does not pose a human health risk but may harm fish and shellfish because it produces a hydrogen peroxide like compound that can damage their gill tissue.

Emergency shellfish closures due to toxic algae blooms, once announced will remain in effect until test results determine it is safe to reopen the waters to shellfishing. For updates on shellfish closure areas, contact the DEM

24-hour shellfishing hotline at 401-222-2900 and/or sign up for the DEM Shellfish Closure  Listserve.

The public is advised to avoid eating shellfish from areas that are closed due to a preliminary finding of domoic acid in the shellfish

Contact with waterbodies experiencing toxic algae blooms is not advised

For updates on shellfish closure areas, contact the DEM 24-hour shellfishing hotline at 401-222-2900 and/or sign up for the DEM Shellfish Closure  Listserve.

For more information on DEM programs and initiatives, visit www.dem.ri.gov. Follow DEM on Facebook, Twitter (@RhodeIslandDEM), or Instagram (@rhodeisland.dem) for timely updates.

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