New Hampshire: Red Tide is Biblical

Throughout history, they have made their presence known

in every ocean and sea on the planet.

In ancient Egypt, the historical note of “and all the waters were turned to blood” was testament to the early blooms of marine algaes. In the 1600’s, early explorers noted that the native tribes of the St. Lawrence River basin had definite “taboos” toward eating shellfish during certain seasons.

However, in New England red tide was relatively unknown until 1972. During the fall of that year, Hurricane Carrie passed through the Gulf of Maine at a snail’s pace during a massive toxic algal bloom in the Bay of Fundy. The counter-clockwise winds intensified the traditional water current patterns and deposited red tide dinoflagellates known as Alexandrium tamarense, along the Maine, New Hampshire and Massachusetts coasts.” [from Mass. Div. of Marine Fisheries]

As already stated, “Red Tide is a global phenomenon. ” However, only since the 1980s has harmful red tide events have become more frequent and widespread.

Currently, shellfish beds are closed to harvesters from Maine to Cape Cod, the result of a toxic “red tide” algae bloom. The ban on clamming and other shell-fishing for the second year in a row comes as the summer season starts. The bloom starts off the Maine coast, and spread quickly. Some sources state the recent heavy rain may aggravate it.

“Red tide,” which is the common name for a highly toxic algae called Alexandrium fundyense, can negatively impact the harvesting of widely popular shellfish such as soft- and hard-shell clams and oysters because these shellfish ingest the algae, making them hazardous and even deadly to eat.

Our local variety of red tide algae produces a potent neurotoxin known as saxitoxin that accumulates in shellfish feeding on these organisms and consequently causes food poisoning in animals that eat the shellfish. Humans are vulnerable to paralytic shellfish poisoning (PSP) only when they eat shellfish that have dangerously high concentrations of the toxin. The shellfish will flush the toxin from their systems within a couple of weeks after the red tide recedes.

No one in New England has become ill or has died from red tide since it first appeared in the Gulf of Maine in 1972.

Last year, one of New England’s worst “red tides” in decades expanded southward, rounded Cape Cod and forced the closure of some of our best shellfish beds.  For the first time, it traveled into Buzzards Bay. It was the worst red tide season since 1972, and caused $50 million in losses to tourism and fishing industries.

We should be happy that the algae that causes red tides off New England’s coast is not the same as that growing in the waters off southern states like Florida, causing noxious fumes, shutting down beaches and poisoning sea life.

Our local variety of “red tide,” Alexandrium fundyense is found along the Atlantic coast from the Canadian Maritimes to southern New England. Alexandrium catenella is  found along the Pacific coast from California to Alaska. Karenia brevis is found in the Gulf of Mexico along the west coast of Florida.


Additional Reading

What is Red Tide?-

Harmful Algal Blooms

-Red Tides-

Red Tide 2005

-Clam Flat Readings-



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