Is "Red Tide" taking over Middletown beaches?
Fortunately, no! In fact, what beach goers are seeing washed up on Aquidneck Island beaches this time of year is not red tide at all, but red seaweed.
What is the difference you ask?
Well, red tide is caused by microorganisms that grow rapidly, causing what scientists refer to as a Harmful Algae Bloom (HAB) or what we know as red tide. The microscopic organisms that cause red tide and HAB produce toxins that kill fish, and make shellfish poisonous to human consumption. Often, red tide is not even red, but brown or orange, and the actual organism cannot be seen with the naked eye.
What has been washing up on local beaches and turning the surf red is not harmful at all, just a big nuisance.
There are a variety of red seaweeds that grow in New England waters and marine biologists have been studying them for decades.
Asian cultures have known about the benefits of red seaweed for more than a thousand years. China and Japan use red seaweed in food, and as a medicine. It's also found in the United States. Commercial uses include baking additives, gelling agents, and cosmetics, even in some candies.
Western medical and scientific uses include a weight control additive and as a base for bacterial cultures.
Dr. James Sears, a marine biologist formerly of University of Massachusetts, Dartmouth, is an expert at classifying algae. I spoke to him about the red seaweed found washed up on Sachuest Point and he identified the microorganism as Spermothamnion repens, fuzzy red seaweed that is native to Rhode Island.
It grows on the ocean floor, on rocks and other bottom structures. The seaweed grows quickly in the late summer months and the mature plants are broken by heavy surf. It continues to grow as a free floating plant. The pieces accumulate in the crescent shaped beaches, driven by the prevalent onshore winds.
The real hazards come when it rains and contaminated runoff is absorbed or trapped by the large masses of seaweed. When this happens, the beaches are closed, not because of the red seaweed per se, but because of the contamination of fecal bacteria from the storm drain runoff. Water samples are taken weekly by the state Health Department to insure that bathers are protected from such contact.
Arden Gardell, from The Saltwater Edge, spoke to me about how the red seaweed affects fishing.
Just like heavy smoke makes it hard for us to breath, large concentrations of red seaweed makes it difficult for fish to breath, as the algae irritates their gills. Striped Bass are more tolerant of the seaweed because they have adapted to coastal waters and shoreline habitats. Other species, such as Albacore, are less tolerant of the algae. Fishing is affected when the seaweed fowls the hooks and limits the visibility of the lure.
Unfortunately, the red seaweed will be around until the wind changes and the fall weather affects the algae's growth cycle.
Editor's Note: The following article first appeared on Middletown Patch in August of 2010. However given all red seaweed turning up lately on Second Beach and all the questions I've received over it lately, it seemed worth repeating.