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Sep 8, 2009 5:22 PMPublication: The East Hampton Press

Toxic 'red tide' returns to East End bays

Sep 8, 2009 5:22 PM

East End marine scientists say that blooms of a toxic red algae have reappeared in bays across the East End in late summer and may pose a threat to larval fish and shellfish populations.

Dr. Chris Gobler, a marine science professor at Stony Brook University, has been monitoring the so-called “red tide” blooms since they first appeared in East End bays in 2004. The algae blooms were more widespread and more intense last year than ever before, and this year’s blooms appear to be nearly as bad, he said.

“Like, 10 days ago, the water in the Peconics and Shinnecock was perfectly clear, and then, all of a sudden, this bloom just showed up out of nowhere,” Dr. Gobler said. “All through the Peconics, Orient, Sag Harbor, Shinnecock east of the canal. It’s very thick, and you can see the red water. If you drive along Montauk Highway and look out into the bay, the water is perfectly red.”

Dr. Gobler said that studies of the red tide algae have shown that, unlike some other red algae species, the blooms are not toxic to humans—but they are very toxic to fish and shellfish, particularly very young larvae. Laboratory studies showed that the algae can kill small fish in as little as an hour.

Last year, baymen around the East End reported large numbers of dead fish in pound nets where fish had been corralled when a red tide bloom drifted through.

“We’ve definitely seen an impact from algae blooms,” said Ian Burliuk, president of the Southampton Town Bayman’s Association. “I haven’t seen any signs of an abundance of dead stuff yet this year, but we’ll see it down the road.”

Dr. Gobler said that studies have shown the algae is particularly deadly to larval shellfish and may have an impact on the spawning recruitment of scallop populations still struggling to recover from the devastation of brown tide algae blooms in the 1980s and 1990s. “We’ve found that even at less than bloom concentrations, shellfish larvae don’t survive,” he said.

Dr. Gobler noted that scientists are now discovering that some scallops may spawn twice in a summer, once in early June and again in late August or early September. He said the appearance of the red tide each September could potentially be devastating to the product of the second spawn.

Making it particularly threatening to shellfish, the red tide algae is a dinoflagellate, meaning it has a tail and is able to swim. This particular species stays on the surface during the day but migrates to the bottom at night, potentially exposing larval shellfish to its toxic effects for 10-to-12-hour stretches.

No specific evidence has yet been found that the algae is killing larval shellfish, Dr. Gobler noted, since identifying die-offs on a microscopic level in the wild is nearly impossible. He acknowledged that despite widespread red tide outbreaks last year, bay scallop populations look to be some of the highest in several years in the Peconic Estuary this year.

Dr. Gobler said that the red tide, which has been found throughout the Eastern Seaboard in recent years, can be expected to last through the end of this month and possibly well into October in local waters.

Scientists say that in addition to its toxic effects on fish species, the red tide may carry a more lasting threat to shellfish because it also appears to kill off other species of algae it comes in contact with. Algae make up the bulk of the diet of shellfish and plankton, another critical link in the marine food chain.

“In some cases, it can kill other algae within a matter of minutes,” Dr. Gobler said. “It’s very uncommon for any of the bloom species we see around here.”

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What species of algae is this? The doctor's comments seem to indicate that it is something other than Alexandrium.
By Split Rock (68), Sag Harbor on Sep 9, 09 2:22 PM
It is.....its part of the same group of phytoplankton (dinoflagellates), which are responsible for the majority of red tide events....the name of the organism is Cochlodinium polykrikoides. We have shown in the lab that it kills a variety of shellfish and finfish, some in under 24 hours....
By Florian (1), mastic on Sep 10, 09 10:33 PM

By davidf (325), hampton bays on Sep 16, 09 7:50 PM