Red algae blooms tested amid Jones Inlet sighting

State environmental officials are investigating red-algae blooms spotted this week off Jones Inlet and in New York Harbor to determine whether they pose a threat to humans or the environment.

A report Monday from the Coast Guard labeled the blooms "red tide" - a layman's term often applied to any algae, toxic or not, that turn water red - and advised swimmers and boaters to steer clear of the patches.

But the state Department of Environmental Conservation said Tuesday that the red-algae varieties found in New York waters don't usually sicken people who ingest or swim through them.

The agency is testing samples taken Tuesday in Raritan Bay near Staten Island and expects to identify the algae by Wednesday at the earliest, spokeswoman Maureen Wren said. Other sites will be tested as resources and time permit, she said.

The DEC's concern: whether the alga is a nasty kind of phytoplankton known as Alexandrium that has been detected in shellfish beds off Northport for a number of years in late spring. Alexandrium produces a toxin that shellfish absorb through filter feeding. Humans who ingest tainted shellfish may suffer paralytic shellfish poisoning, which can be fatal.

"If sampling . . . indicates shellfish are impacted by a biotoxin, then DEC would implement closures as necessary," Wren said in an e-mail.

A boater anchored about three miles off Jones Inlet reported the bloom there on Monday. The Coast Guard confirmed the sighting through a helicopter flyover but could not provide estimates as to the extent of that bloom.

Stony Brook University associate professor Chris Gobler, an expert on harmful algae blooms, said the ones spotted this week were unlikely to be the same kind of red algae that have bloomed in East End waters this summer. That variety, known as Cochlodinium polykrikoides, can kill shellfish and fish that are unable to swim away, but does not seem to have harmed local ecosystems, he said. The alga is not harmful to humans.

Gobler said the red algae spotted off the Jones Inlet and in New York Harbor were more likely to be of a benign type of alga called Mesodinium rubrum, which actually consumes some harmful blooms.

Wren said the DEC will be looking at potential causes of the blooms and triggers, such as sudden temperature shifts or warmer-than-usual waters. The Coast Guard first reported the blooms on Monday, describing the one in the harbor as a "reddish sheen on the water" that stretched 91/2 miles down the Hudson River.