The brown tide that has plagued Long Island's shores has retreated, thanks to the recent stretch of hot weather, a report from Stony Brook University has found.
Samples taken last week from Southampton to Bay Shore indicate an overall sharp decline in algae levels, officials reported.
"Brown tide has an upper temperature threshold; it can't withstand when the water goes above 80 degrees," said Chris Gobler, a professor at the university's School of Marine and Atmospheric Sciences. "The extreme heat we've had this month has caused the brown tide to die off."
Density levels in the algae-causing brown tide have dropped from millions of cells per milliliter to tens of thousands, according to the report. Brown tide concentrations of 50,000 cells per milliliter or more can be harmful to marine life, the report indicated. It doesn't pose a threat to humans.
Shinnecock Bay and Moriches Bay had less than 10,000 brown tide cells per milliliter -- the lowest concentrations in the area. Parts of the Great South Bay, however, still recorded more than 100,000 cells per milliliter, the report found.
"Areas near ocean inlets had cleared up the fastest, and the areas that received the least amount of flushing still had high densities," Gobler said.
Gobler said brown tide also causes problems for commercial fishermen.
"Fish are visual predators and, essentially, when the brown tide moves in, fish will often move out," he said. "The other alternative is that the fish are there, but they can't see the bait."
But Kathy Heinlein, president of the Captree Fleet -- one of the largest fishing fleets on Long Island -- said the brown tide this year hasn't been a problem.
"Fishermen have not been able to fish through it in the past," she said, "but now they've been able to fish through it."
Brown tide appeared in Moriches Bay and Shinnecock Bay for the seventh consecutive year, the report from Stony Brook said. Spurred by heavy rainfall in mid-June, the algae spread in the Great South Bay -- the first time brown tide was spotted there in five years.
Gobler predicted algae levels will remain lower for the rest of the summer.