Rust tide, a harmful algae bloom that can be fatal to marine life, is spreading throughout the Peconic Estuary and has been found in high concentrations from Riverhead to East Hampton.
The algae — fed by warm water temperatures and high nitrogen levels — may have also spread into Shinnecock Bay, said Chris Gobler, a professor at Stony Brook University’s School of Marine and Atmospheric Sciences.
The rust tide was first seen in patches in Sag Harbor and Three Mile Harbor but expanded during the past week. “This type of bloom tends to be more patchy than others,” Gobler said Tuesday. “It moves horizontally and vertically. During the day it tends to aggregate on the surface and that’s when it gets really dense. At night it goes deeper and disperses.”
Concentrations of the algae, Cochlodinium polykrikoides, have been measured at six times the level that can kill fish and shellfish, but no mass dieoffs have been reported this year.
The state Department of Environmental Conservation is monitoring the bloom and will respond if any fish kills are reported, spokesman Sean Mahar said.
“No fish kills have been reported this year (or previous years) from the Peconics,” Mahar said in an email.
The algae has appeared locally since 2004.
In years it has hit Shinnecock, the bloom has wiped out up to 80 percent of the scallops, said Edward Warner Jr., a baymen who is president of the Southampton Town Trustees.
“It can wipe out the scallops in a large area,” Warner said… “Historically it has done a number pushing the fish out of the bay.”
He said it could coat the gills of fish and prevent scallops from filtering water. “The worst part about it is when you do see it, each day it gets a little bit worse and a little bit worse.” Warner said.
Suffolk County will work with the DEC and Gobler to monitor the bloom, which should diminish as the weather cools.
Harmful algae blooms have long-plagued Long Island, with brown tide showing up in the 1980s. Red, rust, mahogany, blue-green and other blooms followed. Some are harmful to humans, others are not. In large amounts, the algae can block sunlight, lead to low oxygen levels and harm waterways.
Nitrogen from septic systems, fertilizers and agricultural activity has long been thought to be a main culprit.
The DEC is developing a plan to reduce nitrogen levels and has established a center at Stony Brook to develop nitrogen removal technologies for septic systems. Suffolk County is also developing a harmful algal bloom action plan and strategy with New York Sea Grant to coordinate research, monitoring and management of blooms to reduce future outbreaks, Department of Health Services Ecologist Mike Jensen said in a statement.
The National Oceanic and Atmospheric Administration has a program focused on monitoring and preventing blooms. One thing the agency is doing is looking at methods to control blooms, said Quay Dortch, who manages NOAAs harmful algal bloom research programs.
But the work has to consider the consequences of action. “What you might do to control a bloom may not be good for the environment,” said Dortch, who is consulting with Suffolk.