Tropical storm Henri caused surprisingly widespread bacterial contamination in Long Island’s waters, likely encouraging algal bloom, although the storm’s winds and rain were far less destructive to Long Island than originally feared, scientists said.
This week’s samples from 30 waters on the north and south coasts showed “high levels of feces that were ubiquitous,” said Christopher Gobler, endowed professor of coastal ecology and conservation and senior researcher at the Gobler Laboratory at Stony Brook University.
In Mount Sinai Harbor, South Oyster Bay and in the bays of Shinnecock and Mattituck, the water quality was rated “Good” in only four samples.
The remainder of the 26 samples were all rated mediocre or poor due to low levels of oxygen or fecal contamination of animals and humans, mainly from nearby sources.
Swimming in water containing bacteria can cause gastrointestinal disorders and infections of the eyes, ears, nose and throat. As a precautionary measure, some vulnerable beaches on Long Island will be closed after storms or until tests show bacteria levels have dropped.
Gobler also checks for dissolved oxygen, which can kill marine life if it’s too low. Algal blooms can make the problem worse after they die and rot to the bottom. Henri broke some algal blooms.
Eastern Great South Bay and the Forge River were infested this week with noxious algal blooms “as well as almost zero dissolved oxygen at night and extremely cloudy water,” according to Gobler’s report.
And the torrent of rust, caused by one of the many species of algae that feed on nitrogen pollution and thrive when the water warms, has intensified in “much of the Peconic Estuary” and has spread throughout that system in recent weeks. ”
The rust tide, which can choke fish and shellfish, first appeared in the waters of Long Island in 2004, likely due to global warming. “The sound was never this warm before,” Gobler said, remembering that this alga stretched all the way from Huntington Harbor on the North Shore to Connecticut last September.
The tide, which stains the water despite not being considered toxic to humans, could still spread into the Great South Bay – and even last through October. “How intense it is in September and how long it lasts depends in part on the temperature,” said Gobler.
Blue-green algae, which are harmful to humans, can also pollute ponds and lakes for several weeks. For red and mahogany tides, however, the season is drawing to a close.
A rare, potentially fish-killing species of algae, Akashiwo, was found in the eastern Great South Bay and the Forge River, Gobler said, which “shows up here and on the west coast from time to time but is rather short-lived. “
The water will be tested for bacteria called enterococci, which are naturally found in humans but signal contamination with feces has occurred, meaning “disease-causing bacteria, viruses and protozoa” could also be present, the US Environmental Protection Agency says.
Rainwater runoff – which occurs when the soil cannot hold all of the rainwater – carries sewage from leaky cesspools and sewage treatment plants, pesticides, fertilizers, oil and various types of debris into sewers, increasing the concentration of bacteria. Animal waste can be another important source.
Senjie Lin, professor of marine science at the University of Connecticut at Groton, quoted Henri as saying, “It appears that the water quality in many places around Long Island was really bad or mediocre.” He added, “We know it happens in a hurricane or a tropical storm, but I was surprised it happened in so many places.”
The State Department of Environmental Conservation said in a statement that it is reviewing Gobler’s report, but it is premature to determine the causes of the algal bloom by the end of the season. “DEC continues to aggressively pursue large-scale efforts to control and reduce harmful algal blooms across the state.”
The DEC couldn’t immediately tell how much untreated sewage, which can mix with rainwater in sewers in New York City during storms, was released by Henri.
The “dead zone” of Long Island Sound, an area in the western part of the Sound where dissolved oxygen has collapsed, came in part from this New York discharge.