Algae Puts Ponds on Lock-Out

Toxic blooms in smaller bodies, while rust tide threatens harbors and bays

Summer may be unofficially over, but the harmful algal blooms associated with the hottest months are proliferating across the South Fork and elsewhere on Long Island. 

Last Thursday, Concerned Citizens of Montauk announced that its sampling conducted on Sept. 5 confirmed a bloom of cyanobacteria, or blue-green algae, in the southern portion of Fort Pond in that hamlet. The northern end of Fort Pond showed elevated risk of a bloom, C.C.O.M. reported, so the entire pond should be avoided. Fort Pond also saw cyanobacteria blooms in 2015 and 2017. 

The East Hampton Town Trustees announced on Monday that cyanobacteria contamination in Georgica Pond in East Hampton, which has experienced blooms of the harmful algae in each of the last seven summers, exceeds the federal Environmental Protection Agency’s standards. The pond is closed to all recreational uses until further notice. 

In an email to Francis Bock, the trustees’ clerk, and Sara Davison, executive director of the Friends of Georgica Pond Foundation, Christopher Gobler of Stony Brook University’s School of Marine and Atmospheric Sciences, wrote that levels of blue-green algae jumped after a sensor in the pond was replaced on Friday, more than doubling over the weekend and continuing to intensify.

“Even more troubling is that the levels of the blue-green algal toxin, microcystin, jumped by an order of magnitude during the past week to 5 micrograms per liter,” above the E.P.A.’s limit for recreation, Dr. Gobler wrote. Microcystins can cause serious damage to the liver if ingested, and may promote liver and colorectal cancers. 

Dr. Gobler monitors waterways under trustee jurisdiction and for the Friends of Georgica Pond Foundation, a group of pondfront property owners who banded together to develop mitigation strategies after a dog died after ingesting the pond’s water in 2012. In May, he and C.C.O.M. announced a partnership to monitor Fort Pond. 

On Friday, the State Department of Environmental Conservation confirmed new blooms of cyanobacteria in Poxabogue Pond in Sagaponack and Old Town Pond in Southampton. On the South Fork, blue-green algae persist in Wainscott Pond, Sagg Pond in Sagaponack, Mill Pond in Water Mill, and Lake Agawam, Cooper’s Neck Pond, Wickapogue Pond, and Little Fresh Pond in Southampton.

Blue-green algae is naturally present in lakes and streams in low numbers, but can become abundant at times, forming blooms in shades of green, blue-green, yellow, brown, or red. They may produce floating scums on the surface of the water or cause the water to look like paint. 

Health officials urge residents not to use, swim, or wade in waters afflicted by cyanobacteria blooms and to keep pets and children away from the area. Contact with waters that appear scummy or discolored should be avoided. If contact does occur, one should rinse with clean water immediately, and seek medical attention if nausea, vomiting or diarrhea; skin, eye or throat irritation, or allergic reactions or breathing difficulties occur after contact.

Another algal bloom, of cochlodinium polykrikoides, or rust tide, appeared late last month in the southern portion of Three Mile Harbor in East Hampton. Rick Drew, a trustee, wrote to Dr. Gobler last Thursday that some residents described it as “the worst one ever seen.” Though not a threat to human health, rust tide is lethal to shellfish and finfish. 

Dr. Gobler’s lab at the university’s School of Marine and Atmospheric Sciences, according to an Aug. 29 press release, has monitored what has grown from an isolated rust tide event in eastern Shinnecock Bay to span Great South Bay, parts of Long Island Sound, and the Peconic Estuary. Last month, tens of thousands of caged oysters and fish in Old Fort Pond in Southampton were killed by rust tide, Dr. Gobler said. Late in August, bloom patches were also detected across Conscience Bay in Setauket and Port Jefferson Harbor. “Beyond large kills in Southampton this year, prior rust tides have brought kills of both natural and aquacultured populations of fish and shellfish on eastern Long Island,” Dr. Gobler said in the release. 

Dr. Gobler pointed to climate change “and specifically warm summer temperatures as a trigger for these large, widespread rust tides” in the Aug. 29 statement. Compared to the 20th century, summer water temperatures “are significantly warmer and it’s been a warmer than usual summer. When we have extended heat as we have seen this summer, intense rust tides often follow.” 

Excessive nitrogen is an equally important factor for rust tides, he said, and can make them more intense and toxic. “As nitrogen loading has increased in Suffolk County waters, these events have intensified,” he said in the Aug. 29 statement. 

Pointing to excessive nitrogen loading from aging septic systems and stormwater runoff, the Friends of Georgica Pond Foundation and C.C.O.M. have encouraged replacement of septic systems with state-of-the-art systems that reduce nitrogen. This week, C.C.O.M., Group for the East End, and Citizens Campaign for the Environment announced a partnership to help raise public awareness about the need for such systems and available funding opportunities for system upgrades as part of the Suffolk County Septic and Nitrogen Awareness Outreach Campaign. The county’s Water Quality Protection and Restoration Program, which is administered by the Department of Economic Development and Planning, has awarded the partners $112,000 to implement the campaign.