Flesh-Eating Bacteria, Toxic Algae, Oxygen-Starved Waters Were Widespread in 2023, Thanks to Nitrogen and Warmer Waters

Record-high temperatures globally and in local waters fueled the steadily worsening water quality crisis in Suffolk County’s groundwater, freshwater ponds, and tidal bays and harbors in 2023, Stony Brook University scientists found, according to an annual summary of the impacts seen by researchers.

Stony Brook University professor Dr. Christopher Gobler said his laboratory team tracked toxic algae blooms in more than two dozen individual bodies of water around the region last summer. New species of algae blooms, bringing new threats to human health, are gaining footholds as water temperatures continue to tick upward.

Most of the blooms were seen in eastern Suffolk County, where high levels of nitrogen in groundwater contaminated by human waste are migrating to surface waters in ponds and bays, where they feed, literally, the blooms of algae and the destructive effects they leave in their wake, Gobler said.

Suffolk County had four to five times as many water bodies impacted by blooms of highly toxic blue-green algae in 2023 as any of New York State’s 61 other counties. Blue-green algae blooms are known to be harmful or even fatal to humans.

Other toxic algae blooms that can turn shellfish toxic, kill fish and shellfish in enclosed bays and cause widespread lack of oxygen have grown more intense, more toxic and shifted their life cycles because of the warming water and high nitrogen levels in local waters, Gobler said.

And Long Island last year saw the emergence of a dangerous new flesh-eating bacteria, Vibrio vulnificus, that has been steadily expanding its range northward along the East Coast as waters have warmed. A Suffolk County resident died and two others were hospitalized from Vibrio infections in 2023. Two others died in Connecticut.

“Warming water means that organisms migrate toward the poles to stay in their optimal comfort zone,” Gobler told a packed auditorium on the Stony Brook Southampton campus on April 3, when he presented his annual State of the Bays report. “Vibrio vulnificus has slowly moved up the East Coast, and they had estimated that we’d see it on Long Island in five years — and five months later, we had cases of it here. This is directly related to there being more heavy rainfall and warmer temperatures.”

Gobler repeated warnings issued by health officials last year against swimming or wading in brackish — part saltwater, part freshwater — waters with open cuts, which can lead to Vibrio infections and, in as many as 20 percent of cases, rapid death.

As he has each year for nearly a decade, Gobler ticked off the destructive cycle that has led to the rise and expansion of harmful algal blooms. Explosions of housing development in the 1960s, 1970s and 1980s, with rudimentary waste disposal systems, have left decades of wastewater from tens of thousands of toilets leaching into groundwater that flows directly into ponds and bays.

The level of nitrogen in Suffolk County’s groundwater is among the highest in the nation. Along with being tied to various direct human health effects, like increased rates of cancer and developmental problems with babies and young children, that nitrogen also sparks algae blooms hungry for nutrients. As waters have warmed, more and more new algae have emerged — many likely had been present all along but were spurred to explosive growth by newly ideal environmental conditions — and evolved, bringing with them new concerns.

The region saw the most ever number of waterbodies contaminated with blooms of a particularly toxic “red tide” saltwater algae, Alexandrium, in 2023, forcing widespread closure of local bay bottoms to shellfishing in the early spring. Other areas saw the blooms of other destructive algae many times more dense than had ever been recorded anywhere.

The blooms of algae themselves are not the only problem. As they die, sometimes every night, they suck oxygen from the water and can create oxygen-starved conditions, know as hypoxia. Gobler said that researchers from his lab found hypoxic conditions at nearly every single site in local bays tested at night.

Gobler dedicated his talk this month to Bob Nuzzi, a marine scientist from East Hampton who was one of the first researchers to conduct focused studies of the infamous “brown tide” outbreak of algae blooms in the mid- and late 1980s. And he punctuated it with tidbits of good news — like the end of hypoxic conditions that had plagued Long Island Sound just 20 years ago, thanks to tens of thousands of homes being hooked up to sewage treatment plants that reduce nitrogen released.

And shellfish seeding, oyster farms and kelp growing have been found to suck nitrogen from surface waters — especially when kelp and shellfish are combined in close-quarters at shellfish aquaculture farms.

Suffolk County has set itself on the right course to addressing its massive problem with obsolete septics, thanks to an extensive study conducted by former County Executive Steve Bellone’s administration. Replacing septics with modern systems eventually will reduce the flow of nitrogen fuel, but with more than 300,000 obsolete systems beneath homes, it will be a long battle.

“Nitrogen-reducing septics are starting to help,” Gobler said. “But it’s going to be a long time.”