Nearly every major water body on Long Island was affected by harmful algae blooms or low oxygen levels at some time during the summer of 2013, according to the results of a study completed by The Nature Conservancy and scientists from Stony Brook University.
Blooms of toxic algae plagued, at some point, nearly all of the East End’s bays and ponds, including three separate blooms of harmful “red tide” and “brown tide” in Shinnecock Bay, Moriches Bay and Peconic Bay. A brown tide bloom persists in western Shinnecock Bay and throughout Moriches Bay and Great South Bay.
The report, released on Monday by the two organizations at a press conference at Stony Brook University’s Southampton campus, blames extremely high levels of nitrogen in all of the Long Island’s water bodies, both freshwater and tidal, for the proliferation of harmful algae blooms. The sources of nitrogen vary, spiked primarily by residential development on the South Fork and by runoff of fertilizers from farm fields on the North Fork, the report claims.
The algal blooms vary widely by region and carry a broad spectrum of threats. Across most of the South Shore Estuary, stretching from Nassau County to the Ponquogue Bridge, brown tide choked nearly every inch of tidal waters. The brown tide algae infamously first emerged in the mid-1980s and devastated shellfish populations throughout Long Island, all but wiping out bay scallops and the thriving community of commercial baymen they supported.
After 1995, it has been largely confined to Quantuck Bay, midway between Moriches and Shinnecock, but in recent years it has spread its reach, blossoming in eastern Moriches and western Shinnecock, and this year it spread across nearly all of Great South Bay as well.
To the east, in eastern Shinnecock Bay and the Peconic Estuary, the plague has been a species of swimming organisms called Cochlodinium that have bloomed in dark red blotches, spreading in density and reach over the last decade. This year the Cochlodinium was observed over a wider area than ever before, the Nature Conservancy study shows, though it does not appear to have been quite as dense, long-lived and destructive as it was in 2012.
Last year, the red tide—or “rust tide,” as scientists have taken to calling it—was blamed for a massive die-off of bay scallops, the population of which is only now mounting what appears to be a rebound from the brown tides of the 1980s and 1990s.
In freshwater bodies and some small embayments, the most destructive issue was a lack of oxygen, which can choke the life out of aquatic organisms. This condition, known as hypoxia, is also caused mainly by algae blooms, typically blue-green algae in freshwaters and brown tide algae in saltwaters, that blossom and then die, sucking oxygen from the water as their cells decay.
“The unifying theme is that the overloading of nitrogen is stimulating problematic algal blooms,” said Dr. Christopher Gobler, a professor at the Stony Brook University School of Marine and Atmospheric Sciences, and the head of the team of scientists that conducted the study for The Nature Conservancy. “Recognition of the causes is the focus. In some places, the role of fertilizers needs to be front and center … in other places, there are sewage treatment plants discharging into just the wrong place in the backs of bays, etc.”
The study, led by The Nature Conservancy and conducted with water analysis by the Stony Brook scientists, was the first to make a comprehensive effort to document all of the issues that face Long Island’s water bodies.
Dr. Gobler said The Nature Conservancy was spurred to take on the study by its repeated frustrations in efforts to restore eelgrass and shellfish populations on Long Island.
“While we had hoped we could simply plant seagrass and clams to bring back our bays, 2013 has taught us that these efforts will only be successful if we can get nitrogen loads under control,” The Nature Conservancy’s senior scientist, Carl LoBue, said in a release outlining the study results.
Dr. Gobler said that the patterns and causal effects are hard to miss.
“They’ve been working on restoring shellfish for more than a decade, and they’ve begun to recognize that they are only having success where they are free of these algal blooms,” Dr. Gobler said. “They see a repeated pattern of having some success, and then a brown tide or red tide moves in and wipes out everything they’ve been working for.”
A team of Stony Brook University scientists, led by Dr. Gobler, authored study results in 2011 that identified a direct link between the increasing occurrences of harmful algae blooms and nitrogen loading caused by increasing density of residential development on Long Island—and, in particular, on the East End. The scientists said that on the South Fork, residential septic systems leaking into groundwaters that then flow into the tidal bays were the largest source of nitrogen reaching the bays.
The spread of the harmful blooms and the direct links to residential sources have spurred a movement among some local officials to try to effect change by reducing the amount of nitrogen that reaches the groundwater from residential septic systems. The issue has been at the fore of local politics and in nearly every discussion about development projects on the South Fork, along with the acknowledgment that solutions will be extraordinarily costly and ambitious to implement.
Environmentalists hope that the recent study will spread that concern to the wider population of the island.
“Long Islanders should take this as a call to arms,” said Adrienne Esposito, executive director of the Citizens Campaign for the Environment, in a release from The Nature Conservancy. “Our bays are dying, and the science clearly shows us why. Now is the time for lawmakers to pass legislation that creates a governing body to protect our bays and creates standards to lower nitrogen entering our coastal waters.”