Suffolk Reporter

Scientists from Stony Brook University have released a new map detailing the state of water quality in Long Island's coastal waters for 2024. Their findings reveal an alarming increase in harmful algal blooms (HABs) and 'dead zones' across the region, posing significant threats to marine life and public health.

The study identified 36 distinct dead zones—areas with less than three milligrams of oxygen per liter—across Long Island during the summer months. These zones are critical as they fall below the New York State Department of Environmental Conservation's threshold necessary for supporting marine life.

Throughout June to September, every major bay and estuary on Long Island was impacted by HABs, oxygen-depleted dead zones, or fish kills. According to researchers, excessive nitrogen from onsite wastewater systems is a primary cause of these issues.

Chris Gobler, PhD, SUNY Distinguished Professor at Stony Brook University’s School of Marine and Atmospheric Sciences, warned about the future: “It has become clear that, absent aggressive change, Long Island should expect the widespread occurrence of low oxygen zones and HABs during summer and these events could worsen with climate change.”

In addition to dead zones, more than two dozen lakes experienced blue-green algal blooms this year. Such blooms pose serious risks as they produce toxins harmful to humans and animals. Suffolk County continues to report more blue-green algal outbreaks than any other county in New York State.

On a positive note, no shellfish beds were closed due to HABs in 2024. However, some bloom events were more intense than previous years. A notable event occurred in August when rust tide spread through Shinnecock Bay into most of the Peconic Estuary.

Gobler emphasized that climate change exacerbates these conditions: “While some folks referred to the August 19th event as a 1-in-1,000-year event...the science shows we should expect more of this in the future.” He called for reducing nitrogen levels entering coastal waters as part of mitigating efforts.

Despite challenges faced over recent years due to HABs and dead zones contributing to habitat loss such as seagrass collapse or fisheries decline like bay scallops or hard clams—efforts are underway toward remediation. Both Suffolk County and Nassau County have completed studies pinpointing wastewater as a significant source of nitrogen pollution while setting reduction goals.

This comprehensive report was produced by Stony Brook University's Gobler Laboratory alongside data from New York State Department of Environmental Conservation and supported by funding through U.S Environmental Protection Agency’s Long Island Sound Study program.