Stony Brook scientist: Nitrogen loading remains ongoing threat in Long Island waters

Stony Brook University scientist Christopher Gobler emphasized again at his annual State of the Bays lecture last Wednesday that excessive nitrogen loading from wastewater is an ongoing threat for Long Island waters. 

“Warming, acidification, hypoxia and harmful algal blooms are the four horsemen of the ocean climate change apocalypse, because they’re all happening together,” he said.

The Suffolk County subwatershed plan, published in 2020, showed nitrogen levels rising in surface and ground waters. Between June and September 2021, documented marine and freshwater harmful algal blooms and dead zones were widespread on Long Island shorelines. 

The rising population on Long Island has correlated with a significant increase in the nitrate levels in the aquifer, according to Mr. Gobler. Epidemiological literature on even low levels of nitrates have been associated with elevated levels of cancer, he said, adding that Suffolk County has higher rates of bladder cancers than anywhere else in the state or country, and higher rates of kidney cancer than average. 

Widespread toxic algal blooms have also impacted water quality and marine ecosystems, including the bay scallop population, he noted. Suffolk County has the most toxic blue-green algal blooms in the state, according to Mr. Gobler, and last year was “pretty bad” for rust tides, with the bloom starting in early August and continuing through October. Last spring, there was also a mahogany tide in many places across the south shore. 

In an October report, Mr. Gobler said conditions causing low oxygen and harmful algae blooms in Long Island waters, including on the East End, have become a “new normal,” with every major bay and estuary that summer suffering from toxic blooms and dead zones in a “dual assault of climate change and excessive nitrogen loading.”

Mr. Gobler described a newer algal bloom to Long Island last Wednesday as well, Dasysiphonia japonica, that has been dying on shorelines. The decay process can potentially release toxic gases into the atmosphere that can have an impact on human health. Scientists have theorized these seasonal die-offs, which are harmful to local marine life, are caused by warming temperatures. 

“This seaweed is all over the South Shore of Long Island,” Mr. Gobler said. “It likes the conditions that we now have, specifically here on Long Island, and that is higher levels of nitrogen and, seasonally, elevated levels of carbon dioxide.”

Harmful algal blooms are not new to Long Island, he noted. Green tide blooms temporarily proliferated in the early-1950s in Long Island’s south bays.

“We entered an era on Long Island where we had the most robust hard clam fishery [and bay scallop fishery] in the history of New York,” Mr. Gobler said. “That went on for a nice stretch of 25 years.”

Brown tides in 1985 caused a decline in the scallop industry, followed by “a succession of other harmful algal blooms” over time. Mr. Gobler pointed to studies about rust tides, a type of harmful algal bloom with an expanding bloom season, that shows “we’re in the bullseye for the expansion of this season.”

“In the 20th century, our waters weren’t warm enough for this organism to hit its maximal growth rate. Now we have a two month window for the rust tide and it’s taking advantage of that,” he said. “This organism grows faster when you give it more nitrogen and does so more frequently than other types of algae.”

Between 2003 and 2020, there’s been as much as a degree Celsius of warming in some Long Island waters, Mr. Gobler said.

“The bottom line is that we’re warming much faster here on Long Island, particularly during summer, than the rest of the globe is on average,” he explained. “That’s important, looking at things within a season. For example, our springs … are not any warmer, statistically, but our summers are and that’s problematic because already at that point, marine organisms are at their maximal tolerance, so they’re hitting their maximal temperatures.” 

The warmer it gets, the less oxygen in the water. One experiment looking at temperature and oxygen levels in the Peconic Estuary showed that higher temperatures and lower oxygen kills off bay scallops, which are also being impacted by a parasite. 

“And it’s not even the end of the story, of course, because we know if you combine nitrogen and higher temperatures, you’re gonna get more rust tide, and that the temperature alone and the rust tide alone is a problem for the scallop, and the oxygen is as well,” Mr. Gobler said. “This is the perfect storm [that] a lot of scientists are focused on. It’s called multiple stressors, we know it’s happening. And this is really a perfect example of how it can push and change ecosystems and fisheries with all these things coinciding together.”

Long Island’s nature as a watershed means all activities on land affect the water, he added. “We’re all in this together.”

Upgrading septic systems remains an important tool for mitigating and reversing water quality impairment, Mr. Gobler said, pointing to Suffolk County’s grant system to replace Long Island septic systems.

Suffolk County runs the Reclaim Our Water Septic Improvement Program, which grants as much as $30,000 to homeowners replacing their cesspool or septic system with new, individual Innovative and Alternative Onsite Wastewater Treatment Systems. Homeowners may also qualify to finance the remaining cost of the systems over 15 years at a 3% fixed interest rate. 

According to Mr. Gobler, Suffolk County once ranked among the “worst counties in the country for wastewater disposal … with every single home taking that wastewater and directing it as far down into the ground and as close to our drinking water supply as possible.”

“But right now, you could argue that there’s no county in the country with a better plan for handling wastewater than Suffolk County. They’re on track for upgrading 200,000 homes,” he said. 

New York State Center for Clean Water Technology is also working to minimize nitrogen and other contaminants in water, with studies examining nitrogen-removing bio-filters. Two iterations are expected to be provisionally approved by the end of this year and a third is expected to be approved next year, according to Mr. Gobler.

Research has also shown that seaweed farming holds promise for improving water quality, he said. Kelp hatcheries so far have produced “amazing” yields while taking nitrogen out of the water, reversing acidification and aiding the oyster population.

“We’re not going to solve harmful algal blooms and climate change with seaweeds. So let me just be really clear with that,” Mr. Gobler said. “We’re not going to solve our nitrogen problem with seaweeds. But we can have localized effects.”

Mr. Gobler also announced the “world’s first water quality app” created by his lab and Stony Brook University, with a “more user friendly release” coming Memorial Day weekend. It tracks hundreds of beaches, over 500,000 acres of shellfish beds, and data such as temperature and oxygen levels from The Gobler Laboratory and government agencies.