Beach season isn’t off to a great start for parts of Long Island. Last weekend, thousands of dead bunker fish washed up on the shores of Long Island’s Peconic Bay, just two weeks after hundreds of dead diamondback turtles were found nearby.

Experts, including the New York State Department of Environmental Conservation, say the culprit in both mass die-offs is a recent red tide—large algal blooms fueled by an excessive supply of nitrogen.

The turtles are believed to have eaten shellfish contaminated by an algae-produced neurotoxin; the fish appear to have suffocated because algal blooms severely reduce oxygen in the water.

Now, community members and environmental groups are renewing their call for a comprehensive, state-level plan to address the region’s water quality issues, once and for all.

As Far As The Eye Can See

Most of the fish kills have been found on public and private beaches in towns surrounding Flanders Bay, but have been reported as far east as Cutchogue and Southold.

Dead bunker fish mark the high tide line. Photo credit: Peter Blasl via RiverheadLocal.

Residents in Riverhead described the high tide line last weekend as “marked by piles of dead fish, stretching out as far as the eye can see.”

“This may be the biggest fish kill I’ve ever seen and I’ve been working for more than 20 years,” Christopher Gobler, a biologist at Stony Brook University’s School of Marine and Atmospheric Sciences, told the Riverhead News Review.

Gobler said levels of the algae Prorocentrum—responsible for the red tide—are some of the highest researchers have seen in the region.

During the day, these algae produce oxygen through photosynthesis, but at night, photosynthesis stops. Algae then use up oxygen right along with other organisms. The lowest dissolved oxygen is often found early in the morning, before photosynthesis begins.

When schools of bunker swim into this “dead zone,” they suffocate and die.

Dissolved oxygen levels have dropped to zero for extended periods of time in this area, noted Gobler.

Bunker fish kills in this area are not uncommon this time of year. Bluefish, a predator fish, will chase schools of bunker up the Peconic River, where they become trapped. The volume of fish combined with low tidal flushing in these areas drives oxygen levels down and the fish die.

However, Gobler said the current die-off is the largest he’s ever seen—and likely the largest in decades.

A Dangerous Neurotoxin

A dead diamondback turtle and dead bunker washed up on the beach at Simmons Point in South Jamesport, May 29. Photo credit: Peter Blasl via RiverheadLocal

Another type of algae also present in the Peconic, Alexandrium, produces saxitoxin, a “dangerous neurotoxin” that can damage or impair nerve tissue. Shellfish filter the toxic algae cells from the water. When other creatures—like turtles—consume the oysters, they can become paralyzed by the toxin and drown.

Gobler said saxitoxin is normally detected in the region’s waters, but he has never seen levels this high and never seen it cause such a wildlife die-off.

Nick Mancuso, a state wildlife technician, collects bodies of dead turtles from Iron Point in Flanders. Photo credit: Peter Blasl via RiverheadLocal.

“We’re seeing bodies washing up in perfect condition. This has never happened before. It’s an alarming thing,” Karen Testa, executive director of Turtle Rescue of the Hamptons, told the AP.

Testa also said the poisoned turtles may have been just coming out of hibernation when they ate the toxic shellfish.

“What that does is it paralyzes them and they would just drown. It’s a horrible death, “she said. “They get their first meal and its poison. It’s horrible.”

Experts say this die-off could have serious and long-term consequences to Long Island’s turtle population. “We’ve seen very few instances like this before,” said Dr. Russell Burke, the chairman of the biology department at Hofstra University, told CBS New York. “It can take decades to recover.”

Shortly before the turtles were found, the DEC issued an emergency ban on shellfish harvesting in Meetinghouse Creek, Terry Creek, both tributaries of Flanders Bay, and James Creek, a tributary of Great Peconic Bay due to the presence of marine biotoxins.

Saxitoxin can also cause paralytic shellfish poisoning in humans, which typically results in numbness and tightening in the face and a loss of coordination. In most cases, patients make a full recovery in a few days, but rare cases have resulted in death.

The Longer We Wait, the Worse it Will Get

Traditional septic systems don’t treat for nitrogen. Instead, nitrogen seeps into groundwater and eventually works its way into coves and harbors, where it can become pollution.

Most of Long Island’s water quality issues—including algae blooms—are a direct result of excess nitrogen. Nitrogen enters waterways from septic/cesspool systems, and waste water treatment plants, as well as run-off from yards and agricultural lands.

As the nutrient leeches into the sandy soil and ultimately the surrounding waters, it acts as an incredible source of plant food, triggering massive algal blooms in the Great South Bay, the Peconic Bay, Moriches Bay, and many other bays, ponds, harbors, and fresh water lakes. These blooms reduce oxygen levels, kill eelgrass and other wildlife, and produce harmful toxins.

“Such occurrences will become the norm if we don’t reduce 30-50 percent of the nitrogen going into the Peconic Estuary,” Kevin McDonald of The Nature Conservancy on Long Island, said in a statement. “While some strides have been made to reduce nitrogen in our waters, the longer we wait to fix our water quality problems, the worse it will get, the longer it will take and the more expensive it will be.”

Cat drinking from faucet. Photo credit: Dave Dugdale / Creative Commons

Nitrogen pollution is also a threat to drinking water. All of Long Island’s drinking water, whether from public or private wells, comes from three underground aquifers: the Upper Glacial, the Magothy, and the Lloyd.

Nitrogen levels in these aquifers are increasing; groundwater with concentrations above 10mg/liter is toxic to humans.

New York State’s 2015-16 budget includes $5 million for a plan to combat nitrogen pollution on Long Island. According to The Nature Conservancy, the funding will be used to “develop an Island-wide plan to identify a thoughtful path forward and make sure that state, county and local water resource planning efforts are coordinated and actively addressing immediate coastal resilience and water quality challenges.”