July 26, 2017

Water Views

Anything But Blue: Toxic Tides Taking Hold

As the summer heats up, East End residents are drawn to the water. Nothing spells relief like a dip into a cool water body on a hot day. We seek the peace and serenity offered by daybreaks and sunsets over the water. Conditions are perfect for fishing, clamming, and boating.

And while we envision all of these activities taking place in a placid, pale blue body of water, the truth is, more and more surface waters on eastern Long Island are taking on colors that signal something is not right. The green lake or pond, the chocolate-colored bay; these are not the images we bring to mind as we dream about our favorite water activities. Yet, these conditions are now ever-present across the East End during summer. And if the concerns ended with a discoloration of the water, one might chalk it all up to a bad day at the beach and move on. However, the fact of the matter is, these discolorations are often caused by algae that are harmful to aquatic life, pets, and even humans. Moreover, the formation of these harmful algal blooms or HABs have been shown to lead to economic disruption in communities that rely on clean water for tourism, fisheries, and boating and have been shown to significantly depress home values in a one mile radius. Just about everyone should be concerned.

These harmful algal blooms can be broken down into two general categories: Those that are harmful to aquatic ecosystems, and those that are toxic and potentially lethal to humans and pets. The first broad category may seem like a small worry in that they can't hurt us directly. But, the truth is, these ecosystem-disrupting blooms have changed the way of life on the East End forever.

For example, in 1984, Long Island was home to the largest hard clam and bay scallop fishery on the US East Coast, and bay bottoms were covered with lush seagrass meadows. In 1985, the first brown tide bloom caused by the algae Aureococcus occurred across the Peconic Estuary and south shore of Long Island and has recurred virtually every year since, leading to a greater than 90 percent loss in the clam and scallop landings and contributing to a 90 percent loss in the coverage of seagrass. As a key nursery habitat for finfish and shellfish, the loss of seagrass has had a devastating, cascading effect on food webs and ecosystems across the East End.

Joining brown tides this century have been rust tides that occur throughout the Peconic Estuary and Shinnecock Bay. Caused by the alga Cochlodinium, a fish-killing algae that has caused late summer mass mortality in fish populations in tributaries and fishing traps known as pound nets.

While collapse of key fisheries and ecosystems is a serious concern, the second class of harmful algae on the East End are literally lethal. For example, red tides caused by Alexandrium produce the potent neurotoxin saxitoxin that is 1000 times more potent than cyanide and accumulates in filter feeding bivalves such as clams, oysters, and mussels.

If shellfish contaminated with the toxin are consumed by humans, it can lead to paralytic shellfish poisoning (PSP). There have been more than a dozen PSP-induced shellfish bed closures on Long Island in recent years and people have died of PSP in parts of the world without proper monitoring.

In other cases, it can lead to mass mortality of marine life as was the case in the deaths of hundreds of diamondback terrapin turtles in Riverhead in 2015. In lakes and ponds, more than a dozen sites across eastern Long Island have experienced blue-green algal blooms during the past decade. These algae synthesize potent neurotoxins and gastrointestinal toxins that have been responsible for dog illnesses and deaths in recent years.

Perhaps the most surprising aspect of the harmful algal blooms that have emerged in the past few decades is that we know the cause and we know how to stop them. For each of these individual algae, research has been published showing that excessive levels of nitrogen delivered from land to sea makes the bloom events more intense and more toxic.

The reverse has been demonstrated as well: In Northport, the upgrade of a sewage treatment plant ended the annual recurrence of toxic PSP events. On eastern Long Island, the majority of nitrogen in groundwater that seeps into bays, harbors, and lakes originates from septic tanks and cesspools, with household and agricultural fertilizer being the second largest source.

The good news is that lawmakers and voters have started to become aware of these issues and are now taking action to 'turn the tides.'

In 2016, East End voters approved an extension of the Community Preservation Fund and approved the use of that fund for improving water quality. Suffolk County has now approved the use of denitrifying septic systems for individual homes that remove 70 percent more nitrogen from wastewater. The change over to the use of these new systems along with reducing the use of fertilizers hold the promise to turn these tides and thus protect our health, protect our economy, and restore our coastal ecosystems.

Dr. Christopher Gobler is Associate Dean for Research, Professor School of Marine and Atmospheric Sciences and Co-Director for the Center for Clean Water Technology at Stony Brook University.

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