Brown tide resurgance in South Shore waters

Recommend

Comment

Email this article

Print this article

Get news alerts

RSS Feeds

Share Digg Mixx Linked In Facebook Twitter Delicious

Peconic Baykeeper Kevin McAllister.

see all images

Bob Dalder, a Southampton Town pump-out boat operator, was navigating through Quantuck Bay on Tuesday, over water in which brown tide is blooming, changing its color from sea green to a copper brown.

“What does it look like to me here? It looks like a toilet,” Mr. Dalder said.

The dubious algae is blooming again in the South Shore waters of Nassau and Suffolk counties and in more widespread areas than last year, threatening the health of eelgrass and shellfish, environmentalists and fishermen said this week.

According to environmentalists, brown tide is a native algae that is thriving in the western portion of Great South Bay, Moriches Bay, Quantuck Bay, and the western part of Shinnecock Bay, west of the Ponquogue Bridge in Hampton Bays.

Dr. Christopher Gobler, a marine biologist with Stony Brook Southampton, said this week the pernicious plant was found in “moderate to high” concentrations throughout those waters. Blooms began in late April and have resulted in concentrations ranging from 250,000 cells per milliliter to 1 million cells per milliliter. The blooms will likely continue throughout the summer, he said.

“All of those concentrations are harmful to shellfish,” Dr. Gobler said, referring to concentrations in water above 100,000 cells per milliliter. “These levels of brown tide can kill juvenile clams, and we know that adult clams tend not to feed during brown tide.”

Once in bloom, brown tide can begin a vicious cycle of destruction by reducing oxygen and visibility in the water for sea life.

As it reproduces and spreads, brown tide consumes oxygen from the water, possibly resulting in fish kills. Blooms also reduce light penetration to the eelgrass on the bottom, harming important nursery grounds used by fish and other sea life. A fish kill in Senix Creek in Center Moriches was documented by environmentalists on May 29.

“Both this year and last year there have been fish kills within tributaries along Moriches Bay with brown tide,” Dr. Gobler said. “The mechanism is likely the algae consuming oxygen at night and the fish expiring due to low dissolved oxygen.”

The Nature Conservancy of Long Island has reported that brown tide levels in the Great South Bay and Shinnecock Bay will result in lower spawning rates for clams this year. The Nature Conservancy, in an attempt to replenish the clam population in both bays, has been “seeding” the waters with millions of clams since 2004.

Carl LoBue, South Shore site director for the Nature Conservancy, said clams, which filter up to a gallon of water per hour, are necessary to preventing future brown tide blooms.

Due to overharvesting in the 1970s, the Great South Bay’s clam population was all but depleted, he said, possibly giving rise to brown tide blooms. The Nature Conservancy’s goal is to reach six clams per square meter in the bay by 2020; currently, the bay now has just 0.4 clams per square meter.

“We know that when the bays 
contain healthy populations of shellfish, they can prevent these blooms,” Mr. LoBue said. “We don’t think it’s to the point that it is killing the clams, but 
we do think they are not fattening 
up like they should do at this time of year.”

Since 2004, the South Shore of Suffolk County has endured consecutive brown tides during the summer. From June to September last year, waters between the Ponquogue Bridge and the Moriches Inlet were inundated with brown tide.

The first documented instance of the algae bloom was in 1985.

Though experts admit there is no smoking gun for the cause of brown tide blooms, the overharvesting of shellfish in the 1970s and over development of East End coastal areas are suspected causes.

On a boat tour of the Quantuck Bay on Tuesday afternoon, Peconic Baykeeper Kevin McAllister said that the bay has become a “ground zero” for brown tide.

He said that due to the bay’s midpoint location between the Shinnecock and Moriches inlets, competing tides from those inlets meet in Quantuck, creating a vacuum of stagnant water there. “Because of this stagnation, it sets up this bay to be prone to brown tide,” Mr. McAllister said. He added that tidal flow from Quantuck Bay has been spreading brown tide to both Shinnecock and Moriches bays.

Storm water runoff carrying fertilizers and pesticides after a rain may have also reduced oxygen levels in the water, he said. Tests of the surface water on Tuesday revealed low oxygen levels.

“No one has put their finger on what causes brown tide. Is it naturally occurring, or is it because of pollution,” Mr. McAllister said. “We’re seeing a great deal of fertilizer use in landscaping which is very likely to enter our waters in rain events.”