Wednesday, September 14, 2005

The Sound is in Bad Shape Again, and We Shouldn't Be Surprised

Hypoxia has not quite loosened its grip on the western end of Long Island Sound. In fact, it seems to be holding on longer than in any year since at least 1997.

After a number of years in the late 1990s and through 2000 when dissolved oxygen levels showed an improvement trend, last year’s hypoxia was characterized as “surprisingly low,” as was 2003’s and 2002’s. This year makes four years in a row of bad conditions.

Perhaps it’s again time to consider severely low dissolved concentrations to be the norm, to go back to thinking of the western Sound as a severely stressed ecosystem, uninhabitable in large parts by marine life. And to stop saying we’re surprised by it.

At Execution Rocks, off New Rochelle, dissolved oxygen concentrations this afternoon were 1.6 milligrams per liter; yesterday they were about 1 milligram higher. Even a bit further east, between Greenwich and Oyster Bay, today’s reading was only 2.6, which is bad.

If you click here you can look at the DEP hypoxia maps through the years. In 2001, DO levels stayed low through at least September 10, but I clicked back through 1997 and found no other year in which they were as low as 1.6.

The Greenwich Time sent reporter Michael Dinan out on the DEP research boat during one of its third-week-of-August cruises. Near Eastchester Bay, it recorded 0.05 milligrams per liter. Quoting Matthew Lyman, the DEP environmental analyst who does the mapping, the reporter wrote:

"It stresses the animals," Lyman said. "The fin fish simply won't stay in a place with no oxygen, some die, and others are unable to reproduce. It can disturb the entire ecosystem by disturbing the food chain."

Other results of hypoxia stations the DEP team visited report 1.97 mg/L at Wescott Cove in Stamford, .94 mg/L at Hempstead Harbor on Long Island's north shore, and .05 mg/L at the DEP's westernmost station near Eastchester Bay in the Bronx.

"That's about as close to zero as you can get," Lyman said of the Bronx reading. "That's what I'd call very severe."

Those who study these things think that in addition to the huge amounts of sewage and other pollutants we continue to put into the Sound, much of the blame for the bad conditions of recent years can be placed on the weather: Hotter temperatures, warmer water, less rain, more rain at the wrong time.

Back in the late 1980s, Eric Smith of the Connecticut DEP Marine Fisheries bureau, made the common-sense point that hypoxia has two causes: nitrogen, the main source of which is sewage, and the weather – and we can’t do anything about the weather.

The premise of the Long Island Sound cleanup was that we can do something about nitrogen, in sewage and elsewhere, and a lot of money was spent on computer models to figure out what to do and where. The result was the requirement that sewage plants in the region take steps to reduce the amount of nitrogen in their discharges to the Sound by 58.5 percent by 2014.

That nitrogen-reduction program is ongoing, and it’s true that until New York City, which accounts for 80 percent of the Sound’s sewage, starts showing progress, all the work done by everyone else is small potatoes.

Dissolved oxygen will rebound soon, of course, as the weather continues to cool and fall storms blow through. But I doubt that hotter summers and warmer water temperatures can be considered abnormal any longer. In fact, they are probably our future. I hope the computer modelers have taken that into account.


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