Thursday, June 21, 2007

The Way We Treat Our Estuaries

For anyone who follows the issue even slightly, the U.S. EPA’s report, issued earlier this month, on the condition of 28 estuaries in the National Estuary Program isn’t all that shocking. It concludes that, in general, the estuaries are in fair condition, and that estuaries in the northeast are in poor condition. We know that, of course: we live near Long Island Sound and we read about Narragansett Bay and Barnegat Bay and all the other places.

But even though the conclusion is not a surprise, the report is worth looking at, as a reminder of what we’ve done to places like the Sound and Chesapeake Bay – namely we’ve decided we’re going to crowd onto their coasts, change a good portion of their natural habitats into urban and suburban developments, and then dump our waste into them. All this of course while acknowledging that estuaries are among the most biologically productive ecosystems on the planet.

The study, called the National Estuary Program Coastal Condition report, divides U.S. estuaries geographically and rates them on water quality, the quality of sediments, the variety of life living on the bottom, and the amount of toxins in their fish. Like the northeast, Puerto Rico’s estuaries are also rated as poor. Gulf Coast and west coast estuaries are in fair condition, and southeast coast estuaries are good.

There’s a clear correlation between the condition of estuaries in a region and population density. The two areas with poor ratings have the highest population density -- Puerto Rico, with 5,055 people per square mile, and the northeast, with 1,055. Densities in the fair and good regions are far less – 421 people per square mile on the west coast, 287 on the Gulf coast, and 168 on the southeast coast.

The real bad news is that if population density is the cause – and who believes that it isn’t? – declining water quality is the future for the other regions as well, because that’s where population growth is the highest: a 133 percent growth rate for the Gulf Coast, 131 percent for the southeast coast, and 100 percent for the west coast. For those of us in the northeast, growth is slower – 24 percent – but of course the horse is already out of the barn here.

On Long Island Sound, the report summarizes what we know – that water quality is poor*, based on concentrations of dissolved nitrogen and phosphorus, on chlorophyll-a, on water clarity (all of which are generally good), and dissolved oxygen:

A large area of the Sound had depleted levels of dissolved oxygen in bottom waters, with 47% of the estuarine area rated fair for this component indicator and 10% of the area rated poor.

Sediment quality is considered poor, as is the diversity of life on the bottom (the benthic community), and the amount of contaminants in fish. Generally things are worse in the western end of the Sound and better as you move east, but that pattern didn’t hold with benthic diversity:

The east to west gradient that was noticeable in other parameters is absent in the results for the benthic index. Rather, the best results are clustered in the western and central portions of the Sound, and the poorest results are grouped in the nearshore waters and tributaries in New York and Connecticut.

You can find the whole thing, divided into PDFs for each estuary, here.

* This is a correction. I originally wrote that the Sound was rated fair. I'm not sure how I made that mistake -- the report clearly said "poor," in my mind I knew it was poor, and yet I typed "fair." Sam, down in south Texas, pointed out the mistake.



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