Monday, September 12, 2011

The Aftermath of Tropical Storms Irene and Lee

Irene was a disaster for lots of us living on shore, but her impact on the Bay was not that severe, in fact, in one respect, it had positive effects, it's strong winds turned over and mixed the bay water, cleaning up the "dead zones" which had settled in the bottom waters:
Hurricane Irene's high winds breathed a little life into the polluted Chesapeake Bay, bringing short-term relief to wildlife by temporarily eliminating the estuary's vast dead zone, according to the Maryland Department of Natural Resources.

The bay's dead zone - a stretch of deep water stretching from Baltimore to Virginia, with dissolved oxygen levels too low to support most aquatic life - emerges every summer and naturally fades with the fall. But this year's dead zone diminished earlier than usual after Irene whipped through the area, mixing layers of water containing varying levels of oxygen.

The revived waters could provide a habitat for marine life in places that were previously not livable, said Jenn Aiosa, Maryland senior scientist for the Chesapeake Bay Foundation.

"It might open up additional habitat that, three weeks ago, wasn't hospitable because the oxygen was low," Aiosa said. "A greater volume of the bay with oxygen is good, primarily for the fish that transit the bay - and, you know, if there's more fish available, birds or the wildlife that rely on those fish species would also benefit."
Tropical Storm Lee, on the other hands, which manifested largely as a long rain event over a large area of the Northeast, with widespread flooding is causing substantial problems:
Near record flows on the Susquehanna River are bringing sewage, sediments and other pollution into the Chesapeake Bay. And that’s threatening bay grasses, oysters and other key species that help improve the bay’s water quality.

The Chesapeake Bay Program says that in addition to the Susquehanna, high flows are also being measured on other waterways in the six-state bay watershed, threatening to cover bay grasses and oyster beds in sediment. Floodwaters could also dilute the salt in the water that oysters need and free chemicals in sediment trapped behind the Conowingo Dam along the Susquehanna.

On the positive side, the bay program says flooding happened after the main bay grass growing season, and sewage and other pollutants are less likely to cause algae blooms now than earlier in the year.
Many observers report extremely turbid waters and large amounts of floating debris, natural and otherwise, further up the Bay.  As we have seen previously, I expect to see major amounts of debris land on our beach in a few days, depending on winds and tides.

People are already starting to talk about the aftermath of Lee as the worst event since Hurricane Agnes in 1972, which had similar flood waters, and caused substantial and long lasting harm to the Bay by lowering the salinity over large areas, and killing animal and plants intolerant of fresh water, and by smothering many more with silt.

Scientists are already at work out on the Bay, trying to see how bad the effects have been.

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