Wednesday, May 23, 2012

It's Official, Sea Grasses Suffered in 2011

I reported on the results for the Chesapeake Bay proper in late March, which showed that seagrasses (or more properly, submerged aquatic vegetation, as few of them are actually grasses) dropped sharply from 2010.

Today's report from Maryland Department of Natural Resources, the Maryland Coastal Bays program, the Virginia Institute of Marine Scientists and the National Park Service shows that seagrasses in the Maryland and Virginia Coastal Bays (the small and medium sized inlets that front on the Atlantic Ocean and not the Chesapeake) also suffered substantial declines in 2011:
Seagrass acreage dropped 35 percent between July 2010 and May 2011, including nearly all of the grass beds in the Assawoman Bay and the Isle Wight Bay, according to figures by several groups.

The drop in seagrasses, which provide food and shelter for crabs, fish, birds and other species, coincided with large decreases in grasses in the lower Chesapeake Bay. Researchers said the grasses are now at levels not seen since the early 1990s, exceeding declines caused by the hot summer of 2005.

"The heat alone doesn't kill them unless combined with the already stressful conditions the plants are living in," said Thomas Parham, DNR Director of Tidewater Ecosystem Assessment Service.

The Chincoteague Bay lost the most — a decrease of more than 2,700 acres or about 27 percent of grasses, split nearly equally between Maryland and Virginia. Assawoman Bay lost about 900 acres, the Isle of Wight Bay, nearly 500, and the St. Martin River lost its last 1.6 acres.

One of the few areas of good news was the continued expansion of eelgrass in Virginia's coastal bays.

Clearer water of the Virginia coastal bays and the proximity of the eelgrass meadows to cooler ocean waters made the summer heat more bearable, said Bob Orth, who oversees the annual aerial survey.
Officials blamed hot summer temperatures, and nutrient pollution for the losses, without actually pointing to any data to support that. It's pretty clear that the huge rain and turbidity events in the Bay resulting from Hurricane Irene and Tropical Storm Lee had a lot to do with the sea grass losses in the Bay, but I note that those events are not mentioned in this article. Does this mean these events had less impact in the coastal bays?  Or is it simply easier to blame pollution and global warming (by implication)?

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