- The Washington Times - Tuesday, April 29, 2008

ANNAPOLIS (AP) — Underwater grasses in the Chesapeake Bay are coming back, but not nearly as quickly as needed to restore the polluted estuary.

An annual aerial survey of Bay grasses by the federal-state Chesapeake Bay Program released yesterday shows that the Chesapeake and its tidal tributaries were covered by 65,000 acres of underwater grasses last year. That is an increase of 10 percent from 2006.

However, the acreage is only about 35 percent of what Maryland, Virginia, Pennsylvania and the District are aiming for by 2010.

The grasses are vital to restoring the Chesapeake because they filter excess nutrients from the water and provide habitat and food for fish and the Bay’s hallmark blue crabs.

“It provides refuge and forage potential for things that we like to eat,” said Lee Karrh, a scientist with the Maryland Department of Natural Resources who worked on the survey (https://www.vims.edu/bio/sav).

The Chesapeake Bay Program bases its annual grass survey on aerial photos from the 1950s. Bay grasses were presumably much more plentiful in centuries past.

Last year’s surveys showed an improvement from the year before, when grasses covered 59,000 acres. Mr. Karrh called the slight improvement from 2006 to 2007 encouraging, but he pointed out that significant progress toward restoring the Chesapeake’s underwater grasses remains elusive. As recently as 2002, the survey showed 90,000 acres covered by submerged vegetation.

“It really hasn’t changed much since the ‘90s; it just kind of bounces around a value,” Mr. Karrh said. “That’s what we need to address.”

The Bay program noted that different parts of the Chesapeake vary widely in revival of grass coverage. The northernmost portion of the Chesapeake, the Susquehanna Flats, is dominated by a massive mat of grass. North of the Chesapeake Bay Bridge, grass acreage is at 80 percent of the scientists’ goal.

But the news gets worse the farther south the researchers looked, with grasses slow to recover in warmer, saltier water.

In the Chesapeake’s midsection, between the Chesapeake Bay Bridge and the Potomac River, grass acreage decreased slightly last year and is at only 26 percent of the restoration goal.

Researchers also noted a slow recovery in the return of eelgrass in the southern portions of the Chesapeake. Eelgrass was dramatically reduced during a hot 2005 summer and has been slow to rebound.

Mr. Karrh said it is not yet clear why grasses in the southern portion of the Bay are worse off, though he pointed out that healthy grass beds are better at surviving pollution than struggling ones.

The woeful plight of Chesapeake grasses helps explain why blue crabs are at such low levels. Maryland and Virginia both have cut the harvest of female crabs this year by more than a third because of low population numbers. Scientists say it is habitat loss, not watermen, that is responsible for record-low crab harvests in the Chesapeake in recent years.

“People ought to understand that blue crabs are the real victims of this,” said Bill Goldsborough, a senior scientist at the Chesapeake Bay Foundation, a nonprofit advocacy group that did not participate in the survey. “If you want to put a face on the effects of nitrogen pollution in the Bay, look at the crabbers who are suffering.”


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