Monday, February 12, 2007

Dead Zones in the Chesapeake Bay and Weed-Infested Forests Lead to a Bleak View of the Future for Species in Virginia


Va.'s species face bleak future

A scientist discusses global warming at a U.S. Senate hearing


Feb 12, 2007

Bigger dead zones in the Chesapeake Bay. Weed-infested forests. Sick fish.

This is scientist Roger Mann's vision of a Virginia afflicted by global warming.

Stressed, dying trees. Forest fires. Diseased oysters.

The list goes on.

"I think it could be quite a big deal," Mann said from his office at Gloucester Point.

Mann, research director at the Virginia Institute of Marine Science, addressed a U.S. Senate panel last week on global warming's potential effects on the state's wildlife and plants.

He was welcomed by Virginia Sen. John W. Warner, the senior Republican on the new panel, a subcommittee looking at global warming and wildlife.

In testimony and in an interview, Mann said global warming appears to be causing some problems now, and more could be on the way.

Among his assertions:

# Trees could become so stressed that insects and disease could kill them more easily. Also, warmer, drier weather could promote forest fires.

# Invasive, hardy plants such as the tree of heaven, Japanese honeysuckle and multiflora rose could get a boost, helping them overtake many of Virginia's native plants.

# The Chesapeake Bay could suffer larger dead zones, which are low-oxygen areas where fish and other animals have trouble surviving. Warm water helps create the zones.

# Striped bass -- commercially and recreationally valuable fish -- could become more vulnerable to disease. The sick fish could die or become pocked with sores.

# Underwater grasses, in which fish and crabs hide, could suffer. Many of the grasses already have died because of pollution and other problems, and experts are working to bring them back.

For an example of a problem today, Mann said rising water temperature appears to be the primary cause of the northward spread of the oyster disease Dermo from the Chesapeake Bay to the Delaware Bay and the Long Island Sound over the past 20 years.

Virginia's oysters already have been decimated by disease and overharvesting. Warmer weather could make Dermo more prevalent and more intense, hurting efforts to restore the oyster, Mann said.

Forty years ago, commercially important surf clams were abundant from southeastern Virginia to Cape Hatteras, N.C. Today, the clams have almost disappeared south of the mouth of the Chesapeake Bay.

Increasing summer water temperatures apparently are forcing the clams to seek cooler northern waters, Mann said.

"We are observing changes in natural populations of endemic plants and animals [in Virginia] that can arguably be linked to global warming, and we expect the trends to continue," Mann testified.

Mann is just the latest Virginia voice to speak up about climate change.

Last month, a report from a state panel of scientists, industry representatives and environmentalists said global warming posed a serious threat to Virginians and their property. The state could see more -- and worse -- heat waves, droughts, storms and floods, among other problems, the report said. It called for a state commission to study the problem.

This month, an international group of scientists said it is 90 percent sure that heat-trapping gases released by human activities are warming the Earth.

University of Virginia climatologist Patrick Michaels, a skeptic of dire global-warming scenarios, did not return calls. But on the Web site of the libertarian Cato Institute, where he is a senior fellow in environmental studies, Michaels wrote that higher temperatures and other factors have aided plant growth in the Northern Hemisphere since 1980.

"This shows that the gradual nature of climatic warming has had visibly positive effects rather than having precipitated doomsday," Michaels wrote.

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