Volume 16, Issue 23 - June 5 - June 11, 2008

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Getting into Hot Water

Rising sea levels will send our wild neighbors packing

by Carrie Madren

We humans can easily forget we’re creatures of the environment. Our homes are climate controlled and grocery stores full of food. We can dress for just about any outdoor temperature.

Wildlife, however, isn’t so lucky. Tied to their natural habitats, creatures of water, land and air are far more susceptible to changes in temperature, air quality and plant makeup.

When global warming washes saltier, warmer waters into the Bay over the next century, there’s a good chance wildlife will have to move — if they can get up and go — or perish. Sea-level rise will raise the tideline and change the makeup of our marshes, according to a new report by the National Wildlife Federation.

You’ve probably read by now that we could lose over half our beaches to rising waters consuming coastal and low-lying lands. Parts of Shady Side, the report predicts, will again become the Great Swamp as the water table rises. Swamp will push the Eastern Shore inland, too.

We’re not the only ones who stand to lose our habitat, from homes to summer beaches and fishing holes. Our wild neighbors will have to move with changing conditions.

Saltier waters will push Bay fish north. Some 66 percent of our region’s commercial fish — including Atlantic menhaden, bluefish, flounder, spot, mullet, croaker and rockfish — depend on coastal marshes for spawning, according to National Wildlife Federation’s report Sea Level Rise and Coastal Habitats of the Chesapeake Bay.

Those are the same coastal marshes we stand to lose, according to lead researcher Patty Glick in the most comprehensive analysis to date of how sea level rise will affect coastal habitats and wildlife.

Changing Places

Salting the Bay would squeeze mammals, migratory birds, turtles, reptiles and such aquatic dwellers as blue crabs.

The National Wildlife Federation estimates that saltier, warmer waters could claim as much as 167,000 acres of undeveloped dry land and 161,000 acres of brackish marsh (468 square miles, or about the size of Prince George’s County). In exchange we’d get some 266,000 acres (415.6 square miles) of newly open water and 50,000 acres of salt marsh. Both gains, however, make for less ecologically diverse ecosystems.

That’s bad news for rockfish, white perch, herring and shad, whose life cycles demand migration between salt and fresh water — plus time in brackish water.

Such drastic losses are a fair estimate, according to the report, as a two-foot water level rise is on the low end of what scientists are predicting.

Blackwater Wildlife Refuge stands to lose even more: the Eastern Shore sanctuary could lose some 90 percent of its tidal fresh marsh, swamp and brackish marsh. Over the last 70 years, Blackwater has already lost over one-third of its marsh area.

Along the Bay, the loss of brackish marshes would be devastating, according to the report, for diamondback terrapins, which call marshes home. Bay beaches would also be lost, meaning less nesting space for terrapins and other endangered marine turtles.

Out on the coast, Atlantic beaches will take a hard hit, too.

“Chincoteague will succumb to overwash from storms,” Glick says, Threatened birds and other species will suffer that loss along with us.

Flying from Rising Waters

Losing marshes and beaches could mean fewer migratory birds stopping over Delmarva and Chesapeake Bay’s western shore.

More than a dozen duck species — including redhead, northern pintail, American widgeon, canvasback and more — depend on underwater grasses for food.

“Highly vulnerable eel grasses are already near the highest temps they can tolerate,” says Dr. J. Emmett Duffy, professor of marine science at the College of William and Mary’s Virginia Institute of Marine Science. The unusually hot summer of 2005 devastated sections of eelgrass that still haven’t recovered. “Climate change could knock these grasses out for good,” says Duffy.

With the marshes and their grasses would go the migratory birds, including mallards and American black ducks, the latter already a species with low numbers.

Wading birds, like herons, would find hunting harder, with fewer shallows to hunt in and fewer small fish to snap up.

The Shifting Circle of Life

Birds are not the only creatures to be affected. Eelgrass beds — the same ones dying in high water temperatures — are also blue crab nurseries.

“Life cycles of animals depend on water temperature,” says researcher Duffy. Already we’re seeing rockfish moving up the Bay starting three weeks earlier than decades ago, he says, because of temperature and water changes.

Fish of many species depend on marshes for food, nesting habitat and nurseries for progeny, so a cut in marshes would mean fewer fish. Fishy foodwebs, too, would get tangled: beaches are nesting grounds for killifish, mummichug, rockfish, herring, silversides, Bay anchovy and more.

Changes in fish habitat and foodwebs would mean changes for people, too. Local economies depend on fishing and fisheries. Chris Conner, a lifelong Bay fisherman, worries that he won’t be able to take his nine-month-old son out fishing someday.

“Just look at the loss of eel grass,” he says. “That means we’re losing areas for small fish, which means fewer larger fish later on.” Conner hopes to see better fisheries management to ensure that we don’t return to days of low rockfish populations, with fishing restrictions.

All these changes in our environment could mean shifting ranges for some mammals, too. On land, rising temperatures — milder winters — in addition to fewer marshes may allow nutria, alien rodents that wreak havoc on marsh plants, to range farther north.

Scientists can’t see the future frame by frame. But they’re predicting that many species — ourselves included — may lose their homes in the big picture.

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