`Invasives' threaten Maryland habitats

Alien plants and animals said to alter landscape

August 18, 2002|By Sandy Alexander | Sandy Alexander,SUN STAFF

Environmental police are moving today to poison a menacing colony of snakehead fish in an otherwise tranquil Crofton pond. Even if the predatory fish are wiped out, a larger struggle against invasive species will be far from won.

Maryland faces uphill battles with dozens of destructive alien organisms.

Multiflora rose, tree of heaven, Vietnamese stiltgrass, mile-a-minute, purple loosestrife, gypsy moths and garlic mustard might not seem as exciting as an air-breathing, ground-traveling fish that can grow to the size of a golf bag, but experts say they are changing the face of Maryland's landscape as they crowd out native wildlife.

On the ecologically fragile Chesapeake Bay, the oyster fishery has been dangerously depleted, in part by a parasitic disease called MSX that arrived in the region with Asian oysters in the 1950s.

Meanwhile, nutria, large rodents brought from South America decades ago to support the fur industry, are eating their way through the vast marsh that provides food and shelter for tens of thousands of waterfowl at the Blackwater National Wildlife Refuge.

Elsewhere around the bay, natural resource experts are struggling to limit damage caused by alien species as diverse as mute swans, phragmites and water chestnuts.

More trouble appears to be on the way by trains, boats and planes that carry countless containers across the nation and around the world into Maryland every day. State environmental officials are worried about 17 "red alert" species that are not established here but could hammer the state soon.

Among them are zebra mussels, which clog water pipes and boat engines; Asian longhorned beetles from China, which might wipe out forests; red imported fire ants, which pack an extraordinarily painful sting; spiny water fleas, which starve small fish and others up the food chain; giant salvinia plants, which congest lakes and ponds; and plum pox, a virus that can ruin peach orchards.

"It's a monumental challenge," said Glenn Therres, associate director of the Wildlife and Heritage Service at the state Department of Natural Resources.

In February, representatives of state, federal and nonprofit groups working together as the Maryland Invasive Species Council released an updated list of 75 invasive species of concern.

Some are regulated by state or federal law, while others are not regulated but made the list because biologists and natural resource managers recognize their negative environmental and economic effects.

Fast growers

Many non-native plants live peacefully in Maryland, including most of the area's food crops and popular garden plants. But some have proved aggressive, taking over parks, forests, yards and roadsides with their quick growth, efficient reproduction and ability to choke out other plants.

They displace native plants and leave little food or habitat for insects, birds and animals further up the food chain - including endangered species.

Invasive plants might also increase erosion, add to pollution in waterways and increase fire dangers as they replace less flammable undergrowth.

In a phenomenon she compares with the supernatural powers in the movie The Sixth Sense, Ellen Nibali, a University of Maryland horticulture consultant, sees unwelcome plant species destroying local foliage where other people observe green leaves and assume nothing is amiss.

"Once you are aware of it ... it's pretty amazing," Nibali said. "It sneaks up on you. ... In some areas, it is reaching a critical mass."

Foreign animals, fish and insects are also causing big trouble. They might have no natural predators here and might consume food sources, eat their way through valuable forests and disturb habitats.

Then there is an indirect impact when people can't enjoy parks and natural areas that might have cost millions of dollars to create.

Nationally, the economic loss from these invaders is estimated at $100 billion a year.

No one knows how much is invested in fighting back.

Maryland spent $1.8 million battling invasive species in 2000, according to the Maryland council. But many other agencies, nonprofit groups and individuals are spending untold millions more to attack invasives, from backyard gardens to large wildlife refuges.

Farmers are forced to spend time and money in efforts to keep invasive weeds from harming their crops, while fishing, cattle and timber industries take steps to limit economic harm from invasives.

A drop in the bucket

Examples such as the $4 million in state and federal money spent over two years to study nutria in Maryland, or the $10 million New York spent annually to reduce the number of sea lampreys in the Great Lakes, are a drop in the bucket, say environmentalists.

Marc Imlay, vice president of the Maryland Native Plant Society, said his and other groups support a bill in Congress seeking $900 million in federal matching funds for efforts across the country.

Although state and federal agencies have plans in place to fight several specific species, Therres said a broader approach is needed.

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