Scientists warn of future Great Lakes invaders

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Bighead Carp. Credit: Michigan Department of Natural Resources

Capital News Service
LANSING — As many agencies try to rid the Great Lakes of foreign plants and animals that are now causing ecological havoc, the National Oceanic and Atmospheric Administration (NOAA) has identified the region’s potential future invaders.
Perhaps to no one’s surprise, two species of Asian carp—bighead and silver—top the enemies list as five Great Lakes states continue a court battle to close Chicago Sanitary and Ship Canal locks to stem the carp’s advance.
The NOAA effort includes potentially troublesome plants like the water lettuce and water hyacinth introduced through aquarium and pond shops.
The NOAA “watch list” of 52 nonnative crustaceans, fish, plants and invertebrates is a step toward the Great Lakes Restoration Initiative’s goals of early detection of and rapid response to invasive species, said Rochelle Sturtevant, a principal investigator on the study and a Great Lakes Regional Sea Grant Extension educator based in Ann Arbor.
That initiative addresses pollution, invasive species and habitat restoration through funding to local, state and federal governments, universities and nonprofit organizations.
Sturtevant said the project started with 20 invasive species and ended up finding 52 that scientific literature and researchers cited for their potential to survive, establish or spread in the Great Lakes.
Species could be added to the list if climate change makes once-uninhabitable environments habitable. Others may be removed as researchers assess whether recent regulations made it harder for them to be transported in the ballast water of ships.
She said some studies considered whether a potential invader could survive a Great Lakes winter but didn’t take climate change into account. “There just isn’t enough data yet on what climate change is realistically going to do to the region, much less on an individual species-by-species basis of whether it’s going to over-winter. The data’s just not there.”
The NOAA list is part of a database of Great Lakes aquatic non-native species that helps lake and resource managers decide how to best manage aquatic invaders.
Potential troublemakers were identified after reviewing scientific studies published between 1998 and 2010. Species were also listed if they could survive and be transported into the Great Lakes, could reproduce there and could be introduced multiple times.
“I see this list as a living document, a work in progress that we hope to go through and update with whatever new literature has been published,” Sturtevant said.
John Magnuson, a zoology and limnology professor emeritus at the University of Wisconsin at Madison, has studied climate change impacts on lakes, rivers and freshwater fish.
“The warm-water fish that do really well in the warmest waters of our shorelines in the Great Lakes are also able to withstand winter temperatures at a couple degrees Centigrade,” Magnuson said. That’s about 36 degrees Fahrenheit.
Warm-water fish include carp, bluegill and crappie.
Climate change may create favorable habitat for species not currently on the watch list, like the golden mussel, according to Alexander Karatayev, director of Buffalo State University’s Great Lakes Center for Environmental Research and Education.
“This species is adapted to higher temperatures than the zebra mussel. Therefore, climate change may further the spread of the species,” he said. The golden mussel is a powerful water filterer, like the invasive zebra mussel, and can clog water intake valves for industrial and power plants, water treatment stations and refineries.
The golden mussel comes from Southeast Asia. Although the Great Lakes are too cold for it now, Karatayev said rising water temperatures may allow it to survive although it prefers warmer water. “It’s very likely that in the near future it can get to North America because now it’s almost everywhere in South America.”
According to NOAA, most species on the list have a “high probability of invasion if introduced to the Great Lakes via residual ballast water” or sediment. Ballast water has long been recognized as a pathway for aquatic invasive species.
Sturtevant, the Michigan Sea Grant Extension educator, said some species may come off the NOAA list in light of new regulations that require ships to flush ballast tanks with seawater, creating a more hostile environment for potential nonnative species.
© 2011, Capital News Service, Michigan State University School of Journalism. Not to be reproduced without permission.

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