Experts predict more Great Lakes invaders ahead

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Capital News Service
LANSING – Amid concern and confusion over Asian carp possibly finding their way into the Great Lakes, many experts involved in the controversy agree that other invasive species are likely to show up too.
Non-native wildlife are common in the Great Lakes, with more than 140 species living in them.
For example, sea lampreys were first found in Lake Ontario in the 1830s. Other invaders followed, with construction of locks and canals increasing the frequency with which new species arrived.
“I don’t think anyone could tell you which species are going to be in the Great Lakes next,” said Brian Roth, a fisheries and wildlife assistant professor at Michigan State University.
“Asian carp may have already traversed the electric barriers connecting the Great Lakes to the Mississippi River,” he said.
Roth is referring to an electric barrier in the Chicago Canal designed to keep the carp out of Lake Michigan. The canal connects Lake Michigan and the Mississippi River.
“It’s possible that other species could do the same,” he said.
“In addition, there are other connections in the eastern part of the country, through the St. Lawrence Seaway. We know that this is a potential place for species to get in because things like sea lamprey and alewife have already gotten in through that mechanism,” Roth said
There’s also the risk that non-native species that are currently present could either grow in population or expand their territories . Roth says that a cousin to an already established non-native species could be the next to expand.
“This is all just speculation, but there are a few invasive species that are in relatively low abundance.
One is the tube-nosed goby. The round goby is fairly common throughout the Great Lakes. The tube -nosed goby is not real common throughout the Great Lakes. It’s in lakes Huron and Eerie right now, and that leaves three others.”
Northern Michigan University biology Professor Jill Leonard says that the temperature needs of some aquatic life could cause them to move further north if the lakes get warmer.
“A lot of what really determines how far a species can go is this temperature gradient that you find across the Great Lakes,” Leonard said. “Up here in Lake Superior, a lot of these species may or may not be present, but they really haven’t blossomed yet.
“One of the predictions for climate change affecting the Great Lakes is that the lakes will warm. That has the potential to shift available habitat for some of these invasive species that we have that are being limited by temperature,” she said.
Leonard says that zebra mussels, which are currently limited to water that has been somewhat warmed – such as around power plants and harbors – could see their habitat expand if lake temperatures rise.
Non-native species are a concern because of the adverse impact they can have on the Great Lakes ecosystem.
Roth says that in an undisturbed ecosystem, “energy flows in an expected manner.
“Large fish prey on small fish. Small fish prey on small crustaceans called zooplankton. Those plankton feed on phytoplankton or algae,” Roth said. “Usually, without any other large disturbances, such as really intense fishing or lots of pollution, those fish communities will sustain themselves.”
Because of the history of pollution and fishing, Roth says the Great Lakes are already a disturbed system.
Zebra mussel infestation that began in the 1960s shows the damage a new animal can bring.
“Zebra mussels are filter feeders and feed on the algae that are normally for the small crustaceans,” he said. “There’s enough algae in the Great Lakes generally to allow the fish food webs to be okay.
We’re still trying to determine exactly how zebra mussels affect the lakes. But the role that any new species could have is disrupting the food web.”
Those disruptions get harder to deal with as the number of invasive species increases, according to Robert McCann, the Department of Natural Resources and Environment press secretary.
“The more of these invasive species that come into the Great Lakes system, the harder it is for us to deal with them,” McCann said. “Some of them just constitute more of a nuisance, while others cause actual damage to the lakes and the streams and the wildlife that live in them.
“That has been ongoing, and it’s only going to get more difficult to deal with if we don’t take action to really close off the doorway that they use to get in here,’ he said.
That increasing difficulty is why Joel Brammeier, the president of the Alliance for the Great Lakes based in Chicago, said that decisive action is necessary.
“That’s exactly why the solutions we look for can’t be temporary,” he said. “If we spend too much time dithering about what to do in the short term, we’re risking our chance to implement a long – term solution that protects the Great Lakes.”
An Asian carp summit is planned for Feb. 8 at the White House. Gov. Jennifer Granholm plans to attend.
© 2010, Capital News Service, Michigan State University School of Journalism. Not to be reproduced without permission.
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