Spiny water fleas thrive, disrupt all Great Lakes

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Capital News Service
LANSING – Self-sustaining populations of the spiny water flea, an invasive species in the Great Lakes, suggest a greater problem, according to researchers.
“They reflect a disruptive food web in the Great Lakes,” said Steven Pothoven, a research biologist stationed in Muskegon for the National Oceanic and Atmospheric Administration.


University of Wisconsin-Madison.

Despite its misleading name, the spiny water flea is a crustacean rather than an insect. Its diet consists mostly of zooplankton. Small fish can’t eat the spiny water flea because of its long, barbed tail spine, but larger species of fish such as an adult paddlefish can do so.

Pothoven said it’s extremely hard for spiny water fleas to establish themselves in a healthy fish community because larger fish will eat them.
Therefore, bodies of water in which the spiny water flea thrives must already have inherent problems, he said. It lives in all five Great Lakes.
The population of spiny water fleas in the Great Lakes hasn’t caused great ecological collapses in the lakes, Pothoven explained, but when combined with other problems in the area, there can be “cascading effects” yet to be seen by researchers.
The major effect on the Great Lakes is a disrupted ecosystem, Pothoven said. These are “more difficult to manage and less predictable” than a healthy ecosystem, making it harder for scientists to address problems in the ecosystem.

Department of Natural Resources

In some of the Great Lakes, spiny water fleas are the dominant predators. Because they feed on zooplankton, they compete for food with small fish, as well as fish in early stages of life, Pothoven said.
According to the U.S. Geological Survey, transoceanic ships unknowingly introduced the spiny water flea, a native of Europe and Asia, to Lake Huron in 1984 via ballast water. By 1987, it was in all of the Great Lakes.
As the spiny water flea continues to move to inland lakes via recreational boaters, it may have a larger impact on those ecosystems because of their smaller size, Pothoven said. Recently, biologists have found it in numerous inland bodies of water in both the U.S. and Canada.
For example, the Department of Natural Resources (DNR) notes that the invader lives in the Upper Peninsula’s 14,000-acre Lake Gogebic, which is best known for its walleye and yellow perch. The department and sporting groups are keeping an eye out for possible adverse effects on the favored species.
And in Ontario, volunteers from the Ontario Federation of Anglers and Hunters, a nonprofit conservation organization, sample water from more than 100 inland lakes for the spiny water flea, said Alison Kirkpatrick, the monitoring and information specialist for the group.
Since the health of the Great Lakes affects both the U.S. and Canada, they signed the Great Lakes Water Quality Agreement in 1972. They amended the agreement in 2012 to include measures to prevent ecological harm, like the spiny water flea and other invasive species.
Pothoven said that the most significant measure taken in the U.S. to prevent its spread has been to educate boaters on boating hygiene.
DNR warns on its website: “Anglers and boaters: You are an important partner in preventing the spread of fish diseases and other aquatic nuisance species.”
In particular, it recommends that they:
•“Clean boats, trailers and other equipment thoroughly between fishing trips to keep from transporting undesirable fish pathogens and organisms from one water body to another.”
•“Allow boats, trailers and other equipment to fully dry for four to six hours in the sun before use.”
David Argent and Derek Gray, who conduct research about the spiny water flea at the California University of Pennsylvania’s Biological and Environmental Sciences Department, also stress the importance for boaters to clean the exterior of their boats, drain bilge water and allow fishing equipment to dry when moving among lakes and rivers because once spiny water fleas “are in a system and the conditions are conducive to survival, they not only expand their range but also thrive.”
Although the spiny water flea established itself in the Great Lakes more than 25 years ago, the long-term effects of its feeding practices are yet to be determined.
“We need to further study the potential effects of shifting zooplankton communities” in the bodies of water where they live, Argent and Gray said.

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