Biological invasions increasing due to freshwater impoundments, says CU-Bou...( The growing number of dams and other...)

The growing number of dams and other impoundments is increasing the number of invasive species and the speed at which they spread, putting natural lakes at risk, says a study led by the University of Colorado at Boulder.

The research team combined data on water chemistry, the distribution of five "nuisance invaders" and boating activity from the Great Lakes region. The results showed the increasing occurrence of such species in impoundments creates "stepping-stone habitats" for them into natural lakes, ponds and waterways in the region, said CU-Boulder Assistant Professor Pieter Johnson, co-lead author of the study.

The researchers looked at invaders like the Eurasian zebra mussel, the Eurasian water plant known as watermilfoil, the Eurasian spiny water flea, the rusty crayfish and the rainbow smelt. Such freshwater invaders often have direct negative effects on lake ecosystems, including reduced fishing success, changes in water clarity and fouling of fishing gear and water-pumping equipment, Johnson said.

The study appears as the cover story in the September issue of Frontiers in Ecology and the Environment, a publication of the Ecological Society of America. Co-authors on the study include Julian Olden of the University of Washington in Seattle and Jake Vander Zanden of the University of Wisconsin-Madison.

Zebra mussels recently jumped to reservoirs in the West, including Colorado, said Johnson, leading to mandatory boat inspections at some landings. The other invaders are either already in Colorado - the rainbow smelt and water milfoil - or have a high probability of being introduced, like the spiny water flea and rusty crayfish, he said.

"We believe impoundments may be functioning as 'hubs' for freshwater invaders, aiding their spread and establishment into natural water bodies," said Johnson of CU-Boulder's ecology and evolutionary biology department. The researchers wrote in the study that "re
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