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U of M study: Plant diversity doesn't protect lakes from invaders

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Eurasian watermilfoil
Eurasian watermilfoil
Photo courtesy U.S. Fish & Wildlife Service

A new study from the University of Minnesota challenges a common belief that lakes with diverse plant life are more resilient to aquatic invaders.

The study by the U's Minnesota Aquatic Invasive Species Research Center looked at 13 years of vegetation survey data collected from about 1,100 lakes by the Department of Natural Resources.

The surprising results: Researchers found no evidence that having a diverse plant community somehow keeps invaders such as curly-leaf pondweed or Eurasian milfoil from taking hold.

"We found that at the local scale the effects of what other species were there was not all that important," said Ranjan Muthukrishnan, a research fellow with MAISRC. "In particular, there wasn't this idea that diverse communities are sort of more resistant or resilient to invaders. Invaders were more of less able to invade independent of how many native species there were."

The researchers found that when invasive plants arrived, they were better able to adapt to less-than-ideal conditions than native species. That could be an important way in which invaders are able to take hold in a new environment, Muthukrishnan said.

"If the native species can only handle sort of these better habitats, there might be this marginal habitat on the edges that invaders can come in and sort of get a toehold in and then expand out from there," he said.

Muthukrishnan said the findings emphasize the importance of taking preventative measures to keep invasive species from spreading, such as cleaning, draining and drying boats before moving them to a different lake or river.

The study was published in the Journal of Ecology.