Timothy Kratz, site manager for the NSF-funded North Temperate Lakes
LTER in Wisconsin, samples open-water fishes with a
vertical gill net. Among the wealth of long-term data gathered from the
lakes is evidence of time lags in how
"invaders" affect lake communities. For example, in
Sparkling Lake a kind of trout called cisco went extinct
sixteen years after smelt found their way in.
Photo: North Temperate Lakes/University of Wisconsin LTER
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