Sinkholes, caves and gill lice

By Duke Welter

While the weather in the Upper Midwest this winter has been marked by repeated stints of below-zero temperatures, that doesn’t mean TU activity in the Driftless Area has been hibernating. 

If you attended the Driftless Symposium last week in La Crosse, you could have been overwhelmed by the range of information presented by scientists and habitat specialists. Presentations to over 160 attendees included reports on geologic research, riparian restoration methods and biology.

Gill lice are “dramatically” increasing in brook trout in Wisconsin Driftless streams, according to Wisconsin DNR coldwater scientist Matthew Mitro.  In Ash Creek in Richland County, gill lice presence more than doubled from 2012 to 2013, he said.  What’s the impact of this little pest?  Mitro says there’s evidence to suggest that brook trout populations decrease following gill lice infestations, and competing brown trout populations increase in those streams. 

Climate change predictions suggest that brook trout will be seen less in Wisconsin in the next half-century, said WDNR’s Paul Cunningham, a coldwater ecologist.  Under current management, he said, some models suggested a loss of 75% of brook trout in the region, “a sobering thought”.  “It’s a crisis we need to talk about and decide what management approach to adopt.”  What is to be done?  He suggested focusing on streams better buffered against climate change impacts, accepting that brown trout would likely do better in many other streams where brookies now reside, and use restoration techniques that give streams more resilience against temperature changes, dramatic rainfall events and drought .  Many such techniques have been suggested and are being debated, and DARE restoration projects work to incorporate experiments that may provide answers in the long term.

Scientists are working hard to understand the geology of the Driftless Area and learn more about its underground rivers, caves, sinkholes and “losing”, or disappearing, streams.   They’re developing more knowledge of its soil types and bedrock, and use sophisticated land mapping techniques to locate features hidden by vegetation.  They use this knowledge to better understand how Driftless waters—whether in your well or the trout stream or spring out back-- are vulnerable to a variety of human-caused insults:  leaky landfills, ag runoff, water withdrawals, etc.

Planning has already begun for the 2015 Driftless Symposium, which will again take place at the LaCrosse Radisson Inn and Convention Center,  February 3 and 4. 


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