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Friday, August 24, 2012

Hot New Findings! Are invaders benefiting from the record breaking high temperatures and drought?

Even us amphibious creatures could not catch a break from the sweltering heat this summer as water temps soared and side-channels sizzled dry under the unrelenting scorching skies.   As the waters recede the neighborhood can get a little crowded, especially with all the new immigrants!  From the Mississippi to the Sugar River, we have seen unwanted guests flocking here like snowbirds to Florida finding great pleasure in the heat.  

In the Mississippi River near Alma, Wisconsin about 1,000 water hyacinth and water lettuce, two of the world’s worst invasive species that are are not regulated here in Wisconsin due to their assumed intolerance of our winter, were found last year.  After a rapid response to squelch this new invasion, WDNR and USFWS staff hoped that the literature was right.  However, low and behold this summer the two plants (nearly 10,000 of them) reemerged from seed to be joined by yet another nasty invader, parrot feather.  For more on this infestation,

Water lettuce and water hyacinth in the Mississippi River (credit: Paul Skawinski)

 Zebra mussels are not new to the Wisconsin River.  However, this year something monumental happened; their populations exploded!  In a recent survey of a native mussel bed near Muscoda 90% of the native mussels collected had juvenile zebra mussels attached to them.  In total there were over 10,000 young zebra mussels.  That is 10,000 future heal cutting shells to litter our sandbars. While they have been in the area since 2008, they have remained a mere minority until this year.  Now at their current numbers they pose a substantial threat to natives, recreational opportunities, and the bottom line of river-based businesses.
Juvenile zebra mussels on from the Lower Wisconsin River

A stone’s throw over the Military Ridge in the Sugar River watershed the mosquitofish, an exotic species that was also thought to not like our Wisconsin winters, is thriving much to the detriment of our native blackstripe topminnow and state endangered starhead topminnow.  This year’s drought has decreased the back water slough habitat within the river where these three species have competed for resources in years past.  A survey last month discovered that there were now no topminnows and a plethora of mosquitofish in what was left of the shallow sloughs. 

Biologists walk through the site of a former slough
One hot summer a trend does not make.  Us river dwellers, like you, hope that this season does indeed prove to be a fluke.  In the meanwhile, it’s time to get down to business to mitigate the damage that has been done.  Stay tuned for more information on what the River Alliance and their partners are doing to keep these invaders at bay.    As for you, please keep an eye out for the unusual while you visit your favorite waters. 

 posted by the River Rat