Thursday, August 9, 2012

Crayfish High and Dry

Fishing Hole?- Click to enlarge
The drought and scorching temperatures takes a toll on aquatic critters as shrinking water supplies constrict their living space.  With much of the middle section of Bull Creek dry, what little water moves is through losing streams under dry stretches of gravel hundreds of yards long.  Needless to say there isn't much oxygenation in what water remains.

There are lots of stories on the impact of the drought on fish and aquatic creatures.  To my surprise we can still find hog nosed suckers and few smallmouth bass in even the small areas of water upstream from the swimming hole.  That raised the question- just what do they do in a drought?

I got some information from our former fisheries biologist, Mary Culler:
"I trust that many of the critters in the stream were able to swim downstream to deeper waters near the lake, but I am sure there have been some that have been trapped in pools. When I was with MDC we worked on a study on Rock Creek near Roaring River and documented that several crayfish species burrow beneath the gravel towards the water table when the intermittent stream went dry.
It was a very interesting study, we would begin digging in the stream in an area that was completely dry, and within a foot deep there were several crayfish living beneath the stream bottom where they had enough moisture to survive. Also, at one site, we hit the water table and discovered a madtom catfish living about 6 inches below the dry stream bed."  The study from 2009 is published here.
Prairie Crayfish- MDC
This should not have surprised me as crayfish can live in environments seemingly devoid of water.  The colorful prairie crayfish lives its life on- what else? - prairies.  To quote from this article from MDC:
"The prairie crayfish occurs widely in grasslands and prairies of northern and western Missouri. It is sometimes called the grassland crayfish. It lives in burrows that are often a long distance from any surface water. These may be six feet of more in depth. Most public prairies in Missouri support large populations, but this crayfish is seldom seen by visitors because of its secretive habits."
The prairie crayfish is a valuable member of the prairie community.  The crawfish frog (Lithobates areolatus depends on the crayfish for its year round home.  Other species also use these tunnels including snakes, lizards, frogs, and other amphibians.  Gratitude being in short supply in nature, some of these same creatures will dine of the crayfish as well.

Although the aquatic populations of Bull Creek are undoubtedly set back a few years, they will return to previous levels in a few years.  They just have to "dig in" for a while.

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