Thursday, March 29, 2012

THE ZEBRA MUSSEL - A DANGEROUS MOLLUSK

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The following link will explain details pertaining to this dangerous little mollusk:


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http://www.nationalatlas.gov/articles/biology/a_zm.html

My friend and coworker, Paul, and I were working on habitat restoration on Melton Hill Reservoir which is located west of Knoxville.  This lake was one of the lakes that I used to work on for TWRA over 8 years ago. As we were unloading materials at the boat dock - I noticed something I have never seen on this lake.  Mollusks were present by the millions.  I have never seen anything like it.  I mentioned to Paul that I never saw these when I worked on Melton Hill 8 years ago. He indicated they were only recently introduced to the fresh water lakes about 5 years ago.  Then he told me their name.   They are zebra mussels.  Then I remembered reading about them.
We had noticed that Melton Hill's water level had been reduced more than normal and we guessed it was to allow the zebra mussels to be high and dry and left to die in the sun.  This action might kill millions of the little mollusks but, million upon millions of them still reside beneath the surface.  The photo above is of mollusks that have been left to bake in the sun on the shoreline.  Note how they are colonized or collected together in mass.  They accumulate like this in water intake plants on water gates and even pump impellers.  They get inside boat engines and create blockages of cooling water flow and can even plague moving parts.
Their origins are the Soviet Union, Poland and the Balkans.  Their first landing in this country was the great lakes, more specifically Lake St Clair in 1988, which connects Erie with Lake Huron.  The aforementioned link will explain the entire story.  Their voyage to Tennessee was enabled by hitching rides on boats by infiltrating boat bilges and even invading and growing within the cooling systems of boat motors. They also attach themselves to the bottom of boat hulls and easily transported from lake to lake.  Large boats as well as small fishing and pleasure boats have spread this dangerous species to the lakes of Tennessee.  It is important for boat owners to flush out their bilges and wash down their boat thoroughly when moving from lake to lake.  Not many folks take these precautions s.  The result is the further infestation of this mollusk across not only Tennessee but, to any lake anywhere that boats travel to and from.

The zebra mussel is a detritus feeder.  It actually "filters" detritus from the water in large quantities.  The mollusk is very efficient preforming this process.  It is so efficient that millions of mollusks in a lake can filter all the detritus from that lake with the result that natural species of fish and other lake residents can suffer to the point of extinction.  The situation is indeed serious.  I don't believe there is any scientific means to eradicate them at this point in time.  They propagate and spread at an alarming rate.
Zebra mussels attached to rocks above the waterline.  Many are still alive.  The entire lake shoreline is covered by these dangerous pests.
Note the mollusks attached to the underwater rocks.  The little snake is a bonus to the picture.
Paul and I were attempting to create fish habitat by sinking bamboo into the lake.  We were going to attach six stalks of bamboo together in close proximity to each other and affix the bundle to the bottom of the lake. This will create dense cover for spawning fish as well as provide them protection from predators.  I've already posted recent entries showing the use of discarded Christmas trees being used as fish habitat.  The bamboo idea is nothing more than just that - an idea.  If it works we have a tremendous supply of wild bamboo growing in quantity in local forests and lake sides.  We'll see.  The work continues tomorrow.
 Fresh cut bamboo from a woods close to a roadway.
The tops of the bamboo stalks.  These tops will provide super hiding places for smaller fish .
I'll see if I can get some shots tomorrow of us actually setting the bamboo on the lake bottom.  I know you'll all be holding onto the edges of your seats on this one.