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WHAT ARE THESE THINGS ??
"Dreissena polymorpha" and "Dreissena rostrifomis bugensis". Isn’t that swell? That’s Government bio-speak for "Zebra Mussels" and "Quagga Mussels" respectively.
For our purposes and in the interest of simplification, we will hereinafter refer to ALL of these things as "Zebra" mussels and drop the "Quagga" business. Most laymen can’t tell one from another anyway, one is just as much trouble as the other, and "Quagga" sounds a lot like something you are trying to clear from your throat.
Never heard of Zebra Mussels? You aren’t alone. Even though these things have been around in U.S. waterways since the 1980’s, we had not heard anything about them either. Not until January, 2007 anyway. That’s when the news was released that casually informed the public that the mussels had been discovered in Lake Mead, the largest man-made impoundment in the United States.
We had heard nothing about them before that because up to that point, the United States Fish & Wildlife Service had done very little to inform the general public, outside the Great Lakes Region, of their existence and the threat that they posed.
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| Mussel encrusted boat hull |
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In the embryonic and larval stages, Zebra mussels are opportunistic free floaters that travel on and with whatever water currents are present. That means that once established, they will eventually spread downstream over the length of an entire waterway, no matter the distance. That is exactly how, after infecting Lake Mead, they were able to continue along the Colorado River system to enter Lakes Mohave and Havasu, go on to the Sea of Cortez, and to migrate through distribution canals into Southern California and Arizona.
As adults, they will attach themselves to whatever is handy in order to get on with the business of making babies once the wanderlust has been satisfied. They prefer to attach themselves to hard surfaces, but they aren’t fussy, and they will hang on to whatever is available as long as water velocities are less than 2m/sec. And if they aren’t happy with the home they find, they have the ability to detach and simply relocate to a better neighborhood.
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| Mussel on monofilament fishing line |
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Remarkably adaptable, the nasty things can tolerate a very wide range of environmental conditions. They can survive water temperatures as high as 86 degrees and as cold as 48 degrees and are still capable of making babies anywhere in between with temperatures in the 60’s ideal for reproduction. They can’t handle 32 degree water. That will kill them. But since water becomes solid at that temperature anyway,, there’s little solace in that news.
They are not happy in bright light. But it does not represent a big problem for them. They will simply relocate to a shaded environment or head deeper in the water column to a zone that light does not penetrate.
They are not fussy about what’s on the menu either. They are filter feeders that thrive on algae, bacteria, and zooplankton. Whatever is in the soup is fine with them, as long as toxicity does not reach lethal levels.
Some fish and waterfowl species will feed on the mussels, but given the quantities and reproductive capabilities involved, there are no natural predators that can hope to make a dent in the mussel populations once they become established.
Once they have a foothold in a body of water, they are in for the duration. There are no eradication methods yet available with today’s technology!
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These are little-bitty things, ranging in size between microscopic at birth to about two inches in length when fully developed. Under the right conditions, these things can reproduce year round, just a few can throw off MILLIONS of offspring, and they can live up to five years.
We do not use the term "Millions" casually. When we speak of actual infestation numbers that quantity description is actually inadequate. Once established in a waterway, there are simply not enough zeros in our numerical system to accurately describe their potential.
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