Column: The dasterdly Zebra Muscle
Published 3:57 pm Thursday, January 19, 2006
After reading my column several weeks ago on the environmental woes of the Great Lakes, several readers have asked what they can do or where money could be donated. I'm not aware of any specific Great Lakes conservation donation programs. I suspect that the restoration projects are so costly that anything meaningful is beyond the scope of donations.
The most important thing we individuals can do is to contact our State and Federal representatives urging them to support sound Great Lakes conservation legislation (such as treatment of ship ballast water) and funding, especially the estimated $21 billion requested by the Great Lakes Restoration Plan now in front of Congress.
Invasive species introduced into the Great Lakes poses one of the larger problems. Of these, the zebra muscle is proving to be one of the nastiest.
It's just a tiny little clam-like thing, tan to brown in color and usually with dark stripes, hence its name. It's no bigger than your fingernail, but the diminutive size belies the havoc it's causing. They colonize by the hundreds of thousands on any submerged solid surface they can find. That includes inside water intake pipes where they restrict water flow to hydroelectric and nuclear power plants, public water systems and industrial facilities.
At one Michigan power plant they stacked up 700,000 per square meter! They foul the engine cooling system of boats and build up on ship's hulls, slowing them down. They colonize in such mass they sink navigational buoys. They also enhance deterioration of wood, metal and even concrete, affecting structures such as piers, buildings, canal walls and ship locks.
Zebra muscles are equally devastating to the ecosystem. They colonize on native muscles, killing them. They eat virtually anything suspended in the water, meaning algae, bacteria, protozoa, phytoplankton and all manner of important little microscopic creatures. This deprives other microscopic organism dependant species like native muscles, minnows and baby fish.
With these particles filtered out ,the water properties change, such as altered oxygen levels and sunlight penetrating deeper. Zebra muscles literally rebuild the entire aquatic habitat, usually to the detriment of native species.
Zebra muscles are native to the Black, Caspian and Azov Seas of Eastern Europe. When Europeans started building canals and expanding shipping during the 1700s, the zebra muscle rapidly spread throughout all of Europe. It was first discovered in the Great Lakes in 1988. It's believed that a single ship coming from the Black Sea discharged its zebra muscle infested ballast water in Lake St. Clair near Windsor, Canada. Monitoring stations were immediately established and shocked scientists stood by helplessly watching the zebra muscle spread throughout all the Great Lakes in just two years.
This remarkable expansion rate is due to the biology of the zebra muscle. A female can lay 40,000 eggs in one breeding period and up to a million in a year. Within 3-5 days, the eggs hatch and the larvae free float on the currents for up to a month. Then they drop to the bottom and transform into juveniles. These crawl on the bottom until they find a solid object to attach to where they grow into adults. One of the things zebra muscles commonly attach to is boat hulls. Here they can be transported great distances before becoming dislodged and start new colonies.
With billions of larvae floating in the currents and adults taking the rapid transit system far and wide their explosive expansion is guaranteed. They can also live out of water for several days so when a boat hosting zebra muscles is trailered to another body of water the invasion marches on. Zebra muscles are rapidly expanding to inland waters throughout the country, largely by this method. It's not known yet if birds may also be a factor.
Dealing with zebra muscles has cost an estimated $2 billion so far. Some ducks eat them, as do sheephead, carp and sturgeon, but the natural predators can't begin to keep up. We poison them with chlorine, cook them with jets of hot water, electrocute them and nuke them with ultraviolet light, among other things, but it's a hopeless battle. It appears the zebra muscle is destined to redefine our aquatic habitat. Carpe diem.