Invasive Species: Zebra Mussels
Introduction |
A Little-Known Problem in Louisiana | Problems & Control | Resources
A Little-Known Problem in Louisiana
Along the Mississippi River, the huge raw water intake pipes servicing power and chemical plants attract zebra mussels seeking a hard surface for settlement. Up-side-down and right-side-up mean nothing to them – they settle on all areas of the inside of the pipe in order to get nutrition from the flowing water. They also settle on each other, and eventually, the stacked-up mussels narrow the pipe opening so that the water’s flow is slowed or stopped. This phenomenon actually closed down a water plant in Michigan in the late 1980s, but it has never closed a plant in Louisiana. Those Louisiana industries along the river with zebra mussel infestations control the animals by periodically treating the intake pipes and other infested equipment with chemicals or scraping them to remove the zebra mussel buildup. These maintenance costs, like other production expenses, are passed on to the consumer.
Zebra mussels are a lesser problem in Louisiana than in Great Lakes states because their growth is limited by two natural factors. Each spring’s spawning period coincides with the time when Mississippi flow is high and swift due to the melting snow on the upper river and upper tributaries. This flow carries a portion of each zebra mussel’s approximately 30,000 larvae out to sea, where they die because they cannot live in saltwater. Each summer, the river level decreases and the river temperature becomes very high, stressing the zebra mussels, which are not heat tolerant. The largest mussels, under the greatest stress, die. Thus, in Louisiana, zebra mussels don’t live as many years and don’t grow as large.
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