Party Crashers: Invasive Species and Iowa Waters   

It is the height of the summer recreation season, and, particularly during this strange time, folks have been enjoying fishing, swimming, paddling, and boating on Iowa waterways. It is important to remember that these waters are not swimming pools, though. I got my own reminder a few weeks ago when I cut my foot on a zebra mussel shell in Big Spirit Lake. I have waded and swum in this lake thousands of times over the years, but recently the zebra mussels have taken hold. Now we must adapt. 

Invasive species disrupt the environment, affect livelihoods, impede recreation, and damage infrastructure. Iowa’s lakes and rivers support complex ecosystems of plants and animals that have evolved together in balance. When non-native species are introduced into these environments, frequently through human activity, some new species may out-compete native species or otherwise harm the balance of the ecosystem. Such species become invasive (or noxious) species, and they pose serious risks to our resources. According to a 2005 study, invasive species cost $120 billion annually in the United States. 

Zebra mussels are infamous invasive species. In addition to having very sharp shells (seriously!), they have wreaked havoc on waterways across the upper Midwest. Native to Asia, these invertebrates arrived in the Great Lakes via cargo ships in the 1980s. In the last several decades, they have spread throughout the Great Lakes, the Mississippi River, and Midwest waterways. Zebra mussels reproduce and spread quickly, and there is no effective way to eradicate them once they are established. These mussels disrupt the food web by filtering phytoplankton and other food sources out of the water in large quantities, out-competing native species for food. They also colonize quickly and in large numbers on hard surfaces such as boats, motors, and even facility intake pipes. Agencies across the region, including the Iowa DNR, have made significant efforts to control and prevent the spread of zebra mussels, but they continue to colonize new waterways across Iowa. 

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