10 Reasons to Care about Aquatic Invasive Species

Written by Madeline Seveland, Education Coordinator with Carver County Water Management

Invasive Species have been steadily gaining more interest with lawmakers, interest groups and the public since the introduction of zebra mussels into Lake Minnetonka and the threat of Asian carp in the Mississippi River. Here are the top ten reasons you should care about preventing the spread of AIS.

10.  CLOGGING: Aquatic invasive species can reproduce very fast and both plants and animals can form dense mats/colonies that clog waters affecting transportation (canals), hydropower and irrigation (ditches). In the early 90s, Hydrilla caused the shutdown of a hydro-electric plant resulting in a record fish kill and the company has spent more than $14 million in control since. Zebra mussels clog intake pipes all over and ruin boat motors by clogging the cooling intake. In the Great Lakes, the annual damage and control costs of zebra mussels who clog intake pipes at electric power plants and water supply facilities is $480 million.

9.  POOR WATER QUALITY: The Great Lakes Water Quality Agreement notes that AIS degrade water quality by increasing turbidity (sediment & algae) and nutrients, reducing dissolved oxygen and concentrating toxins. An example found in many Minnesota lakes and rivers is common carp. These fish are “bottom feeders” and their feeding disrupts shallowly rooted plants muddying the water and releasing phosphorus that leads to algae blooms.

8.  SPREAD OF DISEASE: Many parasites and bugs benefit from thick patches of vegetation. One example is swimmers itch. Eurasian Water Milfoil (EWM) provides good habitat for the parasites that cause swimmers itch (Cercarial dermatitis and Schistosome dermatitis) increasing their numbers.

7.  RECREATIONAL IMPACTS: Lake Tahoe in CA is infested with Eurasian Water Milfoil (EWM).  Water based recreation trips to Lake Tahoe are conservatively estimated at bringing in between $35 and $45 million a year. EWM decreases water quality, clogs boat motors and cooling intakes and the spread of EWM could lead to decrease in recreational uses. Just a 1% decrease in recreation would drop the economic recreational income $500,000 a year.

6.  DECREASE IN PROPERTY VALUES: A paper written by Eric J. Horsch from Stratus Consulting and David J. Lewis from the University of Wisconsin analyzed property values on 170 lakes in northern WI and found property values fell 13% after invasion of Eurasian Water Milfoil. Other studies have found property values to drop 20-40%.

5.  WILDLIFE HEALTH: In addition to the loss of habitat, food, and shelter that affect wildlife when an invasive species moves in, we can add disease. Great Lakes scientists are researching their theory that zebra mussels promote conditions for avian botulism (botulism type E) to grow. It is one of the most toxic substances on earth. On the shores of Lake Michigan it has been the cause of thousands of bird and other wildlife deaths over the past few years.

4.  HUMAN HEALTH: Invasive aquatic plants have become so thick they increased the risk of drowning. One of the most well documented stories took place in Royal City, WA when two men jumped into Red Rock Lake to rescue a boy who became entangled in EWM.  The boy and one man were rescued, the third was so entangled in weeds it took five divers to disentangle his body. Adding to that, zebra mussels have razor sharp shells that can leave painful wounds on your feet if stepped on.

3.  ECONOMY: Much of Minnesota’s economy relies on tourism. Hospitality Minnesota is the third largest employer in the state which includes restaurants, lodgings, resorts & campgrounds, etc.  Much of this industry relies on healthy lakes and rivers. Waters with AIS infestations will see fewer users leading to reduced business and lost jobs. John Madsen, an Associate Research Professor in the Geosystems Research Institute and the Department of Plant and Soil Sciences, Mississippi State University put it simply, “Managing these species economically beats not managing them.”

2.  FISHERIES: Zebra Mussels may clear up the water, but they do so by removing phytoplankton which is the very basis of the food chain. Without phytoplankton, zooplankton populations decrease, resulting in a decrease small fish (planktavores) and then a decrease in game fish (piscivores).  In addition, the clear water allows more sunlight to reach the bottom of the lake resulting in more aquatic plant growth. If there is an invasive plant like EW milfoil established, its population can explode. In short, ZM could = more weeds and less fish.

1.  LONGETIVITY: Many of us will have children and grandchildren. When we are gone we will be leaving our favorite fishing spots, our lake cabins, our tourism businesses, and our stories to our children and grandchildren and will hope they too can enjoy thrill of catching fish, boating, or walking on the beach without risk of cutting up their feet.

Information and examples for this article came from the following sources: Environmental Protection Agency, Journal of Weed Science, MN DNR, MN Sea Grant, WI Sea Grant, Great Lakes Fishery Commission, and MN Dept. of Natural Resources.