Aquatic invasive species (AIS), invaders, exotics—these are the aliens that live among us. For as long as humans have roamed the earth, we have brought other species with us on our travels, both intentionally and unintentionally. The consequences of these movements have been good, bad, and sometimes hard to see. Over time, we realized that these aliens can cause problems to our native ecosystems. Just spend some time on a lake clogged with Eurasian water milfoil; it is not a fun place to boat or swim. AIS can form dense monocultures that are poor habitat compared to the diverse native species that once existed.
The most effective management tool we have against invasive species is prevention. Many prevention activities reduce invasions by decreasing the number of plants and animals being transported. At a Great Lakes scale, ballast water exchange at sea seems to be keeping species from moving into the region. We have had no known AIS species come from ballast water since 2006.
Tabitha (a volunteer in AIS prevention) takes advantage of a lull in boat launches to educate a child on AIS.
Across Wisconsin each summer, inspectors with the Clean Boats, Clean Waters program
are stationed at boat launches to spread the “inspect, remove, drain, never move” message. Informed resource users are less likely to transport AIS that can harm the lakes and rivers they care about. Wisconsin Sea Grant has partnered with the Clean Boats, Clean Waters program and the Wisconsin Department of Natural Resources to hire interns to work at the Great Lakes boat launches to stop the spread of Great Lakes AIS to inland lakes. It is hard to gauge success, but the absence of quagga mussels
(widespread in Lake Michigan) in the inland lakes seems to show that the work is effective. Preventing the movement of species is much more cost effective than trying to manage the populations after they have invaded new areas.
How do we fight these species once they’re here? There are many methods, such as chemical treatment and removal by hand, that can effectively reduce AIS populations. However, these actions are usually ongoing. Treatment of that invasive milfoil in your local lake is likely going to be an ongoing expense. Even very successful programs, like the control of sea lamprey in the Great Lakes
, need to be maintained for the foreseeable future at a substantial cost. We’ve done well against the sea lamprey, thanks mostly to their courteous migrations into streams to spawn. We can then find them and kill them there in the streams with lampricides (chemicals that kill lamprey but don’t kill other species). Other widespread species, like quagga mussels in Lake Michigan, are more dispersed and harder to remove in large numbers.
Dreissenid mussels (zebra and quagga mussels) are common in Lake Michigan and can be unintentionally transported in their free-swimming life stage in bait buckets, live wells, and ballast tanks.
So are things all doom and gloom in the AIS world? Not at all. There is an army of concerned citizens out there working to reduce these populations. In the fight against AIS, “ongoing,” “reduce,” and “control” are the key terms. We may not be able to remove them completely, but we can keep their numbers down and give the native ecosystems a chance to stay in good health.
What will the future bring? New technologies will certainly be used to control AIS more effectively. Some might seem the stuff of science fiction now (targeted viruses, etc.), but someday we might be able to target and remove specific species.
Other pathways that transport and introduce AIS are also being considered. The Habitattitude campaign
focuses on the aquarium hobbyists, backyard pond owners, water gardeners, and others to reduce the risk of releases of potentially invasive species into Wisconsin’s waters. The program educates pet owners about the dangers of releasing animals and plants to local waterways and directs them to facilities that will accept unwanted plants and animals. Pond owners and water gardeners can learn about species to avoid and how to minimize the risk of escape for species they do plant. AIS professionals are constantly re-evaluating new pathways and developing materials to address them.
Aquatic invasive species, as well as terrestrial invasive species, are found across Wisconsin, but with a little education and understanding, we can prevent both their movement and new introductions. With enough resources and commitment, we can manage their impacts once they’re here. No one really likes the song that never ends, so let’s stop aquatic hitchhikers and keep Wisconsin’s inland and Great Lakes great!
Tim Campbell of UW-Extension and Elizabeth White of Wisconsin Sea Grant provided input on earlier drafts.