Gust Annis

September 2022

Great Lakes Invasives: Surveying Aquatic Vegetation in Search for New Invaders

Experts from Michigan, Wisconsin and New York recently traveled to New York’s Irondequoit Bay on Lake Ontario and to Buffalo, New York on Lake Erie to conduct aquatic invasive species (AIS) surveys.

As a conservation scientist with The Nature Conservancy (TNC) and a person who grew up on northern Lake Huron’s shore, I have enjoyed the natural wonders, nature and ecosystems of the Great Lakes since I was a kid. I have also seen the impacts of aquatic invasive species. People living in the Great Lakes region have long been aware of the detrimental effects that AIS can have on the lake ecosystems as well as the negative impacts they have on the economic and recreational benefits that the lakes provide.  

Addressing Invasive Species

The Great Lakes are one of the most heavily invaded freshwater systems in the world. Most people would be surprised to know that there are more than 180 non-native aquatic species established in the Great Lakes today. Of these, about 60 have known negative ecological or socio-economic impacts. 

Sea lamprey and zebra and quagga mussels are probably the most well-known. But a handful of non-native aquatic plants are also causing significant problems in some places. Invasive aquatic plants can replace native ones, alter the physical habitat available to other species like fish and can become so thick as to clog waterbodies for recreational uses such as swimming, boating or fishing.  

Working Toward a Solution

Early detection of newly introduced species provides the best chances for eradication before they become widespread. With funding from the Great Lakes Restoration Initiative (GLRI) through the U.S. Fish and Wildlife Service, TNC and our partners have developed a protocol designed for the early detection of invasive aquatic plants in Great Lakes coastal habitats. In recent years, we have been testing the protocol in select locations across the Great Lakes that are at the highest risk for new introductions, with an eye toward early detection and eradication. 

Most recently, we traveled to New York’s Irondequoit Bay on Lake Ontario and to Buffalo, New York on Lake Erie to conduct aquatic vegetation surveys, assess what is there and look for any newly established invaders. These surveys were implemented with partners that are part of New York’s Partnerships for Regional Invasive Species Management (PRISM) network and were made possible with grant funds from GLRI through the New York State Department of Conservation.   

Survey Design and Modeling

Surveying everywhere is not realistic or practical, so we need to focus our efforts on the places and habitat types that are most likely to support plants. Before heading to the field, we produced some aquatic vegetation richness models for each site to help design a sampling approach that would focus our efforts in areas with the most vegetation. Most of this pre-fieldwork takes more time than what we spend in the field.  

Conducting Surveys in the Field

To conduct the actual surveys, we used a boat and had a crew of four to five people, including the driver. The driver navigates to our pre-determined survey locations using maps and data on digital devices.

To collect aquatic vegetation from the lake bottom for identification, we used rakes attached to a rope; basically, two garden rakes with the handles removed and strapped together with a 25-foot rope attached. This rake, when tossed and retrieved, brings back lake-bottom vegetation.  

In the boat, we rely on an aquatic botanist who identifies each species of plant we pulled up. We record the species and other information, like bottom type and depth, using a hand-held device with data collection forms we designed specifically for this project. 

Fieldwork can be fun and exciting, but you are exposed to the elements (we had lots of rain). One morning we also experienced a recreational fishing boat in distress that was calling for assistance. We zoomed over to assist, but another fishing boat got there first to assist and tow them back to port. We did stand by to be certain no additional assistance was needed. And, thankfully, it was not!  

What Did We Find?

In Irondequoit Bay, we identified 27 species, seven of which were non-native. We also found 27 species in Buffalo, and again seven of these were non-native. Happily, we didn’t find any new non-natives that were not already known from these sites or the Lake Erie or Ontario basins. Back in the office, we will compare the data collected this year to data collected in 2021 and use the information to guide work going forward.

Based on our previous research, we know that when we implement surveys like these we are likely to find most of the plant species present in the area. However, continued surveillance will increase our confidence that we are detecting even very rare species, including newly introduced non-native plants.   

With the Great Lakes spanning a combined area of around 94,250 square miles, it’s essential that we stay vigilant and continue to work together to address the threat aquatic invasive species pose to our freshwater legacy.

Chadderton WL, AJ Tucker, G Annis, A Dahlstrom-Davidson, J Bossenbroek, S Hensler, J Hoffman, M Hoff, E Jensen, D Kashian, S LeSage, T Strakosh, A Trebitz (2022). Aquatic Invasive Species Interstate Surveillance Framework for the U.S. Waters of the Great Lakes. Technical Document, 67 pp.

Tucker AJ, Annis G, Elgin E, Chadderton WL, Hoffman J (2022). Towards a framework for invasive aquatic plant survey design in Great Lakes coastal areas. Management of Biological Invasions, 13(1), 45–67, https://doi.org/10.3391/mbi.2022.13.1.03.

Tucker AJ, Chadderton WL, Annis G, Davidson AD, Hoffman J, Bossenbroek J, Hensler S, Hoff M, Jensen E, Kashian D, LeSage S, Strakosh T (2020). A framework for aquatic invasive species surveillance site selection and prioritization in the US waters of the Laurentian Great Lakes. Management of Biological Invasions, 11(3), 607–632, https://doi.org/10.3391/mbi.2020.11.3.17.  

Egly, Rachel M., Gust M. Annis, W. Lindsay Chadderton, Jody A. Peters, and Eric R. Larson (2019). Predicting the potential distribution of the non-native Red Swamp Crayfish Procambarus clarkii in the Laurentian Great Lakes. Journal of Great Lakes Research, 45(1), 150-159.

Annis, Gust M., Douglas R. Pearsall, Katherine J. Kahl, Erika L. Washburn, Christopher A. May, Rachael Franks Taylor, James B. Cole, David N. Ewert, Edward T. Game, and Patrick J. Doran (2017). Designing coastal conservation to deliver ecosystem and human well-being benefits. PloS one, 12(2), e0172458.

Beletsky, Dmitry, Raisa Beletsky, Edward S. Rutherford, Jennifer L. Sieracki, Jonathan M. Bossenbroek, W. Lindsay Chadderton, Marion E. Wittmann, Gust M. Annis, and David M. Lodge (2017). Predicting spread of aquatic invasive species by lake currents. Journal of Great Lakes Research, 43(3), 14-32. 

Kramer, Andrew M., Gust Annis, Marion E. Wittmann, William L. Chadderton, Edward S. Rutherford, David M. Lodge, Lacey Mason, Dmitry Beletsky, Catherine Riseng, and John M. Drake. Suitability of Laurentian Great Lakes for invasive species based on global species distribution models and local habitat. Ecosphere, 8,(7), e01883. 

Wittmann, Marion E., Gust Annis, Andrew M. Kramer, Lacey Mason, Catherine Riseng, Edward S. Rutherford, William L. Chadderton, Dmitry Beletsky, John M. Drake, and David M. Lodge (2017). Refining species distribution model outputs using landscape-scale habitat data: forecasting grass carp and Hydrilla establishment in the Great Lakes region. Journal of Great Lakes Research, 43(2), 298-307.

Keitzer, S.C., S.A. Ludsin, S.P. Sowa, A.M. Sasson, G. Annis, J.G. Arnold, A. Brennan, P. Daggupati, A.M. Froehlich, M.E. Herbert, M.V. Johnson, C. Vollmer-Sanders, M.J. White, C. J. Winslow, and H. Yen (2016). Quantifying the Potential Water Quality Benefits of Agricultural Conservation Practices for Stream Conservation in the Western Lake Erie Basin. Final Report submitted to NRCS Conservation Effects Assessment Project, 63 pp. 

Keitzer, S. Conor, Stuart A. Ludsin, Scott P. Sowa, Gust Annis, Jeff G. Arnold, Prasad Daggupati, August M. Froehlich et al (2016). Thinking outside of the lake: Can controls on nutrient inputs into Lake Erie benefit stream conservation in its watershed? Journal of Great Lakes Research.