Seeking Invaders: the Exotic Aquatic Plant Watch

Healthy ecosystems include a diversity of animal and plant species that are adapted to live together in harmony. Sometimes, however, an invasive species that is not a natural part of the ecosystem invades the system and upsets this balance. Disturbed ecosystems are especially vulnerable to invasive species, which take advantage of the opportunity to gain a foothold in the system.

Familiar invasive species in Michigan’s aquatic habitats include zebra mussels and purple loosestrife. These species have become highly visible where they have invaded, for example, entire Great Lakes beaches covered with zebra mussel shells, or wetlands dominated by a purple summer blanket of loosestrife blooms. Other invasive species in our lakes and streams are less visible because they grow primarily beneath the surface of the water and, therefore, may go unnoticed until they have spread to potentially unmanageable levels.

MiCorps’ Cooperative Lakes Monitoring Program (CLMP) recognized the risk to our inland lakes from submerged aquatic invasive plants, and developed a pilot volunteer monitoring program that has been in the testing phases for the past three years. In the 2009 monitoring season (going on now), twenty-one lakes enrolled in the pilot program, and in 2010 the Exotic Aquatic Plant Watch will become a permanent part of the CLMP.

The Exotic Aquatic Plant Watch program is open to all lakes, regardless of their previous experience within the CLMP. Volunteers from enrolled lakes attend a training session during the annual CLMP Training held each April in conjunction with Michigan Lake and Stream Associations’ annual conference. During the training, volunteers learn to identify invasive plants and how to differentiate between the invaders and similar native species. Volunteers also learn how to methodically search their lakes for the invaders and how to record and report their findings. After the volunteers complete their lake survey, MiCorps staff can provide expert identification of suspected invasive species at the volunteer’s request. Data from the lake surveys are added to the MiCorps database and new discoveries of invasive species are reported to the Department of Environmental Quality’s Aquatic Nuisance Control program.

The Exotic Aquatic Plant Watch currently focuses on three introduced (exotic) invasive plants of particular conservation importance: Eurasian water milfoil (Myriophyllum spicatum), curly-leaf pondweed (Potamogeton crispus), and Hydrilla (Hydrilla verticillata). Eurasian water milfoil already is widespread in many Michigan lakes, where it creates large mats that crowd and shade out other plants and interfere with recreation. It is difficult to eradicate because it spreads easily. Curly-leaf pondweed is not always a nuisance where it is found, but in some lakes can become a serious problem if not managed, forming thick beds that crowd out other plants. Hydrilla has not yet been found in Michigan, but this aggressive invader has caused serious problems in inland lakes from Florida to California and has been found as close as northern Indiana. In all cases, lakes where the natural plant community has been disturbed by herbicide treatments, mechanical harvesting, or other forces are more vulnerable to invasive plants than undisturbed lakes.

The key to effective management of aquatic nuisance plants is early detection, followed by rapid response. As noted above, submerged aquatic invasive plants can easily be overlooked until they are so widespread that eradication is impossible. If detected early when the population is small, complete eradication of the invader may be possible. In many cases, eradication may be impractical, if not impossible, and the focus will need to be on management control of the plant to prevent its spread beyond parts of the lake where it is already established. Lakes that enroll in this volunteer program will be better prepared to recognize these invaders early and take appropriate action.

If you are interested in enrolling your lake in the 2010 Exotic Aquatic Plant Watch, or would like to learn more, visit the CLMP pages on the MiCorps web site at www.micorps.net/lakevolunteer.html, or contact Dr. Jo Latimore at Michigan State University (latimor1@msu.edu, 517-432-1491).

Summer CLMP Sampling Underway

The CLMP is experiencing another successful summer of secchi depth monitoring, water sample grabbing, and chlorophyll filtering. In July, chlorophyll samples were collected from 113 basins (including 110 unique lakes in 42 counties) and are now being analyzed by the DEQ laboratory. Late summer total phosphorus water samples and the final chlorophyll samples will be taken in late August or September, depending on the location of the lake. Click on the following links to see the monitoring schedule for late summer phosphorus and chlorophyll.

2010 CLMP Enrollment Announced

Enrollment for the 2010 season of the CLMP will begin again in September. Both online and paper enrollment will be available. People who subscribe to the MiCorps-news listserv will be informed via email when this enrollment opens, and reminder postcards will be sent to all current participants.

Authors:
Dr. Jo Latimore
Dept. of Fisheries and Wildlife
Michigan State University

Dr. Paul Steen
MiCorps Staff
Huron River Watershed Council