June 1, 2012 - by Dave Foley
  
Invasive species changing the look of area lakes

Cadillac News
 
On the Outside
(published in Cadillac News , June 1, 2012)

As summer begins everyone is wondering how the lakes will fare this year. Eurasian water milfoil is still the focus of the Lake Mitchell Improvement Board's and the Lake Cadillac Invasive Species Management Committee's weed control programs, but the increasing number of zebras mussels in Lake Cadillac and the discovery of a milfoil hybrid in Lake Mitchell presents new challenges.

Lake Mitchell is treated for milfoil in this photo. More chemical treatment of the lake is expected June 11-13, 2012.

The early spring has produced what looks like a bumper crop of weeds in our lakes. In Lake Mitchell a team of consultants from Lakeshore Environmental INC has completed a survey of the lake and is scheduled to treat the coves on June 11, weather permitting, and the main lake June 11-13. A one-day swimming ban occurs on the day of application. Just ahead of the treatment, lakeshore residents will find treatment postings along the shoreline. Depending on the success of treatments, subsequent chemical applications may occur during the summer.
Lake Cadillac's engineering consultant team from Progressive AE hopes to finish survey today and plans to do chemical treatment next week. Later this summer a total lake survey of Lake Cadillac will be undertaken to determine what species of plants are in the lake and their distribution. This will be compared to a similar study done seven years ago to determine changes in the lake's aquatic vegetation. Lake Mitchell made of survey of its plant population last year.

In Lake Mitchell, the major problem is the red stemmed hybrid milfoil that has appeared in the last year. Traditional dosage of the chemical 2-4D, which has effectively controlled Eurasian water milfoil in the past, is not effective on the hybrid. Samples of the hybrid plant were sent to Lake Superior College where they were submitted to different dosages of 2-4D as well as other chemicals to determine what can safely and effectively be used to treat hybrid milfoil in Lake Mitchell this summer.

The thick weed and algae growth that appears in Lake Mitchell's coves and the canal near Camp Torenta is another challenge facing the Improvement Board. Attempts to control the heavy growth that clogs these waters each summer has not always been successful. Plans are in motion to try a new stronger chemical application in those shallow waters. Harvesting will likely not be done this year.

As yet Lake Cadillac has not found the hybrid plants but will still contend with Eurasian water milfoil. Also of concern are zebra mussels which are small hard-shelled organisms identified by the zebra striped pattern on their shells. First discovered in Lake Cadillac in the fall of 2010, they are now commonly found on dock posts, boat bottoms, submerged wood, and attached to rocks. The sharp edges can provide a painful surprise for swimmers and waders. Wearing a pair of neoprene water shoes offers protection for the feet.

Having these mussels present may bring some changes to our lakes as zebra mussels filter out organisms which improves water clarity. Clearer water allows sunlight to penetrate deeper increasing the depths at which weeds can grow. In addition to stimulating weed growth there may be more algae blooms. Because they are filter feeders, zebra mussels remove sustenance from the water. In this way they compete with plankton which are a food source for small fish. This could effect the growth of sport fish in the lake.

As yet there is no means of controlling or eradicating zebra mussels once they have established a population. In some lakes numbers of zebra mussels have declined, although the reason for this is unknown.

Thousands of lakes throughout the United States are infested with these invasive mussels. While they are a nuisance, problems are generally limited to covering hard surfaces and cutting swimmers' feet rather than having significant impacts on fish populations.
Zebra mussels are now being found in Lake Mitchell as well which has increased that lake's water clarity.

Purple loosestrife, grows along the shores of the coves in Lake Mitchell. Growing four to seven feet high and containing purple-colored flowered spikes, loosestrife is an invasive plant that inhibits growth of native wetland vegetation. As native plants disappear so do the wildlife including ducks, birds, and amphibians that depend on this vegetation. To control this invasive plant, the National Forest Service is underwriting the cost of procuring and planting galerucella beetles in the coves. This project is scheduled to occur on June 22.

Both lakes have tried plantings of milfoil-eating weevils in previous years. Unfortunately this project has shown only very limited success so further weevil plantings are not planned. Within 1000 feet of the mouth of the canal as well as the Clam River outlet DEQ regulations will not allow use of chemical.

The introduction of invasive plants and organisms have created major changes to our lakes and watersheds. These are very different waters than the ones we knew in the 1980s. It is a problem affecting virtually all of Michigan's lakes to some degree. Expect to see new innovations and evolving plans for lake management as our lake boards work to control this problem.