In August, 2003 the Blockhouse Lake Plant Committee met with Sandy Wickman, DNR Plant Specialist, to do a survey of the aquatic plants in the lake. This survey is part of the process for developing an aquatic plant management plan. Members of the committee participating were Mark Wagner, Cliff Verrill, and Jim Williams.
Samples were gathered from different parts of the lake, mostly near the east and south shorelines. A rake was tossed into the lake and retrieved in order to collect the samples.
A total of 32 different plant species were identified. The lake was judged to house a very diverse plant community, more so than most lakes in the region. This is very good, since a diverse population prevents any one species from becoming dominant and overly numerous. A balance of species is better, and reflects a generally healthy lake environment.
The health of the lake is also reflected in specific types of plants that were found. White-stem pondweed, for example is only found in lakes with very good water quality. Excessive turbidity drives the plant out. Large Leaf Pondweed, or Bassweed, is also a good plant because it provides outstanding habitat for fish. It is so valuable that efforts have been made to reintroduce it in lakes where it has disappeared. Some Wild Rice plants were also scattered in various locations. Wild Rice has not been seen in several years.
Our lake has two varieties of bladderwort, the Common Bladderwort and the Creeping Bladderwort. Located on the leaves of the plant are small bladders which trap tiny animals and insect larvae. When prey brush against the trap’s trigger hairs, it springs open and water pressure forces the food inside, where it is digested by the plant. Mosquito larvae is a favorite food.
We are very lucky not to have found any Eurasian Milfoil or Curly Leaf Pondweed. These are not plants which are native to this area, and have proven to be a big problem in some lakes. To prevent these plants from getting started, boaters must exercise caution when moving from lake to lake. Trailers and boats should be inspected and cleaned of any plant material after every use.
For the first time in several years, the center of the lake appears to be relatively plant free, allowing boats to move around fairly easily. In previous years, thick beds of plants would clog boat propellers, forcing frequent stops. This year, plant growth is confined to areas near the shoreline. More than likely this is due to the thick ice cover this past winter, and the cold temperatures. Mild winters produce greater plant growth, as do lower water levels.
After
collecting and identifying the plants,
After completing this survey, we now know a lot more about the nature of the plants in our lake. It is a good idea to repeat the survey periodically to determine whether some plants have disappeared, or new ones are appearing. This information will help the association to develop a comprehensive aquatic plant management plan.
Common Arrowhead Needle Spikerush Northern Wild Rice
Softstem Bullrush Pickerel Weed White Water Lily
White Stem Pondweed Clasping Leaf Pondweed Grass Leaved Arrowhead
Farwell’s Water Milfoil Bassweed Wild Celery
Common Waterweed Stonewort Whorled Water Milfoil
Common Bladderwort Vasey’s Pondweed Small Pondweed
Creeping Bladderwort Ribbon Leaf Pondweed Coontail
Common Bur-reed Watershield Fern Leaf Pondweed
Flat Stem Pondweed Northern Water Milfoil Bushy Stem Pondweed
Elodea Spatterdock Brown Fruited Rush
Filamentaceous Algae Green Algae