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 Lake Habitats
Habitats in the nearshore zone

Coarse woody debris (CWD)
Original land survey records show that "Big Woods" originally covered this part of the state. Hardwoods, mainly red oak, sugar maple, basswood, and American elm dominated these forests.The land around your lake, the riparian zone, also consisted of these large trees which shaded the shoreline and provided a steady supply of organic matter in the form of leaves,branches and logs to the near shore area.Aquatic organisms in the lakes and streams of this area evolved during a time when large trees must have often fallen into the water.

When human development came to the shoreline, trees were removed, and logs were often pulled out of the lake. It was once common practice to remove logs from trout streams too. Now scientists and resource managers have come to realize the importance of coarse woody debris in aquatic ecosystems (and forested ecosystems as well).

Lakeshore development may affect woody debris abundance in the littoral zone and adversely effect lake ecosystems because coarse woody debris does the following for your lake:

  • provides physical structure for aquatic organisms
  • alters water movements and other hydrologic processes
  • affects the flow of organic matter from the terrestrial ecosystem into surface waters and affects the transport of organic material within the aquatic environment
Trees that fall into the water create important fish habitat. Small fish feed on the invertebrates (insects and zooplankton) in the wood and use the cover to hide from predators. Musky, and other large predatory fish, often stalk these logs looking for prey.
A study by the University of Wisconsin Center for Limnology studied fish habitat in 16 northern Wisconsin lakes. Their study showed that as homes become denser the number of fallen trees decreases. Research on the importance of CWD has really just begun. We'll most likely be hearing more in the near future. This trend cannot be totally reversed but shoreland property owners can help. Fisheries management often involves the addition of "structure", cribs etc. You could accomplish similar goals by not removing that branch or log that falls into the lake.
Aquatic macrophyte beds - see Aquatic Plants

Habitats in the off shore zone
Out in the deeper, or limnetic part of the lake the plankton take over. Plankton is a term used to describe those organisms that float freely in the open waters of the lake. Included in this group are the zooplankton (animals) and phytoplankton (algae). Fish, of course, also roam around out here. In a more productive lake the area fish have to roam around gets smaller and smaller as summer progresses. Oxygen in the deeper waters becomes scarcer as dead algae and other detritus rains down into the hypolimnion. Most fish won't be able to survive in dissolved oxygen concentrations less than 5 mg/L. Here's where the RUSS data can help you determine where the fish may or may not be.


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