Biocriteria Development Program

Nick Proulx
500 Lafayette Rd Box 25
St Paul, MN 55155-4025
nick.proulx@state.mn.us
tel. (651) 259-5129

Nonpoint source pollution and habitat degradation are the most pervasive problems threatening aquatic resources in Minnesota. Standard water chemistry and toxicity tests, which provide a "snapshot" of conditions within a lake or stream at the time of sampling, but they may fail to detect short-term toxic events and changes to habitat that impact aquatic life. To determine whether or not a water resource is supporting healthy populations of aquatic life, scientists often sample a grouping of species (i.e., a biological community). Different communities can be used, but commonly sampled species include fish, macroinvertebrates, and plants. The individual species within the community are sampled, and a score is given based on the composition and abundance of each species. The score reflects the relative biological health of the water resource. This method of assessing aquatic life is called an Index of Biotic Integrity. If the score is too low, the water resource is determined to be impaired for aquatic life.

The Biocriteria Development Program is a cooperative effort with the Minnesota Pollution Control Agency to develop Indices of Biotic Integrity for assessing the biological health of Minnesota's water resources. The Minnesota Pollution Control Agency has taken the lead on developing this approach for Minnesota's streams and wetlands. The DNR has developed an approach for assessing the biological health of our lakes by using a fish-based Index of Biotic Integrity that scores the number and abundance of game and non-game fish species. Information on large game fish is gathered by DNR Fisheries staff during the course of their routine survey work. Staff from the Biocriteria Development Program follows up these fish surveys by sampling the nearshore area for non-game and young game fish. This sampling of non-game, young game and adult game fish gives a representative picture of the fish community found within a given lake.

As research continues and new information becomes available, other biological communities will be surveyed and used in the same manner as the fish-based Index of Biotic Integrity.