Stressors to Impaired or Vulnerable Lakes (Based on Fish IBI)

This layer summarizes the <b>stressors to impaired or vulnerable lakes</b>, which are identified from fish-based index of biological integrity (IBI) scores and aquatic life use judgements. The primary stressor(s) corresponding with the <u>most recent assessment year</u> for each lake are displayed; however, primary stressor(s) for all assessment years are included in the layer (i.e., multiple records for each lake may exist and corresponding data can be found in the attribute table).<br/><br/>An IBI is a biologically-based, multi-metric method for measuring the integrity of aquatic systems. Minnesota DNR Fisheries has developed four fish-based lake IBIs that incorporate fish data collected by various methods (trap nets, gill nets, shoreline seines, and backpack electrofishing units) into 8-15 metrics in three categories: species richness, community assemblage, and trophic composition. Each metric represents an aspect of the biological assemblage structure, function, or other measurable characteristic that changes in some predictable way with increased human-induced stress. Fish-based IBI scores respond to differences in land use patterns, trophic state, and aquatic vegetation. Individual fish-based IBI scores and metrics can be viewed at <a href="https://resources.gisdata.mn.gov/pub/gdrs/data/pub/us_mn_state_dnr/env_ibi_lakes_stressors/metadata/../../env_ibi_lakes_fisheries/metadata/metadata.html" target=_blank><b>Lakes with DNR Fisheries IBI Scores</b></a>.<br/><br/>Aquatic life use judgements are made for individual lakes on a rotation occurring approximately once every 10 years as part of Minnesota Pollution Agency’s watershed assessment process. The fish IBI is a tool used for assessing lake impairment as part of Minnesota's 303(d) <i>Impaired Waters</i> assessments. Individual aquatic life use judgements can be viewed at <a href="https://resources.gisdata.mn.gov/pub/gdrs/data/pub/us_mn_state_dnr/env_ibi_lakes_stressors/metadata/../../env_aquatic_life_use_judgement/metadata/metadata.html" target=_blank><b>Lakes with Aquatic Life Use Judgement (Based on Fish IBI)</b></a>.<br/><br/>Lakes that are assessed as impaired or vulnerable to impairment undergo a formal and rigorous process that identifies stressors causing biological impairment. Potential stressors to aquatic life in lakes include eutrophication, physical habitat alteration, altered interspecific competition, temperature regime changes, decreased dissolved oxygen, increased ionic strength, pesticide application, metal contamination, and unspecified toxic chemical contamination. Each category is classified as a stressor, inconclusive, not a stressor, or not evaluated for each lake. More comprehensive stressor identification reports, organized by HUC 08 watershed, contain detailed stressor information for individual lakes and are published to the Minnesota Water Research Digital Library.<br/><br/>For more reference information, see <i>(Section 5: Attributes -- Detailed Citation)</i>.