The Hilsenhoff Biotic Index (HBI) is a quantitative method of evaluating the abundance of arthropod fauna in stream ecosystems as a measurement of estimating water quality based on the predetermined pollution tolerances of the observed taxa.
This biotic index was created by William Hilsenhoff in 1977 to measure the effects of oxygen depletion in Wisconsin streams resulting from organic or nutrient pollution.
A tolerance value of 0 to 10 is assigned to each arthropod species (or genera) based on its known prevalence in stream habitats with varying states of detritus contamination.
Precautions should be taken to account for confounding variables, such as the effects of dominant species over-abundance, seasonal temperature stress,[4] and water currents.
[2] The biotic index is then ranked for water quality and degree of organic pollution, as follows: