Puget Sound Stream Benthos

Hilsenhoff Biotic Tolerance Index

The Hilsenhoff Biotic Tolerance Index is a diagnostic metric used to identify samples with a high degree of pollution tolerant organisms. This index is on a scale from 0 to 10 with higher values indicating more tolerant organism, and more polluted conditions. The formula is ∑ (ni * ti ) / N, where
ni is the number of individuals of the "i"th taxon,
ti is the tolerance index value of that taxon,
N is the total number of individuals in the sample assigned a Hilsenhoff Biotic Tolerance value; some taxa are not included.

Query Taxa Tolerances