Sensitivity values have been determined for aquatic macroinvertebrates that are commonly found in riverine systems of Ontario. Values range from 4 to 0 and are assigned to taxa based on their abundance along the stream continuum (headwaters to mouth). Taxa with a value of 4 are most abundant in creeks, 3 in streams, 2 in rivers (also found along rocky, wave-swept shores of lakes), 1 in large rivers and riverine wetlands, and 0 in lakes, marshes, and ponds (i.e. lentic habitats). Higher values indicate that the greatest abundance of the taxon occurs further upstream in the catchment.

Sensitivity of taxa to environmental variation is hypothesized to correspond with their occurence along the stream continuum. Thus taxa most sensitive to variation in environmental variables will inhabit the headwaters (creeks) of riverine systems, whereas taxa most tolerant of variation in environmental variables will inhabit lentic habitats.

? denotes insufficient data to establish a value.
-- denotes value cannot be established at the taxonomic level indicated.

Further information is available in the report: A Biological Measure of Water Quality for Creeks, Streams and Rivers.