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Puget Sound Stream Benthos

Standard Taxonomic Effort

B-IBI calculations and results are influenced by the level of taxonomic effort specified for benthic macroinvertebrate taxonomic identification. For example, are chironomids identified to the family, subfamily, tribe, or genus-species level for a certain site visit or project year? Comparing data across projects and over time requires some level of taxonomic standardization to ensure that a difference in B-IBI scores and metrics is due to biological condition and not modifications to taxonomic handling.

Three Levels of Taxonomic Effort

We have developed three levels of standard taxonomic effort (STE), fine, medium, and coarse taxonomic resolution, that are used as a guide to labs during taxonomic analysis of samples, as well as during scoring.

Samples analyzed to the fine resolution STE can be rolled up to the medium or coarse STE for scoring. Scoring of certain B-IBI metrics (taxonomic richness, clinger richness, and % dominant) are adjusted based on this selection.

More details about the 3 levels are found in the table and narrative below. Section 2.2 of the B-IBI recalibration report discusses the impact of taxonomic effort on B-IBI and explains how metric scoring was adjusted to ensure B-IBI comparability regardless of STE level.

The effort of various taxa groups for the three levels of standard taxonomic effort.
Taxa Group Fine STE Medium STE Coarse STE
Oligochaeta
(segmented worms)
Subfamily/genus Family Subclass
(“Oligochaeta”)
Acari
(mites)
Genus Subclass
(“Acari”)
Subclass
(“Acari”)
Gastropoda
(snails)
Genus Genus Family
Dytiscidae
(predaceous diving beetles)
Genus
(adults and larvae)
Genus (adults)
Family (larvae)
Family
(adults and larvae)
Simuliidae
(blackflies)
Genus
(larvae and pupae)
Genus (larvae)
Family (pupae)
Family
(larvae and pupae)
Chironomidae
(midges; larvae and pupae)
Genus/species/species group Subfamily/tribe Family
Trichoptera
(caddisflies)
Genus/species/species group Genus (larvae)
Family (pupae)
Genus (larvae)
Order (pupae)
All other taxonomic groups Lowest practical level:
typically genus or species
Lowest practical level:
typically genus or species
Lowest practical level:
typically genus or species

Fine Resolution

This is the taxonomic effort level used by the Washington State Department of Ecology. Oligochaetes at lowest possible level, Acari at genus, Snails at genus, Dytiscidae larvae and adults to genus, Simuliidae larvae and pupae to genus, Chironomids at genus/species/species groups, Trichoptera larvae to genus/species/species group and pupae to family.

View scores: Scores Map

Medium Resolution

This level is between the coarse and fine levels. Oligochaetes at family, Acari at "Acari", Snails at genus, Dytiscidae adults to genus larvae to family, Simuliidae larvae to genus and pupae to family, Chironomids at subfamily/tribe, Trichoptera larvae to genus/species/species group and pupae to family.

View scores: Scores Map

Coarse Resolution

This is the closest to historical, pre-2012 King County sampling efforts. Oligochaetes at "Oligochaeta", Acari at "Acari", snails at family, Dytiscidae to family for adults and larvae, Simuliidae larvae and pupae at family, chironomids at family, Trichoptera larvae to genus/species/species group and pupae to "trichoptera."

View scores: Scores Map