What are macroinvertebrates?

Benthic (meaning “bottom-dwelling”) macroinvertebrates are small aquatic animals and the aquatic larval stages of insects. They include dragonfly and stonefly larvae, snails, worms, and beetles. They lack a backbone, are visible without the aid of a microscope and are found in and around water bodies during some period of their lives. Benthic macroinvertebrates are commonly used as indicators of the biological condition of waterbodies. They are reliable indicators because they spend all or most of their lives in water, are easy to collect and differ in their tolerance to pollution. Generally, waterbodies in healthy biological condition support a wide variety and high number of macroinvertebrate taxa, including many that are intolerant of pollution. (Source: EPA)

What water quality indicators incorporate macroinvertebrates?

Two common water quality indicators that incorporate macroinvertebrate abundance and diversity are the Biological Condition Gradient (BCG) and the Benthic Index of Biological Integrity (BIBI). The BCG is a model tool to interpret the biological condition and health of stream ecosystems. Lower values are associated with conditions in which the natural structure and functional and taxonomic integrity is preserved. Higher values indicate extreme changes in structure and ecosystem function, changes in taxonomic composition and extreme alterations from normal densities. The BIBI scoring system is a quantitative method for determining and comparing the biological condition of streams. In contrast to the Biological Condition Gradient, the higher the BIBI number, the better the biological condition of the stream.

Explore macroinvertebrate conditions within and surrounding the Central Wasatch Mountains by clicking on site locations on the map.