Aquatic Critters Can Tell Us a Lot About How to Improve Stream Health

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A trio of recently released studies shows how fish, macroinvertebrates, and algae are affected by chemical and physical stressors

What do fish, algae, and aquatic macroinvertebrates (think critters like mayflies and caddisflies) have in common? “These three types of aquatic life are widely viewed as indicators of the ecological condition, or health, of streams,” said study lead, Peter Van Metre.

In 2013, the USGS kicked off its first of five regional studies of stream quality. The goals of these studies are to evaluate the water-quality factors that are stressors to aquatic life — contaminants, nutrients, sediment, riparian zone disturbance, and streamflow alteration — and to understand which of these stressors, alone or combined, has the greatest effect on fish, algae, and aquatic macroinvertebrates throughout the region.  

An ebony jewelwing (Calopteryx maculata) perched on a blade of grass in the foreground with a flowing stream in the background

An ebony jewelwing (Calopteryx maculata).

The results of the first study, which focused on 11 Midwestern states, are now available and show that there are no streams in the region that have not been affected by agricultural or urban development. Chemical stressors, primarily nutrients and pesticides, and physical stressors, primarily sediment and a disturbed riparian zone, have altered small streams and affected the number and diversity of fish, algae, and macroinvertebrates that call these streams home.

Though the combinations of stressors affecting Midwestern streams are complex, the insights gained during this study could help resource managers choose more effective stream protection and restoration efforts.

To visualize results for all 100 Midwestern streams sampled, check out our interactive map.

Further reading