The macroinvertebrate indicator assesses the variety and abundance of small organisms, such as aquatic insects and snails, that live on the streambed. They are widely used as indicators of ecological health because they respond to human disturbance, are broadly geographically distributed and are connected to fish (through their role as a food source).

Where are macroinvertebrates collected?

Crews collect macroinvertebrates
from the stream bottom at each
transect of the sample reach. Upstream Downstream

To learn more, see the
NRSA Field Operations Manual.