SummarySpecies richness (birds, fish, invertebrates), for example, the benthic macroinvertebrate community. Species richness can be reduced by stream, riparian, and watershed degradation in response to land-use. Species richness also fluctuates with natural disturbance. General Information about this IndicatorWhat is it?: Similar to aquatic plants, benthic macroinvertebrate (BMI) communities provide a measure of disturbance to aquatic ecosystem. There are a number of different BMI community metrics that are useful for understanding disturbance of stream ecosystems that are commonly used around the world and the California Department of Fish and Game. The Sacramento River Watershed Program and Napa Watershed indicators projects both included BMI metrics.