Aquatic macroinvertebrates (those that live in the river and can be seen with the unaided eye) are the most abundant organisms within a stream, and they are an integral part of the river system's food chain. Buffalo National River has over 128 species of macroinvertebrates; most are from the orders of Mayflies, Caddisflies, Stoneflies, and True flies or Midges.
Diversity and species richness of these communities should be high within the Buffalo River, but recent research indicates that these communities are declining in certain reaches of the river. Changes in landuse, declines in the quality of water from tributaries, introduced non-native species, and degradation of physical habitat are some of the factors causing this decline. The National Park Service is currently developing an inventory and monitoring program to examine the macroinvertebrate communities over a long period of time. This work will be performed in conjunction with standard water quality measurements to detect problem areas early so mitigation efforts can be taken.