in 2001, a total of ten macroinvertebrate taxa were observed in crab run. "chironomidae" was "very abundant", with more than 100 individuals being observed. "simuliidae" and "hydropsychidae" were "abundant", with 25 to 100 individuals being observed. "ephemerellidae", "crydalidae", "tipulidae", "cambaridae", and "oligochaeta" were "present", with 3 to 9 individuals being observed. the taxa "nemouridae" and "heptageniidae" were "rare", with 1 to 2 individuals being observed. the family-level hilsenhoff biotic index value of crab run in 2001 was 5.61.