The response of macroinvertebrate and protozoan colonization dynamics to industrial pollution was determined in a thermal organic effluent and in a metals effluent. The relationship of the time course data to the MacArthur-Wilson model is considered, along with Pinkham and Pearson's community similarity index and traditional community structural parameters. The response of both communities is similar with respect to equilibrium number of taxa at both sites; however, the fitted rate constant, G, was accelerated in the organic effluent for the protozoans. The macroinvertebrate G in the same effluent showed a dose response. There were no differences in rate between stations in the metals effluent for either the protozoans or the macroinvertebrates, although the equilibrium number of taxa was decreased downstream.

Community similarity indices shows similar macroinvertebrate and protozoan communities at all three stations in the organic system at equilibrium, although some differences occur in the early stages of colonization. The communities in the metals effluent are most often significantly different at the downstream station, which was the most impacted. Community diversity indices indicate the same results for the equilibrium community as do the other methods of evaluation. While community colonization studies have been suggested as a method of water quality assessment, colonization dynamics and particularly the fitted rate constant, G, may be misleading unless considered in conjunction with equilibrium information.