A COMPARISON OF MACROSCOPIC AND MICROSCOPIC INDICATORS OF POLLUTION

The most efficient parameter to assess pollution in streams receiving olglnic waste material has been shown to be the benthic macroin\'ertebrate stream community. Benthic olglnisms are more fixed in habitat than are diatoms. Both groups of organisms can adequately express the state of a stream with respect to pollution. Diatoms are sensith'e to waste and are immediately affected by it. Benthic organisms reveal both present and past en\'ironmental conditions, whercas diatoms fC\'eal only present en· vironmental conditions. Equations to express community di\'ersity in the stream have been evaluated. The simple biomass test was satisfactory in representing changes in stream conditions. The similarity index performed better than other indexes examined and, although somewhat difficult to produce, it may be the best way to compare stations on different streams because it can correlate the number of groups common to any two stations. With increasing numbers of complex en-\'ironmental problems. there is need for a simple and meaningful method ' by whic