fact misleading. He (Moriarty) adds that there is no fundamental reason from community structure to suppose that any particular species within the community will give a better measure of impact from pollutants than will another. Pollutants will affect populations of particular species, and which species are first affected will depend on the relative degrees of exposure and susceptibility and these are functions much more of the particular pollutant and of the individual species than of the community. An indicator species can only be used to assess the impact of pollution on a community if quite a lot is known about both the pollution and the community (Moriarty, 69). Concerning the idea of the concept of biological or environmental health being misleading: one may properly refer to the health of a community. A community can change "markedly" if affected by a pollutant, but it will just become a different community that is neither more nor less "healthy" just different (Moriarty, 69). It may be a less desirable community, for economic, social, scientific or aesthetic reasons, but that is quite a different matter. Effects of pollution may be described as a retrogression - a decrease in diversity, productivity, biomass and structural complexity. Moriarty argues that while there may be the appearance of a retrogression process it should not be taken as a generality. In conclusion, on the effect and response of an organism from a pollutant, the most appropriate emphasis is on populations. The effect of pollutants on populations within a community can be complex and apart from reduction or elimination of populations - resurgence, population increase or introduction of rarer species, sublethal effects and genetic changes may all be part of the changes that occur.Another very important characteristic of populations that we cannot overlook is their emetic composition. Much of the variation between individuals is inherited from their parents. It...
