ABSTRACT
It is dif–cult to predict the effects of pollutants on organisms to an acceptable degree of accuracy by simply measuring concentrations of a chemical in the abiotic environment (Figure 11.1). Factors that affect bioavailability of chemicals to organisms include temperature ¨uctuations, interactions with other pollutants, soil and sediment type, rainfall, pH, and salinity. Even using biotic monitoring of chemical residue levels (see Section 11.3), there are considerable dif–culties in knowing the effects of this level of chemical on the organism. This process is made more dif–cult by the presence of mixtures (see Chapter 9) and the considerable interspecies differences in response. In situ biological monitoring attempts to get around these problems by analyzing various parameters of natural populations that re¨ect the situation in the –eld rather than the standardized conditions of laboratory experiments.
