INFLUENCE OF THE ENERGY RELATIONSHIPS OF TROPHIC LEVELS AND OF ELEMENTS ON BIOACCUMULATION

A concern of ecotoxicology is to predict to which trophic levels in bi ocenoses bioaccumulation of compounds or of elements occurs. Transform ity, a measure of the energy required to produce and maintain a compon ent or a flow resulting from an energy transformation process, may hel p predict bioaccumulation potential. This notion derives from two conc epts. First, common substances are more likely to be processed by the biosphere. Moreover, the uptake of rare ones from the physical environ ment by organisms of low trophic levels makes them less unusual to org anisms of high trophic levels, which may evolve a capability of proces sing them. Second, transformity expresses energy relationships between parts of a system. Substances that require more energy to form or con centrate are also the more unusual. The hypothesis was formulated that there is a correlation between the rarity, complexity, and energy req uired for concentrating a substance, and thus its transformity, and th e transformity of the trophic level to which it bioaccumulates. This h ypothesis was tested for a set of elements with published data on thei r biogeochemistry and bioaccumulation and on energy transfers between trophic levels in ecosystems. The transformities of the elements were calculated from the energy required by the biosphere for maintaining a difference in concentration compared to its physical environment. Tra nsformities of corresponding trophic levels were calculated from the e nergy driving the energy flows. There was a significant rank correlati on between the transformity of elements and that of trophic levels. Th is may be an important generalization in ecotoxicology because it may lead to the possibility of predicting bioaccumulation tendency. (C) 19 95 Academic Press, Inc.