tailieunhanh - ECOTOXICOLOGY: A Comprehensive Treatment - Chapter 27

27 Effects of Contaminants on Trophic Structure and Food Webs The empirical patterns are widespread and abundantly documented, but instead of an agreed explanation there is only a list of possibilities to be explored. (May 1981) There has been little synthesis of the relative roles of different ecological forces in determining population change and community structure. Rather, there is a collection of idiosyncratic systems, with their associated protagonists, in which opposing views on the importance of particular factors are debated. (Hunter and Price 1992) INTRODUCTION An understanding of trophic interactions and food web structure is critical to the study of basic ecology and. | 27 Effects of Contaminants on Trophic Structure and Food Webs The empirical patterns are widespread and abundantly documented but instead of an agreed explanation there is only a list of possibilities to be explored. May 1981 There has been little synthesis of the relative roles of different ecological forces in determining population change and community structure. Rather there is a collection of idiosyncratic systems with their associated protagonists in which opposing views on the importance of particular factors are debated. Hunter and Price 1992 INTRODUCTION An understanding of trophic interactions and food web structure is critical to the study of basic ecology and ecotoxicology. Early in the history of ecology feeding relationships were recognized as a fundamental characteristic that defined communities. Trophic interactions provide the fundamental linkages among species that determine the structure of terrestrial and aquatic communities. For some ecologists the study of food webs and trophodynamics is the central unifying theme in ecology Fretwell 1987 . Because energy is a common currency required by all living organisms the study of bioenergetics of individuals populations communities and ecosystems allows researchers to integrate their findings across several levels of biological organization Carlisle 2000 . Despite the importance of food webs and trophic interactions in basic ecology ecotoxicologists have not incorporated significant components of basic food web theory into investigations of contaminant effects. This reluctance is ironic because the concern about food chain transport of contaminants in wildlife populations was at least partially responsible for much of the environmental legislation in the early 1960s. Reports of biomagnification of organochlorine pesticides and the subsequent effects on birds of prey Carson 1962 eventually resulted in the ban of organochlorine pesticides. One important exception to the general neglect of basic food