MICROCOSM EXPERIMENTS HAVE LIMITED RELEVANCE FOR COMMUNITY AND ECOSYSTEM ECOLOGY: COMMENT

In a recent article, Carpenter (1996) suggested that microcosm experiments are disconnected from natural lake systems and concluded that microcosms have limited relevance for community and ecosystem ecology of lakes. Carpenter also chastised academic ecologists for using microcosms for graduate training in aquatic ecology. We feel Carpenter's comments misrepresent microcosm experiments and their contributions to aquatic ecology. The purpose of this comment is to present an alternative view of the role of microcosm experiments for both research and graduate education in aquatic ecology. We argue that there is little information supporting Carpenter's (1996) suggestion that microcosms are disconnected from natural lake systems. Instead we suggest that microcosm and wholelake experiments have revealed similar community responses to major factors regulating lake communities such as nutrients and planktivorous fish. We conclude that no one type of research approach will provide a complete understanding of how lake systems function and that most rapid research progress can be made through the complementary use of microcosms and whole-lake experiments coupled with modeling and long-term observational studies. Carpenter (1996:678) stated that "the size and duration of microcosm experiments exclude or distort important features of communities and ecosystems" and that some "processes and organisms change so rapidly that they can reach unrealistic rates or population densities in the course of microcosm experiments." To support his argument that "limnology provides many examples of disconnection between microcosms and natural systems," Carpenter cited papers by Gerhart and Likens (1975), Stephenson et al. (1984), Bloesch