Biological recovery from lake acidification: Zooplankton communities as a model of patterns and processes

Knowledge of the recovery of aquatic communities from lake acidification is limited. Data from studies of crustacean zooplankton communities, however, do reveal some of the major mechanisms important in the biological recover y process. Important influences on recovery include factors related to habi tat quality and the ability of organisms to colonize. During recovery, exis ting species and colonists from internal and external sources interact to f orm a new community. The relative roles of internal and external influences remain poorly understood. Four general community types can be identified a s possible outcomes of the recovery process: the original community, a norm al alternate community, a community limited by dispersal, and a community l imited by biological resistance. Empirical data indicate that, given suitab le water quality, about a decade is sufficient to permit substantial recove ry of zooplankton communities if there are no severe physical or biological barriers to restructuring.