The use of zooplankton in a biomonitoring program to detect lake acidification and recovery

Abstract

A detailed review of the zooplankton literature found strong evidence that lake acidification consistently causes declines in crustacean and rotifer species richness, the relative abundance of cyclopoids and daphnids, and the relative abundance of 16 particular zooplankton species. Five species were found to consistently increase as lake pH declines. Inconsistent effects were observed on crustacean biomass and mean organism size. Biomonitoring response variables recommended to detect incipient community changes include the relative abundance of pH sensitive species, overall crustacean and rotifer community composition plotted in abundance ordination space, crustacean and rotifer species richness, and the relative abundance of acid tolerant species. If acidification effects have been detected using the above response variables, then more detailed monitoring to understand the functional characteristics of affected systems (e.g. crustacean biomass, rotifer biomass and/or overall community size spectra) is appropriate. A lake selection procedure is recommended to maximize the number of systems containing sensitive species, and ensure a set of reference systems whose acidity is unlikely to change significantly.