Calanoid copepods in central Chilean and Chilean Patagonian lakes (33-55°S, Chile), probable ecological key role in pelagic environments

The Patagonian lakes (38-55?S) are characterized by their marked oligotrophy, low number of species of crustacean zooplankton, and a marked predominance of calanoid copepods. Within this context, we considered that a review about the ecology of the zooplankton in central and southern Chilean lakes would be useful, aiming to understand the ecological importance of this group. Data obtained from the literature for freshwater bodies in central and southern Chilean lakes were analysed. In addition, data from various bays with widely differing trophic status in Llanquihue Lake were examined. The results revealed the existence of originally pristine and oligotrophic sites, all with a low number of species and marked calanoid dominance. However, in northern Patagonia there are many lakes in which human intervention has caused an increase in phytoplankton activity, with a consequent replacement of calanoid copepods by daphniid cladocerans. Other important factors that could affect the zooplankton community would be fish predation, which is due to generate a decrease in large-bodied groups of zooplankton; and stress due to exposure to natural ultraviolet radiation. Ecological, biogeographical, and evolutionary topics are discussed within the framework described.