Abstract

The toxic dinoflagellate Alexandrium catenella, a Paralytic Shellfish Poison (PSP) producer occurs in estuarine fjords and recently in offshore waters of southern Chile (39° to 55°S). This dinoflagellate co-exist with zooplankton assemblages (mainly copepods), being their direct grazers regulating the distribution and abundance of microalgae. Grazing, growth and mortalities rates are scarse for A. catenella and almost unavailable for Chilean fjords. Consequently, the objetive of this study is to generate information about these rates through bioassays with strains of A. catenella. To evaluate the “predator-prey” relationship different treatments were performed subjecting two especies of calanoid copepods (Acartia tonsa and Calanus chilensis