Effects of toxic and non-toxic cyanobacteria on grazing, zooplanktivory and survival of the mysid shrimp Mysis mixta

We measured the effect of toxic and non-toxic cyanobacteria strains on graz ing, predation rates and survival of the mysid shrimp Mysis mixta by means of laboratory experiments. Juvenile and adult M. mixta fed most actively on the non-toxic strains Aphanizomenon flos-aquae and Nodularia sphaerocarpa as on high quality food, the green flagellate Brachiomonas submarina, where as grazing on the toxic N. spumigena was significantly lower than on the ot her strains. The mysids showed normal functional responses; decreasing clea rance rates at increasing concentrations of cyanobacteria. In a separate pr edation experiment, the feeding rates on copepods declined in the presence of aggregated non-toxic cyanobacteria. However, we could not demonstrate in creased mortality in a 7-week experiment where mysids were exposed to high concentrations of toxic N. spumigena (C) 2001 Elsevier Science B.V. All rig hts reserved.