Abstract

The fjords and channel of southern Chile (between Los Lagos, Aysén and Magallanes regions), has historically presented Harmful Algal Blooms (HABs) associated with marine toxins, affecting public health, economic and social activities, particularly those linked to fishing, aquaculture and tourism. Two oceanographic campaigns were carried out in the summer of 2017, aboard the R/V Mirai (January) and the Chilean Navy ship Marinero Fuentealba (February), both in the outer and inland waters of the South Pacific (45°-53° S) respectively. Several sampled stations were selected to determine phytoplankton abundance and composition and the presence of HAB species and associated oceanographic parameters. Water samples were taken at different depths and the phytoplankton was counted in laboratory under inverted microscope. The phytoplankton in both cruises was diverse, dominated by diatoms and dinoflagellates; in the first group, high abundances of species of the Pseudo-nitzschia complex were observed. In dinoflagellates, an important presence was registered, probably multispecific, of the toxic genus Karenia, with a wide geographic distribution in the monitored area, but with higher values of abundance at the stations located in the oceanic and inner zone of the Gulf of Penas. Also, we highlight the detection for the first time within the fjords and channels system of South Pacific Patagonia, of high abundances of the lipophilic toxins producer dinoflagellate Azadinium spp. The oceanic and inland waters detection of ichthyotoxic microalgae Karenia spp. match with the massive mortality caused by a bloom of this genus observed at the end of January 2017 in the wellboats that moves between Magallanes and Los Lagos region, suggesting the occurrence large spatial and geographical scale blooms in the area and with a probably oceanic origin. Finally, the presence of Azadinium spp. confirms the previous detections of azaspiracid toxins in mussels from the area. The implications of the detection of new phytoplankton toxic species for this area of southern Latin America are discussed.