The dinoflagellates Pfiesteria shumwayae and Luciella masanensis cause fish kills in recirculation fish farms in Denmark

摘要: Abstract Fish kills in two geographically separate fish farms northern Denmark 2012, one using marine, the other brackish water ‘Recirculation Aquaculture Systems’ (RAS), were found to be caused by Pfiesteria shumwayae and Luciella masanensis , species of dinoflagellates belonging family Pfiesteriaceae. There no harmful algae present either aquaculture plants. Serious US have been attributed during past 20 years, but this type mortality has not documented elsewhere. L. described recently from Korea USA, previously reported source kills. In marine farm, affected was rainbow trout, farm pikeperch. Light microscopy is presently insufficient discriminate between approx. Pfiesteriaceae described. Identification algal therefore based on molecular sequencing nuclear-encoded LSU rDNA, confirmed scanning electron and, eventually, also examination very thin amphiesmal plates flagellates calcofluor-stained cells a fluorescence microscope. Although differed light salinity conditions, both used re-circulating closed circuit systems. The examined detail shown feed organic material such as live, damaged nematodes, for single pfiesteriacean flagellate known freshwater, Tyrannodinium edax . Algal observed attach their prey an attachment filament subsequently peduncle suck up food. utilizing recirculation technology are gaining popularity due reduced effect environment. cases apparently first RAS which serious reported. ( ) increased dramatically despite treatment with peracetic acid chloramine-T. plant temporarily down pending investigation into cause determine method management control dinoflagellate avoid future ), treated chloramine-T, disappear column, forming temporary cysts. repeated after few days week, when cysts appeared germinate reappeared column.