First report of Gymnodinium pulchellum (Dinophyceae) in North America and associated fish kills in the Indian River, Florida

Fish and invertebrate kills were reported fr om September to October 1996 in the Indian River, Florida, coincident with blooms of the dinoflagellate Gymnodinium pulchellum Larsen 1994. This is the first report of a bloom of this species in the Americas. Fish and invertebrate species affected were common snook (Centropomus undecimalis), striped mullet (Mugil cephalus), hardhead catfish (Arius felis), red drum (Sciaenops ocellatus), sheeps-head (Archosargus probatocephalus), black drum (Pogonias cromis), blue crab (Callinectes sapidus), and shrimp (Penaeus spp.). However, Gymnodinium pulchellum has previously caused fish kills in Japan and Australia. Examination of archived phytoplankton samples from a fish kill reported in the same area of the Indian River in August 1990 confirmed the presence of high concentrations of G. pulchellum. Fish hills associated with Alexandrium monilatum and potentially Pfiesteria-like species in the Indian River also are discussed. Scanning-electron microscopy provided additional morphological detail on this distinct but little-known dinoflagellate.