Following a heavy red-tide causing the death of a great number of caged young yellowtail Seriola quinqueradiata, in Ehime Prefecture of Japan during 1972, Fibrocapsa japonica was described in detail and named by Toriumi and Takano in 1973. Since then, blooms associated with devastating effects on mariculture and causing « Neurotoxic Shellfish Poisoning » (NSP) have been reported in different coastal areas of Japan. In 1991, F. japonica was detected in European coastal waters for the first time : on the channel coasts off Normandy, France and in Dutch coastal waters. Red tides, arising in bays and enclosed marine waters, have been observed along the north-eastern coastline of New Zealand (1992), in the southern central North Sea (1993) and at the Seal station at Friedrichskoog. During this last bloom, the tissue from dead seals contained considerable amounts of fibrocapsin, a toxin specifically associated with F. japonica.
F. japonica is a yellow-brown raphidophyte phytoflagellate. The taxonomic group, raphidophyte, is named for the peculiar extrusive organelles : trichocysts which resemble (under light microscopy) the raphides, thin crystals of calcium oxalate. The major characters distinguishing this class from other classes within the heterokontophyta are : the lack of cell walls; two flagella that are inserted near the apex , one flagellum pointing forwards, while the other is directed backwards along the cell; numerous ellipsoidal chloroplasts (see Figure); rod-shaped trichocysts or spherical mucilage-containing vesicles. Pigments of F. japonica include chlorophyllA, C1, C2 and fucoxanthin. For the ESTTAL project, ESTs will be obtained with the strain CCMP1661 isolated by Moestrup from Port Phillip Bay, Melbourne, Australia in 1988 (obtained from Provasoli-Guillard National Center for Culture of Marine Phytoplankton, Bigelow Laboratory for Ocean Sciences, USA)
The "toxicity scenario" behind the fish kills is under debate. Raphidophycean flagellates produce neurotoxic (fibrocapsin), hemolytic, haemo-agglutinating compounds and oxygen radicals. The high toxicity of F. japonica is proposed to result from the production of a secondary metabolite named fibrocapsin. The toxicity of this phycotoxin is between tetrodotoxin and dioxin. The chemical structure, a cyclic lipophilic polyether, is similar to brevetoxins of the dinoflagellate Krenia brevis. Fibrocapsin is a neurotoxin targeting specifically sodium channels. Fixation of the toxin is thought to provoke hyperexcitability of neuronal cells, and the toxin appears capable of targeting the peripheral and central nervous sytem.