Yessotoxin production by Gonyaulax spinifera

Yessotoxin (YTX) contamination of Greenshell™ mussels (Perna canaliculus) in the Marlborough Sounds, New Zealand, occurred in May 2004 with no known YTX-producing algae present in associated seawater samples. Gonyaulax spinifera, previously considered a non-YTX producer, was isolated from the seawater samples and production of YTX by the cells grown in culture was determined by identification of YTXs by ELISA. The algal identification was based on the type description and cyst form. DNA sequence data for G. spinifera differed from the morphologically similar G. membranacea, G. digitale, and G. cf. spinifera. Protoceratium reticulatum was isolated from the same site as G. spinifera 3 weeks later, but was not a YTX-producer by LC-MS and YTX ELISA analyses. Implications of the discovery that YTX is produced by G. spinifera are that this micro-alga will need to be included in future risk assessments for YTX based on the phytoplankton composition.