First report of diarrhetic shellfish toxins in magellanic fjords, southernChile

Diarrhetic shellfish poisoning (DSP) is a gastrointestinal disease caused b y polyether toxins produced by dinoflagellates and accumulated in shellfish . Until now, in Chile, harmful algal blooms associated with DSP have been c onfined to north of 46 degrees 00 'S. Following a bloom of Dinophysis sp., in Estero Nunez (53 degrees 19 'S, 72 degrees 30 'W) in March 1998, phytopl ankton and mussel samples were collected for qualitative and quantitative a nalysis. Dinophysistoxin-1 (DTX-1), a diarrhetic shellfish toxin, was ident ified and quantified in extracts of Mytilus chilensis Hupe, a chilean nativ e filter bivalve. DTX-1 was measured using precolumn derivatization high-pe rformance liquid chromatography method with fluorometric detection, The pre sence of DSP toxins was determined by a commercial colorimetric protein Pho sphatase assay (VDM-Test), which proved successful for the rapid screening of shellfish to detect DSP toxins. Okadaic acid was not detected in any mus sel samples; the mussel shells showed only the presence of DTX-1, ranging f rom 65.0-583.8 ng of DTX-1 per gram of mussel digestive gland. This is the first report and quantitative analysis of DSP toxins in the Magellan region and extends 500 miles to the south, the known distribution of DSP toxins i n Chilean coasts. The phytoplankton quantitative analysis showed Dinophysis acuminata (Clarapede & Lachmann) as the most probable source of the DSP to xin.