Paralytic shellfish poisoning in Haliotis tuberculata from the Galician coast: Geographical distribution, toxicity by lengths and parts of the mollusc

Abstract

In order to clarify the origin of Paralytic Shellfish Toxins occurring in the ormers, Haliotis tuberculata, various studies were conducted to describe toxicity distribution by area, length and parts of the mollusc. Ormer toxicity from different locations of the Galician coast had a confidence interval of 252925 mg STX eq:100 g of meat (mg of equivalents of saxitoxin:100 g) by mouse bioassay analyses and 454986 mg STX eq:100 g of meat by High Performance Liquid Chromatography (HPLC). No value of below 140 mg STX eq:100 g of meat was detected. No significant differences were observed among locations for the values obtained by HPLC, while some differences were found by mouse bioassay. Toxin composition showed decarbamoylsaxitoxin (dcSTX) as the most abundant component (83–100%) with saxitoxin (STX) in a much smaller proportion. Significant differences were observed in the toxin content for the different length groups, toxin content increasing very significantly in the largest ormers, of over 85 mm. Toxin analyses in the different parts of the mollusc by HPLC showed significantly high values for the epithelium of the foot in comparison with the gut and the rest of the mollusc. They reached 105 102915 102 mg of toxin:100 g of epithelium, against 2895 mg of toxin:100 g of gut and 2796 mg of toxin:100 g of muscle. Considering the weight and the quantity of toxin in each part of the ormer, the epithelium carried 2.6 times more toxin than the muscle