Evaluation of marine biotoxin's accumulation by Acanthocardia tuberculatum from Algarve, Portugal

Abstract

Acanthocardia tuberculatum is a bivalve mollusc that presents recurrent problems of paralytic shellfish poisoning (PSP) contamination in the Mediterranean coasts of Spain and Morocco. Although not commercially exploited from the Portuguese south coast, it represents an alternative for reducing the harvest pressure on species presently exploited. Evaluation of accumulation of marine biotoxins was carried out by HPLC in this species, harvested during a campaign carried out in April 2001 aimed at evaluating bivalve's resources that covered the entire Portuguese south coast. PSP toxins were studied by automated pre-column oxidation. Toxins were found in specimens from all stations, but always under the regulatory limit of 80 μg STX eq./100 g. Saxitoxin and decarbamoyl-saxitoxin were the only PSP toxins unambiguously identified. In commercially exploited species, saxitoxin and analogues were not detected. The amnesic toxin domoic acid was found, but in levels similar to those found in species commercially exploited, and always under the regulatory limit of 20 μg/g. A fast elimination, and not a prolonged retention, of domoic acid seems to occur in A. tuberculatum in view of the levels close to or higher than 20 μg/g found in commercial bivalves harvested the two preceding months. The diarrhoeic toxin okadaic acid was found at trace levels much under the allowable level, similar to what was happening with other species harvested during the same period.