Comparative study on differential accumulation of PSP toxins between cockle (Acanthocardia tuberculatum) and sweet clam (Callista chione) Reqia Sagou a, * , Rachid Amanhir a , Hamid Taleb a , Paulo Vale b , Mohamed Blaghen c , Mohamed Loutfi c a Institut National de Recherche Halieutique, 2 rue Tiznit, Casablanca, Morocco b Instituto de Investigac ¸a ˜o das Pescas e do Mar (IPIMAR), Av. Brasilia, 1449-006 Lisboa, Portugal c Universite ´ Hassan II, Faculte ´ des sciences Aı ¨n Chock, Casablanca, Morocco Received 13 January 2005; accepted 17 June 2005 Available online 15 September 2005 Abstract At the western Mediterranean coast of Morocco, the cockle (Acanthocardia tuberculatum) contained persistent high levels of paralytic shellfish toxins for several years, while other bivalve molluscs such as sweet clam (Callista chione) from the same vicinity were contaminated seasonally to a much lesser extent. In order to understand the causes of this prolonged contamination, a comparative study on PSP decontamination between sweet clam and cockle was conducted from November 2001 untill June 2002. PSP toxicity was analysed by automated pre-column oxidation (Prechromatographic oxidation and LC-FD) in several organs of both species, namely digestive gland, foot, gill, mantle, muscle and siphon for sweet clams. The results showed that cockle sequester PSP toxins preferably in non-visceral organs (Foot, gill and mantle) contrary to sweet clam that sequester them in visceral tissues (digestive gland). The toxin profile of cockle organs indicated dominance of dcSTX, whereas sweet clam tissues contained especially C-toxins. Substantial differences in toxin profile between cockle and sweet clam, from the same area as well as from the composition of PSP toxin producer, Gymnodinium catenatum, confirm the bioconversion of PSP toxins in cockle. q 2005 Elsevier Ltd. All rights reserved. Keywords: Acanthocardia tuberculatum; Callista chione; PSP toxins; Organs; Accumulation 1. Introduction The cockle (Acanthocardia tuberculatum) is known to sequester PSP toxins for a long time in its tissues even when the potentially toxin producing microalgae are not present (Marquez, 1993; Tagmouti et al., 1996; Taleb et al., 1998, 2001; Vale and Sampayo, 2002). Due to permanent contamination of the later species with PSP toxins for several years, the western Mediterranean shore of Morocco was closed for shellfish harvesting since 1992. This situation caused the economic loss for fishermen and a significant effect on the local economy due to decreased of fishery revenue. Acanthocardia tuberculatum is mainly exploited in the canning industry in Morocco and Spain. A Spanish team has demonstrated that after a thermal treatment of cockles at 116 8C for at least 51 min, toxicity drops to undetectable levels by mouse bioassay (Berenguer et al., 1993; Burdaspal et al., 1998). On the basis of the later processing, an exceptional European legislation allows harvesting in Spain Toxicon 46 (2005) 612–618 www.elsevier.com/locate/toxicon 0041-0101/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.toxicon.2005.06.020 * Corresponding author. Fax: C212 22 26 69 67. E-mail address: resagou@yahoo.fr (R. Sagou).