Paralytic shellfish poison accumulation yields and feeding time activity in the Pacific oyster (Crassostrea gigas) and king scallop (Pecten maximus)

Abstract

Pacific oysters and king scallops placed individually in a recirculating flume were fed for 2 weeks with a constant concentration (120 cell ml -1 ) of a toxic strain of Alexandrium minutum. Fluorescence at the outlet of each experimental unit was measured continuously, and biodeposits were recovered twice daily to evaluate feeding time activity (FTA) and rates of organic filtration (OFR), ingestion (OIR) and organic absorption (OAR). Ion-pairing high performance liquid chromatography (IP-HPLC) was performed concurrently to quantify paralytic phycotoxins both (i) individually in shellfish at the end of the contamination period and (ii) in A. minutum cultures to estimate cellular toxin concentration. These data allowed comparison of the actual tissue toxin concentration (TOX) with the theoretical toxin accumulation rate (TAR) calculated from the linear relations between OAR, cell number, fluorescence and cell toxicity. The results show high FTA/TAR and FTA/TOX correlations (R 2 = 0.78) for both oysters and scallops. The TAR/TOX relation, though not yet clearly defined, suggests the minimum quantity of absorbed toxin at which the accumulation process is induced. RésuméRendements d'accumulation des toxines paralysantes (IPFM) et fréquence d'activité nutritionnelle de l'huître creuse (Crassostrea gigas) et de la coquille Saint-Jacques (Pecten maximus). Des huîtres creuses et des coquilles Saint-Jacques ont été placées individuellement dans un circuit fermé et nourries pendant 2 semaines avec un apport constant d'Alexandrium minutum (souche toxique) à la concentration de 120 cell ml -1 . La fluorescence en sortie de chaque enceinte expérimentale a été mesurée en continu et la production de biodépôts évaluée 2 fois/j afin de calculer la fréquence d'activité alimentaire (FTA), le taux de filtration organique (OFR), le taux d'ingestion et d'absorption organique (OIR et OAR). Des analyses en chromatographie liquide par appariement d'ions ont été réalisées en même temps afin de quantifier les concentrations de toxines paralysantes présentes : dans les coquillages contaminés en fin de période de contamination et dans les cultures d'A. minutum. Ces données ont permis de comparer les concentrations en toxines réellement observées dans les tissus (TOX) avec le taux d'accumulation théorique des toxines (TAR) calculé à partir des relations linéaires établies entre OAR, nombre de cellules, fluorescence et toxicités. Les résultats montrent des coefficients de corrélation élevés (R 2 = 0,78) aussi bien pour FTA/TAR que pour FTA/TOX, à la fois pour les huîtres et pour les coquilles Saint-Jacques. La relation TAR/TOX, une fois validée, permettrait d'approcher la notion de quantité minimale de toxine absorbée pour déclencher le processus d'accumulation de toxines.

Genomics Study of the Exposure Effect of Gymnodinium catenatum, a Paralyzing Toxin Producer, on Crassostrea gigas' Defense System and Detoxification Genes

“…As a filter-feeder species, C. gigas may accumulate toxins [1], [4], [5], [32] and xenobiotics [33]–[35]; thus toxin presence is one of the major determinants of its sanitary quality. Toxin mechanisms and effects in human and other mammalian species are widely known.…”

“…In the first scenario, pseudo-feces production has been documented as a fundamental pre-ingestion mechanism [5], [8], [10], not only preventing exceeding the animal's ingestion capacity [10], [32], [37], [40] but also facilitating particle selection: less nutritious particles are rejected, thus the quality of ingested material is proportionally improved [5], [36], [37], [40]. However, in our work we demonstrated that the addition of a toxic dinoflagellate as G. catenatum in a diet added with the haptophyte I. galbana significantly altered C. gigas ' filtering capacity and pseudo-feces production.…”

Domoic acid uptake and elimination kinetics in oysters and mussels in relation to body size and anatomical distribution of toxin

“…In C. gigas this has been associated with their intermittent feeding pattern (i.e. periodic and non-synchronous shell closure) (Bougrier et al, 2003;Baron et al, 2006). It may also be related to genetic differences such as differential enzymatic activity, or differential prevalence of bacterial strains capable of DA degradation in the bivalve gut flora (Stewart et al, 1998;Hagström et al, 2007).…”

Modelling the accumulation of PSP toxins in Thau Lagoon oysters (Crassostrea gigas) from trials using mixed cultures ofAlexandrium catenellaandThalassiosira weissflogii

“…The experimental system used to monitor the physiological state of each oyster in the circuit is as described in several earlier publications (Bougrier et al 2001(Bougrier et al , 2003, slightly adapted for the purposes of this study. The system comprised twenty 0.5 L capacity experimental boxes, 18 containing one live oyster, and two boxes containing empty oyster shells serving as sedimentation process controls.…”