Molluscan shellfish biomarker study of the Quebec, Canada, Saguenay Fjord with the soft‐shell clam, Mya arenaria

Abstract

A spatial and temporal survey of six sites in the Saguenay Fjord and of one adjacent site in the St. Lawrence River estuary (Quebec, Canada) was undertaken to study the possible effects of anthropogenic contaminant input on soft-shell clam (Mya arenaria) populations. Bivalve sampling sites were selected because they reflected a range of areas representative of either no known (or apparent) pollution sources or of areas potentially influenced by different gradients and types of contamination sources. The most upstream site selected in the Saguenay Fjord, nearest to a highly populated and industrialized sector, and the most downstream site, near its mouth with the St. Lawrence River estuary, spanned a distance of some 70 km and encompassed the entire intertidal area suitable for Mya arenaria habitat. To measure effects in collected animals, we used a comprehensive battery of biomarkers composed of metallothionein-like proteins (MT), 7-ethoxyresorufin O-deethylase activity (EROD), DNA damage (DD), lipid peroxidation (LPO), vitellinlike proteins (Vn), phagocytosis (PHAG), nonspecific esterase (NspE) activity, and condition factor (weight-to-length ratio of clams). Vn, PHAG, DD, and NspE biomarkers were assayed in hemolymph (or hemocytes), whereas others (MT, EROD, LPO) were determined in the digestive gland. Whole-tissue metal content was also quantified in clams collected in the spatial survey. The spatial survey conducted in June 1997 showed significant effects at all sites, and principal component analysis indicated in addition that the more important responses were linked to the MT, LPO, and NspE biomarkers. Clams collected from sites closest to the upstream reaches of the fjord generally displayed higher levels of tissue metals (cadmium, manganese), as well as greater responses of NspE activity, MT, LPO, and PHAG. Animals collected from sites influenced by municipal wastewaters had higher levels of Vn, suggesting the presence of environmental estrogens. The results of the temporal survey (six monthly samplings of clams at three sites from May through October, 1997) showed that the bivalve reproductive cycle (vitellogenesis and spawning) can modulate the expression of several biomarkers. Vn levels, for example, were positively correlated with DD and EROD and negatively correlated with MT, suggesting that reproduction can influence the susceptibility of clams to some contaminants. Discrimination analysis over the 6 months of sampling revealed that the mean value of the discriminant function changed significantly over time, suggesting important changes in the relative contribution of each biomarker. In short, this study has provided evidence that clam populations in the Saguenay Fjord are impacted by multiple sources of contamination whose effects can be modulated by reproduction.

Hemocyte parameters of the Pacific oyster Crassostrea gigas a year after the Hebei Spirit oil spill off the west coast of Korea

“…Due to their high phagocytic capacities, granulocytes might have been the hemocytes most aVected by the ingestion of toxic components resulting from the oil spill. These toxins might have induced intracellular disturbances and DNA damage, such as strand breaks and cross-links or mutations, resulting in dysfunctional granulocytes or granulocyte apoptosis (Dixon et al 1985;Nacci et al 1992;Telford et al 1992;VukmiroviT et al 1994;Walker and Sikorska 1997;Blaise et al 2002;Hamoutene et al 2002;Bolognesi et al 2004;Rocher et al 2006;Gagné et al 2008). In contrast, the oil spill-damaged oysters exhibited more blast-like cells than the control oysters (14.7 vs. 10.7%, respectively).…”

Maritime pollutants in shipping and commercial European ports based on relevant physical and biogeochemical environmental parameters (IUPAC Technical Report)

“…It is characterized by a strong ability for bio accumulation and bio-concentration of toxicants, a motionless endobenthic life style and a rather widespread distribution. Consequently, bivalve mollusks serve as bio-indicators and they have been widely used as sentinel species to monitor environmental contamination [75] as well as in biomarker studies to examine the effects of municipal effluents [76,77], pesticides [78] and heavy metals [79][80][81]. Table 4 lists quality and performance indicators for air.…”

Études de biomarqueurs chez la mye commune (Mya arenaria) du fjord du Saguenay : bilan de recherches (1997 à 2006)

“…Par ailleurs, l'étude temporelle réalisée aux sites BE, ASE et BMB de mai à octobre 1997 aura permis de mettre en évidence une plus forte activité de phagocytose chez les hémocytes des myes durant la période estivale, notamment en juillet et en août (BLAISE et al, 2002a). D'une part, l'augmentation de la température de l'eau à cette période est propice à une plus grande prolifération de microbes, ce qui peut en augmenter l'ingestion par les bivalves filtreurs et vraisemblablement induire une stimulation de phagocytose.…”

“…L'indice catégorise l'intensité des réponses de chaque biomarqueur à partir de la somme des rangs obtenus de valeurs moyennes ou de médianes d'un sous-ensemble de n = 16 myes. La somme des rangs pour chaque biomarqueur d'un site établit alors une valeur indicielle qui témoigne de l'intensité de réponse avec laquelle on peut effectuer des comparaisons intersites (BLAISE et al, 2002a). L'indice suggère une dichotomie en matière de stress anthropiques impartis aux myes des zones interdidales du fjord, alors que les sites amont AE, BE et ASJ présentent des valeurs indicielles plus fortes que celles des sites aval PS, ASE, AB et BMB (Figure 2).…”

“…On notera aussi une réponse la plus élevée pour le biomarqueur ADN associée aux sites de référence ASE et BMB. Bien que ces sites ne présentent aucune source de pollution apparente ou directe (Tableau 1), on ne peut y exclure l'influence de source épisodique de pollution, lesquelles ont, dans ce cas-ci, induit des dommages à l'ADN des hémocytes (BLAISE et al, 2002a).…”