Abstract-Mummichog, a small-sized sentinel fish species, has been proposed for use in environmental effects monitoring programs conducted by pulp mills that release their effluent in marine waters. In order to evaluate the suitability of mummichog as a sentinel species and to support the interpretation of biological effects data, tissue concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans, (PCDD/Fs), chlorophenolic compounds (CPs), polychlorinated biphenyls (PCBs), and chlorinated pesticides were investigated in mummichog sampled in the Miramichi Estuary, which was receiving a bleached-kraft mill (BKM) effluent, and in a reference estuary, the Bouctouche Estuary. Higher concentrations PCDD/Fs (up to 50 times), CPs (up to 60 times), DDT, and PCBs (up to 10 times) were found in mummichog sampled at the upstream site of the Miramichi Estuary. At this site, 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent concentrations were slightly above the threshold for ethoxy resorufin O-deethylase induction. Multivariate analyses on congener profiles revealed that the contamination by PCDD/Fs and CPs originated both from the BKM and from a former wood-preservation plant and that PCDD/Fs and CPs typical of the BKM were transported 40 km downstream from the mill. Patterns and levels of persistent contaminants differed between sites within the Estuary, indicating that the fish did not mix during their growing period. These findings support the use of mummichog in environmental effects monitoring programs, because this species bioaccumulates chlorinated compounds contained in BKM effluent and is sedentary. The causeeffect relationship between exposure to the BKM effluent and the observed biological responses will have to be demonstrated by laboratory studies because of the presence of multiple sources of contamination.
ABSTRACT. Field observations using settlement panels, which were carried out in Port Daniel Bay, Baie des Chaleurs, Quebec, Canada, in 1992, showed recruitment by the hydi-oid Tubularla laj-ynx to be unevenly distnbuted with depth Multiple regression on residuals indicated that 2 physlcal factors, water temperature and light intensity, out of 5 tested explained 45%) of the observed variance in the recruitment of T. larynx on the panels In laboratory experiments, warm temperatures increased settlement significantly Contrary to held results, light intensity did not seem to influence the settlement of T. larynxin the laboratory The influence of small scale ( < m m ) substrate heterogeneity was also tested in the laboratory Hlghest settlement rates occurred on smooth surfaces, but field experiments carried out in 1993 did not show any heterogeneity preference by T larynx. The influence of extracts and metabolites of conspecific adults on larval settlement was also tested In the laboratory and field Adult extracts had some influence on settlement in some laboratory trials, but not in others In general, T larynx settled more abundantly on surfaces treated with high concentrations of extract solutions than on other surfaces. As was the case for substratum heterogeneity, there was no influence of adult extracts detected In the held In contrast, adult metabolites sholved little influence on settlement under laboratory c o n d~t~o n s and no influence on recruitment in field experiments
A multibiomarker approach was developed on juvenile Atlantic tomcod (Microgadus tomcod) to evaluate the pertinence of this approach for low-cost screening assessment of the environmental quality of various coastal sites within estuaries. Several biometric indices and biomarkers (ethoxyresorufin-O-deethylase (EROD) activity, metallothionein concentration, and immune responses) were investigated on immature and maturing tomcods (≤ 31 months) collected in four environmentally contrasted sites in the St. Lawrence Estuary (SLE). Simultaneous examination of various age classes provides the opportunity to detect short-term responses in sensitive young-of-the-year fish (e.g., EROD induction) and longer-time effects associated with chronic exposure and bioaccumulation (e.g., metallothionein induction). Principal component analysis was helpful to discriminate between responses possibly related to contaminant exposure (EROD, metallothionein) and responses that could be affected by upstream-downstream gradient (immune response, biometric indices). Measurement of a battery of biomarkers in young tomcods at several sites along the shore of the SLE is a low-cost screening investigation useful to identify hot spots requiring further investigation with chemical analysis and additional reference sites.
Mummichog, a small‐sized sentinel fish species, has been proposed for use in environmental effects monitoring programs conducted by pulp mills that release their effluent in marine waters. In order to evaluate the suitability of mummichog as a sentinel species and to support the interpretation of biological effects data, tissue concentrations of polychlorinated dibenzo‐p‐dioxins and dibenzofurans, (PCDD/Fs), chlorophenolic compounds (CPs), polychlorinated biphenyls (PCBs), and chlorinated pesticides were investigated in mummichog sampled in the Miramichi Estuary, which was receiving a bleached‐kraft mill (BKM) effluent, and in a reference estuary, the Bouctouche Estuary. Higher concentrations PCDD/Fs (up to 50 times), CPs (up to 60 times), DDT, and PCBs (up to 10 times) were found in mummichog sampled at the upstream site of the Miramichi Estuary. At this site, 2,3,7,8‐ tetrachlorodibenzo‐p‐dioxin toxic equivalent concentrations were slightly above the threshold for ethoxy resorufin O‐deethylase induction. Multivariate analyses on congener profiles revealed that the contamination by PCDD/Fs and CPs originated both from the BKM and from a former wood‐preservation plant and that PCDD/Fs and CPs typical of the BKM were transported 40 km downstream from the mill. Patterns and levels of persistent contaminants differed between sites within the Estuary, indicating that the fish did not mix during their growing period. These findings support the use of mummichog in environmental effects monitoring programs, because this species bioaccumulates chlorinated compounds contained in BKM effluent and is sedentary. The cause‐effect relationship between exposure to the BKM effluent and the observed biological responses will have to be demonstrated by laboratory studies because of the presence of multiple sources of contamination.
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