Sylvain Trottier | Université de Sherbrooke (University of Sherbrooke) (original) (raw)

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Papers by Sylvain Trottier

Research paper thumbnail of Comparisons between microscale and whole-sediment assays for freshwater sediment toxicity assessment

Environmental Toxicology and Water Quality, 1998

The use of several microscale assays for evaluating freshwater sediment toxicity was ( investigat... more The use of several microscale assays for evaluating freshwater sediment toxicity was ( investigated to develop a representative and cost-effective test battery. The bioassays evaluated 18 ) assays total included microscale assays performed on solid-phase, pore water, and organic extracts as well as conventional standardized whole-sediment assays with Chironomus riparius and Hyalella azteca on 10 sediment samples collected in the St. Lawrence/ Great Lakes system. Selected sediment physical and chemical characteristics were also conducted to aid in the interpretation of results. Benthic invertebrate assays such as C. riparius and H. azteca endpoints were found to correlate well to ( ) contaminant levels. Microscale assays such as ATP adenosine triphosphate measurement of sediment microbial biomass gave promising results to predict whole-sediment toxicity to benthic invertebrates. Most assays on pore water did not adequately represent whole-sediment toxicity, whereas organic extracts appeared to be more representative, alleviating some potential confounding factors such as interference due to toxicity caused by ammonia.

Research paper thumbnail of Genotoxicity of sediment extracts obtained in the vicinity of a creosote-treated wharf to rainbow trout hepatocytes

Toxicology Letters, 1995

Genotoxicity and cytotoxicity were evaluated in rainbow trout hepatocytes exposed to sediment ext... more Genotoxicity and cytotoxicity were evaluated in rainbow trout hepatocytes exposed to sediment extracts obtained in the vicinity of a creosote-treated wharf. Sediment cores were collected at the intertidal and subtidal sections of the wharf at distances of 1, 5, 40 and 50 m. Moreover, subsamples were also taken at different depths of the cores ranging from 2 to 10 cm below the sediment/water interface. Sediment samples were air-dried and extracted in dichloromethane followed with an exchange into dimethylsulfoxide (DMSO). Rainbow trout hepatocytes were exposed for 24 h at 15 degrees C to several concentrations of the sediment extract. Afterwards, the cells were collected, and cell viability was assayed along with genotoxicity using the nick translation and the alkaline precipitation assays. Results showed that the wharf contained high concentration of polycyclic aromatic hydrocarbons (PAHs), displayed genotoxicity and cytotoxicity to hepatocytes. In addition, PAHs, cytotoxicity and sometimes genotoxicity were detected in all sediment samples and tended to decrease with distance. Chemical contamination and (geno)toxic effects were greater in sediment extracts from the intertidal section than from the subtidal section. However, no evident change in chemical or toxicological characteristics was noted between samples obtained at different depths. Spearman rank-correlation analysis revealed some trends between levels of some PAHs and (geno)toxicity in hepatocytes exposed to sediment extracts.

Research paper thumbnail of Interlaboratory precision study of a whole sediment toxicity test with the bioluminescent bacteriumVibrio fischeri

Environmental Toxicology, 1999

The reproducibility of sediment toxicity bioassays using the Microtoxᮋ solid-phase test ( ) SPT w... more The reproducibility of sediment toxicity bioassays using the Microtoxᮋ solid-phase test ( ) SPT with the luminescent bacterium Vibrio fischeri was estimated in an interlaboratory precision study. A preliminary study, with five labs testing six solid-phase samples, was used to evaluate proposed method modifications. As a result, it was recommended that the SPT protocol be revised to include whole sample testing with subsequent wet-weight to dry-weight correction, and the use of NaNO , 3 rather than NaCl, as the diluent for freshwater sediment samples. The revised protocol was then examined in a definitive precision study, with 18 laboratories each testing eight samples. Coefficients of variation for the eight samples ranged from 35.8 to 78.0%. One possible source of error is the separate moisture content determination performed by each laboratory in order to calculate the wet-weight to ( ) dry-weight correction. Out of a total of 143 bioassays performed by the 18 labs, only two results 1.4% exceeded the critical value of the interlaboratory consistency statistic h. With coefficients of variation comparable to other interlaboratory precision studies, and an extremely low number of results exceeding the critical value of h, it is concluded that the V. fischeri SPT has an acceptable level of precision and can be developed as a standardized test method.

Research paper thumbnail of Molluscan shellfish biomarker study of the Quebec, Canada, Saguenay Fjord with the soft-shell clam,Mya arenaria

Environmental Toxicology, 2002

A spatial and temporal survey of six sites in the Saguenay Fjord and of one adjacent site in the ... more 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.

Research paper thumbnail of Comparisons between microscale and whole-sediment assays for freshwater sediment toxicity assessment

Environmental Toxicology and Water Quality, 1998

The use of several microscale assays for evaluating freshwater sediment toxicity was ( investigat... more The use of several microscale assays for evaluating freshwater sediment toxicity was ( investigated to develop a representative and cost-effective test battery. The bioassays evaluated 18 ) assays total included microscale assays performed on solid-phase, pore water, and organic extracts as well as conventional standardized whole-sediment assays with Chironomus riparius and Hyalella azteca on 10 sediment samples collected in the St. Lawrence/ Great Lakes system. Selected sediment physical and chemical characteristics were also conducted to aid in the interpretation of results. Benthic invertebrate assays such as C. riparius and H. azteca endpoints were found to correlate well to ( ) contaminant levels. Microscale assays such as ATP adenosine triphosphate measurement of sediment microbial biomass gave promising results to predict whole-sediment toxicity to benthic invertebrates. Most assays on pore water did not adequately represent whole-sediment toxicity, whereas organic extracts appeared to be more representative, alleviating some potential confounding factors such as interference due to toxicity caused by ammonia.

Research paper thumbnail of Genotoxicity of sediment extracts obtained in the vicinity of a creosote-treated wharf to rainbow trout hepatocytes

Toxicology Letters, 1995

Genotoxicity and cytotoxicity were evaluated in rainbow trout hepatocytes exposed to sediment ext... more Genotoxicity and cytotoxicity were evaluated in rainbow trout hepatocytes exposed to sediment extracts obtained in the vicinity of a creosote-treated wharf. Sediment cores were collected at the intertidal and subtidal sections of the wharf at distances of 1, 5, 40 and 50 m. Moreover, subsamples were also taken at different depths of the cores ranging from 2 to 10 cm below the sediment/water interface. Sediment samples were air-dried and extracted in dichloromethane followed with an exchange into dimethylsulfoxide (DMSO). Rainbow trout hepatocytes were exposed for 24 h at 15 degrees C to several concentrations of the sediment extract. Afterwards, the cells were collected, and cell viability was assayed along with genotoxicity using the nick translation and the alkaline precipitation assays. Results showed that the wharf contained high concentration of polycyclic aromatic hydrocarbons (PAHs), displayed genotoxicity and cytotoxicity to hepatocytes. In addition, PAHs, cytotoxicity and sometimes genotoxicity were detected in all sediment samples and tended to decrease with distance. Chemical contamination and (geno)toxic effects were greater in sediment extracts from the intertidal section than from the subtidal section. However, no evident change in chemical or toxicological characteristics was noted between samples obtained at different depths. Spearman rank-correlation analysis revealed some trends between levels of some PAHs and (geno)toxicity in hepatocytes exposed to sediment extracts.

Research paper thumbnail of Interlaboratory precision study of a whole sediment toxicity test with the bioluminescent bacteriumVibrio fischeri

Environmental Toxicology, 1999

The reproducibility of sediment toxicity bioassays using the Microtoxᮋ solid-phase test ( ) SPT w... more The reproducibility of sediment toxicity bioassays using the Microtoxᮋ solid-phase test ( ) SPT with the luminescent bacterium Vibrio fischeri was estimated in an interlaboratory precision study. A preliminary study, with five labs testing six solid-phase samples, was used to evaluate proposed method modifications. As a result, it was recommended that the SPT protocol be revised to include whole sample testing with subsequent wet-weight to dry-weight correction, and the use of NaNO , 3 rather than NaCl, as the diluent for freshwater sediment samples. The revised protocol was then examined in a definitive precision study, with 18 laboratories each testing eight samples. Coefficients of variation for the eight samples ranged from 35.8 to 78.0%. One possible source of error is the separate moisture content determination performed by each laboratory in order to calculate the wet-weight to ( ) dry-weight correction. Out of a total of 143 bioassays performed by the 18 labs, only two results 1.4% exceeded the critical value of the interlaboratory consistency statistic h. With coefficients of variation comparable to other interlaboratory precision studies, and an extremely low number of results exceeding the critical value of h, it is concluded that the V. fischeri SPT has an acceptable level of precision and can be developed as a standardized test method.

Research paper thumbnail of Molluscan shellfish biomarker study of the Quebec, Canada, Saguenay Fjord with the soft-shell clam,Mya arenaria

Environmental Toxicology, 2002

A spatial and temporal survey of six sites in the Saguenay Fjord and of one adjacent site in the ... more 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.