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Bibliography of the Maurice Lamontagne Institute


FROUIN, H., M. LEBEUF, M. HAMMILL, M. FOURNIER, 2012. Transfer of PBDEs and chlorinated POPs from mother to pup during lactation in Harp Seals Phoca groenlandica. Sci. Total Environ., 417-418 : 98-107 .

Seven mother–pup pairs of harp seal (Phoca groenlandica) were sampled during the lactation season near Magdalen Islands, QC, Canada. The blubber and serum of pups and mothers as well as the milk of mothers were analyzed for polybrominated diphenyl ethers and several chlorinated persistent organic pollutants (POPs) to evaluate their transfer prior to weaning. Principal component analysis demonstrated significant variations in contaminant distribution patterns between seal tissues of mothers and pups. The selectivity in the transfer of POPs between mothers and pups appeared mainly driven by their log Kow (octanol/water partition coefficient). The most selective transfer step for the POPs examined occurred between the blubber and the serum of the mother. A novel approach to examine temporal changes of POP concentrations in tissues of sealswhich take into account the contamination ofmothers was developed. A general decrease of POP concentrations in pup tissues throughout lactationmay suggest a growth dilution. A concomitant rise of POP concentrationswas observed inmaternal blubber and serumand in milk as lactation progresses. The intensive offloading of contaminants via lactation constitutes a major but selective excretory route for reproductive female seals and also a significant route of exposure for suckling pup seals.©2012 Elsevier B.V.

RAACH, M., M. LEBEUF, E. PELLETIER, 2011. PBDEs and PCBs in the liver of the St Lawrence Estuary beluga (Delphinapterus leucas) : a comparison of levels and temporal trends with the blubber. J. Environ. Monit., 13(3): 649-656 .

Due to their lipophilic properties, persistent organic pollutants (POPs) are commonly assessed using the blubber of marine mammals. However, these chemicals are also accumulating in other tissues including the liver. Some pollutants, namely perfluorinated alkyl acids, are found predominately in the liver and blood of marine mammals, and thus monitored in those tissues. This raises the question whether any tissue would represent an identical trend of POPs in the SLE beluga. The current study reports the first temporal trends of PBDEs and PCBs in the liver of 65 SLE belugas. Neither ?7PBDEs nor major individual PBDE-homolog group concentrations showed significant trends between 1993 and 2007.Also, ?32PCBs did not change over years, although, tetra-, penta- and hepta-PCB decreased by 7.1, 6.8 and 8.5 %, respectively, in males, whereas tetra-, penta- and octa-PCBs declined by 11, 12 and 12.9 %, respectively, in females. In order to compare the distribution of POPs between liver and blubber, a lipid normalised concentration ratio R (blubber/liver) for PBDEs and PCBs was calculated for each individual beluga.For all PBDEand several PCBhomolog groups, mean R values were not statistically different from unity indicating that the partitioning of these POPs is governed by the tissue lipid-content. Temporal trends of R ratios of PBDEs and PCBs were also examined. There were generally no significant temporal trends except for PBDEs inmales where R increased in average by 12.7±2.9 % yearly.The stratification of the blubber into ametabolically active (inner) and less active layers (outer blubber) may result in a slower response time of the blubber (full depth) than the liver to the recent change of contamination in the environment and explain the time trend differences between both tissues. This study suggests that the liver is more representative of recent exposure to lipophilic contaminants.©2011 The Royal Society of Chemistry

LEBEUF, M., M. CHAGNON, 2011. Les biphényles polychlorés (BPC) dans les organismes et sédiments marins côtiers aux Îles-de-la-Madeleine : évaluation de la contamination par le mazout contenu dans les sacs enfouis dans les dunes. Rapp. tech. can. sci. halieut. aquat., 2941, 57 p .

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The sinking of the barge Irving Whale in the Gulf of St. Lawrence in September 1970 led to a major lost of its load and to the formation of a large fuel oil slick. Part of the oil slick washed ashore on the northwestern beaches of the Magdalen Islands (MI). During the clean-up activities, the oil and sand mix was put into bags and buried into nearby dunes. In 1996, more than 25 years later, it was discovered that the oil contained polychlorinated biphenyls (PCB). A research project was undertaken in 2009 to assess whether the bags of fuel oil buried in the dunes contribute to the contamination by PCB of the coastal environment. Four species of marine organisms, Rock crab (Cancer irroratus), Common mussel (Mytilus edulis), Atlantic surf clam (Spisula solidissima) and American razor clam (Ensis americanus) and surface sediments were sampled at five costal sites around the MI. Three sites located on the northwestern side of the MI, were considered as exposed sites, whereas the two other sites, used as reference sites, are located on the southeast sides of the MI. PCB concentrations and patterns in marine organisms and surface sediments from exposed sites were not significantly different from those found in samples from reference sites. We conclude that the bags of oil buried in the dunes do not constitute an identifiable source of PCB for the organisms and the coastal surface sediments around the MI. According to the Canadian Environmental Quality Guidelines, PCB concentrations in organisms and surface sediment samples collected around the MI do not present a risk for the organisms exposed to sediments, consumers of aquatic biota (mammals and birds) or human health.

FROUIN, H., M. LEBEUF, M. HAMMILL, B. SJARE, M. Fournier, 2010. PBDEs in serum and blubber of harbor, grey and harp seal pups from Eastern Canada. Chemosphere, 82(2011): 663-669 .

Serum and blubber of pup harbor (Phoca vitulina), grey (Halichoerus grypus) and harp (Phoca groenlandica) seals from the Estuary and the Gulf of St. Lawrence were analyzed for polybrominated diphenyl ethers (PBDEs). Concentrations of PPBDEs (on lipid weight basis) in tissues of harbor seal pups inhabiting the St. Lawrence Estuary were about five times higher than in those from a colony located in the northern Gulf. Harp seal pups have the lowest levels ofPPBDEs among the seal species born in the Gulf of St. Lawrence. Lipid normalized concentrations of PPBDEs in serum and blubber were strongly correlated, suggesting that the blood collection as a less invasive method could be used to monitorPPBDEs in pups. This study shows that fluvial inputs of PBDEs are important to the St. Lawrence marine ecosystem and that inhabiting harbor seal pups have a substantial exposure to PBDEs at a critical developmental stage. In addition, the observed difference in PBDE levels between harp and grey or harbor seal pups from the Gulf of St. Lawrence is explained by the difference in diets of their mothers which is linked with their residency time in the Gulf and their seasonal migration pattern. ©2010 Elsevier Ltd.

MARTEL, L., M. FOURNIER, G. TRIFFAULT-BOUCHET, D. BERRYMAN, I. GUAY, P.G.C. CAMPBELL, M. LEBEUF, C. COUILLARD, L. PARENT, J. PELLERIN, P. BENOÎT, E. LACROIX, L.E. BURRIDGE (eds), 2010. Proceedings of the 36th Annual Aquatic Toxicity Workshop : September 27 to 30, 2009, La Malbaie, Québec ; Comptes rendus du 36 ième atelier annuel sur la toxicité aquatique : du 27 au 30 septembre 2009, La Malbaie, Québec. Can. Tech. Rep. Fish. Aquat. Sci. ; Rapp. tech. can. sci. halieut. aquat., 2883, 199 p .

FROUIN, H., M. LEBEUF, M. HAMMILL, M. FOURNIER, 2010. Phagocytosis in pup and adult Harbour, Grey and Harp Seals. Vet. Immunol. Immunopathol., 134(3-4): 160-168 .

Knowledge on pinniped immunology is still in its infancy. For instance, age-related and developmental aspects of the immune system in pinnipeds need to be better described. The present study examined the phagocytic activity and efficiency of harbour, grey and harp seal leukocytes. In the first part of the study, peripheral blood was collected from captive female harbour seals of various ages. Data showed an age-related decrease in phagocytosis in female harbour seals from sub-adult to adulthood. In the second part of the study, changes in phagocytosis were quantified during lactation in wild newborn harbour, grey and harp seals and in their mothers (harp and grey seals). In newborns of the same age, leukocytes of harbour and harp seals phagocytosed less than those of grey seal pups. The phagocytic activity and efficiency increased significantly from early to mid-lactation in newborn harbour seals, and from early to late lactation in newborn grey seals, which could suggest that the transfer of phagocytosis-promoting factor(s) in colostrum is an important feature of temporary protection for pups. In contrast, no changes in phagocytic activity and efficiency were observed in lactating females of the two seal species, harp and grey, examined. At late lactation, phagocytic activity in both grey and harp seal pups and phagocytic efficiency in grey seal pups were significantly higher than in their mothers. These results could reflect either the capacity of phagocytes of the newborn harp and grey seals to respond to pathogens. Results from this study suggest that the phagocytosis of the seal species examined is not fully developed at birth as it generally increases in pups during lactation. Thereafter, the phagocytic activity of seals appears to decrease throughout adulthood.©2009 Elsevier B.V.

LEBEUF, M., 2009. La contamination du béluga de l'estuaire du Saint-Laurent par les polluants organiques persistants : en revue;Contamination of the St. Lawrence Beluga by persistent organic pollutants : a review. Rev. Sci. Eau;J. Water Sci., 22(2): 199-233 .

The population of beluga from the St. Lawrence Estuary (SLE) is a wildlife species threatened with extinction. One of the possible causes explaining the current status of the population is its exposure to taxic chemicals, This review paper gathers the published data on the contamination of the SLE belugas by persistent organic pollutants (POP). Parameters and processes influencing the concentrations and the temporal trends of POPs in SLE belugas are discussed. The paper also presents the strengths and limits of monitoring contaminants in the SLE belugas for the population itself and as a sentinel species of its habitat. Between 1980 and 2007, more than 20 scientific papers have reported the presence of a variety of POP in the SLE belugas, Polychlorinated biphenyls (PCB) and dichlorodiphenyltrichloroethane (DDT) and its metabolites have been the most frequently reported POP in SLE belugas, Most chemical analyses have been done on beluga tissues collected from stranded carcasses. Concentrations of PO P that have been regulated in Canada, including PCB and DDT, are decreasing or stable in SLE belugas. However, concentrations of polybrominated diphenyls ethers, an emerging chemical used as Bame retardant, are doubling every 2-3 years in beluga blubber. Concentrations and temporal trends of POP in SLE beluga are influenced by several factors such as the age and sex of animais as well as the time period of their exposure, The quality and the representativeness of samples analyzed or changes in analytical methods can also affect concentrations of POP measured in beluga, In addition, regulations on the use of POP but also changes in beluga diet have affected the exposure of beluga to POP in time. The SLE carcass program has been essential in collecting samples and complementary information on beluga in order to characterize POP contamination and temporal trends in this population. Belugas should not be considered as a good bioindicator species of the decrease of POP in its habitat, but they should be considered as a sentinel species of the presence of bioaccumulative emerging POP entering its habitat.©2009 RSE inc.

FROUIN, H., M. LEBEUF, M. HAMMILL, S. MASSON, M. FOURNIER, 2009. Effects of individual polybrominated diphenyl ether (PBDE) congeners on Harbour Seal immune cells in vitro. Mar. Pollut. Bull., 60(2): 291-298 .

Effects of polybrominated diphenyl ethers (PBDEs) on the immune system of marine mammals are poorly understood. One important innate immune function of granulocytes is the respiratory burst which generates reactive oxygen species (ROS) used to kill engulfed microorganisms. The present study investigates in vitro the effects of BDE-47, -99 and -153, on the formation of ROS, on intracellular level of thiols, on activity and efficiency of phagocytosis and on apoptosis in granulocytes of harbour seals. Compounds were tested at four different concentrations ranging from 1.5 to 12 μM. Results showed that ROS levels, thiol levels and phagocytosis were all affected when harbour seal cells were exposed to the highest concentration (12 μM) of PBDE congeners. Apoptosis was not affected by PBDEs. The observed effects were similar in adults, pups and in the 11B7501 cell line of harbour seals.©2009 Elsevier Ltd.

ROSS, P.S., C.M. COUILLARD, M.G. IKONOMOU, S.C. JOHANNESSEN, M. LEBEUF, R.W. MACDONALD, G.T. TOMY, 2009. Large and growing environmental reservoirs of Deca-BDE present an emerging health risk for fish and marine mammals. Mar. Pollut. Bull., 58(1): 7-10 .

Polybrominated diphenyl ethers (PBDEs) have been the subject of intense scientific and regulatory scrutiny during recent years. Of the three commercial forms (Penta, Octa and Deca) of PBDEs that have been widely used as flame retardants in textiles, furniture upholstery, plastics, and electronics, only Deca-BDE remains on the general market in North America, while a recent ruling of the European Court spells an impending end to its use in Europe. We review here highlights of aquatic research documenting the rapid emergence of PBDEs as a high priority environmental concern in Canada. PBDEs are being introduced in large quantities to the aquatic environment through sewage discharge and atmospheric deposition. In certain environmental compartments, the single congener BDE-209, the main ingredient in the Deca-BDE formulation, has surpassed the legacy PCBs and DDT as the top contaminant by concentration. Limited biomagnification of BDE-209 in aquatic food webs reflects its high log Kow and preferential partitioning into the particle phase. As a result, large environmental reservoirs of BDE-209 are being created in sediments, and these may present a long-term threat to biota: BDE-209 breaks down into more persistent, more bioaccumulative, more toxic, and more mobile PBDE congeners in the environment. Crown Copyright ©2008 Published by Elsevier Ltd.

SOUBANEH, Y.D., M. LEBEUF, B. GOUTEUX, H. XIE, V. NIKIFOROV, J.-P. GAGNÉ, 2008. Investigations on the sorption of a toxaphene model congener, the B7-1450, on marine sediments. Chemosphere, 71(6): 1019-1027 .

Sorption is a natural process that takes place in sediments or soils and changes the mobility and availability of hydrophobic organic compounds, such as toxaphene pesticide in the environment. The sorption of the 2-exo,3-endo,5-exo,8,9,10,10-heptachlorobornane (B7-1450), used as a model compound of the toxaphene heptachlorobornane congeners found in sediments, was investigated for the first time through a series of batch sorption experiments. The losses of B7-1450 due to adsorption onto glass walls and to evaporation occurring during analytical treatment steps were corrected. The study showed that these specific losses ranged from 2 % to 3.5 % for the glass walls adsorption and can be as high as 15 % for the evaporation treatment. The sorption coefficients, Kd and Koc, of B7-1450 could be overestimated by >30 %, particularly for low-concentration samples, if the losses were not corrected. Loss correction equations were established, validated and applied to determine sorption coefficients for the B7-1450 congener. The Koc values for B7-1450 determined over a gradient of concentrations ranged from 3.5 × 104 to 6.5 × 104 ml g-1, revealing a strong affinity of B7-1450 for marine sediments.©2008 Elsevier Ltd.

FORTIN, M.-G., C.M. COUILLARD, J. PELLERIN, M. LEBEUF, 2008. Effects of salinity on sublethal toxicity of atrazine to mummichog (Fundulus heteroclitus) larvae. Mar. Environ. Res., 65(2): 158-170 .

Early life stages from a marine fish species, Fundulus heteroclitus, were exEarly life stages from a marine fish species, Fundulus heteroclitus, were exposed to sublethal doses of 3,30,4,40,5 pentachlorobiphenyl (PCB126) to evaluate its effects on ecologically relevant responses: growth and behavior. A few hours after fertilisation, eggs were treated topically with PCB126 (2.5e50 pg egg1). Four days post-hatching (dph), morphological changes (body length and malformations), spontaneous locomotor activity (active swimming speed, rate of travel, % inactivity), prey capture ability (Artemia franciscana nauplii) and whole body EROD activity were evaluated in larvae. Untreated larvae collected at 0.5, 1, 2, 3, 4 dph were also examined. PCB126 did not increase the mortality or malformation rates. Body length and spontaneous locomotor activity were altered only in larvae treated with the highest dose. Treatment with PCB126 caused a dose-responsive reduction in prey capture ability (rate of decline in the number of Artemia) and induction of EROD activity. The lowest observed effective dose for both of these responses was 5.0 pg PCB126 egg1 or 5.0 TCDD-toxic equivalents pg g1 egg, using a TCDD-toxic equivalent factor of 0.005 and an egg mass of 5 mg. Prey capture efficiency (number of Artemia captured per feeding strike) was reduced at 10.0 pg egg1. In untreated developing larvae, prey capture ability and efficiency increased as post-hatching development progressed and EROD activity remained low. The pattern of behavioral responses observed in PCB126-exposed Fundulus larvae differed from that observed in less-developed larvae indicating that other mechanisms than retarded development were involved. Behavioral dysfunction was a more sensitive response to PCB126 than morphological alterations and it occurred at environmentally relevant concentrations.posed to sublethal doses of 3,30,4,40,5 pentachlorobiphenyl (PCB126) to evaluate its effects on ecologically relevant responses: growth and behavior. A few hours after fertilisation, eggs were treated topically with PCB126 (2.5e50 pg egg1). Four days post-hatching (dph), morphological changes (body length and malformations), spontaneous locomotor activity (active swimming speed, rate of travel, % inactivity), prey capture ability (Artemia franciscana nauplii) and whole body EROD activity were evaluated in larvae. Untreated larvae collected at 0.5, 1, 2, 3, 4 dph were also examined. PCB126 did not increase the mortality or malformation rates. Body length and spontaneous locomotor activity were altered only in larvae treated with the highest dose. Treatment with PCB126 caused a dose-responsive reduction in prey capture ability (rate of decline in the number of Artemia) and induction of EROD activity. The lowest observed effective dose for both of these responses was 5.0 pg PCB126 egg1 or 5.0 TCDD-toxic equivalents pg g1 egg, using a TCDD-toxic equivalent factor of 0.005 and an egg mass of 5 mg. Prey capture efficiency (number of Artemia captured per feeding strike) was reduced at 10.0 pg egg1. In untreated developing larvae, prey capture ability and efficiency increased as post-hatching development progressed and EROD activity remained low. The pattern of behavioral responses observed in PCB126-exposed Fundulus larvae differed from that observed in less-developed larvae indicating that other mechanisms than retarded development were involved. Behavioral dysfunction was a more sensitive response to PCB126 than morphological alterations and it occurred at environmentally relevant concentrations.

FROUIN, H., M. LEBEUF, R. SAINT-LOUIS, M. HAMMILL, É. PELLETIER, M. FOURNIER, 2008. Toxic effects of tributyltin and its metabolites on harbour seal (Phoca vitulina) immune cells in vitro. Aquat. Toxicol., 90(3): 243-251 .

ROSS, P.S., C.M. COUILLARD, M. IKONOMOU, S. JOHANNESSEN, M. LEBEUF, R. MACDONALD, G. TOMY, 2008. Polybrominated Diphenylethers (PBDEs) in the Canadian marine environment : an emerging health risk for fish, marine mammals and their habitat ; Les polybromodiphényléthers (PBDEs) dans le milieu marin canadien : un risque émergent pour la santé des poissons, des mammifères marins et pour leur habitat. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2008/036, 27 p .

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Of the three forms (penta, octa and deca) of polybrominated diphenylethers (PBDEs) that have been widely used in textiles, furniture upholstery, plastics, and electronics, only deca-BDE remains on the market in Canada. DFO and other researchers have documented the rapid emergence of PBDEs, including deca-BDE, as a priority concern in the marine and freshwater environments in Canada. In many matrices, BDE-209, the main ingredient in deca-BDE, has surpassed PCBs and DDT as the number one contaminant. PBDEs are being introduced to the marine environment by sewage discharge and atmospheric deposition. Recent DFO research shows that BDE-209 dominates the PBDEs profile in abiotic components of the marine environment, contributing up to 80 % of the total PBDE concentration in air, water, and sediments. BDE-209 is taken up by low trophic level (e.g. shellfish and invertebrates) and terrestrial animal species, and therefore presents a risk to these species or those relying on these species for food. Although some studies have not reported results for BDE-209 because of technical difficulties in its measurement, BDE-209 has been found to biomagnify in aquatic food webs. The ready breakdown of BDE-209 into more bioaccumulative and toxic (lighter) PBDE forms in the environment presents perhaps the most insidious threat to aquatic biota. There are concerns within the scientific community about escalating risk of adverse health effects in marine biota, including invertebrates, fish and marine mammals, as well as human consumer groups including coastal First Nations communities. The endocrine-disrupting potential of PBDEs has been established in laboratory animals, fish and in seals.

COUILLARD, C.M., M. LEBEUF, B. LÉGARÉ, S. TROTTIER, 2008. Effects of diazinon on mummichog (Fundulus heteroclitus) larvae produced from eggs differentially treated with PCB126. Arch. Environ. Contam. Toxicol., 54(2): 283-291 .

During their formation, fish eggs receive a load of contaminants including polychlorinated biphenyls (PCBs) from their mother and then, after spawning, are exposed to pesticides present in water. This is the first study investigating the interaction between PCBs and organophosphorous pesticides in fish. The effect of diazinon was evaluated in mummichog (Fundulus heteroclitus) larvae produced from eggs differentially treated with 3,3′,4,4′,5 pentachlorobiphenyl (PCB126). A few hours after fertilization, eggs were treated topically with a solution of PCB126 (100 pg/μl) in dimethyl sulfoxide (DMSO) (Group P), DMSO (Group D), or not treated (Group N). Newly hatched larvae from Groups P and D were exposed to diazinon (125–12,900 ng/L) in saltwater and Group N larvae to saltwater alone. Diazinon caused a dose-responsive inhibition of cholinesterase (ChE) activity at environmentally realistic concentrations (≥361 ng/L), with up to 85 % inhibition at 12,900 ng/L. Body length was also inversely related to diazinon at concentrations ≥361 ng/L and was significantly reduced (by 4 %) at 12,900 ng/L compared to controls. Mummichog larvae were highly sensitive to PCB126 with an eightfold induction of the activity of ethoxyresorufin-O-deethylase at a dose of 710 pg PCB126 or 3.6 pg TCDD-TEQ/g wet weight. Treatment with PCB126 also caused a slight reduction in body length but no effect on ChE activity. This study indicates that the effects of PCB126 and diazinon on body length are cumulative because no significant synergistic or antagonistic interactions were observed. Longer term studies with several doses of PCB126 are needed to fully assess the overall impact of joint exposure to diazinon and PCB126 on growth and survival of fish larvae.©2007 Springer Science+Business Media, LLC.

ROSS, P.S., G.A. STERN, M. LEBEUF, 2007. Trouble at the top of the food chain : environmental contaminants and health risks in marine mammals : a white paper on search priorities for Fisheries and Oceans Canada. Can. Tech. Rep. Fish. Aquat. Sci., 2734, 30 p .

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Marine mammals comprise a number of charismatic species that are vulnerable to adverse health effects associated with exposure to environmental contaminants, notably those considered to be persistent, bioaccumulative and toxic (PBT; includes various organic and metallic contaminants). The vulnerability of marine mammals can be attributed to their often long lifespan during which they can accumulate persistent contaminants, their often high position in aquatic food webs which leads to a biomagnification ofPBTs, and their inability to readily eliminate many of these contaminants. In addition, several other classes of contaminants, including some pesticides, metals and hydrocarbons, may present a risk to the health of marine mammals that do not occupy high positions in food webs (such as sediment-fIltering grey whales), or a risk to their prey. Marine mammals can be considered as the ultimate 'biological sinks' for thousands of chemicals released into Canada's oceans. Understanding how different chemical contaminants move into marine mammal food webs, and what the impacts of these are on the health of marine mammals or their prey, represent two fundamental knowledge needs for scientists, conservationists, managers and regulators. Fisheries and Oceans Canada (DFO) plays a vital role in the stewardship of the 40 + marine mammal species inhabiting Canadian waters, be it from the perspective of ecotourism, harvesting (First Nations and otherwise), their role as top predators in food webs, or their intrinsic value to Canadians. Environmental contaminants are cited as conservation threats to the Species At Risk Act (SARA)-designated 'threatened' beluga whales of the St Lawrence estuary, and the 'endangered' and 'threatened' resident and transient killer whales of British Columbia. Marine mammal toxicology research by DFO scientists delivers 'integrated' state of the environment reporting to managers, information on the factors affecting the health (mortality, reproduction, development) of threatened or endangered marine mammal populations, and a unique means of communicating information to the general public and key stakeholder groups. Contaminant research in marine mammals has delivered advice to DFO SARA Recovery Teams, Oceans programs (Marine Environmental Quality [MEQ] and Integrated Management [IM]), and Habitat projects, and has been used to improve conservation or mitigation program delivery by Other Government Departments (Environment Canada, Health Canada, Indian and Northern Affairs Canada), transboundary agencies and efforts (United States Environmental Protection Agency, National Marine Fisheries Service, Stockholm Convention) and Non-Governmental Organizations (NGOs). Priority research needs for DFO include contaminant biomarker development and application ('health effects'), pathways research to understand why marine mammals become highly contaminated and to assess the potential effects of climate variation on exposure, an ecosystem context which documents the conservation impacts of toxic chemicals, the assessment of emerging contaminant risks to marine mammals, and exposure assessments in vulnerable environments such as the Arctic.

LEBEUF, M., M. NOËL, S. TROTTIER, L. MEASURES, 2007. Temporal trends (1987–2002) of persistent, bioaccumulative and toxic (PBT) chemicals in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, Canada. Sci. Total Environ., 383(1-3): 216-231 .

Temporal trends of persistent, bioaccumulative and toxic (PBT) chemicals were examined in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary (SLE), Canada. Blubber samples of 86 adult belugas were collected from animals stranded on the shore of the SLE between 1987 and 2002 and analyzed for several regulated PBTs, including polychlorinated biphenyls (PCBs), p,p''dichlorodiphenyltrichloroethane (DDT) and its metabolites, chlordane (CHL) and related compounds, hexachlorocyclohexane (HCH) isomers, hexachlorobenzene (HCB) and Mirex. In addition, time trends of tris(4-chlorophenyl) methane (TCPMe) and tris(4-chlorophenyl)methanol (TCPMOH), two compounds that may origin from DDT formulations, were also examined. Concentrations of most of the PBTs examined had exponentially decreased by at least a factor of two (half-life time (t1/2)<15 years) in beluga between 1987 and 2002 while no increasing trends were observed for any of the PBTs measured. The decreasing trends of PBT concentrations in SLE beluga may be due to a decline in contamination of its diet following North American and international regulations on the use and production of these compounds or by a change in its diet itself or by a combination of both. Some PBTs did not exhibit any significant trends in beluga possibly because the most intense elimination phase subsequent to legislative regulations occurred prior to the 1987-2002 time period. Other chemicals, such γ-HCH, did not significantly decrease likely because they are still currently used in some restricted applications. Conversely, α-HCH showed a significant decreasing trend indicating that ∑HCHs is not representative of all HCHs. Both TCPMe and TCPMOH exhibited no trends in beluga during the time period examined. The metabolic capacity of SLE beluga has apparently accelerated the depletion of at least one PBT, namely CB-28/31. A significant relationship between the half-life of PBTs in beluga and log Kow was observed for most of the chemicals examined. Several factors are expected to have influenced the temporal changes of PBT concentrations in beluga which limit the usefulness of this species as a bioindicator of changes in PBT contamination in the SLE ecosystem. ©2007 Elsevier B.V.

LEBEUF, M., C.M. COUILLARD, B. LÉGARÉ, S. TROTTIER, 2006. Effects of DeBDE and PCB-126 on hepatic concentrations of PBDEs and methoxy-PBDEs in Atlantic tomcod. Environ. Sci. Technol., 40(10): 3211-3216 .

SJARE, B., M. LEBEUF, G. VEINOTT, 2005. Harbour seals in Newfoundland and Labrador : a preliminary summary of new data on aspects of biology, ecology and contaminant profiles ; Le phoque commun à Terre-Neuve et Labrador : une synthèse préliminaire des nouvelles données concernant certains aspects de la biologie, de l'écologie et du profil de contamination. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2005/030, 38 p .

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Little is known about the current status of harbour seals (Phoca vitulina) in Newfoundland and Labrador given the last, and only comprehensive, study was conducted in the 1970s. Based on a limited number of reconnaissance boat surveys, opportunistic shore-based haulout counts and interviews with fishermen during 2001-2003, the current distribution of harbour seals is generally consistent with observations made in the 1970s. There is also limited evidence suggesting that local abundance of seals at some known haulout sites in the more southern portions of the province may have increased while abundance at sites in more northern areas of the west, northeast and Labrador coast are generally consistent with reports from the 1970s. Analyses of stomach samples collected from 1985-2003 indicated harbour seals consumed a wide variety of fish and invertebrate prey, but ten fish species accounted for almost 95 % of the wet mass of food consumed. Winter flounder, Arctic cod, shorthorned sculpin and Atlantic cod were the most important overall. However, there was evidence of regional variation in the diets of seals sampled from the south, west, northeast and Labrador coasts. Seals fed on fish prey that were 10.4-41.3 cm in length (mean=18.8 cm, SD=6.80). From 2001-2003, a total of 66 tissue samples were collected from harbour seals throughout the province and analysed for heavy metal, trace elements and persistent organic pollutant (POPs) contaminant levels. The relative differences in heavy metal concentrations among tissue types were consistent with values in the published literature. The mean within-sample site concentration of trace elements, and the range among sites in Newfoundland and Labrador, corresponded well with data from harbour seals in Alaska and with northern pinnipeds in general. The trace elements Hg, Se, and Cd showed the greatest variability within and among sampling sites. Changes in renal cadmium concentration with body size were dependent on site; higher concentrations being found in seals sampled along the south and east coasts of the province. The source of cadmium is unknown at this time but it may be Placentia Bay, or alternatively, contaminants are being transported along the southern coast of the province and into Placentia Bay from the St Lawrence River. Based on the suite of persistent organic pollutants (POPS) examined, harbour seals sampled from Newfoundland waters were less contaminated than those from the St Lawrence Estuary population and generally similar to those from the Southern Gulf of St. Lawrence. Mirex and ∑PCB concentrations were 5-10 times higher in the Estuary population while ∑ DDTs and ∑ Chlordanes were 2-5 times higher than in Newfoundland seals. Similar PCB patterns and POP proportions were observed among Newfoundland seals of the same sex and age category suggesting that animals were permanent residents of a limited geographic area from which they extracted POPs. Mature males had higher POP levels than females, but there were no differences between male and female young of the year and juveniles. These new data on the general distribution, local abundance, diet and initial contaminant profiles of harbour seals will provide a basis for future ecological studies, population assessments and for understanding how contaminants accumulate in coastal food chains in eastern Canada.

LEBEUF, M., M. NOËL, S. TROTTIER, L. MEASURES, 2005. Temporal trends (1987 - 2002) of regulated POPs in beluga whales from the St. Lawrence Estuary, Canada. Organohalogen compounds, 67: 1233-1235 .

GOUTEUX, B., M. LEBEUF, M.O. HAMMILL, D.C.G. MUIR, J.-P. GAGNÉ, 2005. Comparison of toxaphene congeners levels in five seal species from eastern Canada: What is the importance of biological factors?. Environ. Sci. Technol., 39(6): 1448-1454 .

Environmentally relevant chlorobornanes (CHBs) were measured in blubber samples of harbor (Phoca vitulina), gray (Halichoerus grypus), harp (Phoca groenlandica), and hooded seals (Cystophora cristata) sampled in different part of the St. Lawrence marine ecosystem (SLME) and ringed seals (Phoca hispida) sampled in the eastern Canadian Arctic waters. The purpose of this study was to compare the levels of six CHBs (Parlar-26, -40/-41, -44, -50, and -62) among the five seal species. Seal species could be separated into three groups based on their respective SCHB mean concentrations (± standard error): gray (49 ± 3.9 ng/g lipid weight) and harbor (80 ± 20 ng/g lipid weight) seals were more contaminated than ringed seals (18 ± 7.6 ng/g lipid weight) but less contaminated than harp (370 ± 87 ng/g lipid weight) and hooded (680 ± 310 ng/g lipid weight) seals. These differences are not expected to be related to different sources of toxaphene contamination, since both the SLME and the eastern Canadian Arctic environments are thought to be mainly contaminated via atmospheric transport from the southeastern part of the United States. Thus, biological factors such as sex, age, nutritive condition; metabolism capacity, and diet of the animals collected were considered. Results reported in this study indicated that the diet is likely the main factor accounting for interspecies variations in toxaphene contamination in seals from eastern Canada.©2005 American Chemical Society

LEBEUF, M., T. NUNES, 2005. PCBs and OCPs in sediment cores from the lower St. Lawrence Estuary, Canada : evidence of fluvial inputs and time lag in delivery to coring sites. Environ. Sci. Technol., 39(6): 1470-1478 .

Three sediment cores were collected along the longitudinal axis of the Laurentian Trough in the Lower St. Lawrence Estuary (LSLE) and an additional one at the junction of the Estuary and the Gulf of St. Lawrence. After core-slicing, each sediment layer was analyzed for polychlorinated biphenyls (PCBs) and some organochlorine pesticides (OCRs) including p,p'- dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB) and Mirex. 210Pb activity was also measured in these sediments, which allowed us to confirm that these cores were too much affected by the overall impact of surface mixing to be dated. Nevertheless, POP sedimentary profiles in cores from the LSLE upstream stations showed well-defined subsurface peak concentrations. Apparently, the peak inputs of POPs to these sediment cores had occurred after the years of maximum sales and production of these chemicals in North America, suggesting a time lag in the delivery of POPs to the LSLE sediments. Concentrations of POPs in the LSLE surface sediments as well as POP inventories in sediment cores decreased in the seaward direction, confirming that the head of the LSLE acts as a sink for sediments and associated constituents. Surface concentrations of ?PCBs, ?ODTs, and HCB in the most upstream core were on average similar to those reported in two fluvial lakes of the St. Lawrence River but were between 12 and 39 times lower than those from Lake Ontario. For Mirex, the surface concentration in that core was 5 and 130 times lower than the average values found in the fluvial lakes and Lake Ontario, respectively. Differences between Lake Ontario sediment cores and the most upstream core from the LSLE were much smaller on the basis of POP inventories than surface concentrations of POPs, but were still important. The total burdens of POPs in LSLE sediments below the 200 m isobath were 8704 kg for ?PCBs, 1825 kg for ?OOTs, 319 kg for HCB, and 27.5 kg for Mirex. These values represent between 1 % and 10 % of the total burdens of these POPs in Lake Ontario sediments. The estimated contribution of POPs by direct atmospheric deposition into the water column area of the LSLE represented at most 30 % of the total sediment burdens of POPs in the LSLE, illustrating the importance of fluvial inputs.©2005 American Chemical Society

COUILLARD, C.M., M. LEBEUF, M.G. IKONOMOU, G.G. POIRIER, W.J. CRETNEY, 2005. Low hepatic ethoxyresorufin-O-deethylase activity correlates with high organochlorine concentrations in Atlantic tomcod from the Canadian east coast. Environ. Sci. Technol., 24(10): 2459-2469 .

VORKAMP, K., F. RIGET, M. GLASIUS, M. PÉCSELI, M. LEBEUF, D. Muir, 2004. Chlorobenzenes, chlorinated pesticides, coplanar chlorobiphenyls and other organochlorine compounds in Greenland biota. Sci. Total Environ., 331: 157-175 .

COUILLARD, C.M., WIRGIN, I.I., LEBEUF, M., LÉGARÉ, B., 2004. Reduction of cytochrome P4501A with age in Atlantic tomcod from the St. Lawrence Estuary, Canada: relationship with emaciation and possible effect of contamination.. Aquat. Toxicol. 68: 235-249 .

This study reports a reduction of ethoxyresorufin-O-deethylase (EROD) activity in large-sized, older Atlantic tomcod (Microgadus tomcod) collected in the St. Lawrence Estuary (Quebec, Canada) and investigates its relationship over a 4-year period to sex, gonadosomatic index (GSI), condition factor (CF) and cytochrome P4501A (CYP1A) mRNA levels. In addition, the concentrations of polychlorinated biphenyls (PCBs) were measured in a subsample of fish. The reduction of EROD activity with age was observed each year in both sexes and was not related to the GSI. A high proportion of large-sized fish, with a body length greater or equal to 225 mm, were emaciated (CF≤0.55). A 6-16-fold reduction of EROD activity and a 2-4-fold reduction of CYP1A mRNA levels were observed in large-sized emaciated females compared to small-sized non-emaciated females. Concentrations of PCBs in liver increased from 1000 to 4000 ng/g lipid weight as the hepatic lipid content and the CF decreased. The inter-annual variation of EROD activity was associated with the variation in CF with lowest EROD activity and CF in 1999. When emaciated fish were excluded from the analyses, EROD activity was still lower (2-5-fold) in large compared to small fish and was no longer related to CF. For similar levels of CYP1A mRNA, EROD activity was lower in large compared to small fish. Thus, there was post-transcriptional inhibition of CYP1A activity in large-sized tomcod, indicative of cellular dysfunction. This response may be related to aging, chronic exposure to toxic contaminants or to selective pressures favoring less responsive individuals. This study demonstrates that fish age, size, and CF are important variables to consider in studies using EROD activity as an indicator of environmental contamination. The main finding was that a large part of the reduction of CYP1A with age in St. Lawrence Estuary tomcod was associated with severe emaciation of a large proportion of large-sized fish. Hepatic concentrations of contaminants covaried with the CF and the effects of these two variables on CYP1A could not be discriminated.©2004 Elsevier B.V.

LEBEUF, M., B. GOUTEUX, L. MEASURES, S. TROTTIER, 2004. Levels and temporal trends (1988-1999) of polybrominated diphenyl ethers in beluga whales (Delphinapterus leucas) from the St. Lawrence estuary, Canada. Environ. Sci. Technol., 38: 2971-2977 .

Polybrominated diphenyl ethers (PBDEs) were determined in blubber samples of 54 stranded adult beluga whales (Delphinapterus leucas) collected between 1988 and 1999 in the St. Lawrence Estuary (SLE), Quebec, Canada. Summed concentrations of 10 PBDE congeners (£PBDEs) measured in beluga samples varied between 20 and almost 1000 ng/g wet weight. According to the PBDE concentrations in marine mammals reported in the scientific literature, SLE belugas appear to be relatively lightly contaminated. Only a few predominant congeners (namely, PBDE-47, -99, and -100) represent on average more than 75 % of £PBDEs in SLE belugas. The accumulation of £PBDEs in both male and female belugas showed significant exponential increase throughout the 1988-1999 time period. The time necessary for beluga to double their blubber concentration of the most prevalent PBDE congeners was no longer than 3 years. The PBDE temporal changes reported in this study are generally faster but in agreement with the trend observed in other organisms collected in Canada, such as lake trout (Salvelinus namaycush) from the Great Lakes, ringed seal (Phoca hispida), and beluga whale from the Canadian Arctic. Some changes in the pattern of PBDEs in belugas were also observed during the time period investigated. The recent and important increase of PBDE levels in SLE belugas could explain the unexpected lack of statistical difference in PBDE contamination between males and females. This suggests that to date PBDEs tend to be accumulated by both male and female belugas, masking the elimination of PBDEs by females through post-natal transfer to their offspring. This study confirms that the growing use of PBDEs as flame retardants has resulted in rising contamination of Canadian aquatic environments. Additional studies are needed to assess the toxicological implications of the PBDE tissue levels found in SLE belugas.©2004 American Chemical Society

McKINNEY, M.A., A. ARUKWE, S. DE GUISE, P. BÉLAND, D. MARTINEAU, A. DALLAIRE, S. LAIR, M. LEBEUF, R.J. LETCHER, 2004. Characterization and profiling of hepatic cytochromes P450 and phase II xenobiotic-metabolizing enzymes in beluga whales (Delphinapterus leucas) from the St. Lawrence River Estuary and the Canadian Arctic. Aquat. Toxicol., 69: 35-49 .

Cytochromes P450 (CYP, phase I) and conjugating (phase II) enzymes can be induced by and influence the toxicokinetics (metabolism) and toxicity of xenobiotic contaminants in exposed organisms. Beluga whale (Delphinapterus leucas) from the endangered St. Lawrence (SL) River Estuary population exhibit deleterious health effects and various severe pathologies that have been associated with contaminant exposure. In contrast, such effects (e.g. reproductive and immunological impairment) are generally less frequent in less exposed populations in the Canadian Arctic (CA). In the present study, opportunistic sampling resulted in the collection immediately after death of liver tissue from a single female neonate SL beluga (SL6) and male and female CA beluga (n=10) from the Arviat region of western Hudson Bay, in addition to sampling of stranded carcasses of male and female SL beluga (n=5) at least 12 h postmortem. We immunologically characterized cross-reactive proteins of hepatic microsomal CYP1A, CYP2B, CYP3A, CYP2E, epoxide hydrolase (EH) and uridine diphosphoglucuronosyl transferase (UDPGT) isozymes. Cross-reactive proteins were found in all SL and CA beluga using anti-rat CYP1A1, anti-rainbow trout CYP3A, anti-human CYP2E1, anti-rabbit EH and anti-human UDPGT1A1 polyclonal antibodies (Abs), whereas faintly cross-reactive CYP2B proteins were only found in SL6 and the CA samples using an anti-rabbit CYP2B1 Ab. In corresponding catalytic activity assessments, only SL6 and all CA beluga microsomal samples exhibited CYP1A-mediated 7-ethoxyresorufin O-deethylase (EROD) activity (51-260 pmol/mg/min), CYP3A-mediated activity (113-899 pmol/mg/min) based on the formation of 6β-hydroxytestosterone using a testosterone hydroxylase assay, and UDPGT activity (830-4956 pmol/mg/min) based on 1-naphthylglucuronide formation. The marginal cross-reactivity with the anti-CYP2B1 Ab and lack of catalytically measurable hydroxytestosterone isomers associated with CYP2B-type activity in all the SL and CA animals is suggestive of low CYP2B-type enzyme expression in beluga. The absence of measurable total P450 enzyme levels and catalytic activities in samples from the stranded SL belugas suggested catalytically inactive enzymes as a consequence of tissue degradation related due to the time delay of sample collection after death. However, all SL and CA animals demonstrated similar, immunologically cross-reactive phase I and II hepatic enzyme profiles, which is suggestive of the importance of metabolism in the toxicokinetics and fate of xenobiotics in animals from both populations.©2004 Elsevier B.V. All rights reserved

LAW, R.J., M. ALAEE, C.R. ALLCHIN, J.P. BOON, M. LEBEUF, P. LEPOM, G.A. STERN, 2003. Levels and trends of polybrominated diphenylethers and other brominated flame retardants in wildlife. Environ. Int., 29(6): 757-770 .

LEBEUF, M., M. HAMMILL, B. SJARE, 2003. Using POPs to distinguish harbour seals (Phoca vitulina) colonies of Atlantic Canada. Organohalogen Compounds, 62: 236-239 .

GOUTEUX, B., M. LEBEUF, J.-P. GAGNÉ, 2003. Toxaphene in beluga whales (Delphinapterus leucas) from the St.Lawrence, Canada : levels and trends. Organohalogen Compounds, 62: 249-252 .

GOUTEUX, B., M. LEBEUF, D.C.G. MUIR, J.-P. GAGNÉ, 2003. Levels and temporal trends of toxaphene congeners in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, Canada. Environ. Sci. Technol., 37(20): 4603-4609 .

TITTLEMIER, S., J. BORREL, J. DUFFE, P.J. DUIGNAN, P. FAIR, A. HALL, P. HOEKSTRA, K.M. KOVACS, M.M. KRAHN, M. LEBEUF, C. LYDERSEN, D. MUIR, T. O'HARA, M. OLSSON, J. PRANSCHKE, P. ROSS, U. SIEBERT, G. STERN, S. TANABE, R. NORSTROM, 2002. Global Distribution of Halogenated Dimethyl Bipyrroles in Marine Mammal Blubber.. Arch. Environ. Contam. Toxicol., 43: 244-255 .

LEBEUF, M., M. NOËL, Y. CLERMONT, 2002. La contamination des ressources marines par les toxines. Saint-Laurent Vision 2000 (Suivi de l'état du Saint-Laurent, 22) 6 p. .

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LEBEUF, M., M. NOËL, Y. CLERMONT, 2002. Toxic contamination of marine resources. St. Lawrence Vision 2000 (Monitoring the state of the St. Lawrence River, 22) 6 p. .

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GOUTEUX, B., M. LEBEUF, S. TROTTIER, J.-P. GAGNÉ, 2002. Analysis of six relevant toxaphene congeners in biological samples using ion trap MS/MS. Chemosphere, 49: 183-191 .

HOBBS, K.E., M. LEBEUF, M.O. HAMMILL, 2002. PCBs and OCPs in male harbour, grey, harp and hooded seals from the Estuary and Gulf of St. Lawrence, Canada. Sci. Total Environ., 296: 1-18 .

LACROIX, A., M. FOURNIER, M. LEBEUF, J.J. NAGLER, D.G. Cyr, 2001. Phagocytic response of macrophages from the pronephros of American plaice (Hipoglossoides [i.e. Hippoglossoides] platessoides) exposed to contaminated sediments from Baie des Anglais, Quebec. Chemosphere, 45(4-5):599-607 .

LEBEUF, M., S. TROTTIER, 2001. The relationship between age and levels of polybrominated diphenyl ethers in beluga whales from the St. Lawrence estuary, Canada. Organohalogen Compounds, 52: 22-25 .

LEBEUF, M., K.E. BERNT, S. TROTTIER, M. NOËL, M.O. HAMMILL, L. MEASURES, 2000. Tris (4-chlorophenyl) methane and tris (4-chlorophenyl) methanol in marine mammals from the Estuary and Gulf of St. Lawrence. Environ. Pollut., 111(1): 29-43 .

LEBEUF M., K. BERNT, M. HAMMILL, L. MEASURES, 2000. Stratification of PCBs in the blubber of beluga whales (Delphinapterus leucas) from the St. Lawrence estuary. Organohalogen Compounds, 46: 487-490 .

LEBEUF, M., I. ST-PIERRE, Y. CLERMONT, C. GOBEIL, 1999. Concentrations de biphényles polychlorés (BPC) et de pesticides organochlorés chez trois espèces de poissons de fond de l'estuaire et du golfe du Saint-Laurent et du fjord du Saguenay. Rapp. stat. can. sci. halieut. aquat., 1059, 108 p .

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Concentrations of polychorinated biphenyls (PCBs) and organochlorine pesticides were determined in muscle and liver of Atlantic cod (Gadus morhua), American plaice (Hippoglossoides platessoides) and Greenland halibut (Reinhardtius hippoglossoides), which were sampled from the Estuary and Gulf of St. Lawrence, and from the Saguenay Fjord. The analyses included measurements of more than 35 organochlorine compounds, including approximately twenty PCB congeners, in 56 tissue samples. This report summarises data from over 1 900 individual measurements. All of the tissues contain measurable quantities of most of the PCBs and organochlorine pesticides. All fish have higher levels of contaminants in liver compared to muscle tissue. Liver concentrations are highest in cod and lowest in plaice, while concentrations in muscle are highest in halibut and lowest in cod. Regardless of the species, concentrations of contaminants are similar in samples from the Saguenay and the Estuary but are generally higher than in samples from the northeastern Gulf. According to the Canadian guidelines for the protection of human health, levels of total PCB and of DDT and its metabolites in fish tissues should not exceed 2 000 and 5 000 ng/g (wet weight), respectively. The levels of PCBs and organochlorine pesticides measured in muscle and liver samples of cod, plaice and halibut in this study are less than these guidelines. In fish livers, the highest concentrations of PCBs are less than one-half of the guideline, while levels of DDT and its metabolites are less than one-tenth of the guideline. In fish muscle, concentrations are up to 10 and 100 times lower than the guidelines, for PCBs and for DDT and its metabolites, respectively.

LEE, K., J.J. NAGLER, M. FOURNIER, M. LEBEUF, D.G. CYR, 1999. Toxicological characterization of sediments from Baie des Anglais on the St. Lawrence Estuary. Chemosphere, 39: 1019-1035 .

BERNT, K.E., M.O. HAMMILL, M. LEBEUF, K.M. KOVACS, 1999. Levels ans patterns of PCBs and OC pesticides in harbour and grey seals from the St. Lawrence Estuary, Canada. Sci. Total Environ., 243/244: 243-262 .

LEBEUF, M., K.E. BERNT, M. HAMMILL, M. NOËL, S. TROTTIER, 1998. Levels of tris (4-chlorophenyl) methane in seals and sediments from the estuary and gulf of St. Lawrence, Canada. Organohalogen Compounds, 39: 445-448 .

GILBERT, M., R. ALEXANDER, J. ARSENAULT, W.R. ERNST, W. FAIRCHILD, P. HENNIGAR, G. JULIEN, T. KING, M. LEBEUF, D. LEFAIVRE, 1998. Contamination par les BPC des sédiments et du crabe des neiges aux environs du site du naufrage de la barge Irving Whale après son renflouage ; PCB contamination of sediments and snow crab (Chionoecetes opilio) around the site of the sinking of the Irving Whale barge after its recovery. Rapp. tech. can. sci. halieut. aquat. ; Can. Tech. Rep. Fish. Aquat. Sci., 2204, 32 p .

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In the spring and early summer of 1997, sediment and snow crab (Chionoecetes opilio) samples were collected around the site where the barge Irving Whale had sunk and been recovered in the southern Gulf of St. Lawrence. The objectives of this sampling program were to : 1) assess changes in the local PCB contamination since the recovery of the barge, and 2) better determine potential impacts on the snow crab fishery in the southern Gulf. In addition, PCB concentrations and congener composition patterns were determined in various compartments of the Gulf ecosystem to provide insight into the fate of the missing PCBs that were lost from the barge and dispersed in the environment. PCB concentrations in sediments within contamination hotspots around the barge footprint decreased since the recovery of the barge and some spatial spreading of PCBs was observed, possibly as a result of local sediment movements during the winter. Although estimates of the total PCB load in sediments within an area of 20,000 m2 southeast of the barge footprint suggest a decrease from 119 kg in October 1996 to 76 kg in the spring of 1997, any apparent loss of PCBs from the site over the winter cannot be clearly established at present. The local PCB contamination of snow crab also decreased since the recovery of the barge, mainly in the concentration of less persistent low chlorinated PCB congeners that are typically found in the Aroclor 1242 PCB mixture of the barge. As a result, no crab samples collected around the Irving Whale site in 1997 had PCB concentrations exceeding the Canadian guideline for human consumption. Potential impacts of the local PCB contamination on the snow crab fishery in the southern Gulf are believed to be negligible, but the current fishing exclusion zone around the site should be maintained to ensure the quality of the fishery and to prevent the resuspension of locally-contaminated sediments.

ABARNOU, A., V. LOIZEAU, M. LEBEUF, A. VAN DER ZANDE, 1997. Bioaccumulation : chemical and biological factors governing the transfer of organic compounds in food chains. Pages 159-171 in Report of the ICES Advisory Committee on the Marine Environment 1997 (ICES Coop. Res. Rep., 222) .

LEBEUF, M., S. MOORE, C. BROCHU, 1996. The influence of PCBs and PCDFs in the sediments of Baie des Anglais on the Lower St. Lawrence Estuary. Organohalogen Compounds, 28: 243-247 .

LEBEUF, M., C. GOBEIL, C. BROCHU, S. MOORE, 1996. Direct atmospheric deposition versus fluvial inputs of PCDD/Fs to the sediments of the Lower St. Lawrence Estuary. Organohalogen Compounds, 28: 20-24 .

FOSTER ROBERTS, M.G., O. COSBY, A. ROUCHDY, M. LEBEUF, C. BROCHU, S. MOORE, 1995. Effective approaches to optimizing recovery of PCDD/DF for sediments. Organohalogen Compounds, 23: 41-45 .

LEBEUF, M., C. GOBEIL, Y. CLERMONT, C. BROCHU, S. MOORE, 1995. Non-ortho chlorobiphenyls in fish and sediments of the Estuary and Gulf of St. Lawrence. Organohalogen Compounds, 26: 421-426 .

LEBEUF, M., C. GOBEIL, C. BROCHU, S. MOORE, 1995. Polychlorinated dibenzo-p-dioxins and dibenzofurans in Laurentian Trough sediments, lower St. Lawrence Estuary. Organohalogen Compounds, 24: 293-298 .

GOBEIL, C., M. LEBEUF, 1992. Inventaire de la contamination des sédiments du chenal Laurentien : les biphényles polychlorés. Rapp. tech. can. sci. halieut. aquat., 1851, 45 p .

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The vertical distribution of polychlorinated biphenyls (PCBs) has been studied in the sediments of the Laurentian Trough, Lower St. Lawrence Estuary. The concentrations of PCBs in the Trough sediments is ten times lower than that of the sediments in Lake Ontario. Contrary to observations in Lake Ontario, PCBs accumulation in the Laurentian Trough sediments has not decreased in recent years. The mean accumulation rate of PCBs in the deep sediments of the Lower Estuary in the last decade is evaluated to similar to 450 kg/a. This value represents a large proportion of the PCB flux in the St. Lawrence River at Quebec City.

GOBEIL, C., D. PATON, F.A. McLAUGHLIN, R.W. MACDONALD, G. PAQUETTE, Y. CLERMONT, M. LEBEUF, 1991. Données géochimiques sur les eaux interstitielles et les sédiments de la mer de Beaufort. Rapp. stat. can. hydrogr. sci. océan., 101, 92 p .

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Five sediment box-cores were collected in the Beaufort Sea in September 1990. This report contains the results of the analyses showing the vertical distributions of nutrients (PO4- 3, SiO4- 4, NO3- plus NO2-, NO2-, NH4+, sulfate, chloride, iron and manganese in the porewaters. The vertical profiles of phosphorus, biogenic silicon, carbon, nitrogen, some metals (Mn, Fe, Al, Cd, Pb, Zn) and 210-lead in the solid phase are also included.