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Zuykov M.,Institute des Sciences de la Mer de Rimouski | Pelletier E.,Institute des Sciences de la Mer de Rimouski | Harper D.A.T.,Durham University
Chemosphere | Year: 2013

Contemporary environmental challenges have emphasized the need to critically assess the use of bivalve mollusks in chemical monitoring (identification and quantification of pollutants) and biomonitoring (estimation of environmental quality). Many authors, however, have considered these approaches within a single context, i.e., as a means of chemical (e.g. metal) monitoring. Bivalves are able to accumulate substantial amounts of metals from ambient water, but evidence for the drastic effects of accumulated metals (e.g. as a TBT-induced shell deformation and imposex) on the health of bivalves has not been documented. Metal bioaccumulation is a key tool in biomonitoring; bioavailability, bioaccumulation, and toxicity of various metals in relation to bivalves are described in some detail including the development of biodynamic metal bioaccumulation model. Measuring metal in the whole-body or the tissue of bivalves themselves does not accurately represent true contamination levels in the environment; these data are critical for our understanding of contaminant trends at sampling sites. Only rarely has metal bioaccumulation been considered in combination with data on metal concentrations in parts of the ecosystem, observation of biomarkers and environmental parameters. Sclerochemistry is in its infancy and cannot be reliably used to provide insights into the pollution history recorded in shells. Alteration processes and mineral crystallization on the inner shell surface are presented here as a perspective tool for environmental studies. © 2013 Elsevier Ltd.

Potvin E.,Seoul National University | Rochon A.,Institute des Sciences de la Mer de Rimouski | Lovejoy C.,Laval University
Journal of Phycology | Year: 2013

Round brown spiny cysts constitute a morphological group common in high latitude dinoflagellate cyst assemblages. The dinoflagellate cyst Islandinium minutum (Harland et Reid) Head, Harland et Matthiessen is the main paleoecological indicator of seasonal sea-ice cover in the Arctic. Despite the importance of this cyst in paleoceanographical studies, its biological affinity has so far been unknown. The biological affinity of the species I. minutum and its phylogenetic position based on the small subunit ribosomal RNA gene (SSU rDNA) and the large subunit ribosomal RNA gene (LSU rDNA) were established from cyst incubation experiments in controlled conditions, optical and scanning electron microscopy, and single-cell PCR. The thecal motile cell obtained was undescribed. Although the motile cell was similar to Archaeperidinium minutum (Kofoid) Jörgensen, the motile cell of I. minutum lacked a transitional plate in the cingular series, which is present in Archaeperidinium spp. Islandinium minutum and Archaeperidinium spp. were paraphyletic in all phylogenetic analyses. Furthermore, Protoperidinium tricingulatum, which also lacks a transitional plate, was closely related to I. minutum and transfered to the genus Islandinium. © 2013 Phycological Society of America.

Joly S.,Institute des Sciences de la Mer de Rimouski | Senneville S.,Institute des Sciences de la Mer de Rimouski | Caya D.,Consortium Ouranos | Saucier F.J.,Institute des Sciences de la Mer de Rimouski
Climate Dynamics | Year: 2011

A regional sea-ice-ocean model was used to investigate the response of sea ice and oceanic heat storage in the Hudson Bay system to a climate-warming scenario. Projections of air temperature (for the years 2041-2070; effective CO2 concentration of 707-950 ppmv) obtained from the Canadian Regional Climate Model (CRCM 4.2.3), driven by the third-generation coupled global climate model (CGCM 3) for lateral atmospheric and land and ocean surface boundaries, were used to drive a single sensitivity experiment with the delta-change approach. The projected change in air temperature varies from 0.8°C (summer) to 10°C (winter), with a mean warming of 3. 9°C. The hydrologic forcing in the warmer climate scenario was identical to the one used for the present climate simulation. Under this warmer climate scenario, the sea-ice season is reduced by 7-9 weeks. The highest change in summer sea-surface temperature, up to 5°C, is found in southeastern Hudson Bay, along the Nunavik coast and in James Bay. In central Hudson Bay, sea-surface temperature increases by over 3°C. Analysis of the heat content stored in the water column revealed an accumulation of additional heat, exceeding 3 MJ m-3, trapped along the eastern shore of James and Hudson bays during winter. Despite the stratification due to meltwater and river runoff during summer, the shallow coastal regions demonstrate a higher capacity of heat storage. The maximum volume of dense water produced at the end of winter was halved under the climate-warming perturbation. The maximum volume of sea ice is reduced by 31% (592 km3) while the difference in the maximum cover is only 2.6% (32,350 km2). Overall, the depletion of sea-ice thickness in Hudson Bay follows a southeast-northwest gradient. Sea-ice thickness in Hudson Strait and Ungava Bay is 50% thinner than in present climate conditions during wintertime. The model indicates that the greatest changes in both sea-ice climate and heat content would occur in southeastern Hudson Bay, James Bay, and Hudson Strait. © 2010 Springer-Verlag.

Boutin S.,Laval University | Bernatchez L.,Laval University | Audet C.,Institute des Sciences de la Mer de Rimouski | Derome N.,Laval University
PLoS ONE | Year: 2013

Interactions between bacteria and their host represent a full continuum from pathogenicity to mutualism. From an evolutionary perspective, host-bacteria relationships are no longer considered a two-component system but rather a complex network. In this study, we focused on the relationship between brook charr (Salvelinus fontinalis) and bacterial communities developing on skin mucus. We hypothesized that stressful conditions such as those occurring in aquaculture production induce shifts in the bacterial community of healthy fish, thus allowing pathogens to cause infections. The results showed that fish skin mucus microbiota taxonomical structure is highly specific, its diversity being partly influenced by the surrounding water bacterial community. Two types of taxonomic co-variation patterns emerged across 121 contrasted communities' samples: one encompassing four genera well known for their probiotic properties, the other harboring five genera mostly associated with pathogen species. The homeostasis of fish bacterial community was extensively disturbed by induction of physiological stress in that both: 1) the abundance of probiotic-like bacteria decreased after stress exposure; and 2) pathogenic bacteria increased following stress exposure. This study provides further insights regarding the role of mutualistic bacteria as a primary host protection barrier. © 2013 Boutin et al.

Bourgault D.,Institute des Sciences de la Mer de Rimouski | Janes D.C.,Memorial University of Newfoundland | Galbraith P.S.,Northwest Atlantic Fisheries Center
Journal of Physical Oceanography | Year: 2011

Remote and in situ field observations documenting the reflection of a normally incident, short, and largeamplitude internal wave train off a steep slope are presented and interpreted with the help of the Dubreil- Jacotin-Long theory. Of the seven remotely observed waves that composed the incoming wave train, five were observed to reflect. It is estimated that the incoming wave train carried E i = (24± 4) 3 10 4 J m -1 to the boundary. The reflection coefficient, defined as the ratio of reflected to incoming wave train energies, is estimated to be R = 0.5 ± 0.2. This is about 0.4 lower than parameterizations in the literature, which are based on reflections of single solitary waves, would suggest. It is also shown that the characteristics of the wave-boundary situation observed in the field are outside the parameter space examined in previous laboratory and numerical experiments on internal solitary wave reflectance. This casts doubts on extrapolating current laboratory-based knowledge to fjord-like systems and calls for more research on internal solitary wave reflectance. © 2011 American Meteorological Society.

Morissette L.,Institute des Sciences de la Mer de Rimouski | Morissette L.,University of British Columbia | Christensen V.,University of British Columbia | Pauly D.,University of British Columbia
PLoS ONE | Year: 2012

Competition between marine mammals and fisheries for marine resources-whether real or perceived-has become a major issue for several countries and in international fora. We examined trophic interactions between marine mammals and fisheries based on a resource overlap index, using seven Ecopath models including marine mammal groups. On a global scale, most food consumed by marine mammals consisted of prey types that were not the main target of fisheries. For each ecosystem, the primary production required (PPR) to sustain marine mammals was less than half the PPR to sustain fisheries catches. We also developed an index representing the mean trophic level of marine mammal's consumption (TLQ) and compared it with the mean trophic level of fisheries' catches (TLC). Our results showed that overall TLQ was lower than TLC (2.88 versus 3.42). As fisheries increasingly exploit lower-trophic level species, the competition with marine mammals may become more important. We used mixed trophic impact analysis to evaluate indirect trophic effects of marine mammals, and in some cases found beneficial effects on some prey. Finally, we assessed the change in the trophic structure of an ecosystem after a simulated extirpation of marine mammal populations. We found that this lead to alterations in the structure of the ecosystems, and that there was no clear and direct relationship between marine mammals' predation and the potential catch by fisheries. Indeed, total biomass, with no marine mammals in the ecosystem, generally remained surprisingly similar, or even decreased for some species. © 2012 Morissette et al.

Simon Q.,University of Quebec at Montréal | St-Onge G.,Institute des Sciences de la Mer de Rimouski | Hillaire-Marcel C.,University of Quebec at Montréal
Geochemistry, Geophysics, Geosystems | Year: 2012

The late Quaternary Baffin Bay sediments provide exclusive records of Greenland, Innuitian and Laurentide ice sheet margin activities, as well as information about the Arctic and northern Atlantic ocean linkages through the Canadian Arctic Archipelago. Because of specific oceanographic conditions, foraminiferal δ18O-stratigraphies and radiocarbon ages fail to provide reliable chronologies. Here we propose an original chronostratigraphy spanning the last glacial cycle based on high-resolution paleomagnetic investigations on a 741-cm long core (HU2008-029-016PC) raised from the deep central Baffin Bay, near ODP site 645. Two major difficulties were encountered: (1) the high-frequency occurrence of rapidly deposited layers related to short ice sheet margin events (e.g., ice surges), and (2) the magnetic grain size variability. Physical and magnetic mineralogical properties were used to screen out unreliable magnetic sediment layers. The obtained relative paleointensity (RPI) proxy matches reference paleomagnetic stacks and regional records. Moreover, the resulting record depicts two major excursions which were assigned to the Laschamp and the Norwegian-Greenland-Sea events. It has thus been possible to derive a robust 115ka chronology for the cored sequence. We concluded that even under such a dynamic sedimentary regime, magnetic properties of the sediments can provide a reliable chronostratigraphy, together with information on sedimentary processes. © 2012 American Geophysical Union. All Rights Reserved.

Bringue M.,Institute des Sciences de la Mer de Rimouski | Rochon A.,Institute des Sciences de la Mer de Rimouski
Marine Geology | Year: 2012

Late Holocene paleoceanography and climate variability of the Southeastern Beaufort Sea (Canadian Arctic) have been investigated on the basis of sedimentary cores collected over the Mackenzie Slope. Piston, trigger and box cores were sampled at station 803 in 2004 aboard the CCGS Amundsen at 218m water depth. The chronology of the piston core is constrained by 4 AMS- 14C dates, as the sedimentation rate in the box core is assessed from 210Pb data. We obtain a continuous composite sequence covering the last 4600years, with a sedimentation rate of ~140cm.kyr -1. Transfer functions (modern analogue technique) based on dinoflagellate cyst (dinocyst) assemblages were used to reconstruct the evolution of sea-surface conditions over the time period covered by the cores.Palynological data reveal that dinocyst assemblages are dominated by Operculodinium centrocarpum sensu lato (mean of 43.3%) throughout the core, with the accompanying taxa Brigantedinium spp. (19.6%), Islandinium minutum (15.6%) and cysts of Pentapharsodinium dalei (13.7%). Four zones have been established on the basis of dinocyst relative abundances. Dinocyst assemblage zone 1 (D1), from 4600 to 2700. cal years BP, is dominated by O. centrocarpum (mean of 49.0%). In zone D2 (2700-1500. cal years BP), the relative abundances of O. centrocarpum decrease (34.4%) in favour of the opportunistic, heterotrophic taxa Brigantedinium spp. (28.8%) and cysts of Polykrikos sp. var. arctic/quadratus (2.8%). Dinocyst zone D3 (1500-30. cal years BP or 450-1920. AD) is characterised by the high relative abundance of the peridinioid taxa I. minutum (19.9%). The last zone (D4), spanning from 1920 to 2004. AD, is again dominated by O. centrocarpum (44.5%), and shows low relative abundances of Brigantedinium spp. and cf. Echinidinium karaense.Quantitative reconstructions of past sea-surface parameters (August sea-surface temperature: SST, August sea-surface salinity: SSS, and duration of sea-ice cover) indicate relatively stable conditions over the last 4.6. kyr, with episodic cooling events (SST of ~. 1.5°C below the modern value of 6°C) that took place between 700 and 1820. AD. We associate the last and the longest of these cooling events (1560-1820. AD) with the Little Ice Age. Reconstructed SSS shows decadal oscillations since 1920. AD that we tentatively associate with the accumulation of freshwater by the Beaufort Gyre and the subsequent Great Salinity Anomalies. Our data suggest that similar salinity anomalies could have occurred ca. 1860 and 1790. AD.Stable isotopic data show a slight increase in δ 13C values (from ~-27.1‰ at the base to ~-25.8‰ at the top) over the last 4.6kyr that we associate with the gradual increase in atmospheric CO 2 concentration as recorded by Antarctic ice cores. Variations in the δ 15N profile suggest variations in Pacific water influence from 4600 to ~1300cal years BP, associated with centennial scale shifts of the Arctic Oscillation phases. © 2011 Elsevier B.V..

Doiron K.,Institute des Sciences de la Mer de Rimouski | Pelletier E.,Institute des Sciences de la Mer de Rimouski | Lemarchand K.,Institute des Sciences de la Mer de Rimouski
Aquatic Toxicology | Year: 2012

The use of silver nanoparticles (AgNPs) in consumer products is increasing drastically and their potential environmental impacts on aquatic organisms from bacterial communities to vertebrates are not well understood. This study reports on changes in marine bacterial richness using denaturing gradient gel electrophoresis (DGGE), and overall community abundance determined by flow cytometry in marine microcosms exposed to polymer-coated AgNPs (20±5nm) and ionic silver (Ag+). Our study clearly demonstrated that at low concentrations (5 and 50μgL-1 total silver), un-aggregated polymer-coated AgNPs and dissolved Ag+ contamination produced similar effects: a longer lag phase suggesting an adaptation period for microorganisms. As richness decreased in the treated samples, this longer lag phase could correspond to the selection of a fraction of the initial community that is insensitive to silver contamination. Polymer-coated AgNPs preserved their bactericidal properties even under the high ionic strength of estuarine waters. © 2012 Elsevier B.V.

Crespel A.,Institute des Sciences de la Mer de Rimouski
G3 (Bethesda, Md.) | Year: 2013

Discriminating between genetic and environmental causes of phenotypic variation is an essential requirement for understanding the evolutionary potential of populations. However, the extent to which genetic variation differs among conspecific groups and environments during ontogeny has rarely been investigated. In this study, the genetic basis of body mass was measured in three divergent strains of brook charr (Salvelinus fontinalis) in different rearing environments and at different time periods. The results indicate that body mass was a heritable trait in all strains but that the level of heritability greatly differed among strains. Moreover, heritability estimates of each strain varied differently according to environmental rearing conditions, and cross-environments correlations were all significantly lower than unity, indicating strain-specific patterns of genotype-environment interactions. Heritability estimates also varied throughout ontogeny and decreased by 50% from 9 to 21 months of age. This study highlights the divergence in genetic architecture and evolutionary potential among these strains and emphasizes the importance of considering the strain-specific potential of the response to selection according to environmental variation.

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