Downstream variations of phytoplankton in the St.Lawrence River (Québec, Canada)

Longitudinal variations of phytoplankton biomass and composition were assessed in a 250 km-long section of the St.Lawrence River, which alternately runs through narrow (< 2 km) river cross sections and wide (up to 10 km) fluvial lakes. In the main river stem, concentrations of suspended matter and total phosphorus increased with distance downstream, whereas light penetration decreased. Seasonal changes in plankton composition and biomass were more important than those resulting from differences in water mass (tributary) of origin. Sampling at three cross river sections and in two fluvial lakes showed a progressive downstream decrease in phytoplankton biomass and changes in size structure and taxonomic composition. River plankton was primarily composed of small (< 10 µm equivalent spherical diameter), truly planktonic cells belonging to Cryptophyceae and diatoms, with Chlorophyceae in summer. Plankton sampled in summer among rooted macrophytes in fluvial lakes exhibited a higher biomass of resuspended periphytic algae than in the main river stem, which contributed slightly to downstream phytoplankton biomass.Successive river cross sections always shared about 50% of their taxa, indicating a rapid downstream transport of algae within the main water mass. However, the proportion of species common to all cross sections was highest during the spring freshet, and lowest during summer low discharge, likely resulting from the development of a distinct flora in fluvial lakes during summer. Conversely, about 30% of the identified taxa were exclusive to a cross section and were replaced by others occurring downstream. Overall, phytoplankton composition along the St.Lawrence River is primarily controlled by advective forces, which result in a homogeneous flora in the main river stem, with a local contribution of resuspended periphyton from fluvial lakes.     

Genetic epidemiology of lipoprotein lipase deficiency in Saguenay-Lac-St-Jean (Québec, Canada).

Familial hyperchylomicronemia due to the lipoprotein lipase (LPL) activity deficiency (Type I hyperlipoproteinemia) is an autosomal recessive disorder with a prevalence estimated at one case per million. Thirty-four type I individuals are known in Saguenay-Lac-St-Jean (SLSJ), a geographically isolated region of Quebec. The prevalence of type I and LPL deficient heterozygote in this region was estimated at 1/6382 and 1/46 inhabitants respectively. The mean inbreeding coefficient was slightly elevated in the type I group compared with three control groups. The mean kinship coefficient was 15.1 times higher in the type I group than in the control groups. The high prevalence of type I in SLSJ appears to be the result of the emigration of carriers of LPL deficiency from Charlevoix, another isolated region of quebec to the SLSJ region. Endogamy also played a crucial role in increasing the prevalence of type I in SLSJ.     

Biogeography of copepods in lakes and ponds of subarctic Québec,Canada

We aimed to determine whether the copepod assemblages in lakes and ponds of northern Québec, Canada, were closer in composition to those found in southern Québec, or to those reported from the subarctic and arctic. Six calanoid and five cyclopoid species were identified from 37 ponds and lakes located in the region between 55° N and 59° N. Species diversity was generally low, ranging from 0 to 4 species per lake. Dominant species were Leptodiaptomus minutus and Acanthocyclops vernalis. The species assemblages showed high affinity with those found in forested regions of southern Québec. Exceptions were Leptodiaptomus tyrrelli, previously only recorded west of Hudson Bay, and Hesperodiaptomus arcticus, hitherto recorded north of 58° N. Relationships between the lakes, species, and environmental variables were explored using multivariate analysis. Lakes situated along the coast and on two offshore islands clustered together and were characterised by higher conductivity and pH than those lakes located further inland. Leptodiaptomus tyrrelli was common in these coastal lakes. Canonical correspondence analysis revealed statistically significant relationships between copepod distributions and conductivity, dissolved organic carbon and pH. These three variables accounted for 70% of the variation in the species' distribution.     

Tree-ring analysis of white cedar (Thuja occidentalis L.) archaeological and historical wood in Québec City (Québec,Canada)

In Québec City, a segment of an old wooden palisade built for protection was found buried in situ. The palisade was excavated by the Laval University archaeology field school in 2004–2005, and 29 posts were recovered and sampled. The palisade enclosed the Intendant's Palace compound, which was the residence of the governor of New France at the end of the 17th century. Tree-ring analysis was performed on wood excavated from the Intendant's Palace archaeological site (PDI) and additional wood from two historical military buildings, the Artillery Park (ART) (early 18th century) and the Québec Citadel (CIT) (17th–19th centuries). Wood identification revealed that white cedar (Thuja occidentalis L.) was used for wood construction at the three sites. Many trees used for the construction of the PDI palisade were felled after the 1690 growing season, likely in September/October 1690. Posts probably came from trees growing close to the site on the banks of the Saint-Charles River. A white cedar ring-width chronology from the Rimouski area, approximately 300 km northeast of Québec City, along the St. Lawrence River, was used for cross-dating. Archaeological and historical wood samples from two of the three sites (PDI and ART) were first assembled in a 235-year tree-ring chronology, called the Québec chronology, extending from 1489 to 1723. The two master chronologies (Québec and Rimouski) were merged into a single 513-year tree-ring chronology (1489–2001), called the Saint-Laurent chronology.     

Targeted surveillance of raccoon rabies in Québec,Canada

Data from wildlife disease surveillance programs are used to inform implementation of disease control (e.g., vaccination, population reduction) in space and time. We developed an approach to increase detection of raccoon rabies in raccoons (Procyon lotor) and skunks (Mephitis mephitis) of Québec, Canada, and we examined the implications of using this approach for targeted surveillance. First we modeled the probability of a rabid animal relative to environmental characteristics of sampling locations. Rabid animals were more likely to be found in low-lying flat landscapes that had higher proportions of corn-forest edge habitat and hay agriculture, and that were within 20 km of one or more known rabies cases. From the model, we created 2 complementary risk maps to identify areas where rabid animals were most likely to be sampled. One map accounted for habitat and known rabies case locations, and can be used to define an infection zone from which surveillance can be targeted along the periphery to determine if disease is continuing to spread. The other map only accounted for habitat and can be used to locate areas most likely to contain rabid animals when the disease is present. In a further analysis we compared the 2 most successful methods for detecting raccoon rabies in Québec, given the disease was present. Government trapping operations (active surveillance) detected more cases in the short-term, but citizen notification (passive and enhanced) was more effective after 12 trapping days from which the initial rabies case was found. Our approach can benefit wildlife and public health agencies wanting to assess the disease status of regions by targeting surveillance to habitats most likely to contain infected animals and by defining the duration over which sampling methods are effective. © 2011 The Wildlife Society.     

Exploratory multiscale analysis of the fish assemblages and habitats of the lower St. Lawrence River,Québec,Canada

This work presents a multiscale analysis of the fish diversity of the lower St. Lawrence River which flows from the Laurentian Great Lakes of North America. A database of about 14,000 fish sampling stations from the lower St. Lawrence is linked to five different habitat maps of the study area: hydrographical units, water masses, depth, sediment type and wetland type. We hypothesize that species turnover (beta diversity) will be significant among these habitat maps. For each map, we calculate a UPGMA dendrogram based on the Jaccard coefficient of similarity in species occurrences as a first assemblage–habitat model. A randomization test is then used to identify the significant dendrograms from which we infer fish assemblages. We then show that many species are actually selecting or avoiding habitats. Finally, species selecting particular habitats are described by some selected ecological traits that are expected to occur frequently in those habitats. We found assemblages for the hydrographical units but not for the water masses. The fluvial section is selected by many stenohaline and some euryhaline species, while the freshwater estuary and the brackish estuary are only selected by euryhaline species. In the fluvial section at the hydrographical unit scale, many species associated with lentic habitats are limnophilic and more vegetation-dependent while many species selecting lotic habitats are rheophilic insectivorous species. Significant assemblages are defined for depth, sediment type and wetland type. Taken together, we found strong empirical evidence of a diverse actively selecting littoral assemblage of small, low mobility fishes opposing a channel assemblage of larger, more mobile fishes.     

Variations in water temperatures and levels in the St. Lawrence River (Québec,Canada) and potential implications for three common fish species

The implications for fish populations of long- (multi-decadal, 1919–2007), medium- (inter-annual) and short- (seasonal, daily) term variations in water temperatures and levels were examined in the St. Lawrence River (SLR). The effects of the seasonal thermal regime of the SLR and its tributaries on the thermal budgets of resident and migrating fish were contrasted. Over the 1919–2007 period, the mean annual water level in Montreal declined significantly; for a discharge of 8,000 m³ s⁻¹, levels dropped steadily by about 3.6 cm year⁻¹ between 1955 and 1982, coinciding with the period of major shoreline alteration and channel excavation. Between 1960 and 2007, the annual water temperature of the SLR rose by 1.3°C (0.027°C year⁻¹); none of the 10 coldest years and six of the 10 warmest years were observed since 1981. Temperature differences between the warmest and coolest years were greatest in spring and fall (by about 2.5°C); fish growing season (>5°C) was longer by 5 weeks and represented 20% more degree-days for the warmest years. In comparison with its tributaries, SLR water was slower to warm up in the spring but remained warmer in the fall: fish migrating seasonally between water masses could thus enhance or reduce their thermal budgets by 1–2°C daily. Northern pike recruitment years (year-class strength index [YCSI] values above the time series median) were best with June water levels >4.9 m IGLD85 (International Great Lakes Datum of 1985), combined with June air temperatures >18.6°C. For yellow perch, water temperatures >16.2°C in June alone explained six out of the eight best recruitment years in the time series. Conversely, an episode of massive carp mortality in 2001 exemplifies the inherent risk of using shallow flooded habitats for spawning when rapidly dropping levels coincide with hot, sunny weather. The effects of water temperature and level, singly and in combination, thus appear to be critical variables in determining successful fish recruitment in shallow riparian areas—areas which constitute the most important yet the most elusive fish spawning and nursery habitats.     

Ichthyophonus-like infection in wild amphibians from Québec, Canada

Myositis associated with infection by Ichthyophonus-like organisms was diagnosed in 35 of 260 (13%) wild amphibians collected in Quebec, Canada, from 1959 to 1964 (n = 30), and 1992 to 1999 (n = 230). Infection was diagnosed in 17 green frogs Rana clamitans, 9 wood frogs R. sylvatica, 4 red-spotted newts Notophthalmus viridescens, 3 bullfrogs R. catesbeiana, 1 spring peeper Pseudacris crucifer, and 1 pickerel frog R. palustris. The spring peeper and one of the bullfrogs were collected in 1964 from the Mont Saint-Hilaire Biosphere Reserve, indicating long-term presence of the organism. Spores of the organisms invaded striated muscle fibers and were associated with variable degrees of granulomatous and eosinophilic inflammation. Infection was considered fatal in 2 green frogs, 1 wood frog, and 1 red-spotted newt. It was considered potentially significant in 3 additional green frogs in which up to 100% of the fibers of some muscles were replaced by spores associated with a severe granulomatous reaction. Ultrastructural features of Ichthyophonus-like spores included a thick trilaminated wall, a paramural cytoplasm, multiple nuclei, oval mitochondria with short tubulo-vesicular cristae and numerous ribosomes. This report represents 4 new host records and shows that ichthyophonosis is enzootic in amphibians from Quebec.     

Hydrocarbons,Pb-Concentrations,and Pb-Isotope Ratios in Contaminated Alluvial Soils (Southern Québec,Canada)

Hydrocarbon-contaminated layers found over 100 kilometers of riverbanks (southern Québec) were investigated. Analytical results for hydrocarbons, trace metals, Pb concentrations, and Pb isotopic signatures (²⁰⁶Pb/²⁰⁷Pb, ²⁰⁸Pb/²⁰⁶Pb, ²⁰⁴Pb/²⁰⁶Pb) of contaminated soil are presented. Soil samples show hydrocarbon concentrations (C₁₀-C₅₀) ranging from <60 to 660 mg kg^?1. Higher concentrations were found in the Richmond site (southern Québec). The values for Pb-concentrations ranged between 7 and 149 mg kg^?1 with median value of 23 mg kg^?1. For the Pb isotope ratios, the values obtained in the hydrocarbon layer range from 1.124 to 1.175 ± 0.011 (²⁰⁶Pb/²⁰⁷Pb), 2.085 to 2.126 ± 0.011 (²⁰⁸Pb/²⁰⁶Pb), and 0.054 to 0.057 ± 0.000 (²⁰⁴Pb/²⁰⁶Pb). The combination of various techniques used allows us to distinguish the various sources of contaminants. The study also reveals that Pb and other trace metal elements continue to be found in the fluvial environment, even after many years, and this soil pollution could affect the quality of streams and living organisms.     

Chitinozoan zonation of the Late Ordovician and the Early Silurian of the island of Anticosti, Québec, Canada

A reappraisal of chitinozoan distribution across the Ordovician-Silurian boundary on the Island of Anticosti has led to the recognition of a new zone, the Ancyrochitina ellisbayensis biozone, in the uppermost part of the Ellis Bay Formation. This biozone lies between the well defined Upper Ordovician Spinachitina taugourdeaui biozone and the lowest Silurian (Rhuddanian) Plectochitina nodifera biozone of the Becscie Formation. The occurrence of such diagnostic species as P. nodifera, Belonechitina postrobusta, Conochitina electa and Ancyrochitina ramosaspina in the Lower Silurian of Anticosti points to a close similarity to faunas in Estonia and north Latvia and indicates an age ranging from the Parakidograptus acuminatus to the Coronograptus cyphus in terms of graptolite zones. The chitinozoan biozonation harmonizes with that based on conodonts and, to a lesser extent, with the known graptolite faunal succession. Five new species: Ancyrochitina ellisbayensis sp. nov., Clathrochitina postconcinna sp. nov., Conochitina gunriveris sp. nov., Clathrochitina perexilis sp. nov., Bursachitina basiconcava sp. nov. and three species in open nomenclature are described.     

A study to assess the microbial contamination of Mya arenaria clams from the north shore of the St Lawrence River estuary, (Québec, Canada)

The aims of the present study were to assess the microbial quality of Mya arenaria clams from the north shore of the St. Lawrence River estuary and to validate various microbial indicator microorganisms of bivalve mollusks contamination. Clams were collected from nine sites, including four harvesting sites closed by virtue of the Canadian Shellfish Sanitation Program (CSSP). Six contamination indicators (fecal coliforms, somatic coliphages, F-specific coliphages, fecal streptococci, Clostridium perfringens, and Escherichia coli) and four pathogens (Campylobacter sp., Cryptosporidium parvum, Giardia sp., and Salmonella sp.) were identified in the clams. Indicators sensibility, specificity and predictive values with respect to the presence of pathogens were calculated. Pathogenic microorganisms detection frequency in clams was important (92%). Globally, pathogens tend to be less frequently detected in opened harvesting sites (p = 0.086). Although the assessed indicators were not perfect, when F-specific coliphages are associated with E. coli or fecal coliforms, a good sensibility (62%-64%) and good positive predictive value (88%) with respect to the investigated pathogens are obtained.     

Genotyping by sequencing suggests overwintering of Peronospora destructor in southwestern Québec,Canada

Several Peronospora species are carried by wind over short and long distances, from warmer climates where they survive on living plants to cooler climates. In eastern Canada, this annual flow of sporangia was thought to be the main source of Peronospora destructor responsible for onion downy mildew. However, the results of a recent study showed that the increasing frequency of onion downy mildew epidemics in eastern Canada is associated with warmer autumns, milder winters, and previous year disease severity, suggesting overwintering of the inoculum in an area where the pathogen is not known to be endogenous. In this study, genotyping by sequencing was used to investigate the population structure of P. destructor at the landscape scale. The study focused on a particular region of southwestern Québec—Les Jardins de Napierville—to determine if the populations were clonal and regionally differentiated. The data were characterized by a high level of linkage disequilibrium, characteristic of clonal organisms. Consequently, the null hypothesis of random mating was rejected when tested on predefined or nonpredefined populations, indicating that linkage disequilibrium was not a function of population structure and suggesting a mixed reproduction mode. Discriminant analysis of principal components performed with predefined population assignment allowed grouping P. destructor isolates by geographical regions, while analysis of molecular variance confirmed that this genetic differentiation was significant at the regional level. Without using a priori population assignment, isolates were clustered into four genetic clusters. These results represent a baseline estimate of the genetic diversity and population structure of P. destructor.     

Distribution, abundance, and seasonal ecology of Listronotus maculicollis (Coleoptera: Curculionidae) on golf courses in Québec, Canada

The weevil Listronotus maculicollis Dietz (Coleoptera: Curculionidae) is a major pest of annual bluegrass, Poa annua L., on golf courses in northeastern North America. To determine the distribution, abundance, and seasonal ecology of L. maculicollis on golf courses in Québec, Canada, we sampled 19 golf courses (GC1-GC19) from different geographic and climatic conditions during 2001, 2002, and 2003. L. maculicollis was found on all golf courses except GC19, which was located in northeastern Québec. In most sites, L. maculicollis completed two generations per year. A linear regression model comparing L. maculicollis larval densities as a function of spatial coordinates revealed that L. maculicollis were more abundant in western Québec than in eastern Québec. Pearson correlations on the probability of both L. maculicollis larval and pupal presence with soil parameters indicated significant positive correlations for fine sand (larvae) and soil pH (pupae) and negative correlations for gravel.     

Factors influencing aboveground production of Scirpus marshes in the St. Lawrence estuary,Québec,Canada

Aboveground production of macrophytes in tidal marshes was studied for 3 years at Montmagny and Cap St. Ignace on the south shore of the St. Lawrence River in Québec, Canada. Year-to-year variation of production of the dominant species, Scirpus americanus Pers., was observed and related to variation in weather during the growing season. With the exception of Zizania aquatica L., relative production of the macrophytes for different parts of the marshes remained constant in successive years. A multiple regression procedure was used to establish the relationship between production and a series of independent variables including biotic (goose use and plant competition) and abiotic factors (submersion, substrate hardness, soil texture and sedimentation). A lower percentage of organic matter in the soil and a firm substrate were associated with a greater production of S. americanus. Accretion of sediments was positively correlated with the production of S. americanus and Sagittaria spp., whereas the percentage of time of submersion was negatively related with production of Sagittaria spp., Eleocharis spp. and Scirpus torreyi Olney. Competitive interference was apparent between S. americanus and S. torreyi and between Eleocharis spp. and Zizania spp. No measured abiotic characteristic of the marsh explained the variation of Zizania production.     

Evaluation of a Questionnaire-Based Method for the Estimation of Methylmercury Exposure of Recreational Anglers in the James Bay Territory (Québec,Canada)

The impoundment of reservoirs temporarily increases the methylation of mercury bound to flooded soils and vegetation and the transfer of methylmercury (MeHg) to fish. MeHg levels in various fish species of hydroelectric reservoirs located in the James Bay territory increased by factors of 3 to 7, then gradually declined toward initial concentrations 10 to 20 years after flooding, depending on reservoir characteristics. The potential risk of increased MeHg exposure for recreational anglers who consume fish from these reservoirs had not been assessed previously. A less invasive method than systematic measurement of Hg levels in hair was developed to determine MeHg exposure of recreational anglers. A fish consumption questionnaire-based approach was combined with a toxicokinetic model to estimate the corresponding hair MeHg concentrations. The results were compared with actual analytical determinations of hair Hg levels for the 94 recreational anglers recruited for the study. The values predicted by the model based on self-reporting consumption overestimated actual hair Hg levels by an average factor greater than 6. The mean hair level predicted for the most recent period (September-October) was 23.3?µg.g^?1 compared to 3.6 µg.g^?1 for the measured value. Although the questionnaire protocol may certainly be improved to increase the precision of estimations, direct hair Hg measurement remains the more effective means to assess Hg exposure.     

Seasonal water chemistry and diatom changes in six boreal lakes of the Laurentian Mountains (Québec,Canada): impacts of climate and timber harvesting

The physical and chemical variabilities as well as the distribution of diatoms of six boreal lakes in the Laurentian Mountains (southern Québec, Canada) were studied. The lakes are located along an altitudinal gradient and were sampled at a biweekly resolution from May through October, 2002. In general, we found later onset and weaker lake stratification under colder climates. Lake circulation and SiO₂ are strongly correlated and together significantly explain the distribution of diatoms of the individual lakes. Diatoms that accumulated in the sediment traps were mostly composed of benthic species, suggesting resuspension. However, diatom flux and lake circulation were not significantly correlated, the diatom assemblages in the sediment traps were similar in two consecutive years, and species–environment relationships were comparable among lakes, which indicates that the effects of resuspension were minimal. In addition, we found that one lake was more productive due to forest logging. The forest in the catchment of Lake Maxi was entirely clear-cut shortly prior to our sampling. Mean total phosphorus, dissolved organic carbon, and chlorophyll a concentrations were significantly higher when compared to the other five study lakes. This study seeks to improve our understanding of how diatoms in boreal lakes respond to climate change and forest clear-cut.     

High concentrations of viruses in the sediments of Lac Gilbert, Québec

Viruses were found to be very abundant in the top layer of the sediments of Lac Gilbert, Québec. Viruses were extracted from the sediments using pyrophosphate buffer, and viruses from the diluted extracts were pelleted onto grids and enumerated using transmission electron microscopy. Viral abundance in the sediments ranged from 6.5 × 10⁸ to 1.83 × 10¹⁰ ml^–1, which is 10- to 1,000-fold greater than the number observed in the water column. This increase corresponds well with the 100- to 1,000-fold increase in bacterial abundance in the sediments. Viral abundance differed significantly among the surface sediment samples taken at different bottom depths and among samples taken at different depths of the water column. Viral abundance also varied significantly between the oxic and anoxic zones of the water column and the sediments. The virus-to-bacteria ratio varied greatly among the different sediment sites but not among depths in the water column. Viral abundance in the water column was related to bacterial abundance and chlorophyll concentration, whereas viruses in the sediments were most abundant in sediments with high organic matter content. Elevated viral abundance and their erratic distribution in the sediments suggest that viruses might play an important role in sediment microbial dynamics. Correspondence to: Roxane Maranger     

Isolation and diversity of culturable rhizobacteria associated with economically important crops and uncultivated plants in Québec,Canada

Plants are chronically associated with microorganisms, residing all tissues. Holonomic analysis of diversity of established rhizobacteria in uncultivated plants is scarce. Thus, the present study was conducted to access the root-associated bacterial diversity of 6 crops (maize, canola, soybean, reed canarygrass, alfafa, and miscanthus) and 20 uncultivated plant species in the region of Sainte-Anne-de-Bellevue, Québec, Canada, using pure-culture methods. Based on 16S rRNA gene sequence analysis, 446 bacterial isolates were distributed onto four phyla (Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes), 32 families and 90 genera. Proteobacteria constituted the largest group of isolates (240), 40% of ectophytic and 61% of endophytic bacteria. Representatives of the genera Bacillus and Pseudomonas dominated in rhizosphere soil; Microbacterium and Pseudomonas were the predominant endophytes. Some genera were associated with specific plant species, such as Stenotrophomonas, Yersinia, Labrys and Luteibacter. Several endophytes were occasionally observed in the rhizosphere, and vice versa. This is the first survey of culturable endophytic bacteria associated with uncultivated plants in Québec. The culturable bacterial community studied herein are assumed to represent a portion of the entire phytomicrobiome of the evaluated plants. Results confirmed that the crops and uncultivated plants of Québec represent an extremely rich reservoir of diverse rhizobacteria.     

Vegetation patterns to characterize stream valleys in Hilly Southern Québec,Canada

Patterns in vegetation landscapes depend on a complex interplay between processes operating at various scales in time and space. Large-scale variations in environmental factors such as climate and landforms set a background in which smaller local-scale processes are involved. Disturbances superimpose variations on environmental factors and are also dependent on these. Stream valleys of hilly land in Southern Québec have been examined at different scales. Vegetation landscape units have been characterized at the level of landform (vegetation pattern), topographic gradient (geosigmassociation) and ecosite (synassociation). Extension of the methodology up to biogeographical units and practical applications are considered. xx]Nomenclature: plants: Scoggan, 1979; phytosociological units: Ansseau \s& Grandtner, 1986 \s& 1988; Theurillat \s& Moravec, 1990a, b. papers presented at the Vth INTECOL Congress at Yokohama 1990.