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.     

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.     

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.     

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.     

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.     

Physiological, Endocrine, and Genetic Bases of Anadromy in the Brook Charr, Salvelinus Fontinalis, of the Laval River (Québec, Canada)

Brook charr, Salvelinus fontinalis, often display alternate life history styles in coastal areas. In the Laval River, some brook charr remain freshwater residents, while others undergo seasonal migrations between freshwater and saltwater environments. In the present paper, we examined physiological (electrolyte concentrations, gill Na⁺, K⁺-ATPase activity, and thyroid hormone levels) as well as genetic differences (neutral genetic markers) between anadromous and river-resident fish from the Laval River. We also examined how artificial rearing conditions affected seasonal variations in the osmoregulatory physiology of a domestic strain derived from wild anadromous fish. Sympatric anadromous and resident forms of brook charr of the Laval River exhibited differences in gill Na⁺, K⁺-ATPase activity, plasma thyroxine (T₄), and triidothyronine (T₃) concentrations. In domestic anadromous charr, rearing conditions during development had no negative impact on osmoregulatory ability or on gill Na⁺, K⁺-ATPase activity. These results argued for an important hereditary component of gill Na⁺, K⁺-ATPase activity. However, the spring increase in T₄ was present only in wild fish. Significant differences observed at microsatellite loci further suggested that at least some level of reproductive isolation may have occurred between anadromous and resident charr in the Laval River.     

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.     

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.     

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.     

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.     

Non‐native freshwater fish species in the Yellow River Basin: origin,distribution and potential risk

Environmental Biology of Fishes - Invasions of non-native fishes are recognized as a serious threat to freshwater biodiversity across the globe. Being the China’s second-largest river, the...     

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.     

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.     

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.     

A general and flexible methodology to define thresholds for heat health watch and warning systems, applied to the province of Québec (Canada)

Several watch and warning systems have been established in the world in recent years to prevent the effects of heat waves. However, many of these approaches can be applied only in regions with perfect conditions (e.g., enough data, stationary series or homogeneous regions). Furthermore, a number of these approaches do not account for possible trend in mortality and/or temperature series, whereas others are generally not adapted to regions with low population densities or low daily mortality levels. In addition, prediction based on multiple days preceding the event can be less accurate if it attributes the same importance to each of these days, since the forecasting accuracy actually decreases with the period. The aim of the present study was to identify appropriate indicators as well as flexible and general thresholds that can be applied to a variety of regions and conditions. From a practical point of view, the province of Québec constitutes a typical case where a number of the above-mentioned constraints are present. On the other hand, until recently, the province’s watch and warning system was based on a study conducted in 2005, covering only the city of Montreal and applied to the whole province. The proposed approach is applied to each one of the other health regions of the province often experiencing low daily counts of mortality and presenting trends. The first constraint led to grouping meteorologically homogeneous regions across the province in which the number of deaths is sufficient to carry out the appropriate data analyses. In each region, mortality trends are taken into account. In addition, the proposed indicators are defined by a 3-day weighted mean of maximal and minimal temperatures. The sensitivity of the results to the inclusion of traumatic deaths is also checked. The application shows that the proposed method improved the results in terms of sensitivity, specificity and number of yearly false alarms, compared to those of the existing and other classical approaches. An additional criterion based on the Humidex is applied in a second step and a local validation is applied to historical observations at reference forecasting stations. An integrated heat health watch and warning system with thresholds that are adapted to the regional climate has thus been established for each sub-region of the province of Quebec and became operational in June 2010.     

Parasitism ofLygus lineolaris eggs onCoronilla varia,solanum tuberosum,and three host weeds in southeastern Québec

Parasitism ofLygus lineolaris (Palisot de Beauvois) eggs by three species ofMymaridae, Anaphes iole Girault,Erythmelus miridiphagus Dozier andPolynema pratensiphagum Walley and one species ofScelionidae, Telenomus sp., was investigated at Ste-Anne-de-Bellevue, Québec. The maximum level of field parasitism ofL. lineolaris eggs by individual species was 15.4, 53.8, 70.0 and 16,7%, respectively. Parasitoids were retrieved from eggs ofL. lineolaris inserted in stems and branches ofAmaranthus retroflexus L.,Chenopodium album L.,Coronilla varia L.,Rumex obtusifolius L. andSolanum tuberosum L. Amaranthus retroflexus andS. tuberosum sustained a large population ofL. lineolaris and egg parasitism was high enough to consider it as a potential control factor.      

Abundance and individual size of American eel (Anguilla rostrata) in the St. Lawrence River over the past four decades

Changes in abundance indicators and the mean size of American eel (Anguilla rostrata LeSueur) in the lower St. Lawrence River (SLR) over the past 40 years were assessed to determine the chronology of the species decline and the possible effect of hydroclimatic factors on that trend. Daily catches at commercial weirs and at an experimental fishery were used to model the long-term trend in silver eel availability. Eel landings started declining in the mid-1980s; whereas the modelled catch-per-unit-effort (CPUE) index shows a monotonic declining trend since the late 1960s. Landings and CPUEs were not strongly correlated, and landings cannot be a valid proxy for silver eel abundance in the SLR. Variations in summer river discharge contributed to interannual fluctuations in CPUE by affecting eel availability to the fishing gears. No relationship was found between CPUE and the North Atlantic Oscillation index of climatic variability. Correlations between hydroclimatic variables lagged by 1–20 years and CPUE indices revealed no measurable effect of riverine hydroclimatic variability on eel recruitment. The average size of silver eels increased by 30% between 1997 and 2007, as a result of poor recruitment during the mid-1980s. Since the onset of the silver eel decline preceded the major decline in recruitment in the mid-1980s, we suggest that the decline in spawning stock size was not due to poor recruitment but rather to large-scale mortality factors associated with high exploitation in upstream Lake Ontario and to construction of hydropower dams in the late 1950s.     

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.     

Area prioritization for biodiversity conservation in Québec on the basis of species distributions: a preliminary analysis

Results are presented which prioritize areas for potential protection in Québec on the basis of biodiversity considerations. These results are relevant to the ongoing public discussion in Québec about designating new parks and refuges so that the province may fulfil its obligations to Canada's Endangered Spaces Campaign. The prioritization algorithm used in this analysis is based on rarity and complementarity. It attempts to sample biodiversity in as area-efficient a way as possible. The biodiversity surrogates used here comprise a subset of 743 species for which data on spatial distributions are publicly available; the analysis begins with 394 species at risk. It is shown that: (i) the existing network of protected areas in Québec does a poor job of protecting these biodiversity surrogates; (ii) adding adjacent areas to this network will not be the optimal way of protecting these biodiversity surrogates; (iii) many of the areas that have highest priority are in southern Québec, which has a high human population density; (iv) because of (iii), designating parks may not be economically or sociologically feasible and more adaptive alternative conservation plans will have to be devised; (v) coastal areas, riparian habitats, and other wetlands should have high priority for protection but are currently very inadequately represented in the reserve network; (vi) there is some reason for concern about the clear-cut logging of boreal forests in northern Québec; and (vii) the islands, Île d'Anticosti and the Îles-de-la-Madeleine, emerge as being of very significant conservation value and plans for the protection of areas on them should be an immediate goal for biodiversity conservation in Québec.