Structural and functional responses of benthic invertebrates to imidacloprid in outdoor stream mesocosms

Structural and functional responses of a benthic macroinvertebrate assemblage to pulses of the insecticide imidacloprid were assessed in outdoor stream mesocosms. Imidacloprid pulses reduced invertebrate abundance and community diversity in imidacloprid-dosed streams compared to control streams. These results correlated well with effects of imidacloprid on leaf litter decomposition and feeding rates of Pteronarcys comstocki, a stonefly, in artificial streams. Reductions in oxygen consumption of stoneflies exposed to imidacloprid were also observed in laboratory experiments. Our findings suggest that leaf litter degradation and single species responses can be sensitive ecotoxicological endpoints that can be used as early warning indicators and biomonitoring tools for pesticide contamination. The data generated illustrates the value of mesocosm experiments in environmental assessment and how the consideration of functional and structural endpoints of natural communities together with in situ single species bioassays can improve the evaluation and prediction of pesticide effects on stream ecosystems. (C) 2009 Elsevier Ltd. All rights reserved.Environment Canada’s Pesticide Science FundFC

Trisomy 21 activates the kynurenine pathway via increased dosage of interferon receptors

Altres ajuts: This work has also been supported by a "Marató TV3" grant (20141210 to J.F. and 044412 to R.B.).Trisomy 21 (T21) causes Down syndrome (DS), affecting immune and neurological function by ill-defined mechanisms. Here we report a large metabolomics study of plasma and cerebrospinal fluid, showing in independent cohorts that people with DS produce elevated levels of kynurenine and quinolinic acid, two tryptophan catabolites with potent immunosuppressive and neurotoxic properties, respectively. Immune cells of people with DS overexpress IDO1, the rate-limiting enzyme in the kynurenine pathway (KP) and a known interferon (IFN)-stimulated gene. Furthermore, the levels of IFN-inducible cytokines positively correlate with KP dysregulation. Using metabolic tracing assays, we show that overexpression of IFN receptors encoded on chromosome 21 contribute to enhanced IFN stimulation, thereby causing IDO1 overexpression and kynurenine overproduction in cells with T21. Finally, a mouse model of DS carrying triplication of IFN receptors exhibits KP dysregulation. Together, our results reveal a mechanism by which T21 could drive immunosuppression and neurotoxicity in DS

A reevaluation of the National Emission Standards for Hazardous Air Pollutants (NESHAP - 40 CFR 61, Subpart H) program at Sandia National Laboratories, New Mexico

The initial National Emission Standards for Hazardous Air Pollutants (NESHAP - 40 CFR 61, Subpart H) Program at Sandia National Laboratories, New Mexico (SNL/NM) required: (1) continuous air monitoring of sources if the calculated effective dose equivalent (EDE) to the maximum exposed individual (MEI) was > 0.1 mrem/yr; (2) the determination of emissions based on measurements or measured parameters if the EDE to the MEI was < 0.1 mrem/yr; and (3) the calculation of worst case releases when the expected air concentrations were below detection limits using standard monitoring equipment. This conservative interpretation of the regulation guided SNL/NM to model, track, and trend virtually all emission sources with the potential to include any radionuclides. The level of effort required to implement these activities was independent of the EDE contributing from individual sources. A recent programmatic review found the NESHAP program to be in excess of the legal requirements. A further review found that, in summation, 13 of 16 radionuclide sources had a negligible impact on the final calculated EDE to the MEI used to demonstrate compliance at 20 separate on-site receptor locations. A reevaluation was performed to meet the legal requirements of 40 CFR 61, Subpart H, and still be reasonable and appropriate under the existing circumstances

Chironomidae larvae from the lower Athabasca River, AB, Canada and its tributaries including macroscopic subfamily and tribe keys, indices for environmental tolerance and trait-based information for biomonitoring

Since 2011 the Joint Oil Sands Monitoring (JOSM) program has been conducted in the lower Athabasca River by the Governments of Canada and Alberta to assess the freshwater health in areas associated with oil sands development. The majority of the benthic invertebrate assemblage of the Athabasca River and its tributaries are Chironomidae larvae. Assessments of such benthic assemblages are made difficult because the identification of Chironomidae larvae is costly and time consuming. To facilitate this identification process, we aimed to develop a simple taxonomic key for Chironomidae larvae of this region. This taxonomic reference and identification key makes use of the known taxonomic details on these Chironomidae species. Moreover, we provide details on their geographical distribution, ecology, habitats, environmental tolerance values for species, and traitbased morphological characters. Our main goal was to make this information readily available to both non-specialists and specialists so that biomonitoring programs can more readily utilize these organisms in biomonitoring

Chironomidae (Insecta: Diptera) from the eastern Canadian Arctic and subarctic with descriptions of new life stages, a possible new genus, and new geographical records

Chironomidae larvae constituted the largest proportion of benthic invertebrates collected from 99 rivers stretching from northern Labrador (latitude 58°N) to northern parts of Ellesmere Island (82°N). We describe 92 species of Chironomidae (mainly larval forms) providing new descriptions, a revision for the adult female of Parametriocnemus boreoalpinus Gowin et Thienemann, a possible new genus (larval form only), and 9 larval forms that may represent a new species. In addition, new geographical distribution records are specified for 1 Nearctic species, 6 species in Canada, 10 for Labrador, and 17 for Nunavut. This work contributes to Environment Canada’s International Polar Year output (2007-2009)

Evaluating diffuse and point source phosphorus inputs to streams in a cold climate region using a load apportionment model

Variation in the timing and quantity of diffuse versus point-source inputs of phosphorus (P) to streams can be evaluated by examining P concentration-flow relationships. Diffuse load inputs usually increase with stream flow (due to increased delivery caused by precipitation); whereas, point-source concentrations decrease with rising river flow (due to increased dilution). This study tested the suitability of a load apportionment model (LAM), a power-law function of flow, to estimate contributions of diffuse and point inputs to P loads for eight sub-watersheds in the Red River Valley, a cold-climate rural region of Manitoba, Canada. For all but two sub-watersheds, annual and seasonal (snowmelt and summer) models of P concentration versus flow best fit a strictly diffuse source contribution. The models identified significant point-source inputs (in addition to diffuse sources) in two sub-watersheds, during summer in both watersheds (consistent with the fact that wastewater from sewage lagoons is discharged to upstream reaches between June and September) and during snowmelt for one watershed. Application of a LAM proved to be a simple and rapid method for nutrient source apportionment as well as detection of unknown sources for cold-climate, rural sub-watersheds. Such information is critical for developing the most effective mitigation strategies to reduce P concentrations and eutrophication risk

Incorporating traits in aquatic biomonitoring to enhance causal diagnosis and prediction

The linkage of trait responses to stressor gradients has potential to expand biomonitoring approaches beyond traditional taxonomically based assessments that identify ecological effect to provide a causal diagnosis. Traits-based information may have several advantages over taxonomically based methods. These include providing mechanistic linkages of biotic responses to environmental conditions, consistent descriptors or metrics across broad spatial scales, more seasonal stability compared with taxonomic measures, and seamless integration of traits-based analysis into assessment programs. Atraits-based biomonitoring approach does not require a new biomonitoring framework, because contemporary biomonitoring programs gather the basic site-by-species composition matrices required to link community data to the traits database. Impediments to the adoption of traits-based biomonitoring relate to the availability, consistency, and applicability of existing trait data. For example, traits generalizations among taxa across biogeographical regions are rare, and no consensus exists relative to the required taxonomic resolution and methodology for traits assessment. Similarly,we must determine if traits form suites that are related to particular stressor effects, and whether significant variation of traits occurs among allopatric populations. Finally, to realize the potentialof traits-based approaches in biomonitoring, a concerted effort to standardize terminology is required, along with the establishment of protocols to ease the sharing and merging of broad, geographical trait information

Hydrological variability affects particulate nitrogen and phosphorus in streams of the Northern Great Plains

Study region: The study area is located in southern Manitoba, in the prairie region of Canada Study focus: This study examined the impact of hydrological variability on the timing and magnitude of nutrient export from seven agriculturally-dominated watersheds in the Red River Valley, Manitoba, Canada. New hydrological insights for the region: In 2013, discharge showed a seasonal pattern typical of streams traversing the Canadian prairies: high discharge during snowmelt followed by cessation of flow in early June due to lack of precipitation. In 2014, discharge still peaked during snowmelt but, compared to 2013, was 49% lower during snowmelt yet 21% higher during summer and fall due to greater rainfall. These hydrologic differences were associated with differences in fractionation of nutrients between years. Thus, higher concentrations and loads of particulate phosphorus (P) and nitrogen (N), and a greater (p < 0.05) share of the total nutrient pool in particulate forms (particularly for P), were observed during the snowmelt- dominated year (2013). Our findings show that the nutrient concentrations, fractionation and export from prairie watersheds differ between years, and amongst hydrological seasons, in relation to hydrological conditions. Additional management actions may be required to address changes in the quantity, timing and fractionation of nutrient export associated with rainier summers forecasted under future climate scenarios. Keywords: Nutrients, Hydroclimatology, Canadian prairies, Lake Winnipeg, Eutrophicatio