Heavy ionic pollution disrupts assemblages of algae, macroinvertebrates and riparian vegetation.

Urban streams display consistent ecological symptoms that commonly express degraded biological, physical, and chemical conditions: the urban stream syndrome (USS). Changes linked to the USS result in consistent declines in the abundance and richness of algae, invertebrates, and riparian vegetation. In this paper, we assessed the impacts of extreme ionic pollution from an industrial effluent in an urban stream. We studied the community composition of benthic algae and benthic invertebrates and the indicator traits of riparian vegetation. The dominant pool of benthic algae, benthic invertebrates and riparian species were considered as euryece. However, ionic pollution impacted these three biotic compartments' communities, disrupting these tolerant species assemblages. Indeed, after the effluent, we observed the higher occurrence of conductivity-tolerant benthic taxa, like Nitzschia palea or Potamopyrgus antipodarum and plant species reflecting nitrogen and salt contents in soils. Providing insights into organisms' responses and resistance to heavy ionic pollution, this study sheds light on how industrial environmental perturbations could alter the ecology of freshwater aquatic biodiversity and riparian vegetation.

Effects of catchment area and nutrient deposition regime on phytoplankton functionality in alpine lakes.

High mountain lakes are a network of sentinels, sensitive to any events occurring within their waterbodies, their surrounding catchment and their airshed. In this paper, we investigate how catchments impact the taxonomic and functional composition of phytoplankton communities in high mountain lakes, and how this impact varies according to the atmospheric nutrient deposition regime. For two years, we sampled the post snow-melt and the late summer phytoplankton, with a set of biotic and abiotic parameters, in six French alpine lakes with differing catchments (size and vegetation cover) and contrasting nitrogen (N) and phosphorus (P) deposition regimes. Whatever the nutrient deposition regime, we found that the lakes with the smallest rocky catchments showed the lowest functional richness of phytoplankton communities. The lakes with larger vegetated catchments were characterized by the coexistence of phytoplankton taxa with more diverse strategies in the acquisition and utilization of nutrient resources. The nutrient deposition regime appeared to interact with catchment characteristics in determining which functional groups ultimately developed in lakes. Photoautotroph taxa dominated the phytoplankton assemblages under high NP deposition regime while mixotroph taxa were even more favored in lakes with large vegetated catchments under low NP deposition regime. Phytoplankton functional changes were likely related to the leaching of terrestrial organic matter from catchments evidenced by analyses of carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in seston and zooplankton. Plankton δ15N values indicated greater water-soil interaction in lakes with larger vegetated catchments, while δ13C values indicated the effective mineralization of the organic matter in lakes. The role played by catchments should be considered when seeking to determine the vulnerability of high altitude lakes to future changes, as catchments' own properties will vary under changes related to climate and airborne contaminants.

No association between the use of Bti for mosquito control and the dynamics of non-target aquatic invertebrates in French coastal and continental wetlands.

The environmental safety of Bacillus thuringiensis subsp. israelensis (Bti) is still controversial, mainly because most of the previous field studies on its undesired effects were spatially limited and did not address the relationship between community similarity and application time and frequency. No general statement can therefore be drawn on the usage conditions of Bti that insure protection of non-target organisms. The present study was conducted in eight sites distributed over the main geographical sectors where mosquito control is implemented in mainland France and Corsica. Changes in non-target aquatic invertebrates were followed at elapsed time after repeated applications of two Bti formulations (VectoBac® WDG or 12AS) up to four consecutive years. We examined the influence of both larvicide treatments and environmental variables on community dynamics and dissimilarity between treated and control areas. As it can be argued that chironomids are the most vulnerable group of non-target invertebrates, we scrutinised potential Bti-related effects on the dynamics of their community. The use of VectoBac® WDG and 12AS in coastal and continental wetlands had no immediate or long-term detectable effect on the taxonomic structure and taxa abundance of non-target aquatic invertebrate communities, including chironomids. This applied to the main habitats where mosquito larvae occur, regardless of their geographic location. Flooding, whose frequency and duration depend on local meteorological and hydrological conditions, was identified as the main environmental driver of invertebrate community dynamics. Our findings add support to the environmental safety of currently available Bti formulations when following recommended application rates and best mosquito control practices.

Sono and electrochemical synthesis and characterization of copper core-silver shell nanoparticles.

Cu-Ag core-shell nanopowders have been prepared by ultrasound-assisted electrochemistry followed by a displacement reaction. The composition of the particles has been determined by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). The XRD patterns versus time displacement show that higher are the silver peaks intensities, weaker are the copper ones. That exhibits the progressive recovering of copper by silver. EDX results and quartz crystal microbalance results indicate that various reaction mechanisms are implied in this process. Transmission electron microscopy (TEM) points out variable nanometric diameter grain and some small agglomerates. Elemental mapping obtained by electron energy-loss spectroscopy (EELS) underlines the core-shell structure.

Effects of ultraviolet light (315 nm), temperature and relative humidity on the degradation of polylactic acid plastic films.

The influence of temperature (30, 45 and 60 degrees C) and relative humidity (RH) (30%, 50% and 100%) on the degradation of poly(l-lactic acid) (PLA) films were studied. In addition, the effects of ultraviolet (UV) light (315 nm) on the degradation of PLA films were also analyzed. Various analytical techniques were applied to observe changes in the properties of PLA polymer films. FTIR spectroscopy was used as semi-quantitative method to get information about the chemistry of the degradative process. The degradation rate of PLA was enhanced by increasing temperature and RH, factors responsible for a faster reduction of the weight-average molecular weight (M(W)), of the glass transition temperature (Tg) and of the percentage of elongation at break. Moreover, UV treatment accelerated these phenomena.

Case of megaloblastic anemia caused by intestinal taeniasis.

A 61-year-old eutrophic male was diagnosed with vitamin B12 deficiency and megaloblastic anemia. A modified Schilling test suggested intestinal malabsorption unrelated to intrinsic factor deficiency. Subsequent colonoscopy revealed the presence of a Taenia tapeworm. The anemia resolved within days under therapy with niclosamide and temporary vitamin B12 supplements. The present case suggests that, in addition to other well-known parasitic agents, e.g., Diphyllobothrium latum and Giardia lamblia, Taenia infestation can also be a cause of intestinal vitamin B12 malabsorption.

[A new approach to biodiversity: morphological plasticity of a fresh-water diatom]. / Une nouvelle approche de la biodiversité: plasticité morphologique chez une diatomée d'eau douce.

Population responses of a planktonic freshwater diatom, Asterionella formosa Hassal, to the hydrodynamic anthropic disturbances were studied at the landscape scale, along a series of nine reservoirs, for a period of 18 months. The analysis of biotic descriptors as cell abundance, cell length and architecture has shown a strong morphological plasticity of this diatom. The morphological variability of A. formosa in response to hydrodynamic conditions favours the colonization of lacustrine freshwater ecosystem for this species. The determination of architectural indices allowed us to distinguish a modification of biodiversity along a disturbance gradient for population level.