Earthworm cast production as a new behavioural biomarker for toxicity testing

There is currently a lack of ecotoxicity tests adapted to earthworm species of higher ecological relevance and whose endpoints could be directly related to their ecological role in the soil. We propose a new and relatively simple ecotoxicity test based on the estimation of cast production (CP) by Lumbricus terrestris under laboratory conditions. CP was found to be linearly correlated to earthworm biomass and to be greatly influenced by soil water content. Azinphos-methyl had no effect on CP at all the concentrations tested. Significant decreases were observed at the normal application rate for other pesticides with (imidacloprid, carbaryl, methomyl) or without (ethyl-parathion and chlorpyrifos-ethyl) a clear concentration-effect response. For the highest concentration tested, reduction in CP varied between 35 and 67%. CP is straightforward and rapidly measured and ecologically meaningful. We thus believe it to be of great use as an endpoint in ecotoxicity testing.     

Influence of different levels of dissolved oxygen on the success of Greenland halibut (Reinhardtius hippoglossoides) egg hatching and embryonic development

The aim of this study was to determine the influence of different levels of dissolved oxygen (DO) on embryonic development (ED) and hatching success of Greenland halibut (Reinhardtius hippoglossoides) eggs. Fertilized eggs from six females were exposed to five DO levels: severely hypoxic (10 and 20?%sat [percent saturation]), moderately hypoxic (35 and 50?%sat), and normoxic (100?%sat). Greenland halibut eggs were highly tolerant to hypoxia, with hatching occurring at levels as low as 20?%sat. In severely hypoxic conditions (10?%sat), ED was impaired and no hatching occurred. Lipid composition, during ED, changed as a function of female origin and DO levels. Phospholipids were the dominant lipid class in eggs. Although triacylglycerols were a minor lipid class in terms of abundance, they were only used under severe hypoxia. The results suggest that severe hypoxia (between 10 and 20?%sat) has detrimental effect on the early development of Greenland halibut and may result in reduced recruitment and lower population abundance if the decreasing trend in the DO levels observed in the bottom waters of the Gulf of St. Lawrence continues in the future. Other species that share similar life histories may also be at risk.     

Acetylcholinesterase activity in the terrestrial snail Xeropicta derbentina transplanted in apple orchards with different pesticide management strategies

Apple orchards are highly manipulated crops in which large amounts of pesticides are used. Some of these pesticides lack target specificity and can cause adverse effects in non-target organisms. In order to evaluate the environmental risk of these products, the use of transplanted sentinel organisms avoids side-effects from past events and facilitate comparison of multiple sites in a short time. We released specimens of the terrestrial snail Xeropicta derbentina in each 5 of two kinds of apple orchards with either conventional or organic management strategies plus in a single abandoned orchard. After one month, individuals were retrieved in order to measure acetylcholinesterase (AChE) activity. Mean values of AChE activity were significantly reduced in all conventional apple orchards compared to the others. Results show that the measurement of biomarkers such as AChE inhibition in transplated X. derbentina could be useful in the environmental risk assessment of post-authorized pesticides.     

Characterization of the toxic effects of cadmium and 3.5-dichlorophenol on nitrifying activity and mortality in biologically activated sludge systems—effect of low temperature

Background, aims, and scope  Sometimes, urban wastewaters convey a more or less significant part of toxic products from industries or the craft industry. Nitrifying activity can be affected by these substances, implying higher ammonia concentrations in the outlet effluent and contributing to toxicity for the aquatic environment. Moreover, the more stringently treated wastewater standards now require a reliable treatment for nitrogen. One of the key issues is the identification of the inhibition behavior of nitrifying bacteria facing a toxic substance. This new understanding could then finally be integrated into models in order to represent and to optimize wastewater treatment plants (WWTP) operation in cases involving ‘toxic scenarios’. Materials and methods  The toxic substances studied in this work, cadmium and 3.5-dichlorophenol (3.5-DCP), are representative of chemical substances commonly found in municipal sewage and industrial effluents and symbolize two different contaminant groups. The effects of Cd and 3.5-DCP on nitrification kinetics have been investigated using respirometry techniques. Results  IC50 values determination gives concentrations of 3.1 mg/L for 3.5-DCP and 45.8 mg/L for Cd at 21 ± 1°C. The variation to low temperature seems to have no real effect on IC50 for DCP, but induces a decrease of cadmium IC50 to 27.5 mg/L at 14°C. Finally, specific respirometric tests have been carried out in order to determine the potential effect of these toxic substances on the nitrifying decay rate b _a . No significant effect has been noticed for Cd, whereas the presence of 3.5-DCP (at IC50 concentration) induced a dramatic increase of b _a at 20°C. The same behavior has been confirmed by experiments performed in winter periods with a sludge temperature around 12°C. Discussion  The target substances have different modes of action on activity and mortality, notably due to the abilities of the contaminant to be precipitated, accumulated, or even to be progressively degraded. Studies realized at low temperature confirmed this assumption, and put in evidence the effect of temperature on toxic substances capable of being biosorbed. However, the change in the sludge sample characteristics can be pointed out as a problem in the investigation of the temperature effect on nitrification inhibition, as biosorption, bioaccumulation, and predation are directly linked to the sludge characteristics (VSS concentration, temperature) and the plant operating conditions (loading rates, sludge age, etc.). Conclusions  This work brings new understandings concerning the action mode of these specific contaminants on nitrifying bacteria and, in particular, on the role of temperature. The experiments lead to the determination of the IC50 values for both toxic substances on biological nitrification. The inhibition mechanisms of Cd and 3.5-DCP on nitrifying activity have been simply represented by a non-competitive inhibition model. Recommendations and perspectives  Other experiments carried out in a continuous lab-scale pilot plant should be done with a proper control of the operating conditions and of the sludge characteristics in order to better understand the mechanisms of nitrification inhibition for each contaminant. Finally, these first results show that toxic substances can have an effect on the growth rate but also on the decay rate, depending on the characteristics of the toxic substance and the sludge. This eventual double effect would imply different strategies of WWTP operation according to the behavior of the contaminant on the bacteria.     

Detection and Phylogenetic Analysis of the Hepatitis E Virus in a Canadian Swine Production Network

Viral contamination along the production chain is a significant concern in both food safety and livestock health. Pigs have been reported to act as a reservoir for zoonotic viruses, sometimes emerging ones, and epidemiological studies have shown direct links between the consumption of uncooked pork offal and cases of hepatitis caused by the hepatitis E virus (HEV) genotype 3 in humans. The presence of HEV in swine herds has been reported, but its dissemination in pork production environments is still unknown. To investigate viral contamination sources in the swine industry, 452 environment and fecal samples, including samples from livestock transportation vehicles, were collected over a period of 11 months from ten farms and one slaughterhouse that together represent a single production network. Hepatitis E virus RNA was detected by nested RT-PCR in 32 samples from both inside and outside farm buildings, on trucks, and, mostly, from fomites collected in the slaughterhouse yard, such as on a utility vehicle. Phylogenetic analysis showed a wide diversity of HEV genotype 3 strains, similar to human and swine strains previously found. According to the results of this study, the movements of trucks and utility vehicles might play an important role in HEV dissemination on a slaughterhouse site and throughout an entire network.     

Influence of earthworm bioturbation on metals phytoavailability and human gastric bioaccessibility

Environmental Science and Pollution Research - At the global scale, urban agriculture is increasingly developing in cities due to demographic growth and sustainable food concerns. But, urban soils...     

Persistence of culturable Escherichia coli fecal contaminants in dairy alpine grassland soils

Our knowledge of Escherichia coli (E. coli) ecology in the field is very limited in the case of dairy alpine grassland soils. Here, our objective was to monitor field survival of E. coli in cow pats and underlying soils in four different alpine pasture units, and to determine whether the soil could constitute an environmental reservoir. E. coli was enumerated by MPN using a selective medium. E. coli survived well in cow pats (10(7) to 10(8) cells g(-1) dry pat), but cow pats disappeared within about 2 mo. In each pasture unit, constant levels of E. coli (10(3) to 10(4) cells g(-1) dry soil) were recovered from all topsoil (0-5 cm) samples regardless of the sampling date, that is, under the snow cover, immediately after snow melting, or during the pasture season (during and after the decomposition of pats). In deeper soil layers below the root zone (5-25 cm), E. coli persistence varied according to soil type, with higher numbers recovered in poorly-drained soils (10(3) to 10(4) cells g(-1) dry soil) than in well-drained soils (< 10(2) cells g(-1) dry soil). A preliminary analysis of 38 partial uidA sequences of E. coli from pat and soils highlighted a cluster containing sequences only found in this work. Overall, this study raises the possibility that fecal E. coli could have formed a naturalized (sub)population, which is now part of the indigenous soil community of alpine pasture grasslands, the soil thus representing an environmental reservoir of E. coli.     

Investigation of Motorcyclist Cervical Spine Trauma Using HUMOS Model

Objective: With 16 percent of the total road user fatalities, motorcyclists represent the second highest rate of road fatalities in France after car occupants. Regarding road accidents, a large proportion of trauma was on the lower cervical spine. According to different clinical studies, it is postulated that the cervical spine fragility areas are located on the upper and lower cervical spine. In motorcycle crashes, impact conditions occur on the head segment with various orientations and impact directions, leading to a combination of rotations and compression. Hence, motorcyclist vulnerability was investigated considering many impact conditions. Method: Using the human model for safety (HUMOS), a finite element model, this work aims to provide an evaluation of the cervical spine weaknesses based on an evaluation of injury mechanisms. This evaluation consisted of defining 2 injury risk factors (joint injury and bone fracture) using a design of experiment including various velocities, impact directions, and impact orientations. Results: The results confirmed previously reported clinical and epidemiological work on the fragility of the lower cervical spine and the upper cervical spine segments. Joint injuries appeared before bone fractures on both the upper and lower cervical spine. Bone fracture risk was greater on the lower cervical spine than on the upper cervical spine. The compression induced by a high impact angle was identified as an important injury severity factor. It significantly increased the injury incidence for both joint injuries and bone fractures. It also induced a shift in injury location from the lower to the upper cervical spine. The impact velocity exhibited a linear relationship with injury risks and severity. It also shifted the bone fracture risk from the lower to upper spinal segments.