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There is a paucity of large-scale field investigations on the effects of organic toxicants on stream macroinvertebrate community structure and ecosystem functions. We investigated a total of 29 streams in two study areas of France and Finland for pesticide exposure, invertebrates and leaf-litter breakdown. To link pesticide exposure and community composition we applied the trait-based Species At Risk (SPEAR) indicator system. In the French region, pesticide stress was associated with a decrease in the relative abundance and number of sensitive species in the communities. The presence of undisturbed upstream reaches partly compensated the effects of pesticide contamination. Functional effects of pesticides were identified by a 2.5-fold reduction of the leaf-litter breakdown rate that was closely correlated with the structural changes in the contaminated streams. No effects of pesticides were observed in Finnish streams since contamination with pesticides was very low. In a follow-up analysis, the SPEAR approach successfully discriminated between reference and contaminated sites across different biogeographical regions, also including results of a previous field study in North Germany. Furthermore, change of the community structure was detectable at a concentration range as low as 1/100 to 1/1000 the acute 48 h-LC50 of Daphnia magna. Our findings demonstrate that pesticides may influence the structure and function of lotic ecosystems and that the SPEAR approach can be used as a powerful tool in biomonitoring over large spatial scales. [Copyright &y& Elsevier]

The immediate response and recovery of the macrobenthic communities of nonisolated and isolated freshwater outdoor 9 m3 mesocosms following an acute stress caused by the addition of deltamethrin were studied over a 14-month period. To discriminate between internal and external recovery mechanisms, half of the treated ponds were covered by 1-mm mesh lids that restricted aerial recolonization. Both structural (abundance of the different taxonomic groups) and functional (litter breakdown) parameters were monitored. Insects were broadly reduced in numbers by deltamethrin addition. In general, noninsect groups were not affected or increased in abundance in deltamethrin-treated ponds, probably because of relative insensitivity to deltamethrin, reduced predation, and lower competition for food. No major change in litter breakdown rates were seen, probably because of functional redundancy among the macrobenthic community. Chironominae larvae recovered in open, treated mesocosms 62 d after deltamethrin addition and most insect groups recovered 84 d after the treatment date. However, the presence of lids significantly reduced insect recovery rate, suggesting that it largely depends on the immigration of winged forms (i.e., external recovery) from surrounding non- or less affected systems. These results indicate that the recovery time of macrobenthic communities in an affected natural pond would depend on spatial characteristics of the landscape and also the season that exposure occurs. Isolated ecosystems would display posttreatment insect recovery dynamics very different from highly connected ones, evolving toward alternate pseudoequilibrium states, possibly with lower biodiversity but with preserved functionality. Consequences for higher tier risk assessment of pesticides are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Sudden exposure of an aquatic system to an insecticide can have significant effects on populations other than susceptible organisms. Although this is intuitively obvious, little is actually known about how such exposure might affect bacterial communities and their relative metabolic activity in ecosystems. Here, we assessed small sub-unit (ssu)-RNA levels in open and shaded 9m3 aquatic mesocosms (16 units – 2×2 factorial design in quadruplicate) to examine the effects of sudden addition of deltamethrin to the units. When deltamethrin was added, a cascade of bacterial then phytoplankton “blooms” occurred over time. The bacterial bloom, which most likely included organisms from the plastid/cyanobacterial phylogenetic guild, was almost immediate (within hours), whereas the phytoplankton (algal) bloom lagged by about 4days. This sequential response can be explained by an apparent sudden release of nutrients consequent to arthropod death that triggered a series of responses in the microbial loop. Interestingly, bacterial blooms were noted in both open and shaded mesocosms, whereas the algal bloom was only seen in open units, suggesting that both deltamethrin addition (and presumptive nutrient release) and an adequate light supply was required for the phytoplankton response. Overall, this work shows that microbial activities as reflected by ssu-rRNA levels can respond dramatically via apparently indirect effects following insecticide application. [Copyright &y& Elsevier]

The effects of fenitrothion exposure on fourth-instar Chironomus riparius larvae were investigated on biochemical, physiological, and population-level parameters. Biochemical effects were investigated through measurements of acetylcholinesterase and cytosolic superoxide dismutase activities. Water content and dry weight of the larvae were used as physiological parameters, and the emergence rate of adults was used as a descriptor of population-level effects. Results showed that the response of most parameters exhibited a concentration-dependent relationship. Although biochemical parameters proved to be very sensitive, no direct relation was observed with effects at a higher level of biological organization. Perturbations of osmoregulation, as reflected by changes in water content of the larvae, were more directly related with emergence failure. This study demonstrates that the use of several biological parameters can provide complementary information about the effects of chemical exposure. Therefore, use of a multilevel approach in C. riparius seems to be a promising way to diagnose environmental quality. [ABSTRACT FROM AUTHOR]

Ecotoxicological effects of the diphenyl ether herbicide fomesafen, applied alone or in combination with the adjuvant Agral 90® (mixture of polyethoxylated derivatives of nonylphenol), were assessed on planktonic communities in 18-m³ outdoor mesocosms during a nine-month study. Four mesocosms were treated with fomesafen only (nominal concentration: 40 µg/L), four were treated with the mixture fomesafen--Agral 90 (nominal concentration: 40 µg/L and 90 µg/L, respectively), and four were kept as the controls. Five treatments were performed every three weeks from April 18, 2000. Mean (± standard error [SE]) values of fomesafen concentration in water of 62.5 (±5.3) and 19.4 (±7.6) µg/L were measured at the end of the treatment period in fomesafen- and mixture-treated mesocosms, respectively. Fomesafen, either alone or in mixture with Agral 90, had a significant positive effect on the abundance and biovolume of Cyanobacteria, Cryptophyceae, Dinophyceae, and Bacillariophyceae. Chlorophyceae were inhibited by the herbicide and laboratory toxicity tests confirmed that green algae were more sensitive toward fomesafen than other algal classes. A positive effect of treatments on phytoplankton taxonomic diversity also was observed, indicating that, like natural disturbances of intermediate strength, xenobiotics sometimes may enhance the diversity of algal communities. Fomesafen alone did not have any clear effect on zooplankton. Abundance of calanoid copepods was reduced significantly in the mixture-treated ponds, suggesting either a direct effect of the adjuvant and/or an enhancement of herbicide toxicity by Agral 90. The abundance of other zooplanktonic herbivorous groups increased due to a reduced competition for food for herbivorous species and a higher availability of preys for predators. No algal bloom was observed in the treated ponds, presumably because of grazing pressure and the low availability of nutrients. [ABSTRACT FROM AUTHOR]

Along with the development of citizen sciences, an increasing number of initiatives concerning soils are emerging. Soils are key components of ecosystems and original objects for citizen sciences since they integrate the multiple impacts of human activities (agroecology, biodiversity, food, climate). This article presents an analysis of 20 on-going projects in France. It is based on a questionnaire circulated to the project leaders, regarding i) properties, use context and co-building processes between the actors of research and of society, ii) lessons learned from a conference associating the actors involved in these projects, on the needs, outputs for research and for society, difficulties and successes, and potential pooling between projects. This first conference on soil citizen sciences, which gathered some one hundred participants, may hopefully boost exchanges between projects and lead to developing a national network of actors concerned. [ABSTRACT FROM AUTHOR]

Life-history patterns and food habits are described for two sympatric species of Hydropsyche (H. pellucidula and H. contubernalis) sampled for 15 months in a second-order stream, the Essonne (France). Both species showed univoltine life cycles with remarkable differences in winter. H. contubernalis overwintered mainly in the 4th or 5th larvalinstar; whereas, the more abundant H. pellucidula overwintered in the 2nd or 3rd larval instar. The main larval growth periods of the twospecies were also different, and this could be due to ecological segregation, which allows both species to share a similar ecological niche. The two species shared the same food habits throughout all larvalinstars; however, they both changed their food habits as they passedfrom one instar to another, and earlier instars were more predatory than the older ones. [ABSTRACT FROM AUTHOR]

A profound transformation of agricultural production methods has become unavoidable due to the increase in the world’s population, and environmental and climatic challenges. Agroecology is now recognized as a challenging model for agricultural systems, promoting their diversification and adaptation to environmental and socio-economic contexts, with consequences for the entire agri-food system and the development of rural and urban areas. Through a prospective exercise performed at a large interdisciplinary institute, INRAE, a research agenda for agroecology was built that filled a gap through its ambition and interdisciplinarity. It concerned six topics. For genetics, there is a need to study genetic aspects of complex systems (e.g., mixtures of genotypes) and to develop breeding methods for them. For landscapes, challenges lie in effects of heterogeneity at multiple scales, in multifunctionality and in the design of agroecological landscapes. Agricultural equipment and digital technologies show high potential for monitoring dynamics of agroecosystems. For modeling, challenges include approaches to complexity, consideration of spatial and temporal dimensions and representation of the cascade from cropping practices to ecosystem services. The agroecological transition of farms calls for modeling and observational approaches as well as for creating new design methods. Integration of agroecology into food systems raises the issues of product specificity, consumer behavior and organization of markets, standards and public policies. In addition, transversal priorities were identified: (i) generating sets of biological data, through research and participatory mechanisms, that are appropriate for designing agroecological systems and (ii) collecting and using coherent sets of data to enable assessment of vulnerability, resilience and risk in order to evaluate the performance of agroecological systems and to contribute to scaling up. The main lessons learned from this collective exercise can be useful for the entire scientific community engaged in research into agroecology. [ABSTRACT FROM AUTHOR]

Both the increase in human mobility and climate change contribute to the globalization of vector-borne diseases. Some mosquito species are efficient disease vectors in Europe, thus increasing the risk of epidemic (re)emergence., Bacillus thuringiensis var. israelensis ( Bti) is considered as the most efficient larvicide to control mosquito populations with negligible environmental impacts. However, repeated field applications of Bti over many years raise the question of possible long-term effects on non-target invertebrates with putative subsequent alterations of food webs., Environmental effects of Bti have mainly been studied in continental freshwater wetlands. Much less is known for brackish water coastal wetlands. We investigated whether repeated treatments with Bti, applied as VectoBac® WG over seven consecutive years, may affect non-target invertebrate communities in wetlands of the French Atlantic coast. Particular attention was devoted to invertebrates potentially used as food sources by shorebirds and wading birds., Invertebrates were sampled in the water and sediment of control and VectoBac®-treated saltmarsh pools between 2006 and 2012. Taxa abundance data were used to calculate community descriptors and to analyse the potential structural changes due to VectoBac® using the principal response curve method and similarity analysis. Physicochemical parameters were measured in the same pools so that homogeneity of the environmental conditions between the control and treated areas could be tested., We demonstrated that long-term use of VectoBac® WG in French Atlantic coastal wetlands had no influence on the temporal evolution of the taxonomic structure and taxa abundance of non-target aquatic invertebrate communities, which is highly driven by abiotic factors. In addition, over the long term, the amount of invertebrates that could be used as food resources by birds is maintained in VectoBac®-treated areas., Synthesis and applications. Reduced application rate and targeted spraying of VectoBac® WG in mosquito breeding sites minimize potential environmental impacts of Bacillus thuringiensis var. israelensis ( Bti). Even so, surveillance of its possible primary side effects is needed, which requires comparable control and treated areas. Indeed, systematic temporal trends and subtle differences in the range of variation of abiotic factors result in discrepancies between control and treated area in terms of invertebrate abundance, which could be wrongly attributed to VectoBac®. Management decisions and mitigation measures may therefore benefit from (i) extending surveillance to a time frame that allows for coverage of the immense temporal variation in taxa abundance and diversity and (ii) the inclusion of environmental variables in the monitoring of non-target animal communities potentially exposed to Bti. [ABSTRACT FROM AUTHOR]

This review examines information generated over the past decade on the pollution of rivers in regions with a mediterranean-type climate (med-climate). Pollution has clearly increased in the last 100 years and is correlated with the development of industry, agriculture and human population. Important efforts have been made in some med-climate countries in order to characterise the chemical status of rivers. In addition, the number of chemical substances detectable in mediterranean-climate rivers (med-rivers), as well as the limits of detection, have improved from the development of better analytical methods. New substances detected in rivers are gaining attention. We discuss available knowledge regarding real and potential effects of pollutants on the biota and ecosystems in med-rivers, taking into account natural environmental characteristics of these rivers. The extreme seasonal conditions in med-rivers add to the potential risk because these characteristics can enhance pollutant effects. Efforts and policies to prevent or reduce pollution effects on med-rivers are linked to the knowledge about pollution pressures associated with the degree of economic development. Aquatic communities in med-rivers are more sensitive to pollutants because they are exposed to strong natural and human stressors. [ABSTRACT FROM AUTHOR]

Effects of physical (hypoxia, hyperoxia) and chemical (potassium dichromate, fenitrothion) stress on antioxidant enzyme activities and hemoglobin content in Chironomus riparius Mg. (Diptera, Chironomidae) larvae were evaluated under laboratory conditions in order to identify pertinent biomarkers of stress. Hypoxia and hyperoxia caused an increase in Cu, Zn-superoxide dismutase (SOD) and Mn-SOD activities and a simultaneous decrease in total peroxidase (Px) and glutathione peroxidase (GSHPx) activities. A parallel increase in hemoglobin concentration in the hemolymph was observed. The exposure to sublethal concentrations of both potassium dichromate and fenitrothion led to an increase in Cu, Zn-SOD and Mn-SOD activities and to a decrease in GSH-Px activity. Activation of catalase (CAT) was observed in the larvae exposed to high fenitrothion concentration (20µg/L). The response of SODs was rapid and sensitive to low chemical concentrations, but changes in CAT, Px, and GSH-Px were more specific and less sensitive. [ABSTRACT FROM AUTHOR]

Abstract: Descriptors of trophic niche and of food web structure and function have been suggested as integrative and sensitive endpoints of toxicant effects. In the present study, carbon and nitrogen stable isotope signatures were used to assess the effects of the dithiocarbamate fungicide thiram (35 and 170μg/L nominal concentrations) and of a petroleum distillate (0.01, 0.4, 2 and 20mg/L nominal loadings as Hydrocarbon Emulsion or Hydrocarbon Water Accommodated Fraction) on the trophic niche of two freshwater gastropods in artificial streams (Radix peregra) and ponds (Lymnaea stagnalis). Results were analyzed using classical univariate statistical methods and recently proposed uni- and multivariate metrics of the realized trophic niche of species. The trophic niche metrics were highly sensitive to both types of chemicals, but exposure resulted in different response patterns according to the nature of the tested compound. Thiram clearly affected gastropod trophic niche leading to a change in the food resources used and resulting in trophic niche expansion (i.e., increase of diversity of used resources, especially dead animals) or trophic niche contraction (i.e., decrease of diversity of used resources) across time. Both gastropod taxa exposed to hydrocarbons showed a clear trophic niche expansion. Trophic niche metrics therefore provide a promising way of investigating non-lethal effects of exposure to organic chemicals on aquatic invertebrates, and subsequent disturbances in food webs. [Copyright &y& Elsevier]

Ecological risk assessment of chemicals in mesocosms requires measurement of a large number of parameters at the community level. Studies on invertebrate communities usually focus on taxonomic approaches, which only provide insights into taxonomic structure changes induced by chemicals. In the present study, abundance, biomass (B), theoretical production (P), and instantaneous P/B ratio were used as endpoints to assess the effects of the commercial form of the dithiocarbamate fungicide thiram (35 µg/L and 170 µg/L nominal concentrations) and of the hydrocarbon water accommodated fraction (HWAF) of a petroleum distillate (0.01 mg/L, 0.4 mg/L, 2 mg/L, and 20 mg/L loadings) on the zooplankton community in freshwater pond mesocosms. Endpoints were measured during a 4-wk treatment period (1 pulse/wk) followed by a 5-mo posttreatment period to evaluate zooplankton population recovery. The chlorophyll a concentration in water was significantly increased after treatment with HWAF, whereas it was not affected by thiram treatment. Zooplankton abundance-based analysis showed effects on a limited number of taxa, whereas other endpoints (mainly the P/B ratio) revealed that more taxa were impacted, with recovery depending on the chemical and concentration. Exposure to HWAF mainly had a negative impact on cladocerans, which resulted in top-down effects (between cladocerans and phytoplankton). Thiram negatively affected rotifers and copepods, suggesting more direct toxic effects. The results show that the use of secondary production as an endpoint provides a more comprehensive assessment of potential direct and indirect effects of chemicals on a community, and they also support evidence of alteration in functional processes. Environ Toxicol Chem 2014;33:836-846. © 2013 SETAC [ABSTRACT FROM AUTHOR]

Abstract: The ecological consequences of freshwater land-based salmonid farms on rivers were studied by monitoring eight farms with substantial differences in annual trout production (29–368tyear−1) connected to rivers of contrasted hydrology (mean annual discharge ranging from 0.3 to 4.8m3 s−1) in France. Samples of water and benthic invertebrates were collected in the river immediately upstream and at two locations downstream of fish farm outlets during low flow period in summer. Suspended solids, PO4 3− and NH4 + concentrations increased downstream of the outlets, suggesting that fish food-derived wastes led to a dilute mixture of suspended solids and dissolved nutrients. The total abundance of benthic invertebrates consistently increased immediately downstream of the effluent outlets, and a positive correlation was observed with the biomass of fish in the aquaculture facilities at the sampling date. The proportions of oligochaetes and chironomids increased downstream of the farms and, conversely, proportions of ephemeropterans, plecopterans and trichopterans decreased. Similarly, the relative abundances of shredders and scrapers decreased in the benthic invertebrate community downstream of the outlets, whereas deposit-feeders and filter feeders increased. This consistent pattern outlined a major change in the ecosystem functioning, with particulate organic matter from fish food-derived wastes becoming a central source of energy in river benthic food webs. Furthermore, the taxonomic-based ecological indicator usually used for monitoring biotic integrity in French Rivers overlooked these functional impairments in larger streams (mean annual discharge above 2m3 s−1). This study outlines the interest of using benthic invertebrate functional feeding groups together with the results of water chemistry analyses for monitoring the ecological disturbances induced by land-based salmonid farm effluents in running waters. [Copyright &y& Elsevier]

There is a growing interest for the use of ecological models to improve the Ecological Risk Assessment (ERA) of toxic pollutants. However, although several models have been proposed, there is little information available on their relevance (i.e., validation through comparison with original data) and on their sensitivity to the input parameters. In this study, the Aquatox Model was used to simulate biomass dynamics of various biological compartments in artificial streams designed for measuring the effects of pollutants on aquatic communities. Calibration and validation of the model were performed using data from control streams. Multi-variate sensitivity analysis was implemented to identify those parameters that exert a prominent role in the outputs of the model. The calibrated model was able to adequately describe the dynamics of most of the simulated biological compartments of a stream. Using data from other streams, it was shown that between-streams natural variability was a source of discrepancy between observed and simulated data. Sensitivity analysis showed that the model was highly sensitive to the parameters related to the temperature limitation, maximum rate of photosynthesis of producers and consumption by consumers. This strongly suggests that particular attention should be devoted to the estimation of these parameters if this model has to be used for ERA of toxicants in aquatic ecosystems. [Copyright &y& Elsevier]

The influence of relative isolation on the ecological recovery of freshwater outdoor mesocosm communities after an acute toxic stress was assessed in a 14-month-long study. A single concentration of deltamethrin was applied to 8 out of 16 outdoor 9-m3 mesocosms to create a rapid decrease of the abundance of arthropods. To discriminate between external and internal recovery mechanisms, four treated and four untreated (control) mesocosms were covered with 1-mm mesh screen lids. The dynamics of planktonic communities were monitored in the four types of ponds. The abundance of many phytoplankton taxa increased after deltamethrin addition, but the magnitude of most increases was relatively small, probably due to low nutrient availability and the survival of rotifers. The greatest impact on zooplankton was seen in Daphniidae and, to a lesser extent, calanoid copepods. Recovery (defined as when statistical analysis failed to detect a difference in the abundance between the deltamethrin-treated ponds and corresponding control ponds for two consecutive sampling dates) of Daphniidae was observed in the water column 105 and 77 d after deltamethrin addition in open and covered mesocosms, respectively, and <42 d for both open and covered ponds at the surface of the sediments. Rotifers did not proliferate, probably because of the survival of predators (e.g., cyclopoid copepods). These results confirm that the recovery of planktonic communities after exposure to a strong temporary chemical stress mostly depends upon internal mechanisms (except for larvae of the insect Chaoborus sp.) and that recovery dynamics are controlled by biotic factors, such as the presence of dormant forms and selective survival of predators. [ABSTRACT FROM AUTHOR]