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La question de l’antagonisme apparent entre biodiversite, d’une part, et agriculture et systemes alimentaires, d’autre part, est posee par de nombreuses analyses recentes realisees a l’echelle mondiale. L’un des enjeux de la recherche agronomique du XXIe siecle est d’explorer de nouvelles pistes pour transformer cet antagonisme en synergie. Il s’agit, grâce aux recherches sur et pour la biodiversite, de contribuer a transformer les systemes agri-alimentaires pour assurer la securite alimentaire et nutritionnelle, en particulier via la diversification et la transition agroecologique ; de conserver et restaurer la biodiversite, tout en promouvant son utilisation durable ; de proteger et gerer durablement les ressources naturelles indispensables a la vie (l’eau, les sols, l’air) ; de preserver la sante humaine et celle de l’environnement ; et de contribuer a la lutte contre les changements climatiques et leurs impacts dans une double strategie d’attenuation et d’adaptation.

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.

Higher-tier ecological risk assessment (ERA) in mesocosms is commonly performed in lotic or lentic experimental systems. These systems differ in their physico-chemical and hydrological properties, leading to differences in chemical fate, community characteristics and potential recovery. This raises the issue of the relevance and sensitivity of community-level endpoints in different types of mesocosms. In this study, macroinvertebrate abundance and biomass estimates were used to assess the effects of a dithiocarbamate fungicide, thiram (35 and 170 A mu g l(-1)), and a petroleum middle distillate (PMD; 0.01, 0.4, 2 and 20 mg l(-1)) in outdoor stream and pond mesocosms. Streams were continuously treated during 3 weeks followed by a 2-month long post-treatment period. Ponds were treated weekly for 4 weeks, followed by a 10-month long post-treatment period. Taxonomic structure of macroinvertebrate communities was characterized using the alpha, beta and gamma components of taxa richness, Shannon and Gini-Simpson indices. Computations were based either on abundance or biomass data. Results clearly highlighted that the effects of chemicals depended on the exposure regime (for thiram) and type of system (for the PMD). Causes of the differences between streams and ponds in the magnitude and nature of effects include differential sensitivity of taxa dwelling in lentic and lotic systems and the influence of hydrology (e.g., drift from upstream) and mesocosm connectivity on recovery dynamics. This study also showed complementarities in the use of both types of mesocosms to improve the characterization of chemical effects on communities in ERA.

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.

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.

Bacillus thuringiensis var. israelensis (Bti) is commonly used for selective control of larval populations of mosquitoes in coastal wetlands. A two year-study was implemented to investigate whether repeated treatments with Bti applied either as a liquid (VectoBac (R) 12AS) or a water-dispersible granule (VectoBac (R) WG) formulation may affect the abundance and diversity of non-target aquatic invertebrates in saltmarsh pools. Taxonomic composition of the invertebrate communities was typical of brackishwater intermittent ecosystems, with a dominance of annelids, crustaceans and nematocerans. Conditions were contrasted between the two years of the survey, both in terms of annual cumulative rainfall and rainfall distribution throughout the year. As a consequence, the hydroperiod and some other environmental characteristics associated with pool drying played a major role in the dynamics of the invertebrate community. In summer 2006, pool drying reduced the abundance of the polychaete worm Nereis diversicolor, of the amphipod crustacean Corophium volutator and of chironomid larvae. These taxa were able to recolonize rapidly the pools after flooding in September 2006. In 2007, rainfall was more regularly distributed across the year, and the pools did not get dry. Hydrozoans, Chironomini and Orthocladiinae larvae, and oligochaetes were more abundant in treated than in control pools, especially in VectoBac (R) WG-treated pools. No adverse effects of the treatments were shown on the abundance of N. diversicolor, C. volutator and midge larvae, suggesting that the availability of these food sources for birds was not negatively affected by Bti applications. It is concluded that, as currently performed in Western France coastal wetlands, land-based treatments of saltmarsh pools for larval mosquito control with Bti, used either as VectoBac (R) 12AS or VectoBac (R) WG, did not adversely impact non-target aquatic invertebrate communities. (C) 2011 Elsevier Inc. All rights reserved.

The immediate response and recovery of the macrobenthic communities of nonisolated and isolated freshwater outdoor 9 ml 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.

La croissance pondérale estimée par le taux instantané de croissance (b) d'Asellus aquaticus L. a été évaluée dans des conditions de laboratoire et en milieu naturel dans des mésocosmes. L'influence d'une contamination par du lindane (insecticide organochloré) a été étudiée. Au laboratoire, la durée d'exposition au lindane a été de 20 jours, sa concentration de 4 µg.l-1 au départ était de l'ordre de 2 µg.l-1 à la fin de la période d'exposition : la température a été constante (15 °C) et la photopériode 12/12 heures. Dans les mésocosmes, l'expérimentation a duré du mois de juin au mois de février. Au départ, la concentration du lindane était de 4,5 µg.l-1, elle était voisine de zéro en février. On constate que le taux instantané de croissance (b) est plus élevé dans les mésocosmes qu'au laboratoire, en milieu contaminé qu'en milieu témoin. Dans les conditions de laboratoire il est environ 2,6 lois plus élevé pour des aselles contaminées (de poids compris entre 7 et 12 mg) que pour les aselles témoins. Cette augmentation est significative de l'action du lindane. Dans les mésocosmes, l'augmentation du taux instantané de croissance des aselles maintenues en milieu contaminé par rapport à celles provenant de milieu non contaminé n'est statistiquement significative qu'au septième mois après le début de la contamination par le lindane, elle ne l'est plus au huitième. Il semble que d'autres facteurs puissent expliquer cette augmentation, en particulier la qualité de l'alimentation est discutée. Aussi ne peut-on affirmer que le lindane dans les conditions naturelles est responsable d'une élévation du taux instantané de croissance de l'aselle., We estimated the ponderal growth (instantaneous growth rate) of a fresh-water invertebrate Asellus aquaticus L. (Crustacea, isopoda), bred under laboratory conditions and in experimental mesocosms. Contamination by the insecticide lindane (Pepro 99 % purity) was studied.To estimate the instantaneous growth rate we used the formula Wt = Wo exp Mt) in what Wo is the median weight class of Asellus at the beginning of experiment. Wt is the median weight after 20 days, dj is the days number multiplied by median temperature above 3 °C of considered period (3 °C is considered as minimal temperature below that no development is possible). Seven classe were constituted : class 1 (2 mg to 6.99 mg), 2 (7 to 11.99), 3 (12 to 16.99), 4 (17 to 21.99), 5 (22 to 26.99), 6 (27 to 31.99) and 7 (32 to 36.99). The instantaneous growth rate is calculated for this seven class weight and for each replicate, next median and standard error were calculated for each class. The number of replicate vary among class weight. It was : 22, 33, 29, 22, 16, 15 and 13 respectively for class 1, 2, 3, 4, 5, 6 and 7.Asellus were preleved in natural ponds, acclimated in laboratory conditions during a minimal period of 15 days before that they are used for experiment. (glass containers of 30 litres, filled with hall tap-water hall pond-water, feed with maple leaves).In laboratory conditions Asellus were kept in glass aquarium (15 x 20 x 18 cm) filled with 2 litres of water.Physico-chemical parameters of water were : pH = 8.2; total hardness =155 mg 1-1 measured as Ca C03; nitrites = 0.055 mg 1-1; nitrates = 3 mg 1-1; chloride = 73 mg l-1 as Na C1. Laboratory breeding conditions were a tempera-tare of 15 °C and a 12/12 hours photoperiod. Contamination tasted 20 days, lindane concentration was 4,5 µg. l-1 (near the median lethal concentration, 48 hours : 5.14 µg.1-1) at the beginning of the experiment and approximatively 2 µg.1-1 at the end. Twenty Asellus of the same weight class were deposed in each glass. The diet was constitued with maple leaves. For contamination study only Asellus of class 7 to 11.99 was study. Ten replicates were realised.The mesocosms were constituted by two rectangular basins 10 meters in length, 2.5 m in width and 50 to 60 cm in deep. To secure a good water-thightness, bottom and sides were covered with black polyane 150 µm in thick, sediment and sand were deposed on the bottom on 5 to 10 cm in thick. Next basins were gradually (July 1987 to January 1988) filled up with tapwater. Natural colonization by phytoplankton and insects were observed, whereas vegetable (Ranunculus aquatilis, Typha angustifolia, Scirpus palustris and Ceratophyllum submersum) and invertebrates (Asellus, Planaria and Leech) were introduced by us. One mesocosm was contaminated by surface spraying with lindane acetonic solution.Thirty of a same weight class were placed in 25 x 12 x 7 cm plastic box, with a total of 20 lateral openings on either side (1.2 cm in diameter) disposed in two rows and covered with fine mesh net (150 µm in opening). The center part of the lid was cut out and also covered with the same fine mesh net. A bed of maple leaves was placed on the bottom of the box. This containers were then distributed throughout bath the control and lindane contaminated basins. Between 15 to 20 days later, this containers were collected and brought back to the laboratory. All the specimens were weighted and once divided into size classes and returned to their experimental basins. The experiment started in June 1988 and lasted till February 1989. The lindane concentration was 4.5 µg.l-1 at the beginning and near zero at the end.For the control, in laboratory condition or in mesocosm, we observed that the instantaneous growth rate decrease when the median weight of the class increase. It vary to 0.1131 mg.mg- 1.dj-1 to 0.0183 mg.mg-1.dj-1 and to 0.2704 mg.mg-1.dj-1 to 0.0879 mg.mg-1.dj-1 respectively in laboratory condition and mesocosm. Significant correlation (level 0.001) was observed between the logarithm of instantaneous growth rate and logarithm of the weight. Slope of regression lines does not vary, only position differ. Growth rate was higher in the mesocosm than in laboratory. In laboratory conditions lindane contamination induce a variation of instantaneous growth rate. An significant increase of 2.6 was observed between contaminated and control for Asellus of weight class 7 to 11.99 mg. In the contaminated mesocosm, a correlation is noted between instantaneous growth rate and weight, it is significant only for 3 collections dates (December 1988, January 1989 and February 1989). No variation in the slope of linear regression is noted, position differ significatively (level 0.01) only in February. For this collection date instantaneous growth rate is higher in contaminated mesocosm than in control. It appear that other factors that lindane contamination may also explain this increase. Among these, food quality has been envisaged by different authors. In conclusion is noted that in laboratory condition lindane induce an increase of instantaneous growth rate, in mesocosm we can't affirm that lindane was the responsible for the increase of instantaneous growth rate. Other experiments are necessary to confirm this observation.

INRA-Onema "Phylogeny and Polluosensitivity" program This work was supported by the INRA-Onema 2013-2014 "Phylogeny and Polluosensitivity" program. The authors thank Marc Collinet and Antoine Gallard for technical assistance. Elsevier sci ltd; International audience; The use of standardized monospecific testing to assess the ecological risk of chemicals implicitly relies on the strong assumption that intraspecific variation in sensitivity is negligible or irrelevant in this context. In this study, we investigated genetic variation in copper sensitivity of the freshwater snail Lymnaea stagnalis, using lineages stemming from eight natural populations or strains found to be genetically differentiated at neutral markers. Copper-induced mortality varied widely among populations, as did the estimated daily death rate and time to 50% mortality (LT50). Population genetic divergence in copper sensitivity was compared to neutral differentiation using the Qs-r-FsT approach. No evidence for homogenizing selection could be detected. This result demonstrates that species-level extrapolations from single population studies are highly unreliable. The study provides a simple example of how evolutionary principles could be incorporated into ecotoxicity testing in order to refine ecological risk assessment. (C) 2015 Elsevier Ltd. All rights reserved.

The effects of fenitrothion exposure on fourth-instar Chimnomus 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.

Short-term (24 h) effects of four stressors (hypoxia, hyperoxia, potassium dichromate, fenitrothion) on the activity of the electron transport system (ETS) and total lipid, glycogen and protein contents were assessed in 4th instar larvae of Chironomus riparius. Hypoxia and hyperoxia caused an increase in ETS activity and protein content. Glycogen content decreased when larvae were placed under hypoxic conditions. ETS activity increased following exposure to 2 microg x l(-1) of fenitrothion. It decreased in larvae exposed to 20 microg x l(-1) of this insecticide. A decrease in lipid and glycogen contents was observed in larvae exposed to potassium dichromate or fenitrothion. Changes in ETS activity and lipid and glycogen contents may be related to the activation of the respiratory chain due to an increase in energy cost associated with homeostatic phenomena, such as detoxification processes. These results suggest that some parameters related to energy metabolism, such as ETS activity and lipid and glycogen contents, may be used as biomarkers of environmental disturbance in Chironomus riparius larvae.

Micro- and mesocosms are frequently required in regulatory procedures of aquatic risk assessment for pesticides. However, many questions are still a matter of debate with regard to the use of these systems for environmental risk assessment, especially considering the inter-system variability of the measured parameters and its consequences on experimental design and data analysis. In this paper, variability of physico-chemical and biological parameters measured during two long-term experiments (8 to 9 months) in uncontaminated outdoor freshwater lentic mesocosms (8 m3) is analysed. Consequences on the design of ecotoxicity tests in mesocosms and on data analysis are also addressed. Water temperature, pH, dissolved oxygen concentration and concentration of suspended solids exhibited a very low variability whereas nutrient concentrations displayed elevated levels of variability. Among biological parameters, those measured at the individual level were less variable than those measured at the community level. Functional descriptors frequently exhibited a lower inter-mesocosm variability than structural descriptors. Aggregation of data proved to significantly reduce inter-mesocosm variability. The results indicate that univariate statistical methods may be used for physico-chemical or species-level (e.g. biometric parameters) data which exhibit a moderate inter-mesocosm variability. The use of multivariate techniques is suggested for other levels of investigation. Nevertheless, variability is not sufficient to identify useful parameters. The sensitivity towards chemicals and ecological relevance of descriptors within the experimental context must also be considered.

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 (GSH-Px) 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 (20 micrograms/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.

The activities of superoxide dismutase (SOD) isoenzymes were measured in fourth instar larvae of Chironomus riparius Mg. Three types of superoxide dismutase were identified: Cu,Zn-SOD in hemolymph and postmitochondrial fraction; Mn-SOD in mitochondrial fraction and presumably Fe-SOD in postmitochondrial fraction. The latter could have an endosymbiotic or a parasitic origin. Extracellular and cytosolic SOD activities, especially Cu,Zn-SOD, tended to increase in the last phase of larval development, independently of protein or hemoglobin contents. This supposes that SOD activity in Ch. riparius larvae is probably activated at the end of fourth instar stage. Cu,Zn-SOD and Mn-SOD activities showed a significant increase under severe hypoxia and slight hyperoxia. Oxygen radical scavengers such as SOD may play a role in the increased tolerance of Ch. riparius to oxidative stress. These results suggest that the specific induction of some SOD isoenzymes could be used as a biomarker of environmental disturbance such as oxidative stress initiated by xenobiotics.

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 larval instar; whereas, the more abundant H. pellucidula overwintered in the 2nd or 3rd larval instar. The main larval growth periods of the two species 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 larval instars; however, they both changed their food habits as they passed from one instar to another, and earlier instars were more predatory than the older ones.

Freshwater mesocosms were used to study the long-term sublethal effects of atrazine and hexachlorobenzene (HCB) on a basommatophoran gastropod, Lymnaea palustris (Mueller). Growth, fecundity, and biochemical parameters related to polysaccharide metabolism of pesticide-exposed snails were compared with those of control animals maintained in untreated mesocosms. HCB inhibited body growth and stimulated egg production, whereas atrazine had no relevant effect on these physiological parameters. Also, HCB stimulated the activity of polysaccharide-hydrolyzing enzymes, suggesting that changes in the metabolism of reserve polysaccharides (glycogen) may be involved in the inhibition of growth and increase of fecundity. In contrast, atrazine had no effect on the metabolism of polysaccharides. It is concluded that the effects of HCB are related to its neurotoxicity that would have affected the neurohormonal control of growth and reproduction of exposed snails. It is suggested that polysaccharide-hydrolyzing enzymes may be used as biomarkers to predict the effects of neurotoxic pesticides on freshwater snail populations.

Although a number of biomarkers of pollutant exposure have been identified in invertebrate species, direct linkage with changes at population and/or community levels are poorly documented and, despite the ecological importance of invertebrates, there is no conclusive evidence that individual measurements of biochemical parameters may allow the effects of pollutants on populations and communities to be predicted. Among the various biochemical parameters used as biomarkers in invertebrates exposed to pollutants in the field, only those for which changes at population or community level can be suggested are discussed in the present review. At population and community levels, the development of resistance to pesticides and changes in behaviour, reproduction and development are analysed as putative consequences of biochemical and physiological alterations. Limits to the use of biochemical parameters as biomarkers of invertebrate exposure to pollutants are discussed. Future research trends and experimental approaches to the validation of invertebrate biomarkers in environmental pollution assessment are suggested.

Two freshwater mesocosms (10 and 20 m 3 ) were sprayed with lindane and deltamethrin, respectively. We determined the time-dependent changes in pesticide concentration in water, sediment, macrophyte and gastropod samples and the effects on phytoplanktonic, periphytic and insect communities. Lindane residues persisted 19 weeks in water, 18 weeks in sediment, 14 weeks in macrophytes and 13 weeks in gastropods. Lindane had only transitory effects on periphytic and insect communities, resulting in a slight increase in periphyton ash-free dry weight and a moderate reduction of the number of captured insects. Deltamethrin residues persisted in water for only 96 h. Residues were detected in the macrophyte samples for 5 weeks after treatment but never in the sediment and only 24 h after treatment in the gastropod samples. The phytoplanktonic and periphytic communities were positively affected by the treatment whereas emerging insect abundance was strongly reduced. The presence of the control mesocosms as a source of fauna significantly enhanced the re-establishment of the insect community in the treated mesocosms.

The uptake and elimination of lindane by adult Lymnaea palustris (Muller) were studied using a static contamination system. First-order one-and two-compartment models were used to quantitatively describe these phenomena. The accumulation of residues was triphasic and the observed steady-state bioconcentration factor lay between 36.8 and 56.4 but did not significantly depend on the initial lindane concentration (6, 60, and 600 μg liter −1 ). Accumulation was inferior to that observed for other aquatic organisms and this was attributed to the relatively low lipid content of L. palustris tissues (mean of 0.81 ± 0.17% of fresh weight). The transfer of snails to lindane-free water after 72 hr of exposure was followed by a biphasic elimination of residues with a halflife of 0.7 hr in the central compartment and of 130.2 hr in the peripheral compartment. Additional experiments showed that the residues enter the snails through the foot and are afterward stocked within the visceral mass which contains approximately three times more lipids than the foot (1.03 ± 0.13% of fresh weight vs 0.37 ± 0.03%).

The distribution (both specific and individual) of four pulmonate gastropods was studied in a ditch near Orsay, France, from April 1987 to August 1988. Physa fontinalis L. and Anisus albus (Muller) were restricted to the part of the ditch which never dries up and positively associated with the hydrophytes Ceratophyllum submersum L. and Callitriche hamulata Kuntz. On the other hand, Anisus rotundatus (Poiret), which is drought resistant, was abundant in the shallowest part of the ditch and was positively associated with helophytes while Lymnaea palustris (Muller) was ubiquitous and present throughout the ditch. Plant morphology appears to be a major factor determining snail-plant relationships. Within their respective habitats, each species presented an aggregated distribution; their variances were stabilized by logarithmic transformation for L. palustris, Downing's transformation for P. fontinalis and Taylor's transformation for the two remaining species.

There is a paucity of large-scale field investigations on the effects of organic toxicants on stream macro invertebrate 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. (c) 2007 Elsevier B.V. All rights reserved.

The first deliberately constructed artificial aquatic ecosystems were designed for ecological studies to develop and validate new theories on ecosystem structure and function (Hall et al. 1970; Lawton 1995). Such systems are currently used worldwide and seem to be promising in the developing field of ecological engineering (Kangas and Adey 1996; Odum 1996). It became rapidly evident that model ecosystems could also provide valuable information for the assessment of the fate and effects of chemicals. In particular, they provide the opportunity to simultaneously identify direct and indirect effects of toxicants and to investigate responses at many different levels of biological organization in fairly controlled conditions of exposure. Processes that reduce, such as adsorption on suspended solids or sediments, or enhance, such as bioturbation or bioaccumulation, the bioavailability of contaminants can also be taken into account using such experimental devices. Because of their relevance in environmental risk assessment, mesocosms have sometimes been required for the registration of new chemicals, especially pesticides, and corresponding guidelines and guidance documents have been proposed (Touart 1988; Crossland 1990; SETAC-RESOLVE 1992; SETAC-Europe 1992). New guidelines are currently under evaluation (OECD 1996; USEPA-OPPTS 1996).

Common terns (Sterna hirundo) exhibit a remarkable range of variation in reproductive success. Several factors are known to contribute to reproductive failure either before hatching or between the time of hatching and fledging : predation pressure, food availability, flooding, competition for nesting sites, and toxic chemicals. Contaminants such as organochlorine pesticides, polychlorinated biphenyls (PCBs), polychlorodibenzodioxins (PCDDs), polychlorodibenzofurans (PCDFs), mercury and selenium were proved to significantly impair tern reproduction. During the reproductive period of 1988, an important mortality of common terns was observed in french colonies around the river Rhine. Approximately 50% of the young died a few days after hatching. The objective of the present study was to determine whether the intoxication by chlorinated compounds could have been responsible for the observed reproductive failure. 25 refs., 1 tab.

The effects of fenitrothion exposure on fourth-instar Chimnomus 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.

Après une présentation des besoins en matière d'évaluation de la qualité des milieux aquatiques continentaux, ce document présente l'état de l'art sur le développement des bioindicateurs tels qu'il a été présenté lors du séminaire organisé par l'Onema les 19 et 20 avril 2011 à Paris. Il s'agit donc d'une synthèse des journées "DCE et bioindication"

Action 9 INRA Thonon-Rennes / ONEMA; Des bioindicateurs pour évaluer l’impact ou la restauration vis-à-vis des pesticides – Invertébrés. Colloque ONEMA Les méthodes d'évaluation de l'état des eaux : situation et perspectives dans le contexte de la DCE