3 research outputs found
Field assessment of reproduction-related traits of chironomids using a newly developed emergence platform (E-Board)
Further progress in the development of reliable biomonitoring strategies requires to better link effects in aquatic ecological systems to ambient concentrations of chemical contaminants. Among existing tools, in situ bioassays using caging method represent an interesting way to achieve this challenge. However, elaboration of adapted exposure chambers and suitable operating procedures is still required, particularly to assess ecological relevant traits such as those related to the reproduction. In such context, we developed a new device (Emergence board E-Board) which allows assessing in rivers the development of the Chironpmus riparius species from the early fourth instar larvae to the adult stage. The system acts as a suspended matter trap floating in the subsurface of the water equipped of an emergence trap for catching adults. The system was tested in actual field conditions. Its easy handling allowed obtaining data which demonstrated its applicability for assessing the development of the chironomids. Moreover, by adapting energy-based models (DEB) specifically developed in the laboratory for the species C. riparius, we were able to predict the growth pattern and the emergence of chironomids in real environmental conditions. The E-Board represents thus a promising new in situ tool in perspective of evaluation of the quality of the ecosystems
Evaluation intĂ©grĂ©e et multidisciplinaire de la qualitĂ© du milieu par lâapproche âWeight-of-Evidenceâ : application Ă une Ă©tude de cas le long de la Seine (PIREN-Seine)
National audienceLâĂ©valuation de la qualitĂ© des environnements fortement anthropisĂ©s, tel que le bassin de la Seine, et donc assujettis Ă des apports chroniques trĂšs complexes, constitue un vĂ©ritable challenge et doit sâappuyer conjointement sur des analyses chimiques du milieu et les rĂ©ponses du biote face Ă cette pression. La prĂ©sente Ă©tude propose lâintĂ©gration et la synthĂšse dâun jeu de donnĂ©es pluridisciplinaire variĂ© acquis lors du suivi de trois sites-ateliers le long de la Seine (Ă lâamont et Ă lâaval de Paris) au cours de quatre campagnes Ă©talĂ©es sur une annĂ©e, dans le cadre du programme PIREN-Seine (Phase 6). Lâanalyse repose sur lâapplication de lâapproche « Weight-of-Evidence » consistant Ă examiner quatre volets ou lines of evidence combinant analyses chimiques du milieu (eau et sĂ©diment), biodisponibilitĂ© des contaminants (bioaccumulation) et mesures de biomarqueurs chez des gammares exposĂ©s in situ, et rĂ©ponses de tests de toxicitĂ© en laboratoire. Les rĂ©sultats de chaque LOE reflĂštent parfaitement le gradient anthropique de la zone dâĂ©tude avec des niveaux de contaminations et des perturbations biologiques croissants de lâamont Ă lâaval de Paris. En se basant sur la moyenne annuelle, le risque environnemental global a pu ĂȘtre classĂ© comme « modĂ©rĂ© » pour le site amont et « sĂ©vĂšre » pour les deux sites aval. Lâanalyse a Ă©galement permis de mettre en Ă©vidence une certaine variabilitĂ© saisonniĂšre, identifiant la campagne hivernale comme la moins fortement impactĂ©e. Le modĂšle a notamment Ă©tĂ© affinĂ© par lâutilisation de valeurs de rĂ©fĂ©rence et de seuils de rĂ©ponses issus dâĂ©tudes menĂ©es Ă large Ă©chelle gĂ©ographique et intĂ©grant certains facteurs confondants. La dĂ©marche appliquĂ©e ici sâest avĂ©rĂ©e trĂšs adaptĂ©e et performante, et pourrait reprĂ©senter un outil dâaide Ă la dĂ©cision dâun intĂ©rĂȘt indĂ©niable pour les diffĂ©rents acteurs environnementaux dans le cadre dâune analyse du risque environnemental
Role of Biofilms in Contaminant Bioaccumulation and Trophic Transfer in Aquatic Ecosystems: Current State of Knowledge and Future Challenges
International audienceIn freshwater environments, microbial assemblages attached to submerged substrates play an essential role in ecosystem processes such as primary production, supported by periphyton, or organic matter decomposition, supported by microbial communities attached to leaf litter or sediments. These microbial assemblages, also called biofilms, are not only involved in nutrients fluxes but also in contaminants dynamics. Biofilms can accumulate metals and organic contaminants transported by the water flow and/or adsorbed onto substrates. Furthermore, due to their high metabolic activity and their role in aquatic food webs, microbial biofilms are also likely to influence contaminant fate in aquatic ecosystems. In this review, we provide (1) a critical overview of the analytical methods currently in use for detecting and quantifying metals and organic micropollutants in microbial biofilms attached to benthic substrata (rocks, sediments, leaf litter); (2) a review of the distribution of those contaminants within aquatic biofilms and the role of these benthic microbial communities in contaminant fate; (3) a set of future challenges concerning the role of biofilms in contaminant accumulation and trophic transfers in the aquatic food web. This literature review highlighted that most knowledge on the interaction between biofilm and contaminants is focused on contaminants dynamics in periphyton while technical limitations are still preventing a thorough estimation of contaminants accumulation in biofilms attached to leaf litter or sediments. In addition, microbial biofilms represent an important food resource in freshwater ecosystems, yet their role in dietary contaminant exposure has been neglected for a long time, and the importance of biofilms in trophic transfer of contaminants is still understudied