Biological responses of aquatic organisms and assessment water contamination and ecotoxicity
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Change of scale: from cell to population
Contamination and transfers
Innovative approach and new tools in environmental research
Marine and continental ecosystems are subjected to many stresses related to human activities because they emit a large number of molecules whose toxicological and ecological effects are currently poorly studied. Assessing water quality is a real challenge for the authorities. Additionally, in a changing world (extreme events, amplified seasonality, etc.), it is crucial to adapt water management actions with a view to protecting sensitive human populations as well as biodiversity and ecosystem services such as drinkability or recreational uses. To preserve the quality of resources, it appears necessary to specify the effects of environmental contamination (chemical and biological) on water quality. In this context, the application of the European Water Framework Directive (WFD; Directive 2000/60/EC) for the monitoring of water chemical contamination involves two main objectives based on (1) the assessment of the chemical status of water bodies and (2) the evaluation of the temporal trends of contamination in the different environmental compartments of aquatic ecosystems. As water is a fluctuating medium, its chemical status does not reflect the true hazards for populations and ecosystems. Moreover, the effects on aquatic populations fail to provide predictive information for adequate hazard management. However, to check the compliance of chemical analyses with Environmental Quality Standards (EQSs), the biota appears as a new interesting matrix. Similarly, the biota is proposed as an integrative matrix and recognized as a preferential matrix for several substances (Directive 2008/105/EC) in the monitoring of contamination trends. In fact, aquatic organisms can concentrate and retain substances in their tissues for a long time. Therefore, proposing aquatic organisms as a tool to assess water quality represents an interesting integrative method. Furthermore, even if analyses of bioaccumulated pollutants have the great advantage of evidencing the bioavailable fraction of xenobiotics, they provide no information about their potential biological effects. Therefore, the relationship between exposure to pollutants and adverse effects is of growing importance in environmental risk assessment and management. In this way, the response of sentinel species at a sub-individual level could be recognized as an early-warning system to monitor the degree of contamination and also the associated risk.
This special issue cannot fully reflect all the studies and research works presented at the SEFA annual Workshop. So the special issue highlights 11 selected papers which address the assessment of bioavailability, bioaccumulation, and transfer (including trophic transfer under fluctuating environmental parameters such as temperature and pH) of various contaminants (mainly trace metals) present in different compartments (water, sediment, food) to organisms and their usefulness as bioindicator species. In addition, the responses of organisms exposed to these different contaminants were investigated at different biological levels including detoxification mechanisms, DNA integrity measurements, or the modification of different functions (digestion, spermatogenesis) and life history traits. Furthermore, several papers characterize the measurement of these biological effects (genotoxicity, reprotoxicity) with a view to a potential application to in situ aquatic biomonitoring surveys. Finally, one paper presents MOSAIC, a user-friendly web interface dedicated to statistical analyses in ecotoxicology.