Benthic microbial communities as diagnostic tools to assess the impact of micropollutant contamination on ecological and functional quality of lotic ecosystems

Abstract

In the last decades, anthropic activities have led to the degradation of aquatic ecosystems worldwide. In Europe, the Water Framework Directive aims to protect aquatic ecosystems, in particular by implementing biomonitoring programmes to evaluate their ecological and chemical quality. Nevertheless, current biomonitoring programmes present numerous shortcomings in particular considering the complexity of environmental exposure to contaminants (e.g. multicontamination, temporal variability of concentrations) as well as the various biological responses to contaminants (e.g. standard toxicity tests based on poorly ecologically-relevant species, mixture effects not taken into account). In this context, the present article describes the state of knowledge about the contribution of benthic microbial communities to the evaluation of the ecotoxicological and functional quality of lotic ecosystems exposed to micropollutants. Various microbial indicators helpful for the diagnosis of both the exposure to and the effects of micropollutants are described: diatom morphological alterations, microbial adaptation and acquisition of tolerance, organic matter decomposition rates... Later, the pros and cons of the application of those diagnosis tools in environmental management are discussed, highlighting the limits to overcome before their implementation, such as the lack of standardized protocols and general references or the need to better acknowledge the relevance of microbial communities in aquatic ecosystems.