Abstract
The Water Framework Directive (WFD) regulates freshwater and coastal water quality assessment in Europe. Chemical and ecological water quality status is based on measurements of chemical pollutants in water and biota together with other indicators such as temperature, nutrients, species compositions (phytoplankton, microalgae, benthos and fish) and hydromorphological conditions. However, in the current strategy a link between the chemical and the ecological status is missing. In the present WFD, no microbiological indicators are foreseen for integrating the different anthropogenic pressures, including mixtures of chemicals, nutrients and temperature changes, to provide a holistic view of the freshwater ecosystem water quality. The main aim of this work was to evaluate if natural microbial populations can be valuable indicators of multiple stressors (e.g. chemical pollutants, temperature, nutrients etc.) to guide preventive and remediation actions by water authorities. A preliminary survey was conducted to identify four sites reflecting a contamination gradient from the source to the mouth of a river suitable to the objectives of the European Marie Curie project, MicroCoKit. The River Tiber (Italy) was selected as a pilot case study to investigate the correlation between bacteria taxa and the chemical status of the river. The main physicochemical parameters, inorganic elements, organic pollutants and natural microbial community composition were assessed at four selected sites corresponding to pristine, agricultural, industrial and urban areas for three consecutive years.The overall chemical results indicated a correspondence between different groups of contaminants and the main contamination sources at the selected sampling points. Phylogenetic analysis of the microbial community analyzed by Fluorescence In Situ Hybridization method (FISH) revealed differences among the four sampling sites which could reflect an adaptive bacterial response to the different anthropogenic pressures.
Highlights
In Europe many different chemical pollutants are released into the aquatic environment, mainly from agriculture, industry, and households
The ecological quality assessments of freshwater bodies are based on biological quality elements, hydromorphological parameters, physicochemical quality elements and the concentration of river basin chemical pollutants
Pathogen microorganisms have been used as indicators of fecal contamination, natural microbial populations can be used to assess the functional efficiency of ecosystems being useful for environmental assessment as complementary methods to chemical monitoring (Boi et al, 2016)
Summary
In Europe many different chemical pollutants are released into the aquatic environment, mainly from agriculture, industry, and households. Pathogen microorganisms have been used as indicators of fecal contamination, natural microbial populations can be used to assess the functional efficiency of ecosystems being useful for environmental assessment as complementary methods to chemical monitoring (Boi et al, 2016). For these reasons, the changes that can be observed in a microbial community can be analyzed from a global and multivariate perspective, to understand and assess the impact of the wide and complex mixture of chemical and physical parameters on the ecological status of the environment
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