title: Relative influence of chemical and non-chemical stressors on invertebrate communities: a case study in the Danube River.
abstract: A key challenge for the ecological risk assessment of chemicals has been to evaluate the relative contribution of chemical pollution to the variability observed in biological communities, as well as to identify multiple stressor groups. In this study we evaluated the toxic pressure exerted by >200 contaminants to benthic macroinvertebrates in the Danube River using the Toxic Unit approach. Furthermore, we evaluated correlations between several stressors (chemical and non-chemical) and biological indices commonly used for the ecological status assessment of aquatic ecosystems. We also performed several variation partitioning analyses to evaluate the relative contribution of contaminants and other abiotic parameters (i.e. habitat characteristics, hydromorphological alterations, water quality parameters) to the structural and biological trait variation of the invertebrate community. The results of this study show that most biological indices significantly correlate to parameters related to habitat and physico-chemical conditions, but showed limited correlation with the calculated toxic pressure. The calculated toxic pressure, however, showed little variation between sampling sites, which complicates the identification of pollution-induced effects. The results of this study show that the variation in the structure and trait composition of the invertebrate community are mainly explained by habitat and water quality parameters, whereas hydromorphological alterations play a less important role. Among the water quality parameters, physico-chemical parameters such as suspended solids, nutrients or dissolved oxygen explained a larger part of the variation in the invertebrate community as compared to metals or organic contaminants. Significant correlations exist between some physico-chemical measurements (e.g. nutrients) and some chemical classes (i.e. pharmaceuticals, chemicals related to human presence) which constitute important multiple stressor groups. This study demonstrates that, in large rivers like the Danube, the variation in the invertebrate community seems to be more related to varying habitat and physico-chemical conditions than to chemical pollution.
authors.affiliation: IMDEA Water Institute, Science and Technology Campus of the University of Alcalá, Avenida Punto Com 2, 28805 Alcalá de Henares, Madrid, Spain. Electronic address: andreu.rico@imdea.org.
authors.forename: Andreu
authors.initials: A
authors.lastname: Rico
authors.affiliation: Alterra, Wageningen University and Research centre, P.O. Box 47, 6700 AA Wageningen, The Netherlands; Department of Aquatic Ecology and Water Quality Management, Wageningen University, Wageningen University and Research centre, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Van den Brink
authors.affiliation: Institute of Hydrobiology and Aquatic Ecosystem Management, Department of Water, Atmosphere and Environment, BOKU, University of Natural Resources and Life Sciences, Vienna, Austria.
authors.forename: Patrick
authors.initials: P
authors.lastname: Leitner
authors.affiliation: Institute of Hydrobiology and Aquatic Ecosystem Management, Department of Water, Atmosphere and Environment, BOKU, University of Natural Resources and Life Sciences, Vienna, Austria.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Graf
authors.affiliation: Alterra, Wageningen University and Research centre, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Andreas
authors.initials: A
authors.lastname: Focks
mesh_terms: D000818:Animals; D058448:Biota / Q000187:drug effects*; D004784:Environmental Monitoring; D005060:Europe; D007448:Invertebrates / Q000187:drug effects*; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*; D014877:Water Pollution, Chemical
chemical_list: D014874:Water Pollutants, Chemical
keywords: Aquatic communities; Aquatic invertebrates; Biological traits; Ecological risk assessment; Multiple stressors; Toxic units