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Microbenthic communities in European Rivers used to assess effects of land-derived toxicants


The aim of the proposed study is to assess community effects of toxicant fluxes in rivers. This can be achieved through a new methodology incorporating the large biological and chemical differences among European rivnrs. The fate and biological effectivity of toxicants in river system is supposed to be greatly affected by the concurrent loading with humics and various ions. To verify this, the speciation of metals, herbicides and PAH will be quantified. For metals, an experimental mobile voltametric instrument will be used together with sorption on chelating resins.
Dialysis of isotope-labelled organic toxicants will be used to assess Sifferences in speciation of selected herbicides and PAH among rivers. When chemicals are present in biologically effective concentrations, these are likely to induce changes in the tolerance profile and species composition of communities. Such changes will be assessed in a selection of rivers, using natural communities of closely stacked micro-algae, Bacteria and microfauna, settled on sand and cobbles. Short-term metabolic tests will be used to describe the sensitivity of photosynthesis in algae (14 C-technique), DNA multiplication in bacteria (3H-thymidine method), and replication in eukaryotes (e.g.ciliates; adenine/thymidine method).
Differences in tolerance to selected compounds (metals, herbicides, PAH), neasured with these physiological techniques will be compared with longterm community changes observed at river stations polluted with either a single type of contaminants or complex mixtures. Communities in artificial streams are used to verify questions raised in these field studies.
Photometric alternatives for the isotope-based physiological techniques will be developed to allow wider application in future and a mobile Facility for in situ community tests will be created.
The project will bring the biological and chemical approaches together into case studies of river pollution in northern, western and southern Burope. The complementary expertise of the partners allow an assessment of the consequences and risks of toxicant input in rivers that differs considerably from traditional methods based on a strategy of 'one species at a time' and 'one substance at a time'.
The proposed research is likely to fulfil the needs of a growing Matchment oriented management of pollutants in Europe.
KEYWORDS (max 10):
river communities, speciation of toxicants, physiological endpoints, mesocosms, ecological risk-assessment

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Universiteit van Amsterdam
1098 SM Amsterdam

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Participants (4)