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Sources of variability in phytobenthos biomass measurements using the BenthoFluor

Sources of variability in phytobenthos biomass measurements using the BenthoFluor. Corina Carpentier AquaLife Workshop, Kiel, Germany 2 nd June 2010. Introduction. Why phytobenthos analysis in rivers? Why in situ phytobenthos measurements? Sources of variability substrate

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Sources of variability in phytobenthos biomass measurements using the BenthoFluor

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  1. Sources of variability in phytobenthos biomass measurements using the BenthoFluor Corina Carpentier AquaLife Workshop, Kiel, Germany 2nd June 2010

  2. Introduction • Why phytobenthos analysis in rivers? • Why in situ phytobenthos measurements? • Sources of variability • substrate • patchy distribution • representativeness of results

  3. European Water Framework Directive (WFD) HIGH { GOOD Low { MODERATE Moderate No deterioration { POOR High Restoration { BAD Severe Impact Ecological Status { None or minimal Links between chemical and ecological status? Courtesy Peter Pollard, Scottish Environment Protection Agency

  4. Implementation of the WFD

  5. Research objective • Development of a method for the assessment of phytobenthos biomass as an indicator for the trophic status of flowing waters • This method has to be: • sufficiently sensitive for trophic status assessment • practical • fast • cheap

  6. CEN Guidance Standards EN 13946 and 14407: removal efficiency of sampling procedure?

  7. Avoid sampling errors by performingin situ measurements • BenthoFluor measurements in the field: • many measurements in a short time • determine suitable spots for biodiversity sampling • major difference as compared to phytoplankton analysis: the presence of a substrate

  8. The influence of the substrate

  9. Substrate-dependent correction factor

  10. Reflection factor based on 700 nm value yi = bixi (1+baixi) yi = real value at wavelength i; xi = raw value at wavelength i; ai = wavelength-dependent empirical factor; b = factor expressing the reflection properties of the substrate(b = 1 for stone; b = 2.1 for black background)

  11. Patchy distribution Hildebrandia rivularis

  12. Patchiness (2)

  13. CEN Guidance Standards EN 13946 and 14407: 5 samples per site left bank right bank Danube River, Bratislava (SK)

  14. How many measurements? 1.46 0.41 0.26

  15. Danube River data: 2,477 measurements n = 33 Width of 95% CI: 0.5  reached after 33 measurements

  16. In conclusion Substrate-dependent correction factor improves results considerably In situ BenthoFluor measurements provide insight into patchy distribution of phytobenthos Limited number of measurements (25-35) provides statistically representative results in little time (appr. 10-15 minutes)

  17. Thank you for your attention! Corina Carpentier AquaLife Workshop, Kiel, Germany 2nd June 2010

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