1. Corina Carpentier AquaLife Workshop, Kiel, Germany 2nd June 2010
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)
Impact
Ecological Status {
None or minimal
HIGH
GOOD
MODERATE
POOR
BAD
No deterioration
Low {
Restoration
Moderate {
High {
Severe {
Links between chemical and
ecological status?
Courtesy Peter Pollard, Scottish Environment Protection Agency

4. Implementation of the WFD
biological quality elements
hydro-morphological pressures
nutrients
organic
pollution
toxicity
acidification
benthic invertebrates ++
+++ +
phytobenthos, macrophytes -
phytoplankton
fish

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?
Substrate
Before
(µg/cm2)
After (µg/cm2)
removal
cyanobacteria
1.20
0.45
62.4%
diatoms
0.17
0.15
13.4%

7. Avoid sampling errors by performing in 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
black plastic
Black cloth
dye-filter
10.5 µg/cm2
12.8 µg/cm2

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)
substrate
original result
(µg/cm2) black
(µg/cm2) stone
corrected result
(µg/cm2) 700nm
black
10.47
stone 7 p1
19.29 (+84%)
7.38 (-29%)
9.90 (-5.5%)
stone 7 p2
17.10 (+63%)
6.61 (-37%)
10.02 (-4.3%)
stone 8 p3
11.89 (+ 13.5%)
4.78 (-54%)
11.28 (+7.7%)
stone 8 p4
11.23 (+ 7.3%)
4.57 (-56%)
10.96 (+4.7%)

11. Patchy distribution
Hildebrandia rivularis

12. Patchiness (2) sample green algae (µg/cm2) cyanobacteria (µg/cm2)
diatoms (µg/cm2) 1
0.00
1.58
0.34 2
0.55
1.01 3
1.12
0.72 4
0.26
1.00
0.44

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
Width of 95% CI: 0.5  reached after 33 measurements
n = 33

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 minutes)

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