1. Alan Hildrew Martin Pusch Klement Tockner
Intercalibration of rivers and lakes
Alan Hildrew
Martin Pusch
Klement Tockner

2. The challenge to the reviewers
Dense, complicated and long!
Statistical conjuring tricks!
Variety of approaches
Realism and idealism

3. The hard question - has it worked?
Yes and no!
For rivers:
As presently feasible, intercalibration has been achieved for:
Macroinverts, C-B, N, Alpine, Medit., E-C…..but not for large rivers etc
Phytobenthos, N and Alpine….but not for C-B or Medit. (but for ‘good reasons’)

4. Problems (with a rivers bias)
A network of intercalibration sites - none emerged
Reference conditions
Information on pressures
Typology

5. The circularity in setting reference conditions
Northern GIG (phytobenthos) - “the use of the biota to define reference conditions - is not encouraged as the ND define ecological status in relation to the biota expected under undisturbed conditions…and the use of land-use and pressure data to define ‘undisturbed conditions’ ensures rigour and objectivity in the definition of the expected value”
i.e. the means used to define the environmental pressure and the ecological response must be independent. We were not convinced this was always the case.

6. There are no reference sites
“The EC GIG agreed to follow an alternative approach to resolve these issues by defining IC type specific , harmonised quality criteria. In general, the GIG set common high-good (type RE1) and good-moderate (types R-E2-4) quality class boundaries for the national assessment methods using existing data assembled within the EC GIG calibration exercise. The main idea….is to overcome the lack of (near natural) references by defining alternative references.”

7. The value of large rivers
availability of
reference
sites
Value
……………………..n
Stream order

8. Intercalibration - reference conditions were not consistent among MS
Central-Baltic (phytobenthos) - “There was considerable variation in the values of four metric computed at reference sites between MS. It is not clear…whether these differences are due to underlying differences in the unimpacted state between MS or whether they reflect failures to screen data adequately”
Northern (phytobenthos) - “The challenge is to differentiate between those differences in national reference states that reflect genuine biogeographical variability across the GIG and those that reflect differences in approach by those responsible for implementation”

9. There are not enough pressure data
Mediterranean GIG (macroinverts) - “Due to the lack of data…, the occasional use of expert judgement was an accepted means of validating reference sites especially in interpreting the use of different forms of chemical determinants throughout the GIG. A central pressures database was not available to verify reference sites.”

10. Problems with typology

11. Problems with typology
Central Baltic (phytobenthos) -
“Overall, these date suggest that the IC typology has no meaning for phytobenthos and subsequent analyses analyses ignore the IC types”

12. Problems with typology
Northern GIG (phytobenthos) - “this river typology was derived primarily for the macroinvertebrate intercalibration ……common intercalibration river types for the CB-GIG..did not distinguish between diatom assemblages…(and therefore)..the N-GIG working group agreed that a ‘no types’ approach was fit for purpose”
Shouldn’t ‘types’ be consistent among biological quality elements?

13. Problems with typology
Central-Baltic (macroinverts) - “A number of issues underlined the recommended use of the ‘all types combined’ option…..
Variation in MS IC river type boundary values attributable to differences in IC typology (that) cannot be quantified
Type specific variation within each IC river type…
The range of variability between MS boundary values is greater than the variability between river types…

14. Problems with typology
“….the whole concept of compartmentalising communities into a number of distinct types is fundamentally flawed, and that the overwhelming body of evidence (and theoretical arguments) suggests there is normally a gradual adjustment of species composition along environmental gradients. Nevertheless, the use of community ‘types’ persists as an integral part of many monitoring systems across Europe and we fear it will significantly limit our understanding of ecosystems and hence our ability to detect degradation.” (Woodward, Friberg & Hildrew, in press)

15. Problems with typology

16. Classifying a continuum…..

17. The future
Uncertainty

18. Incorporating uncertainty (Jones et al. in press)
Probability of
miscalculation
SE of estimate
as % of band
width

19. The future Functional indices Independent of biogeography
Species traits
Ecosystem processes
Independent of biogeography
Easier to reconstruct reference conditions
Incorporate new understanding/science

20. The future Intercalibration sites
“..an excellent step..establish a number of key catchments across Europe…sites with background data..and where ‘reference conditions’ could be objectively defined…include facilities for manipulative or statistical experiments at large scales. Against such reference sites, gradients of human pressures would enable us to determine reductions in ecological status -” AND TO INTERCALIBRATE EXISTING AND NEW MONITORING TECHNIQUES

21. The “LOCAR” catchments

22. An impressive body of work
Intercalibration of rivers and lakes
Good progress
An impressive body of work
An ongoing process
Direct calibration at key sites