The weight-of-evidence approach in classification of the ecological status of water bodies in Finland

Transcription

1 Second Nordic workshop on Harmonisation and realisation of the WFD in the Nordic countries with emphasize on lakes/rivers and heavily modified water bodies October, 2009 The weight-of-evidence approach in classification of the ecological status of water bodies in Finland Highlights/examples of rivers & humic lakes Kari-Matti Vuori SYKE

2 OUTLINE Key actions in WFD beyond classification? Assessment approaches using multiple quality elements Why? Classification approaches? WFD, OoAo, integration, feasibility Classification in practice FinEQ, highlights: river and lake cases Performance and relevance of different approaches

3 Key actions of WFD beyond classification? (Article 5, Article 6, Annex II, Annex III) To characterise river basin districts in terms of water body types, type-specific reference conditions, pressures, impacts and economics of water uses establish a register of protected areas lying within the river basin district carry out assessment of the risk for individual water bodies of failing the environmental objectives Pressure,impact&risk assessment is a wider and more holistic issue than (calculatory) classification based on single, intercalibrated BQEs BUT: no intercalibration, no specific guidance or common understanding on RA

4 Assessment approaches using multiple quality elements in classification/risk assessment -why? High spatial and temporal variation in environmental pressures and ecological conditions Neither natural and anthropogenic stressors, nor organisms & their responses are uniformly distributed in space and time Single organism groups/variables insufficient to provide cause-effect data necessary for river basin management options In most real-life cases: multiple pressures, multiple response mechanisms interact single elements seldom credible as such: need for a holistic RA-approaches Feasibility issues Ecosystem, stakeholders, citizens overall status/ecosystem functioning, not only a specific fraction/compartment of the ecosystem Early-warning signals, cautionary principles

5 Classification approaches EU Water Framework Directive (WFD) Stipulates to use multiple BQEs Focus on One-out, All-out approach (OoAo) If straightforwardly applied, may ignore the multiple lines of evidence and very basic principles of ecological risk assessment scientific debate open: risks for misclassifications, management implications Integrating multiple quality elements/lines of evidence Eg. Averaging and weighting BQE combinations (also in WFD) ERA, Weight-of-evidence approaches FinEQ

6 One-out, All-out, ECOSTAT

7 The Finnish Ecological Quality Assesment System FinEQ

8 The FinEQ classification system Ref.conditions spatially based / expert judgment Class boundaries using relevant percentiles for the H/G boundary, G/M, M/P & P/B boundaries equal width or reflecting tresholds Harmonization & integration: QEs & metrics are made comparable by scoring (IBI approach) Final status class BIOLOGY><PHYSICO-CHEM. WEIGHT-OF-EVIDENCE QUALITY ELEMENTS & PRESSURES REPRESENTATIVENESS of the data CAUSALITIES, CREDIBILITY UNCERTAINTIES included Class Score High 0.9 Good Poor 0.3 Bad 0.1

9 CLASSIFICATION METRICS I Biological quality elements Phytoplankton (lakes, coastal waters) a-chlorophyll, total biomass Bluegreen algae-% (tentative criteria supporting classification) Periphyton: diatoms, IPS-indice (rivers) Benthic macroinvertebrates PMA-indice (percent model affinity), number of type-specific species, number of type-specific EPT-families (rivers, general pressures) BQI/BBI (benthic quality indices, lakes/coastal), in lakes also PMA (tentative metric) Fish Biomass, number of individuals, cyprinid%, >15cm percid%, indicator species (lakes) Salmon/trout 0+, cyprinid %, species number, sensitive species %, tolerant % (rivers) Macrophytes Proportion of type-specific species, PMA, reference-indice (lakes) Maximum depth of Fucus (coastal waters)

10 CLASSIFICATION METRICS II Physico-chemical quality elements (tentative) Lakes TotP, TotN (epilimnion, long-term annual median) Rivers TotP, TotN (long-term annual median) Coastal waters Tot P (January-March, long-term median) Secchi depth

11 CLASSIFICATION METRICS III Hydro-morphological quality elements Scoring system based on tentative criteria for proportion/degree of water body altered by Dams, water reconstructions, channelization, regulation of water level/discharge Lakes: 6 assessment factors Rivers: 5 assessment factors

12 GENERAL PRINCIPLE: Final decision of the status class is based on integration of multiple lines of evidence 1) Face values from biological classifications Treated as tentative, calculatory assessment results Mainly applicable at the station level 2) Final decision on the status class Assessed conditions in the whole water body for Biological quality elements Physico-chemical quality elements Hydromorphological quality elements Ecotoxicity, concentrations of specific harmful substances ALL evidence on non-point/point-source pollution and other pressures causing eutrophication, siltation, habitat degradation, ecotoxicity

13 Integration applying ERA framework & WoE Exposure profile Effect profile Causative relations Association between pressures & effects Uncertainties? Weight of evidence Likelihood and extent of deteriorated Ecol. quality RISK MANAGEMENT: WFD PROGRAMME OF MEASURES

14 Hydrologic al pressures Morphological pressures Diffuse sources <= Pressure Transparency Oxygen conditions Nitrogen Phosphorous Suspended solids Phytoplankton Macrophytes Macroinvertebrates Fishes Hydrology Morphology River continuity FinEQ, Pressure-impact matrix Impacts => o-chemical quality el Biological quality elements Hydromorpholo gical quality elements Scattered settlements sewage Agriculture diffuse Forestry Atmospheric deposition Dams (transversal) Weirs (transversal) Longitudinal embankments Straightening Dredging Shore protections Urbanisation Flow regulation (rivers) Hydropeaking Level regulation (lakes) Change in riverprofile All together (cumulative impact)

15 WoE risk characterization Modified after Johnston et al LEVEL OF EXPOSURE? NONE, equal to reference conditions LOW MODERATE SUBSTANTIAL SEVERE LEVEL OF ECOLOGICAL EFFECTS? RISK INTERPRETATION NONE/MINOR None None Low Low MODERATE OBVIOUS Low Low Low High High High

16 Case study, the Kymijoki river Obs! Tentative classification

17 Kymijoki Problem Past gross pollution, prevailing problems with eutrophication and toxic substances Industrial and municipial waste waters Diffuse pollution (agriculture) Discharge and habitat alterations hydropower production & regulation, flood protection Analysis Exposure: chemical concentrations Data, degree of habitat alterations Ecological effects: Biological quality elements Data Risk characterization Weight-of-evidence Expert judgment

18 Diatom status class IPS-indice (Eloranta, unpublished data) Average 14.8 MODERATE

19 Fish status class Multimetric fish indice (average score GOOD) Species number, %cyprinids, %sensitive, %tolerant species

20 Benthic macroinvertebrate status class Benthic indice (average score GOOD) Type-specific species richness, EPTfamilies, PMA

21 Toxic substances: morphological biomarker of caddisfly larvae indicating toxic conditions 0 % Also: Chironomus mentum-deformities 54% in pool habitats 40% 15-25% % Cheumatopsyche lepida Tracheal gill damages: ecotoxicity indicator Vuori & Kukkonen 2002, Freshw. Biology 47:

22 Overall status (average across median scores) Good? EQR:

23 Weight-of-evidence Integrating lines of evidence

24 Weight-of-evidence from hydromorphological pressures LEVEL OF HYDROMORPHOLOGICAL ALTERATIONS NONE, equal to reference conditions LOW MODERATE SUBSTANTIAL SEVERE LEVEL OF ECOLOGICAL EFFECTS: status Risk level High/good None/low None/low None/low Low High Poor/Bad High High High Interpretation: moderate level of hydromorphological alterations not fully in agreement with the EEA, not a sufficient condition for considering the classification results to be credible (OoAo -diatom results)

25 Weight-of-evidence from pollutant loading/nutrient status LEVEL OF NUTRIENT LOADING/CONCENTRATIONS NONE, equal to reference conditions LOW MODERATE SUBSTANTIAL SEVERE LEVEL OF ECOLOGICAL EFFECTS: status Risk level High/good None/low None/low None/low Low High Poor/Bad High High High Interpretation: the considered level of nutrients do not fully support classification results. Point and non-point sources have caused eutrophication of the river ecosystem. Mesotrophic conditions prevail, increasing the risks of failing the good ecological status

26 Weight-of-evidence from exposure to toxic substances LEVEL OF TOXIC SUBSTANCES/ECOTOXICITY INDICATORS NONE, equal to reference conditions LOW MODERATE SUBSTANTIAL SEVERE LEVEL OF ECOLOGICAL EFFECTS: status Risk level High/good None/low None/low None/low Low High Poor/Bad High High High Interpretation: ecotoxicological evidence do not support classification results. Exposure is substantial, but patchy and has at least moderate impacts on the benthic populations. While considering risks from all of the lines of evidence, moderate status appears most credible.

27 Case study of small humic lakes Alahuhta J., Vuori K.-M., Hellsten S., Olin M., Järvinen M., Korhonen P., Rask M. & Palomäki A. 2009: Defining ecological status of small forest lakes using multiple biological quality elements and paleolimnological analysis. Fundam. Appl. Limnology (in press)

28 Practical comparison of the O-a,Ao principle & WoE-approach

29 Counts of classification scores for different biological quality elements across all metrics in the reference (black triangles) and impacted (grey triangles) lakes. The boundary between good and moderate status is a score of 0.6 (broken line)

30 Status score averages (± SE) for each quality elements in reference (black columns) and impacted lakes (grey columns). The boundary between good and moderate status is a score of 0.6 (broken line)

31 Classification scores across all metrics (for the list of metrics, see Table 2) for the study lakes: reference (black triangles) and impacted (grey triangles) triangles

32 Cumulative median status scores for the study lakes. Status score value of each element is cumulatively piled for every study lake. Values above the bars are status score medians calculated for all the quality elements (left) and the status scores of the weakest quality element according to the "One-out, All-out" (OoAo) principle (right)

33 Weight-of-evidence Water quality, pressures & biological community structure in general In general: good status, no major deviations Some lakes chararacterized with very specific features (not easily allocated to the type): suspect for the criteria BQE classification Several shortcomings, the lowest BQE results not credible Palaeolimnology Indications of past changes, BUT lack of credibility for this specific lake type and geographical area CONCLUSION: the integrated assessment result was most credible, lakes in good/high status

34 CONCLUDING REMARK: Applying ERA in status assessment and classification increases realism Helps to integrate multiple lines of evidence different classification metrics present & past anthropogenic pressures characteristics of the ecosystem Weight-of-evidence: opens the status assessment for critical discussions Credibility of results Relative importance of different factors, cause-effect relations Systematic framework for bringing more science and realism into the status assessment and RBMP

35 Kiitos, Thank you!