2012 INTERCALIBRATION TECHNICAL REPORT
MEDITTERANEAN RIVER GIG – PHYTOBENTHOS
Draft 28 February 2012
1. Introduction
The Mediterranean GIG successfully completed intercalibration for Phytobenthos in the first round. Results were included in the first Commission Decision on intercalibration (COM DEC 2008/915/EC) and the work was documented in the 2009 technical report.
The new intercalibration guidance includes updated procedures for the intercalibration process with the new Annex V criteria describing the technical steps of the intercalibration process.
For the second intercalibration round, the Mediterranean GIG has decided to repeat the whole exercise to be fully compliant with the requirements of the new guidance and to take into account new method development in the Member States and using larger data sets.
2. National assessment methods and their compliance with the WFD normative definitions
Participating countries in the work of the Mediterranean GIG for the BQE river phytobenthos were Cyprus, France, Italy, Portugal, Slovenia and Spain. Greece, and Malta, although geographically part of the GIG, did not participate.
An overview of the national methods that were intercalibrated is provided in Table 1 below. Detailed descriptions of the national methods, including the metrics used, the methodology for setting national reference conditions and the methodology for setting class boundaries, are provided in Annex A. All methods are finalized, formally agreed national methods, and all methods are included in the WISER method overview (www.wiser.eu).
Table 1 – Overview of national methods
Member State / MethodCyprus / IPS (Coste in Cemagref, 1982)
France / IBD 2007 (Coste et al, Ecol. Ind. 2009)
AFNOR NF-T-90-354, December 2007
Arrêté du 25 janvier 2010 modifié relatif aux méthodes et critères d’évaluation de l’état écologique {…} des eaux de surface
Italy / ICMi (Intercalibration Common Metric) Index (Mancini & Sollazzo, 2009)
Portugal / IPS (Coste in Cemagref, 1982)
Slovenia / Slovenian Ecological Status assessment system for rivers using phytobenthos based on the Saprobic index (Rott et al. 1997) and the Trophic index (Rott et al. 1999)
Spain / IPS (Coste in Cemagref, 1982)
Using the information reported in Annex A, the national methods were checked for compliance with the WFD normative definitions (Table 2).
Table 2 – Check of national methods against the WFD normative definitions
Compliance criteria / Compliance checking conclusions1. Ecological status is classified by one of five classes (high, good, moderate, poor and bad). / CY – yes
FR - yes
IT - yes
PT – yes
SI - yes
SP - yes
2. High, good and moderate ecological status are set in line with the WFD’s normative definitions (Boundary setting procedure) / CY – yes; High-good boundary derived from metric variability at near-natural reference sites. Possible reference sites were selected based on diatoms community structure and IPS values and were screened for pressures using experts judgment. Sites with minimum pressures were then selected as Reference sites.
The H/G boundary was set as the 25th percentile of STAR ICMi values at reference sites.
The G/M boundary was set as H/G boundary*0.75.
The M/P boundary was set as H/G boundary*0.5.
The P/B boundary was set as H/G boundary*0.25.
FR – yes.
- First enforcement for IBD 2000 : Ministerial Circular DE/MAGE/BEMA 05 n°14 of the 28th July 2005.
- The same procedure has been then reproduced to derive new threshold values of the good ecological status for French rivers using IBD 2007 (AFNOR NF-T-90-354, December 2007 and Arrêté interministériel d’Evaluation du 25/01/2010, Journal Officiel Français modifié relatif aux méthodes et critères d’évaluation de l’état écologique {…} des eaux de surface).
High-good boundary by type has been derived from metric variability at near-natural reference sites. The good/moderate boundary was then calculated using a two step procedure (this procedure based on diatom-derived biotypes to define the threshold values of the good ecological status of French rivers):
1- For each type, the remaining range below the H/G boundary and the IBD minimum value was split into 4 equal classes to derive a preliminary G/M boundary, following a procedure proposed in the REFCOND guidance.
2 - This preliminary boundary was then increased by 1 point on the IBD scale for all national types.
This procedure of boundaries calculation was chosen to be congruent with the French macroinvertebrates approach.
Then the IBD values obtained were checked to verify their compliance with normative definitions: the graph below shows the percentage of sensitive species (‘oligotraphent’ + ‘mesotraphent’ species: van Dam et al., 1994) in reference conditions and along the ecological status gradient.
This graph shows:
- no significant difference in sensitive species % between reference conditions and high status;
- a very slight but significant decrease of sensitive species between high and good status;
- a drop in the percentage of sensitive species between good and moderate status.
IT – yes; The basis for the choice of the Ecological status boundaries, were distribution and relative abundances of sensitive species to different pressure level, for each river typology. High-good boundary derived from metric variability at near-natural reference sites. Good –Moderate boundary has been set up, taking into account the abundance decrease or absence of sensitive species and spread of tolerant species, related to eutrophication and organic pollution. Equidistant division for the remaining class boundaries Moderate Poor and Poor-Bad.
PT – yes; High-Good classes boundary: 25th percentile of reference sites; the range below was divided in 4 equal classes; Good-Moderate = H/G x 0.75; Moderate-Poor = H/G x 0.50; Poor-Bad = H/G x 0.25
SI – yes; Equidistant division of the EQR gradient High-good boundary derived from metric variability at near-natural reference sites.
SP – yes; Equidistant division of the EQR gradient High-good boundary derived from metric variability at near-natural reference sites.
3. All relevant parameters indicative of the biological quality element are covered (see Table 1 in the IC Guidance). A combination rule to combine parameter assessment into BQE assessment has to be defined. If parameters are missing, Member States need to demonstrate that the method is sufficiently indicative of the status of the QE as a whole. / See Table 3 below for more detailed information
CY – relative abundance and taxonomic composition
FR – relative abundance and taxonomic composition
IT – relative abundance and taxonomic composition
PT – relative abundance and taxonomic composition
SI – relative abundance and taxonomic composition
SP – relative abundance and taxonomic composition
Concerning possible forms of combination between phytobenthos and macrophytes, this was not addressed in the present exercise.
4. Assessment is adapted to intercalibration common types that are defined in line with the typological requirements of the WFD Annex II and approved by WG ECOSTAT / CY – yes
FR - yes
IT - yes
PT – yes
SI - yes
SP – yes
The common typology has been adjusted according to data analysis.
5. The water body is assessed against type-specific near-natural reference conditions / CY - yes
FR - yes
IT - yes
PT - yes
SI - yes
SP - yes
6. Assessment results are expressed as EQRs / CY - yes
FR – yes
IT - yes
PT - yes
SI - yes
SP - yes
7. Sampling procedure allows for representative information about water body quality/ ecological status in space and time / CY – sampling twice a year (spring and autumn) and repeated the year after but only in spring
FR – sampling once a year (low flow conditions)
IT – sampling 4 times a year (spring, summer, autumn and winter)
PT – sampling once a year (spring)
SI – sampling once a year (low flow conditions)
SP – sampling three times a year (spring, summer and autumn)
8. All data relevant for assessing the biological parameters specified in the WFD’s normative definitions are covered by the sampling procedure / The sampling procedure of all national assessment methods consider taxonomic composition and relative abundance; they do not consider absolute abundance, undesirable disturbances or bacterial tufts. MedGIG experts agree with the analysis of the NGIG and CBGIG to these issues (Appendix 1 of the Rivers/X-GIG Milestone 5 report) which is that if a precautionary approach to boundary setting is taken using other properties, the probability of undesirable and bacterial tufts should be minimal when ecological status is good or better, so there is no need to include this in the IC exercise. Concerning the abundance issue we quote Rivers/X GIG Milestone 5 Report “Relative abundance adds value to taxonomic composition, by giving information on the organization and relative importance of taxa within the phytobenthos assemblage, giving greater emphasis to common taxa (presumed to be those thriving at the time of sample collection) and downweighting rare taxa.”
Diatom communities were used as proxies for phytobenthos. Other phytobenthos groups were not sampled (CY, FR, IT, PT, SP) or not included in assessment methods (SI).
9. Selected taxonomic level achieves adequate confidence and precision in classification / CY – yes (species level)
FR – yes (species level)
IT – yes (species level)
PT – yes (species level)
SI – yes (species level)
SP – yes (species level)
The phytobenthos group performed a ring test at the X-GIG to examine comparability of data (see X-GIG Milestone 6 report) and the reproducibility of the results was good.
Table 3 – Coverage of the relevant parameters indicative of the BQE in the national methods
MS / Taxonomic composition / Abundance / Undesirable disturbances / Bacterial tufts / Combination ruleCY / Diatoms only / Relative abundance / Not included in national metric / Not included in national metric / Not defined yet
FR / Diatoms only / Relative abundance / Not included in national metric / Not included in national metric
Included in national macrophyte assessment tool (IBMR) / Not defined yet
IT / Diatoms only / Relative abundance / Not included in national metric / Not included in national metric
Included in macrophyte assessment tool (IBMR) / Not defined yet
PT / Diatoms only / Relative abundance / Not included in national metric / Not included in national metric / Not defined yet
SI / Diatoms only (other groups sampled but not included in the assessment) / Relative abundance / Not included in national metric / Not included in national metric / Not defined yet
SP / Diatoms only (algae included in macrophyte sampling) / Relative abundance / Not included in national metric / Not included in national metric / Not defined yet
Contrarily to macroalgae (namely in Mediterranean regions), diatom taxonomy is well known and diatom species have well established responses to several pressures. More basic research has to be conducted in Mediterranean regions in order to have fully operational methods including other algae and the knowledge of reliable responses to pressure. For the moment, diatoms should be considered a good proxy for the phytobenthos sub-element (See for example Kelly, MG, L King, RI Jones, PA Barker and BJ Jamieson (2008) Validation of diatoms as proxies for phytobenthos when assessing ecological status in lakes. Hydrobiologia, 610:125-129).
All methods being used include the taxonomic composition at species level and the relative abundance, and responses to pressure using relative abundance are well documented Europe-wide. The improvement related to the use of absolute abundances when compared to relative, has not been demonstrated, and proved irrelevant in some non-Med MS (Appendix 1 of the Rivers/X-GIG Milestone 5 report). There are also technical difficulties not yet solved when sampling and interpreting absolute abundance values.
Bacterial tufts are not considered to influence classification because they only occur when other elements already classify quality as poor or bad, so the H/G and G/M boundaries are unlikely to be affected. Relationship between the four components of the normative definitions is yet to be examined.
“Undesirable disturbances” is a subjective expression and hard to translate into quality assessment metrics, and it should be defined specifically for phytobenthos. UD are not considered to influence classification because they only occur when other elements already classify ecological quality as poor or bad, so the H/G and G/M boundaries are unlikely to be affected. In any case what can be considered as undesirable disturbances (e.g. lack of oxygen) is covered by the present assessment and also by other quality elements.
The assessment methods of the MS were considered compliant and ready for intercalibration.
3. IC feasibility checking
Typology
Table 3 – Overview of common intercalibration types in the Mediterranean rivers GIG and MS sharing the types
Common IC type / Type characteristics / MS sharing IC common typeRM1 / catchment <100 km2; mixed geology (except non-siliceous); highly seasonal / SP, FR,IT,PT,SI
RM2 / catchment 100-1000 km2 ; mixed geology (except non-siliceous); highly seasonal / SP, IT,PT,SI
RM3 / catchment 1000-10000 km2 ; mixed geology (except siliceous); highly seasonal / This type cannot be intercalibrated due to the lack of comparability between MS methods and insufficient number of reference sites.
RM4 / non-siliceous streams; highly seasonal / IT,CY,SP,FR
RM5 / temporary rivers / SP,IT,PT,CY,SI
The same broad types were used as in the first intercalibration round, but the borders of the types were redefined for a better adjustment to the ecological reality. The redefinition was presented, discussed and agreed in the GIG meetings.
Furthermore, the biological analysis of benchmark sites revealed a poor segregation between types. RM1, RM2 and RM4 were therefore treated together throughout the IC process, but RM5 was treated separately due to distinct hydrological conditions when compared to RM124.
It was concluded that intercalibration is feasible in terms of typology. RM3 type could not be intercalibrated due to the lack of comparability between MS methods and insufficient number of reference sites.
Pressures
Table 4 below lists the pressures addressed by the national methods, based on the information gathered in the method compilation of the WISER project (www.wiser.eu). All methos assess a group a group of common pressures, mainly nutrients and organic matter.
Table 4 – Overview of the sensitivity to pressures of the national methods
Method / PressureIPS (CY, PT, SP) / Eutrophication, organic matter, acidification, salinity
IBD 2007 (FR) / Eutrophication, general degradation, pollution by organic matter, acidification
ICMi (IT) / Eutrophication, general degradation, pollution by organic matter
Slovenian Ecological Status assessment system for rivers using phytobenthos (SESAR) / Eutrophication and pollution by organic matter
Additionally, and using the MedGIG database, we tested the response of the common metric (ICM) to individual types of pressures (Table 5) and to a general degradation gradient (obtained from PCA axes scores), assuming that if the national methods are well correlated to the common metric (see Fig. ***) and if the common metric responds well to individual and global pressure, then the national methods do it too.