Review of Member State approaches to the Macrophyte and Phytobenthos Biological Quality Element in lakes

Transcription

1 Review of Member State approaches to the Macrophyte and Phytobenthos Biological Quality Element in lakes Report to ECOSTAT Martyn Kelly (Bowburn Consultancy, UK) Sebastian Birk (University of Duisburg-Essen, Germany) Contents Contents... 1 Summary... 1 Introduction... 2 Evaluation principles... 2 Evaluation of justifications... 3 Evaluation framework... 3 What constitutes a strong justification?... 4 State of play... 5 Summary This report contributes to an ongoing discussion in ECOSTAT about correct interpretation of the Macrophytes and Phytobenthos Biological Quality Element (BQE) in lakes. A previous report had highlighted variation in practice around the EU, and also demonstrated that the unique information contributed by phytobenthos may be limited if a Member State (MS) already has phytoplankton and macrophyte assessment systems. One recommendation from this report was that decisions not to use phytobenthos needed to be supported by a justification. In this report, the type of evidence that might constitute a valid justification for excluding phytobenthos is described, and the current situation of implementation of the Macrophyte and Phytobenthos BQE in lakes is summarised for each MS. 11 MS now have evaluation methods that comply with the Normative Definition for this BQE. Of the others, five have had justifications accepted, seven have methods under and six have no natural lakes. 1

2 Introduction There has been considerable discussion within ECOSTAT around the treatment of the macrophyte and phytobenthos BQE in lakes. Almost all Member States (MS) treat the BQE as two separate subelements, with some evaluating both and then combining the result, whilst others assess just one component (usually macrophytes) and argue that this fulfils their obligations. A third group of countries are still developing national approaches, and look to ECOSTAT for guidance on whether to develop standalone approaches for phytobenthos assessment or whether a macrophyte-only method is adequate. The present report describes an evaluation of each individual Member State s compliance with the requirement to evaluate Macrophytes and Phytobenthos in lakes, based on the principles outlined in the 2015 report, but incorporating issues raised by representatives from Member States at ECOSTAT meetings. The report addresses natural water bodies only; however, the principles should also apply to HMWBs and to some AWBs, although exceptions may occur. Also, the assumption throughout is that where only one element of the BQE is assessed, this is usually the macrophytes and, therefore, that MS need to justify the exclusion of phytobenthos. It is possible that the opposite situation may arise (i.e. a phytobenthos method is developed and a Member State argues to exclude macrophytes) although this situation has not yet arisen for lakes. A final principle that has been adopted for this report is that justifications that were accepted in 2012 as part of the intercalibration review process will not be reviewed again. Evaluation principles 1. The normative definition refers to Macrophytes and Phytobenthos. A national method should include both. 2. The normative definition does not say how phytobenthos should be assessed. There is no particular reason why a national method cannot consider filamentous macroalgae to be a proxy for all phytobenthos in the way that many national methods currently regard diatoms as proxies for all microalgae. 3. The unique information gained from using phytobenthos might be reduced if a MS also has a phytoplankton assessment system. 4. Legal compliance is achieved IF both macrophytes and phytobenthos are incorporated in some means; legal compliance is not the same as best practice. 5. Deviations from the legal minimum must be supported by strong evidence; deviations from best practice should also be supported by evidence to show that this will not impair long-term achievement of WFD objectives. 6. Evidence should be based on data collected from same MS (ideally), a neighbouring MS or from primary literature. That several MS have standalone phytobenthos systems suggests that it is possible and justifications should focus on why a separate phytobenthos will not offer distinct benefits to the MS in question. 7. Two questions need to be answered by all MS: a. Does a national approach compliant with the Normative Definitions? b. Is it possible that a national approach that does not include analysis of phytobenthos result in poor decisions on the condition of lakes (especially around the good-moderate boundary) and thereby prejudice achievement of long-term objectives of WFD? 2

3 Evaluation of justifications Evaluation framework (see overleaf): See Table 1. Situations 1 and 2 are compliant with Normative Definitions. Situation 3 are technically not compliant but could be justified with appropriate evidence (e.g. a case based on primary evidence from the MS or a neighbouring MS to show that phytobenthos assessment is redundant). Situation4 cannot be justified except in situations where there are no natural lakes within a MS. Some justification is necessary for all situations except 1, but this is mostly evidence that should have been gathered during method phases. The justifications are, really, just proof that the MS has considered the matter carefully and is not cutting corners in WFD implementation. Table 1. Framework for evaluating compliance with the wording of the macrophyte and phytobenthos BQE for lakes The situations assume that all MS have macrophyte assessment methods; in theory, the converse situation may apply (i.e. MS has a phytobenthos assessment method, but no method using macrophytes). Situation Rationale Justification with supporting evidence 1. MS has separate (or combined) macrophyte and phytobenthos methods Best practice ; captures condition of entire BQE at several scales None required 2. Macrophyte method includes filamentous / macro-algae Legal compliance ; condition of microscopic algae inferred from condition of macrophytes plus filamentous/macro-algae. Limited risk of misclassification, especially if MS has operational phytoplankton classification tool Required: Justification explaining how macroalgae have been included in the macrophyte method Recommended: evidence of relationship between macrophytes and microphytobenthos 3. Macrophyte method not including filamentous / macro-algae 4. MS has neither a macrophyte nor a phytobenthos method Not compliant; condition of microphytobenthos inferred from condition of macrophytes. Does not meet best practice or legal compliance criteria; potential risk of misclassification. Risk reduced if phytoplankton BQE is used for classification Not compliant. MS is unable to demonstrate condition of water bodies to a satisfactory standard Required: Evidence of relationship between macrophytes and microphytobenthos required Reason for lack of a method needs to be explained 3

4 What constitutes a strong justification? Five justifications have been used by MS so far: Redundancy (with respect to macrophytes); Spatial/temporal variability; Short pressure gradients; Technical issues; Absence of natural lakes in a MS (the present exercise does not include Artificial Water Bodies). Arguments for redundancy of phytobenthos with respect to phytoplankton alone cannot be accepted as phytoplankton is a separate BQE. The strength of a case for omitting part of a BQE should be evaluated in terms of the number of justifications and the strength of each justification. Table 2 suggests a framework for this, with quality of evidence evaluated as follows: Levels of evidence: 4 - based on primary data from the MS itself; 3 - based on primary data from a neighbouring MS (same ecoregion, similar lake types?); 2 - based on studies in the peer-reviewed literature relevant to the MS (i.e. same country or a neighbour with similar conditions); 1 - other. Whilst there is some subjectivity in deciding on what quantity and quality of evidence represents adequate justification, all will agree that a single piece of circumstantial evidence is weak whilst several criteria supported by primary data is strong. A single well-argued criterion should be enough, but there may also be situations where two or three justifications are presented, based on less robust data. Table 2. Decision matrix for determining the strength of a case for omitting a component of a BQE. Quality of evidence (see text for details) Quantity of evidence /5 1 Weak Weak Weak Moderate 2 Weak Weak Moderate Strong 3 Moderate Moderate Strong Strong 4 Strong Strong Strong Strong Quality of evidence refers to the highest category assigned to any one criterion presented; quantity refers to the number of criteria used. Notes: There is an inherent circularity here, as a MS that does not have a phytobenthos assessment system will not necessarily have a metric with which to demonstrate redundancy. However, the evidence from intercalibration is that widely-used diatom metrics (e.g. IPS, TI, TDI) give results that can be used across the continent and will give an indication of the scale of redundancy with respect 4

5 to nutrients and general degradation. Alternatively, macrophyte assessment data may be correlated with the primary axis of an ordination based on phytobenthos data. State of play Tables 3 summarise the latest situation: 11 Member States have both macrophyte and phytobenthos methods (pending IC review) and are therefore fully compliant (BE*, DE, FI, HU, IE, IT, LT, PL, SE, SI, UK) 3 Member States do not have a dedicated phytobenthos method but do include macroalgae in the macrophyte assessment system (EE, LV, NL), their justifications approved by the Intercalibration review panel; 2 Member States had justifications approved by the Intercalibration review (AT, ES); 6 Member States have no natural lakes (CY, CZ, LU, MT, PT, SK); 7 Member States are still developing methods (with the option, too, of delivering a justification if this proves impractical) (BG, DK, GR, FR, HR, NO, RO). * BE: Flanders has an intercalibrated phytobenthos method; Wallonia has no natural lakes. The justification of no natural lakes may need to be revisited when ECOSTAT considers the sufficiency of methods for assessing Good Ecological Potential in AWBs. Steps will be needed to ensure that MS who are still developing methods do actually deliver either a method or a reasoned justification. Given these caveats, and accepting that the intercalibration of some methods is still not finalised, most MS are either compliant, or moving towards compliance with the requirement to assess both macrophytes and phytobenthos. Table 3. Overview of justifications for omitting phytobenthos from Member States Justification for omitting Member Notes phytobenthos method State Provided Reason State of play Austria X Redundancy Justification accepted Belgium Bulgaria Cyprus Not needed No natural lakes Croatia Czech Republic Denmark Not needed No natural lakes Will either deliver phytobenthos method or justification Estonia X Redundancy Accepted Macroalgae in macrophyte method Finland France 5

6 Member State Justification for omitting phytobenthos method Provided Reason State of play Notes Germany Greece X Redundancy Hungary Ireland Italy Latvia X Redundancy Accepted Macroalgae in macrophyte method Lithuania Method intercalibrated, summer 2016 Luxembourg Not needed No natural lakes Netherlands X Accepted Macroalgae in macrophyte method Norway Poland X Under Will either deliver phytobenthos method or justification Malta Not needed No natural lakes Portugal Not needed No natural lakes Romania Slovakia Not needed No natural lakes Method under ; will be submitted for IC review in near future Slovenia Spain Sweden United Kingdom Various Accepted (by the previous review panel) 6