Deliverable D4.4-3, Report detailing Multimetric fish-based indices sensitivity to anthropogenic and natural pressures, and to metrics’ variation range

The Water Framework Directive (WFD) aims at achieving good ecological status (GES) for surface water bodies throughout Europe, by 2015. Consequently European countries are currently developing and intercalibrating methods based on biological, hydromorphological and physico-chemical quality elements for the assessment of their transitional waters, including fishes. The present work focuses on the response of fish indicators and indices to anthropogenic pressures and natural factors. For doing that, datasets from the Basque and Portuguese estuaries, in the North East Atlantic, have been used. Hence, biological data from fish (and in some cases, crustaceans), together with different types of pressure (population, industry, ports, dredging, global pressures, pollution, channeling, etc.) and hydromorphological data (flow, estuary volume, depth, intertidal surface, residence time, etc.) have been analyzed. Together with fish assemblages composition and individual metrics (richness, trophic composition, etc.), two fish indices (Basque AFI and Portuguese EFAI) have been investigated. Additionally, the response of five fish indices (AFI, EFAI, ELFI, TFCI, Z-EBI) were tested on a common dataset, within Portuguese estuaries, to check the time lag in the metrics’ response to different human pressures and the variability in the strength of responses to those pressures. This work also focuses on the sensitivity analysis of two European fish-based indices (French ELFI and British TFCI) to changes in their respective metric scores through their observed dynamic range. Sensitivity analyses were run simulating different scenarios of metric score changes, taking into consideration the relationship between metrics. This allowed the metrics with stronger influence in the index score and the resulting water body classification to be highlighted. Importantly, the identification of the most influential metrics could help to guide management efforts in terms of achieving GES by 2015. In general, the fish metrics and indices tested responded to anthropogenic pressures in the Atlantic estuarine sites, yet at the individual metrics level environmental chemical quality was the main driver for observed differences. Also, some metrics did not respond to pressures as expected, which is most likely related to sampling gear efficiency, namely the low capture efficiency of diadromous species with beam trawl. The cause-effect relationship study emphasized that fish-based indices developed to assess the water quality of estuarine systems did not detect all the pressures with the same sensitivity in terms of strength and time-lag, and gave more importance to some pressures, namely chemical pollution. The fish-based indices developed to assess the water quality of estuarine systems do not allow the individualization of pressure effects, which may constitute a problem to put forward the correct specific measures for management and rehabilitation of estuaries. On the other hand, some indices also do not seem relevant, in a short time, to detect changes of the ecological quality which may constitute a handicap for management or an indication for their restructuring. The sensitivity analysis indicates that a number of estuarine resident taxa, a number of estuarine-dependent marine taxa, a number of benthic invertebrate feeding taxa and a number of piscivorous taxa have the greatest influence on the TFCI classification. For the French index ELFI, the most influential metrics are mainly DT (total density) and DB (density of benthic species), followed by RT (total richness). These results suggest a high sensitivity of the quality indication provided by these indices on richness related aspects of the fish assemblages. Management should therefore prioritize efforts to conserve or restore estuarine attributes underpinning abundance and ecological diversity, for example the diversity of fish habitats, food resources and shelter or the hydrological integration between coastal and transitional waters.info:eu-repo/semantics/publishedVersio

Deliverable D4.4-5: Precision and behaviour of fish-based ecological quality metrics in relation to natural and anthropogenic pressure gradients in European estuaries and lagoons

This report summarises the work conducted in Work Package 4.4 – BQE fish in transitional (i.e. estuarine and lagoon) waters (TW) within the project WISER under the sponsorship of the European Commission. It omits most technical details of the analyses given in the four previous Work Package reports, but still provides the necessary information to understand the rationale, approach and underlying assumptions necessary to discuss the results. The focus is therefore to discuss and integrate the results obtained within Work Package 4.4 and with this, make recommendations to improve fish-based ecological assessments in TW, principally estuaries and lagoons. In addition, and to assist with the WFD implementation which is the overarching theme of WISER, the deliverable includes, where appropriate, case studies where we have used multi-metric fish indices currently under development, or already in use for WFD compliance monitoring across Europe. Furthermore, results of the work package have been shared with relevant Geographical Intercalibration Groups (GIGs) supporting the harmonization and equalization process across transitional fish indices in Europe. Development strategies for fish indices in TW vary but generally include: (1) the calibration of metrics to anthropogenic pressures, (2) the development of reference conditions, (3) the calculation of ecological quality ratios, and (4) the designation of thresholds for Ecological Status (ES) class. New fish indices are developed for a defined geographical area, using specific sampling method and under locally relevant pressure fields. The former two factors, area and sampling methods, define the relevant reference condition in the calculation of Ecological Quality Ratios (EQR) and the latter factor, human pressures, define the índex structure and especially the fish metric selection. To assess index relevance across areas, we calculated a suite of transitional fish indices on a standardized WISER dataset and then compared the agreement of the outcomes (using correlation analysis). The application of current indices to areas (or countries) different from the area in which it was originally developed leads to inconclusive or spurious results. The failure to accommodate the diferente indices to a standardized dataset in this work clearly demonstrates the fundamental reliance of current fish indices on the sampling methods and design of monitoring programmes used in the development of the index. Despite this, for some indices, correlations although weaker are statistically significant, also indicating the possible agreement in successful intercalibration between these indices. Harmonization of BQE fish methodologies across Europe (common metrics) is unlikely by adapting or creating new fish indices but inter-comparison assessments are possible and valid using a common pressure index to harmonise diferente indices on a common scale. We found a negative response of fish quality features to pressure gradients which make BQE fish in TW suitable for greater ecological integration than other BQEs. However, successful assessment of Ecological Status (ES) require a matching combination of fish index, reference values and local dataset gathered with compatible sampling methods. Whole indices provide more consistent overall ES assessments but fish metrics considered individually may be more useful as a means to focus restoration measures. Future work is needed to identify those specific pressures affecting fish assemblages providing targets for minimising the effects of stress in mitigation and restoration plans. In order to achieve this, and although the interpretation of outcomes is still difficult, more recent transitional fish indices are leading in the use of comprehensive appraisal and validation exercises to test the responsiveness of BQEs for the assessment of ES. Here we proposed for the first time a simple sensitivity exercise under realistic scenarios of metric change to explore the expected inertia (i.e. the tendency to buffer ES change after quality alterations), dynamic range (i.e. the ratio between the largest and smallest possible ES values) and most relevant metric components (i.e. the those driving the most likely scenarios leading to ES change) from a multi-metric fish índex under relevant human pressure gradients. Overall, the behaviour of multi-metric índices under manipulations of metric scores clearly indicated that metric type, number of metrics used and correlations between metrics are important in determining the index performance, with indices including more and/or uncorrelated metrics or metrics with skewed distribution being less affected by extreme metric manipulations. Results of this analysis may be used to set realistic management targets and also to identify the aspects of the indices that are more likely to affect the outcomes leading to more robust and responsive indices. Further improvements of fish indices may be attained by reducing the variability confounding biological quality metrics. This variability is undesirable noise in assessments and can be technical (i.e. linked to the method of assessment including sampling effort) or natural (physicochemical and biological). The implication for assessments is that different facts might then confound the metric-pressure correlation (the ‘signal’ in the signal-to-noise ratio in the assessments) increasing uncertainty in ES assignment. Models showed that salinity class, depth, season, time of fishing (day vs. night) and year of fishing may influence the values of the fish metrics. The modelling exercise also demonstrated that unexplained variance remains generally much higher within-systems than between-systems suggesting a higher importance of sources of variability acting at the WB level. Modelling and improved standardization in monitoring campaigns should reduce uncertainty in ES assignment. One important factor that was assessed further was the effect of sampling effort. The results suggest that richness-based metrics require larger sampling efforts although a similar effortrelated bias may be an issue for density-based metrics if fish distribution is very patchy (i.e. schooling fish or those aggregated in specific habitats) and insufficient replicates are taken to fully characterise the patchiness in their distribution. It is apparent that to overcome a potential large source of error, the Reference Conditions must be defined according to the level of effort used in the monitoring programme or, conversely, the monitoring must be carried out at the same level of effort used to derive the Reference Condition. The WP finally explored the use of a predictive linear modelling approach to define reference conditions for fish metrics in transitional waters. The fish response data was modelled together with Corine Land Cover (CLC)-derived pressure proxies (% agricultural, urban and natural land coverage). Based on the obtained models, the expected metric score was predicted by setting pressure levels either to the lowest observed pressure in the dataset or to zero in order to define the sample and theoretical reference condition, respectively. Even when significant, the effect of pressures on fish metrics was generally very weak, probably reflecting the use of too-generic pressure indicators (such as land cover data instead of more relevant estuarine proxies such as dredging, port development, waterborne pollutants, etc). The best explanatory models included sampling factors and natural characteristics considered important discriminant features in the definition of water body types. In particular, the present work argues for considering not only estuaries and lagoons as different typologies but also other natural and design characteristic such as the gear type, the sampling season and the salinity class. Furthermore, a relevant reference needs to account for survey design bias, including rare species contribution to assessment datasets, patchiness, choice of pressure proxies or sampling gear. The modelling approach of fish metrics against the physicochemical variables has proved useful to derive Reference Conditions. This is important for the computation of relevant EQRs in Europe where there is a general lack of pristine areas or historical data on fish BQE and it provides an alternative to best professional judgment. Taking all WP analysis and case studies together, the work conducted has highlighted the following key messages and linked research needs necessary to optimize BQE fish for the quality assessment of transitional waters: Key Message 01: Harmonization of BQE fish methodologies across Europe (common metrics) is unlikely by adapting or creating new fish indices but inter-comparison assessments are possible and valid using a common pressure index to harmonise diferente indices on a common scale. Research needs to be focused on more widely-applicable fish indices will require the formulation of completely new indices based on a more flexible use of fish metrics according to system typologies, relevance and, probably, an increased use of functional traits. For current indices, further research on a method of intercalibration is needed. Key Message 02: BQE Fish in TW respond consistently to human pressure gradients across transitional waters providing the means to assess Ecological Status (ES). Further work will be needed to identify those specific pressures affecting fish assemblages providing targets for minimising the effects of stress in mitigation and restoration plans. Key Message 03 Although the interpretation of outcomes is still difficult, more recente transitional fish indices are leading in the use of comprehensive appraisal and validation exercises to test the performance of BQEs in the assessment of Ecological Status (ES). Further appraisal of fish indices behaviour is needed to understand the meaning of the quality outcomes, to set realistic management targets and also to identify the aspects of the índices that are more likely to affect the outcomes leading to more robust and responsive indices Key Message 04 Uncertainty levels associated with metric variability in multi-metric fish indices can be managed to increase the confidence in Ecological Status (ES) class assignment. Further research is needed to include knowledge of habitat partition within systems, to understand metrics behaviour and precision, to test new combination rules allowing metric weighting by robustness and importantly to evaluate more robust sampling tools and methods. Key Message 05 Reference conditions for BQE fish-based quality assessments can be objectively estimated using predictive modelling. Further refinements will require the use of better pressure proxies, robust metrics amenable to modelling and to account for survey design bias (effort & choice of sampling gear) at the relevant scales used in monitoring programmes.info:eu-repo/semantics/publishedVersio

Deliverable D4.4-2, part 1: Testing the adaptability and behaviour of 6 fish indices on a common dataset composed of multiple gears samplings from 8 estuaries and lagoons

The Water Framework Directive (WFD) aims at achieving good ecological status for surface waterbodies throughout Europe, by 2015. Consequently European countries are currently developing and intercalibrating methods based on biological, hydromorphological and physicochemical quality elements for the assessment and the monitoring of their rivers, lakes, coastal and transitional waters. In this context, the FP7 WISER project aims to support the implementation of the WFD by contributing (i) to making the existing assessment methods more comparable, and (ii) to estimating the uncertainty along each step of the assessment. The present work focuses on fish indicators for estuaries and lagoons (transitional waters in the WFD). Six fish indices (AFI, EFAI, ELFI, TFCI, BHI, Z-EBI) were tested on a common dataset, covering eight estuaries and lagoons throughout Europe. Fish sampling was carried out using several gears in 2009 and 2010. The objectives were twofold: (i) to test the adaptability of fish indices to different gears and different types of transitional waters; and (ii) to compare the behaviour of the indices with regard to their level of agreement. Five out of the six tested indices were gear-specific and all were specific to some type(s) of transitional waters and have particular data needs. Therefore calculating the indices on a common dataset raised many difficulties, especially regarding the determination of appropriate reference condition values. However, taking some reasonable assumptions it was possible to calculate most of the indices on the majority of the available data, thus showing their relative adaptability. The indication of extreme values for quality (high or bad) was relatively rare and the results of the indices often differed: when used outside of their initial framework, geographical limits or with different sampling methods, fish indices’ results are highly uncertain. This shows that the assessment of quality using fish indicators highly depends on the assessment tool, the sampling methodology and the type of transitional water. Despite these results, some statistically significant correlations between pairs of indices’ results were found, indicating the possibility of intercalibration between some of the tested indices. This work corresponds to the first step of WISER WP4.4 Deliverable 2. In a second step, some fish metrics in the indices tested here will be selected for a more in depth study: the effect of several natural sources of variability on these metrics will be studied and uncertainty will be quantified along the assessment process, from the sampling to final EQS formulation using WiserBugs software..info:eu-repo/semantics/publishedVersio

Three hundred ways to assess Europe’s surface waters: an almost complete overview of biological methods to implement the Water Framework Directive

According to the Water Framework Directive (WFD), the status of European surface waters is assessed using aquatic organism groups. Here we present an overview of 297 assessment methods, based on a questionnaire survey addressing authorities in all countries implementing the WFD. Twenty-eight countries reported on methods applied to rivers (30 %), coastal waters (26 %), lakes (25 %) and transitional waters (19 %). More than half of the methods are based on macroscopic plants (28 %) or benthic invertebrates (26 %); in addition, phytoplankton (21 %), fish (15 %) and phytobenthos (10 %) were assessed. Countries of Central and Western Europe had developed almost all methods required for the WFD implementation. Two main sampling strategies were discernable: Small-scale sampling of the taxonomically diverse groups of benthic invertebrates and phytobenthos that demand elaborate processing, versus large-scale sampling of vast, species-poor plant stands or the mobile fish fauna. About three-quarters of methods identified organisms to species-level while in particular phytoplankton-based methods used class- or phylum-level, or included no taxonomic information. Out of nine metric types distinguished, river methods used more sensitivity and trait metrics while for other water categories abundance metrics prevailed. Fish-based methods showed the highest number of metrics. Fifty-six percent of methods focussed on the detection of eutrophication and organic pollution, with shares decreasing from autotrophic to heterotrophic organism groups: phytoplankton > phytobenthos > macroscopic plants > benthic invertebrates > fish fauna. The order was almost reverse for hydrological or morphological deterioration: fish fauna and macroscopic plants > benthic invertebrates > phytoplankton > phytobenthos. These pressures were mainly assessed by methods applied to rivers and transitional waters. The pressure-impact relationship of about one-third of methods was not tested empirically with methods for transitional waters being the least validated. The strength of relationships differed significantly between organism groups and water categories. The correlation coefficients generally covered a broad range (0.8), but on average with the pattern: phytoplankton > macroscopic plants > benthic invertebrates > phytobenthos and fish fauna. In terms of water categories the following order resulted: coastal waters > lakes > transitional waters > rivers. Status boundaries were mostly defined using statistical approaches. We advocate better reflection of the necessary sampling effort and precision, full validations of pressure-impact relationships and an implementation of more ecological components into classificationJRC.H.5-Rural, water and ecosystem resource

Three hundred ways to assess Europe's surface waters: An almost complete overview of biological methods to implement the Water Framework Directive

According to the Water Framework Directive (WFD), the status of European surface waters is assessed using aquatic organism groups. Here we present an overview of 297 assessment methods, based on a questionnaire survey addressing authorities in all countries implementing the WFD. Twenty-eight countries reported on methods applied to rivers (30%), coastal waters (26%), lakes (25%) and transitional waters (19%). More than half of the methods are based on macroscopic plants (28%) or benthic invertebrates (26%); in addition, phytoplankton (21%), fish (15%) and phytobenthos (10%) were assessed. Countries of Central and Western Europe had developed almost all methods required for the WFD implementation. Two main sampling strategies were discernable: small-scale sampling of the taxonomically diverse groups of benthic invertebrates and phytobenthos that demand elaborate processing, versus large-scale sampling of vast, species-poor plant stands or the mobile fish fauna. About three-quarters of methods identified organisms to species-level while in particular phytoplankton-based methods used class-or phylum-level, or included no taxonomic information. Out of nine metric types distinguished, river methods used more sensitivity and trait metrics while for other water categories abundance metrics prevailed. Fish-based methods showed the highest number of metrics. Fifty-six percent of methods focussed on the detection of eutrophication and organic pollution, with shares decreasing from autotrophic to heterotrophic organism groups: phytoplankton > phytobenthos > macroscopic plants > benthic invertebrates > fish fauna. The order was almost reverse for hydrological or morphological deterioration: fish fauna and macroscopic plants > benthic invertebrates > phytoplankton > phytobenthos. These pressures were mainly assessed by methods applied to rivers and transitional waters. The pressure-impact relationship of about one-third of methods was not tested empirically with methods for transitional waters being the least validated. The strength of relationships differed significantly between organism groups and water categories. The correlation coefficients generally covered a broad range (0.8), but on average with the pattern: phytoplankton > macroscopic plants > benthic invertebrates > phytobenthos and fish fauna. In terms of water categories the following order resulted: coastal waters > lakes > transitional waters > rivers. Status boundaries were mostly defined using statistical approaches. We advocate better reflection of the necessary sampling effort and precision, full validations of pressure-impact relationships and an implementation of more ecological components into classification. (C) 2011 Elsevier Ltd. All rights reserved

Current developments on fish-based indices to assess ecological-quality status of estuaries and lagoons

Estuaries and lagoons are especially affected by anthropogenic pressures. This has resulted in symptoms of degradation including water quality impairment and loss of aquatic biota. Protection of aquatic biodiversity and management of these coastal systems require robust tools to asse ss habitat integrity. Fish populations have been extensively used to define habitat integrity in freshwater systems. Comparatively much less has been achieved in estuarine, lagoonal and related coastal systems classified as transitional systems under the European Water Framework Directive (WFD). The implementation of the WFD has prompted the rapid development of estuarine fish indices across Europe. In this context, this paper reviews seventeen published fish-based indices applied to estuarine systems worldwide and summarises common development strategies. Most indices are computed from a number of independent metrics and are based on assemblage composition or functional attributes of fish species (guilds). Among metric groups, species richness-composition metrics are the most widely used in current indices, followed by habitat guild, trophic guild, abundance and condition, and finally nursery function metrics. Within these, indicator species or guilds associated with estuarine quality features often dominate the indices. Development strategies vary but generally include (1) selection and calibration of metrics to anthropogenic pressure; (2) development of reference conditions; (3) comparison of metric values to reference ones; and (4) designation of thresholds for ecological status class. All index developers invest a large amount of effort on the definition and formulation of the reference values. Comparatively less effort is invested in the evaluation of the relevance and precision of the assessment. Only about half of the indices reviewed attempt any validation of the index outcomes and these are limited to simple correlation analysis and misclassification rate analysis by comparing index value with anthropogenic pressure proxies. Currently there are no European-wide consistent fish indices for transitional waters. Widening of the geographical relevance will require better precision in the formulation of reference conditions and greater inclusion of functional attributes in the indices. More recent transitional fish indices have paid increased attention to sampling method and effort, as well as metric sensitivity and robustness. This trend has continued parallel to the implementation of WFD-monitoring programmes across Europe. Further improvements are still needed to link pressures with index response and the characterisation of uncertainty levels in the index outcomes. © 2012 Elsevier Ltd. All rights reserved