Combination of multiple biological quality elements into waterbody assessment of surface waters

The Water Framework Directive (WFD) requires EU Member States to classify the ecological status of surface waters by using multiple biological quality elements (BQEs). According to the WFD Classification Guidance, a ‘one-out-all-out’ (OOAO) rule should be applied when integrating multiple BQEs into an overall biological status of a waterbody, i.e. classification is determined by the lowest status BQE. Using both simulated and monitoring datasets, we analyzed the effects of different combination rules in classification outcome and classification reliability. The OOAO represented the strictest combination rule in terms of increased probabilities of waterbodies being in moderate or worse status in comparison to other rules. The OOAO approach gave acceptable results when different BQEs were complementary, showing the effects of different pressures, and when level of uncertainty in the metrics used in the assessment was not high. Increasing the number of BQEs used in the assessment affected the classification outcome when using the OOAO approach; this was especially problematic if all BQEs address the same pressure. Our study showed that grouping of metrics and metrics uncertainty has a large influence on classification outcomes and that this should be carefully considered to ensure that final classification adequately reflects ecological status.     

A new approach to species distributional indicators for the Marine Strategy Framework Directive (MSFD)

We propose alternative fish-populations spatial indicators for use in the Marine Strategy Framework Directive (MSFD). Following Commission Decision 2010/477, we have applied two different spatial indicators to three fish populations with “slow type” life-history traits, i.e. slow growing like Helicolenus dactylopterus, or large bodied like Merluccius merluccius and Lophius budegassa. We tested their efficiency separately and combined. One of these indicators, the presence/absence of the population in sampling squares, had already been applied during the initial assessment of the MSFD in Spain. Another indicator, the geographical spread, is proposed here as a new monitoring tool for the MSFD in Spanish waters. The results demonstrate for the three populations analyzed that neither indicator was sufficient alone to describe the population spatial pattern or its evolution. Thus, the approach to implementing the MSFD indicated in Commission Decision 2010/477 is not sufficient to provide integrated information about the spatial behavior of the fish populations analyzed. Although numerical targets or threshold values cannot be set, directional targets could be proposed, based on the results of both indicators, if evaluation of them is extended to more species and more geographical areas. The analysis could be extended to other “slow type” populations within the fish community and also to different ecoregions. We propose an approach including the estimation of two different indicators to monitoring both the area occupied and the geographical spread of fish populations within communities, interpreting them together to generate a more complete picture of the spatial patterns of those populations. In spite of the difficulties in fixing numerical targets or thresholds, or in distinguishing between environmentally and human driven changes in the population spatial distributions, this approach helps to summarize fish spatial behavior. It improves information from the indicators applied alone and reduces the requirement for a large number of maps (except for some particular event or population). The proposed indicators can be readily used by managers and politicians.     

A benchmarking and assessment framework to operationalise ecological indicators based on time series analysis

The call for ecosystem considerations in marine management has instigated the use of ecosystem indicators. Many ecosystem indicators have been suggested under new policy frameworks such as the EU Marine Strategy Framework Directive or the Common Fisheries Policy. But many of these indicators are still under development and cannot be considered as yet operational for environmental assessments. A common reason for this lack of operationability is the absence of valid assessment benchmarks. This study introduces a two-stage approach for the benchmarking and assessment of time series (TSBA) against a priori chosen rationale of improvement or maintenance of current conditions. TSBA uses breakpoint- and trend-analysis to obtain long-term benchmarks and assess short term progress. Depending on the outcome of both analyses the action requirements for management can be determined. The method is exemplified on a case study on the size-structure of large North Sea gadoid stocks, which are considered as being sensitive to the impacts of fishing. Three out of six stocks reached their assessment benchmarks, while the three other stocks failed. TSBA is generic and can be applied to any indicator used within any marine policy assessment framework. A strength–weaknesses–opportunity–threat analysis (SWOT) investigated the advantages and disadvantages of TSBA in the context of the currently high political demand of operational ecosystem indicators. Contrary to benchmarks derived from ecological concepts or pressure-state relationship TSBA benchmarks are not specifically linked to limits of resilience or sustainability. However, TSBA may be especially useful in situations where assessment benchmarks from other sources will not be readily available or are associated with high uncertainty.     

Assessing eutrophication in the Portuguese continental Exclusive Economic Zone within the European Marine Strategy Framework Directive

This study reports the state and causes of eutrophication in the Portuguese continental Exclusive Economic Zone (EEZ), during a 14-year period (1995–2008), following the European Marine Strategy Framework Directive (MSFD) and using the trophic index TRIX for an integrated evaluation of indicators of eutrophication, and identifies areas where monitoring is needed to improve the eutrophication assessment. A non-continuous dataset for the 8 indicators specified by the MSFD for eutrophication assessment was used, including published and grey data. Eutrophication indicators were validated and thresholds reviewed, considering regional differences. The diatom:flagellate ratio was found a poor indicator of eutrophication as shifts in the diatom:flagellate ratio naturally occur associated with alternating water column turbulence and upwelling, and stratification, and therefore, could not be associated with anthropogenic nutrient enrichment effects. Assessment areas were, as a whole, classified as non-problem areas concerning eutrophication. Although nutrient enrichment was observed in coastal waters, related to river plume influence, nutrient enrichment direct and indirect effects were generally not detectable, possibly due to water column dispersion and mixing processes. Only occasionally, mild eutrophication was found in specific areas under the influence of major river (Douro, Vouga and Guadiana) plumes, associated with high nutrient and phytoplankton biomass levels and seagrass decline, which indicates the need for directed monitoring on eutrophication in those areas.     

Integrated assessment of ecological status and misclassification of lakes: The role of uncertainty and index combination rules

The European Water Framework Directive (WFD) requires that the ecological status of waterbodies is assessed using multiple biological quality elements (BQEs) that are combined into a single status class. The recommended combination rule (the “one-out, all-out” rule; OOAO) has been criticised for being unreasonably conservative and for being sensitive to uncertainty. In this study, the objective was to compare the sensitivity to uncertainty of four different combination rules: (1) OOAO, (2) OOAO with exclusion of one element, (3) average and (4) weighted average. Index values for 5 BQEs (phytoplankton, phytobenthos, macrophytes, macroinvertebrates and fish) sampled from 10 lakes in the Wel River catchment in Poland were used to classify the lakes according to the OOAO and the three alternative combination rules. Based on the mean and (where possible) standard deviation of these index values, we modelled the risk of misclassification by simulating 10,000 resamples for each BQEs in each lake, classifying each resample and calculating the proportion of misclassified resamples under each combination rule. For individual BQEs, the risk of misclassification increased both with higher uncertainty (standard deviation) and with the proximity of the index value to a class boundary. Under the OOAO rule, the risk of misclassification was more biased towards worse status (“underclassification”) than towards better status. Furthermore, risk of underclassification was more affected by uncertainty under the OOAO rule compared with the alternative combination rules. This analysis has demonstrated the weaknesses associated with the OOAO rule for integration of BQEs for lake classification. However, the alternative combination rules are associated with other shortcomings, such as the need for subjective judgement, and involve a higher risk of not protecting the most sensitive BQE and thus the whole ecosystem. We recommend that future versions of instructions for WFD implementation consider alternatives to the OOAO combination rule, and provide guidelines for weighting of individual BQEs.     

Cost-Effective Marine Protection - A Pragmatic Approach

This paper puts forward a framework for probabilistic and holistic cost-effectiveness analysis to provide support in selecting the least-cost set of measures to reach a multidimensional environmental objective. Following the principles of ecosystem-based management, the framework includes a flexible methodology for deriving and populating criteria for effectiveness and costs and analyzing complex ecological-economic trade-offs under uncertainty. The framework is applied in the development of the Finnish Programme of Measures (PoM) for reaching the targets of the EU Marine Strategy Framework Directive (MSFD). The numerical results demonstrate that substantial cost savings can be realized from careful consideration of the costs and multiple effects of management measures. If adopted, the proposed PoM would yield improvements in the state of the Baltic Sea, but the overall objective of the MSFD would not be reached by the target year of 2020; for various environmental and administrative reasons, it would take longer for most measures to take full effect.     

A simulation-approach to assess the size structure of commercially exploited fish populations within the European Marine Strategy Framework Directive

Assessing the size structure and composition of fish stocks, as demanded by the Marine Strategy Framework Directive (MSFD), is considered to be critical for the evaluation of the health status of exploited populations. The MSFD explicitly contains the concept that many large individuals within a population are indicative of a healthy stock. To reflect the abundance of large individuals, the EU-Commission suggested several size-based indicators (SBI). Only few of these SBI have been tested within a pressure-state relationship, in which a state indicator is sensitive, responsive and specific to a given pressure. Sensitivity and responsiveness of pressure-state relationship can be validated by cross-correlating time-series of pressure and state indicators. In the real world, however, time-series of ecological indicators are not only affected by the influence of a pressure, but by natural variability, changes in the sampling method and stochasticity. Hence observed cross-correlations between pressure and state indicator time-series may not be based on a true causal link, especially if time-series are short (less than 30 years). To overcome these limitations, the performance of eight SBI was tested with a population model in which pressures (fishing mortality) and states of ecosystem components (SBI) were precisely known. We distinguished between relative SBI reflecting proportions of size-classes and absolute SBI reflecting absolute entities of the size-distribution such as the observed maximum size in a given survey year. Relative SBI were more sensitive to recruitment than absolute SBI, but not to fishing pressure, which makes relative SBI unsuitable for the assessment of the abundance of large individuals within a population. The outcomes of the model simulation were confirmed by a case study on North Sea cod, where the mean length of the largest ten individuals caught in a given survey year (L_max10) emerged as a promising indicator for the assessment of size structure. Exemplary, we demonstrate how the L_max10 may be incorporated into the existing International Council for the Exploration of the Sea (ICES) assessment framework by defining target and limit values of the good environmental status.     

Semi-automated classification method addressing marine strategy framework directive (MSFD) zooplankton indicators

Semi-automated classification of zooplankton allows increasing the number of processed samples cost-effectively, albeit with a relatively limited taxonomic accuracy, partly because cost-efficiency trade-off but also due to technological limitations that might be overcome in the future. The present study tests the suitability of using a cost-efficient semi-automated classification methodology as a tool to assess zooplankton indicators for the purpose of the EU Marine Strategy Framework Directive, using samples collected in the Baltic Sea. In this brackish ecosystem the zooplankton individuals are small-bodied and therefore their identification with semi-automated classification is challenging. However, results show that semi-automated zooplankton classification provides a taxonomic classification level that is sufficient for a number of proposed indicators. This analysis also points out weakness of the methodology and proposes already proved solutions based on the latest development of these methodologies applied to zooplankton classification. As proved in the Baltic Sea, complementing manual zooplankton analyses with the semi-automated classification offers new advantages for marine environment assessment.     

Transitional and coastal waters ecological status assessment: advances and challenges resulting from implementing the European Water Framework Directive

The derivation, performance, sensitivity and inherent uncertainty of ecological quality indicators have become major topics in developing tools for the management of marine, transitional and coastal waters. In reviewing the advances in these waters, related to an ecological status assessment, we show the future challenges to be addressed within the European Water Framework Directive (WFD). Using new analyses carried out under the research project ‘Water Bodies in Europe: Integrative Systems to Assess Ecological status and Recovery’, we provide a complete set of assessments for the biological quality elements (BQEs) (phytoplankton, macroalgae-seagrasses, macroinvertebrates and fish) to be assessed, as well as the validation of existing indicators and multimetric indices and, in some cases, the development of new assessment indices. We show that these indices respond differently to different human pressures and they each have challenges in defining reference conditions against which future changes are judged. In investigating good ecological potential, as the response to heavily modified water bodies, we show that there are flaws in the Directive, not least in its definitions. Our analyses have also focussed on uncertainty in using the indices and we emphasise the problems of defining ecological class boundaries based on indices which themselves may be combined indices (multimetrics). The analysis shows that some of those multimetrics are redundant and/or are inter-correlated and thus may reduce the sensitivity in defining ecological class boundaries. If this is related to the drivers-pressures-state change-impacts-response approach then there are lessons for management measures aimed at achieving good ecological status and even the potential for legal challenges to decisions based on uncertain indices under the WFD. Hence, we conclude the continued need for advances in assessing pressures and gradients, and defining reference conditions for state change, index development, impact assessment and the validation of indices for each BQE.     

Sampling techniques and inter-surveyor variability as sources of uncertainty in Polish macrophyte metric for lake ecological status assessment

According to the Water Framework Directive, the results of the ecological status assessment should be accompanied with estimates of the level of confidence and precision of the determination. The Polish macrophyte-based method for lake assessment (Ecological State Macrophyte Index, ESMI) was tested for its uncertainty. The data from 12 lakes surveyed using four modifications of the sampling procedure, different numbers of transects and by two or three independent surveyors were analysed and the risk of misclassification was estimated. The choice of the sampling technique had no effect on abundance parameters (C _max and %cover), but it affected significantly the taxonomic composition indices (H and J′). It did not influence, however, the final assessment result, since in all the methods used, the ESMI values were comparable and showed no significant differences of means. Although the mean ESMI values were statistically indifferent and gave the same assessment result irrespective of the number of transects surveyed, the lower the number of transects, the higher the SD value and the more uncertain the assessment result. The risk of misclassification of the 12 lakes varied from 0.5% to over 40% depending on the sampling standard deviation value and the proximity of the index observed value to the class boundary.     

On the Use of Mixture Toxicity Assessment in REACH and the Water Framework Directive: A Review

This review seeks to connect the scientific theory of mixture toxicity to its implementation within different regulatory frameworks. The aim is to demonstrate how mixture toxicity assessment can be more thoroughly integrated into the European chemical regulations, REACH, and the Water Framework Directive (WFD), using the experiences gained through other regulatory frameworks. The article consists of (1) an examination of the scientific underpinnings of the common mixture toxicity assessment methods; (2) a discussion of how these methods have been used in regulatory frameworks; and (3) a discussion of how the methods could be applied within REACH and the WFD. It is concluded that concentration addition should be applied as a default model for mixture toxicity assessment. Furthermore, it is concluded that REACH and the WFD only include mixture toxicity assessments in specific situations. However, it is shown that it is scientifically feasible and regulatorally practicable to integrate a more holistic mixture toxicity approach into both legislations. In this connection, the experience gained from the U.S. frameworks on mixture toxicity assessment could be useful. The construction of a database that includes data on chemicals in the European environment could be used for mixture toxicity assessment of the chemicals with individual PEC/PNECs > 0.1.     

Ability of invertebrate indices to assess ecological condition on intertidal rocky shores

The implementation of directives such as the European Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD) has promoted the development of several tools and methods for assessing the ecological health of marine ecosystems. Within the scope of the WFD and in terms of rocky shores, several multimetric tools were developed based on the macroalgae biological quality element (BQE), in addition to those based on macroinvertebrates.The WFD requires member states to assess each BQE separately. The present work aimed to test the ability of ecological indices to distinguish sites within anthropogenic disturbance gradients caused by organic enrichment, using macroinvertebrate communities on intertidal rocky shores. Owing to the lack of more specific indices (for rocky shore), indices based on abundance, diversity and/or taxonomic composition were selected from several widely used indices in ecological studies and/or developed for soft-bottom macroinvertebrate communities.Present findings reveal several indices based on diversity and/or taxonomic composition able to distinguish sites within the disturbance gradients, showing increasing quality from the site nearest the source of organic enrichment to that farthest from it, especially indices calculated using biomass data, and in the summer season. Such results open good perspectives for the use of intertidal macroinvertebrate communities from rocky shores, and also help add the perspective of this biological quality element in the ecological quality assessment of coastal waters.     

Long-term monitoring studies as a powerful tool in marine ecosystem research

The EU-funded research project WISER (“Water bodies in Europe: Integrative Systems to assess Ecological status and Recovery”) developed new assessment methods required by the EU Water Framework Directive (WFD) for lakes, coastal and transitional waters. WISER also addressed the recovery of biotic assemblages from degradation. The results are summarised in five key messages, supported by papers in this special issue and by WISER results published elsewhere: (1) Response to stress differs between organism groups, water types and stressors; a conceptual model is proposed summarising how the individual organism groups respond to different types of degradation in rivers, lakes, transitional and coastal waters. (2) The sources of uncertainty differ between BQEs and water types, leading to methodological suggestions on how to design WFD sampling programmes. (3) Results from about 300 current assessment methods indicate geographical variations in metrics but assessments are comparable at an aggregated level (“ecological status”). (4) Scale and time matter; restoration requires action at (sub)-basin levels and recovery may require decades. (5) Long-term trends require consideration; the effects of both degradation and restoration at the water body or river basin scales is increasingly superimposed by multiple stressors acting at large scales, in particular by climate change.     

Application of signal detection theory approach for setting thresholds in benthic quality assessments

The European Marine Strategy Framework Directive requires EU Member States to prepare national strategies and manage their seas to achieve good environmental status (GES) by 2020. There are many multimetric indices proposed as indicators of the ecological quality of the benthic environment. Their functionality and utility are extensively discussed in the literature. Different frameworks are suggested for comparative assessments of indicators with no agreement on a standardized way of selecting the most appropriate one. In the current study, we apply signal detection theory (SDT) to evaluate the specificity and sensitivity of the Benthic Quality Index (BQI), its response to the eutrophication pressure, and its performance under the effects of estuarine water outflow. The BQI showed acceptable response to total nitrogen, total phosphorus and chlorophyll-a concentrations in the study area. Based on the results, we suggest using SDT for setting GES thresholds in a standardized way. This aids a robust assessment of the environmental status and supports differentiation between the quality classes.     

Watershed-based self- and peer-appraisal indices for integrated environmental assessment with a case study of the Mid-Atlantic region

Environmental indicators are often aggregated into a single index in environmental studies. Commonly, an aggregated index is derived in a specific weighting scheme imposed from the outside. The paper presents a novel approach by letting each unit under study choose a set of weights. It applies the concept of self- and cross-appraisal in generating various aggregated indices from two linear programming optimization models. The proposed method is illustrated via a case study of the Mid-Atlantic region. Results show that the derived aggregated indices reveal environmental conditions of the study area in an objective and robust fashion. The proposed method is a valuable tool for integrated environmental assessment.