The use of benthic indicators in Europe: from the Water Framework Directive to the Marine Strategy Framework Directive

The Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD) are the European umbrella regulations for water systems. It is a challenge for the scientific community to translate the principles of these directives into realistic and accurate approaches. The aim of this paper, conducted by the Benthos Ecology Working Group of ICES, is to describe how the principles have been translated, which were the challenges and best way forward. We have tackled the following principles: the ecosystem-based approach, the development of benthic indicators, the definition of ‘pristine’ or sustainable conditions, the detection of pressures and the development of monitoring programs. We concluded that testing and integrating the different approaches was facilitated during the WFD process, which led to further insights and improvements, which the MSFD can rely upon. Expert involvement in the entire implementation process proved to be of vital importance.     

Constraints on the use of phytoplankton as a biological quality element within the Water Framework Directive in Portuguese waters

The European Union Water Framework Directive (WFD), a new regulation aiming to achieve and maintain a clean and well-managed water environment, refers to phytoplankton as one of the biological quality elements that should be regularly monitored, and upon which the reference conditions of water quality should be established. However, the use of phytoplankton as a biological quality element will result in several constraints, which are analyzed in this article with examples from Portuguese waters. Specifically, the establishment of reference conditions of water quality may be difficult in some water bodies for which no historical data exists. The sampling frequency proposed for phytoplankton monitoring does not seem suitable to assess phytoplankton succession, and may preclude the detection of algal blooms. Finally, the use of chlorophyll a as a proxy of phytoplankton biomass and abundance has been proposed by some authors, but it may overlook blooms of pico- and small nanophytoplankton, and overestimate the importance of large microphytoplankton. Furthermore, most studies in Portugal have used only inverted microscopy for phytoplankton observation and quantification; this method does not permit the distinction between autotrophic and heterotrophic cells, especially in samples preserved with Lugol's solution, and does not allow the observation of smaller-sized cells. Finally, some techniques, such as remote sensing and chemotaxonomic analysis, are proposed to be used as supplements in phytoplankton monitoring programs.     

The use of macroalgal species richness and composition on intertidal rocky seashores in the assessment of ecological quality under the European Water Framework Directive

The EC Water Framework Directive (WFD) suggests using abundance and species composition of intertidal seaweed communities for ecological quality classification of rocky seashores. There are two difficulties with this. According to WFD all sensitive species should be present on a shore. There is no accepted list of sensitive seaweed species and those which may be sensitive in one location may not be so in another. Second, natural successions can result in very large abundance changes of common species, e.g. from almost completely fucoid-dominated shores to almost totally barnacle-dominated shores, without any change in ecological quality. Studies have shown that numerical species richness, not the list of actual species present, is broadly constant in the absence of disturbance. The ephemeral species, possibly the sensitive members of the community, change regularly in such a way as to conserve species richness. It is proposed that species richness on a defined length of shore be used as a criterion of ecological quality. A database of species found on over 300 shores in the British Isles, under strictly controlled sampling conditions, has given ranges of values of species richness to be expected and has allowed for variations in these values due to sub-habitat variability, wave exposure and turbidity to be factored in. A major problem in applying such a tool is the lack of expertise of many workers in critical identification of seaweed species. A reduced species list has been extracted from the database using species commonly present and identifiable with reasonable certainty. A numerical index of ecological quality is proposed based on scores for various aspects of the physical nature of the habitat combined with a score for species richness which may be based on the reduced species list. The scoring system also uses further aspects of community structure, such as ecological status groups and the proportions of rhodophyta, chlorophyta and opportunist species. For this system to be effective there has to be close control of the way in which sampling is carried out to ensure a uniform level of thoroughness.     

An approach to the intercalibration of benthic ecological status assessment in the North Atlantic ecoregion, according to the European Water Framework Directive

The European Water Framework Directive (WFD) establishes a framework for the protection and improvement of transitional and coastal waters; its final objective is to achieve at least 'good water status' for all waters, by 2015. The WFD requires Member States (MSs) to assess the Ecological Status (ES) of water bodies. This assessment will be based upon the status of the biological, hydromorphological and physico-chemical quality elements, by comparing data obtained from monitoring networks to reference (undisturbed) conditions, and then deriving an Ecological Quality Ratio (EQR). One of the biological quality elements to be considered is the benthic invertebrate component and some structural parameters (composition, diversity and disturbance-sensitive taxa) must be included in the ES assessment. Following these criteria, several approaches to benthic invertebrate assessment have been proposed by MSs. The WFD requires that these approaches are intercalibrated. This contribution describes the comparison of the different methodologies proposed by United Kingdom, Spain, Denmark and Norway. Results show a high consistency between the approaches, both with regard to determining the EQR and boundary settings for the ES.     

A new methodology based on littoral community cartography dominated by macroalgae for the implementation of the European Water Framework Directive

Macroalgae is a biological key element for the assessment of the ecological status in coastal waters in the frame of the European Water Framework Directive (WFD, 2000/60/EC). Here we propose a methodology for monitoring water quality based on the cartography of littoral and upper-sublittoral rocky-shore communities (CARLIT, in short). With the use of spatial databases, GIS, and available information about the value of rocky-shore communities as indicators of water quality, it is possible to obtain an environmental quality index representative of the ecological status of rocky coasts. This index, which completely fulfils the requirements of the WFD, is expressed as a ratio between the observed values in the sector of shore that is being assessed and the expected value in a reference condition zone with the same substrate and coastal morphology (Ecological Quality Ratio, EQR). The application of this index to the coast of Catalonia (North-Western Mediterranean) is presented.     

Integrating long-term water and sediment pollution data, in assessing chemical status within the European Water Framework Directive

The European Water Framework Directive (WFD) establishes a framework for the protection and improvement of estuarine (transitional) and coastal waters, attempting to achieve good water status by 2015; this includes, within the assessment, biological and chemical elements. The European Commission has proposed a list of priority dangerous substances (including metals such as Cd, Hg, Ni and Pb), with the corresponding list of environmental quality standards (EQS), to assess chemical status, but only for waters. In this contribution, a long-term (1995–2007) dataset of transitional and coastal water and sediment trace elements concentrations, from the Basque Country (northern Spain), has been used to investigate the response of these systems to water treatment programmes. Moreover, the approach proposed in the WFD, for assessing water chemical status (the ‘one out, all out’ approach), is compared with the integration of water and sediment data, into a unique assessment. For this exercise, background levels are used as reference conditions, identifying the boundary between high and good chemical status. EQS are used as the boundary between good and moderate chemical status. This contribution reveals that the first approach can lead to misclassification, with the second approach representing the pattern shown by the long-term data trends. Finally, the management implications, using each approach are discussed.     

The French approach to managing water resources in the Mediterranean and the new European Water Framework Directive

The main content of the new European Water Framework Directive is presented. Within its river basin management approach, a special mention of coastal waters status is made. Among the issues at stake are the setting up of river basin management plans, including coastal waters, and water quality assessment system leading to an harmonized definition of quality objectives and their appropriate indicators. The Rhone-Mediterranean-Corsica Water Master Plan, launched in 1996, is considered to be well fitted to this river basin approach and the necessary tools which go with it. It shows up how a river quality assessment system (SEQ) can be adapted to the coastal waters and how it can progressively lead to an efficient set of publishable environmental and performance indicators. Since planning and implementation are devolved to the lowest appropriate level, a close look is then been given at how such a system can work at the local level through different selected case studies on the French Mediterranean coast. In conclusion, some guidelines are drawn up for future initiatives towards integrated coastal area and river basin management.     

Temporal and spatial changes in marine benthic habitats in relation to the EU Water Framework Directive: The use of sediment profile imagery

In 2002 to 2006, sediment profile imagery (SPI) was used to study the environmental impact of eutrophication-induced irregular and seasonal hypoxia on marine benthic habitats in six regions in the Skagerrak and Kattegat (West Sweden). The benthic habitat quality (BHQ) was assessed by parameterisation of biogenic structures observed by the SPI technique, and benthic quality status was related to the EU Water Framework Directive (EU-WFD). The temporal changes were analysed by a 5-factor nested ANOVA and significant temporal differences were recorded within three of the regions. Two of these were affected by hypoxia in the deeper parts and one was probably affected by hypoxia below the halocline. The environmental quality status according to the EU-WFD was bad to high in two regions, moderate to good in three regions, and good to high, i.e., acceptable according to the EU-WFD, in only one region. As BHQ is highly correlated to benthic faunal data, measures have to be taken to improve the coastal water quality in five of the six studied areas.     

Theoretical and practical aspects on benthic quality assessment according to the EU-Water Framework Directive – Examples from Swedish waters

A previously presented objective method to calculate each species sensitivity to disturbance is here slightly modified and implemented in the Benthic Quality Index (BQI) for marine benthic invertebrates. A framework for assessment of water bodies based on multi-site BQI-values is also presented, where a certain variation of BQI-values is allowed to cover the heterogeneity within each water body. The 20th percentile, using bootstrapping, from the available sites’ BQI-values is compared with the status boundaries for quality assessment. The reliability of the assessment depends on the background information available for the boundary setting as well as the number of sampling sites included in the assessment. Agreement between time series of quality assessments in areas with known changes in anthropogenic disturbances is encouraging. Problems associated with water body assessment based on few or no samples, as well as multiple sampling occasions during the 6-yr WFD cycle are discussed.     

A revisitation of TRIX for trophic status assessment in the light of the European Water Framework Directive: application to Italian coastal waters

The trophic status classification of coastal waters at the European scale requires the availability of harmonised indicators and procedures. The composite trophic status index (TRIX) provides useful metrics for the assessment of the trophic status of coastal waters. It was originally developed for Italian coastal waters and then applied in many European seas (Adriatic, Tyrrhenian, Baltic, Black and Northern seas). The TRIX index does not fulfil the classification procedure suggested by the WFD for two reasons: (a) it is based on an absolute trophic scale without any normalization to type-specific reference conditions; (b) it makes an ex ante aggregation of biological (Chl-a) and physico-chemical (oxygen, nutrients) quality elements, instead of an ex post integration of separate evaluations of biological and subsequent chemical quality elements. A revisitation of the TRIX index in the light of the European Water Framework Directive (WFD, 2000/60/EC) and new TRIX derived tools are presented in this paper. A number of Italian coastal sites were grouped into different types based on a thorough analysis of their hydro-morphological conditions, and type-specific reference sites were selected. Unscaled TRIX values (UNTRIX) for reference and impacted sites have been calculated and two alternative UNTRIX-based classification procedures are discussed. The proposed procedures, to be validated on a broader scale, provide users with simple tools that give an integrated view of nutrient enrichment and its effects on algal biomass (Chl-a) and on oxygen levels. This trophic evaluation along with phytoplankton indicator species and algal blooms contribute to the comprehensive assessment of phytoplankton, one of the biological quality elements in coastal waters.     

Using historical data, expert judgement and multivariate analysis in assessing reference conditions and benthic ecological status, according to the European Water Framework Directive

The European Water Framework Directive (WFD) establishes a framework for the protection and improvement of estuarine and coastal waters, trying to achieve 'good surface water status at the latest 15 years after the date of entry into force of this Directive'. One of the biological elements that should be analysed is the benthos and, as such, the WFD normative definitions describe the aspects of the benthic communities that must be included in the ecological status assessment of a water body. Therefore, it is essential to include, in the assessment, the different metrics that address those parameters identified in the normative definitions for each of the ecological status classes. In this contribution the use of the AMBI, richness and diversity, combined with the use, in a further development, of factor analysis together with discriminant analysis, is presented as an objective tool (named here M-AMBI) in assessing ecological quality status. This assessment requires previous classification of water bodies and typologies, together with the definition of reference conditions; this is undertaken in this contribution using historical data, expert judgement and multivariate analysis. The study has been undertaken by examining changes in benthic communities in the Basque Country, over the last decade, as a case-study, to demonstrate the accuracy and potential of these methodologies.     

Towards the application of the Water Framework Directive in Italy: Assessing the potential of benthic tools in Adriatic coastal transitional ecosystems

The potential of four benthic indices (AMBI/M-AMBI, BENTIX, BITS) was assessed in Italian coastal transitional ecosystems. The community composition showed a strong dominance of lagoonal, tolerant species, and out of more of 400 species found, only about 40 taxa were dominant. The full agreement of the four indices on an undegraded (Good or better) or degraded (Moderate or worse) status occurred only in 32.3% of stations. This study evidenced that BENTIX is inappropriate for eutrophic Adriatic lagoons, and that in such environments M-AMBI classification is actually too much dependent on diversity and richness, and seems unable to capture some peculiarities of benthic assemblages in transitional waters. AMBI and BITS gave similar classifications despite the different level of taxonomic identification needed. The unmodified use of these indices might impair accurate assessment of ecological quality status and decision-making on the managers’ point of view.