The CARLIT method for the assessment of the ecological quality of European Mediterranean waters: Relevance,robustness and possible improvements

The application of the European Union (EU) Water Framework Directive (WFD) requires the assessment of the ecological status (ES) of coastal waters in order to detect environmental changes and implement management plans to prevent their further deterioration. The ES of a water body (WB) has to be assessed on the basis of the status of several biological indicators, referred to as biological quality elements (BQE), such as phytoplankton, macroalgae, seagrasses, macroinvertebrates and fish. We present the most extensive assessment ever undertaken of the ES of Mediterranean waters, by means of the CARLIT index, the most widely used index for the Mediterranean Sea. This index is based on the Ecological Quality Ratio (EQR) between a measured value of Ecological Quality (EQ) and a value corresponding to a reference site. This assessment is based on an extensive field study, covering the whole of the Mediterranean French coasts (including Corsica), 40 WBs and ∼2 970 kilometres of shore (at a 1/2 500 scale). The original Ballesteros CARLIT method is compared to the Nikolić modified method, and we have undertaken the challenge of developing an alternative new simplified CARLIT method. This simplified method, which requires less expert judgement, is easier to implement by local authorities, and provides results similar overall to those of the original method. Previous attempts, if any, to correlate EQRs with anthropogenic stressors (through pressure indices) were mainly based upon land uses or on comprehensive lists of stressors, some spatially very sporadic, temporally highly variable, non-representative of the WB and with the impact poorly established on species and communities. To date, the LUSI (Land Uses Simplified Index) and the MA-LUSI-WB have been the most widely used pressure indices. Here, we propose a new pressure index (HAPI) taking into consideration the possible shortcomings of previous indices. It takes into account the actual pressures at community levels considered by the CARLIT method. It accounts well for the EQR values of the study area, as evidenced by the high correlation coefficient between EQRs and HAPI, better than that of the other pressure indices. The present study provides a comprehensive view of the ES of the French Mediterranean coasts. Surprisingly, the picture is far less cause for concern than expected, although this could result from an artefact due to the focus on superficial waters and habitats inherent to the CARLIT method. Where two successive assessments were performed (23 WBs, 2007–2010 vs 2012–2015), the results were similar, which stresses the robustness of the method and/or the relative stability over time of the overall ES of the WBs, and suggests that the successive assessments could be carried out at low frequency.     

基于基尼系数的中国水生态分区研究

提出了反映水生态系统空间分布规律和特征差异的水生态分区方案,并与国家现有的水资源分区、生态功能区划、水功能区划等相关区划成果相互衔接,为水资源综合利用、流域生态保护和经济社会发展规划提供实用的自然基础。以我国自然地理特征的空间变异与地域关联为依据,以流域为基本单元,进行水生态区划的初步研究,提出了分区的指标体系、步骤和区划方法,形成了两级的全国水生态分区体系。首先,划分为东部区、中部区、西北区和西南区4个水生态一级区;进行水生态二级区划时选取水资源量、降雨量、人口密度、NDVI作为分区的评价因子,根据洛伦茨曲线和基尼系数对分区合理性进行了检验。验证结果表明,各个水生态二级区的水资源量与降雨量、人口密度和NDVI值之间的基尼系数均不超过0.4,分区方案比较合理,从而形成34个水生态二级区,分布在东部13个,中部10个,西北6个,西南5个。     

The seagrass Posidonia oceanica as indicator of coastal water quality: Experimental intercalibration of classification systems

The pervasive use of ecological indices is increasingly requiring actions of harmonisation. Specifically, within the EU Water Framework Directive, an important effort in methods intercalibration is being done. However, a significant limitation in comparability assessment arises from the datasets used, which have different geographic origins. The purpose of our study was to perform an experimental intercalibration, where data were collected specifically on a set of common sites and following all the requirements of the methods being assessed. Three indices based on the marine angiosperm Posidonia oceanica, the POMI, the BiPo and the PoSte, were applied to sites in three different geographical areas of the western Mediterranean: Catalonia, Corsica and Southern Italy (Ischia), distant between hundreds and more than thousands of kilometers. Two indices, POMI and BiPo, showed not only a very good relationship with human pressures (measured on a common scale for all sites) but also a high comparability, in all aspects investigated. The differences found for the third one (PoSte) are hypothesised as being due to a different rationale used to define reference conditions, the different metrics used in the index, and in particular to a different definition of ecological status in relation to the time scale of the response to anthropogenic pressures. Our study demonstrates that indices with very different approaches can provide fully reliable and comparable results.     

洱海流域水生态分区

分区边界的确定是生态分区的重要步骤,但目前多数水生态分区的边界确定以定性分析、专家判断为主。本研究以洱海流域为例,建立了一套两级分区体系。该体系基于GIS技术,用子流域作为分区基本单元,并用相关分析法,定量筛选一、二级分区指标。其中,一级分区指标为高程、坡度和植被归一化指数(NDVI),二级分区指标为农田百分比和城镇百分比。通过指标图层的叠加和重分类,合并同质性子流域,从而将洱海流域划分为5个一级区和9个二级区。藻类群落分布的验证结果表明分区合理。本研究将定量分析和子流域边界应用于水生态分区,使分区边界的确定更科学,在实际管理中更具有可操作性。本研究结果为水生态分区研究提供了新的方法,为洱海流域水生态管理提供了基本管理单元。     

A comparative approach of assessing ecological status in two coastal areas of Eastern Mediterranean

This work presents an assessment of the ecological quality status of two marine coastal areas in the Aegean Sea (Greece, Eastern Mediterranean) based on the benthic macroinvertebrate quality element. S. Evvoikos and Thessaloniki gulfs, two coastal areas subjected to slight and heavier anthropogenic pressures, were selected to test the biotic index Bentix developed for the assessment of the ecological status. Other ecological indicators, such as the Shannon diversity index (H′), the species richness (S) and the AMBI biotic index were also applied and evaluated comparatively. Faunistic data were also used to interpret results. The resulting classification was validated with the use of physicochemical parameters and pressure information. This work also provides an insight into the structure of the Bentix classification scheme within the scope of its use in Water Framework Directive (WFD) implementation.     

Phylogenetic and functional metagenomic profiling for assessing microbial biodiversity in environmental monitoring

Decisions guiding environmental management need to be based on a broad and comprehensive understanding of the biodiversity and functional capability within ecosystems. Microbes are of particular importance since they drive biogeochemical cycles, being both producers and decomposers. Their quick and direct responses to changes in environmental conditions modulate the ecosystem accordingly, thus providing a sensitive readout. Here we have used direct sequencing of total DNA from water samples to compare the microbial communities of two distinct coastal regions exposed to different anthropogenic pressures: the highly polluted Port of Genoa and the protected area of Montecristo Island in the Mediterranean Sea. Analysis of the metagenomes revealed significant differences in both microbial diversity and abundance between the two areas, reflecting their distinct ecological habitats and anthropogenic stress conditions. Our results indicate that the combination of next generation sequencing (NGS) technologies and bioinformatics tools presents a new approach to monitor the diversity and the ecological status of aquatic ecosystems. Integration of metagenomics into environmental monitoring campaigns should enable the impact of the anthropogenic pressure on microbial biodiversity in various ecosystems to be better assessed and also predicted.     

A biotic index using the seagrass Posidonia oceanica (BiPo), to evaluate ecological status of coastal waters

The development of ecologically based indices that respond to disturbances in a predictable manner has been stressed by the EU Water Framework Directive. The seagrass Posidonia oceanica, given its ecological indicator characteristics, has been identified as one of the elements to determine ecological status under the EU Water Framework Directive. The purpose of this study is therefore to develop a biotic index based on P. oceanica (BiPo), focussing on: (i) the necessity of an index that may be applied over the largest geographical extent possible, (ii) the necessity of a tool for a baseline evaluation of P. oceanica status in the Mediterranean, (iii) the compliance with WFD requirements, (iv) the efficiency of the method in terms of reliability and cost. The BiPo index is developed on the basis of all P. oceanica monitoring data available in the western Mediterranean and on a standard assessment of anthropogenic pressures. The index metrics are selected and evaluated on the basis of this pressures assessment, and are subsequently integrated for the evaluation of ecological status. The index is then tested on 15 sites around Corsica (France). The results show that the BiPo well reflects meadow health status and ecological status. Furthermore it is reliable, standard and cost-effective, and can be applied to a wide array of management and conservation purposes.     

Cartography of littoral rocky-shore communities (CARLIT) as a tool for ecological quality assessment of coastal waters in the Eastern Adriatic Sea

Littoral cartography is a valuable tool which uses shallow water macroalgal communities for monitoring ecosystem health and water quality. Cartography of littoral rocky-shore communities (CARLIT) is a European Union Water Framework Directive-compliant monitoring method widely used in the Western Mediterranean Sea. This non-destructive method is based on a visual observation of the type and length of coast occupied by rocky-shore communities in the upper-sublittoral zone. Here we present the first wide-scale application of CARLIT in the Adriatic Sea. The reference values calculated specifically for the Croatian coast (Eastern Adriatic Sea) ensure accurate calculation of the ecological status. The measured ecological quality ratio values (EQR) show a good linear relation with the Land Uses Simplified Index (LUSI) and appropriately reflect an increase in nutrient concentrations. The results suggest that this method can be used as a reliable biomonitoring tool in the Eastern Adriatic Sea. This study highlighted that Cystoseira forests thrive in 39% of the surveyed coastline and 23% of the coastline seems to be subjected to overgrazing by sea urchins. Our results provide a spatially accurate information on the abundance of different upper-sublittoral communities and the associated ecological status, which can be used in future management plans for improving water quality.     

A multimetric diatom index to assess the ecological status of coastal Galician rivers (NW Spain)

There are many rivers in northwest Spain as a consequence of the mountainous landscape and the granitic geology subjected to Atlantic influences. Water and epilithic diatoms samples were collected at 72 sites in Galicia flowing into the Atlantic Ocean and Cantabrian Sea in summer 2002–2003 and spring 2004. These sites included minimally disturbed sites, defined as reference sites, and impacted sites which were influenced by different human pressures. We used the diatom assemblages to calculate diatom indices using the Omnidia software, but we also developed new metrics based on the similarity of species composition in reference sites. The response of the metrics was tested in relation to physicochemical variables. We developed a diatom multimetric index (MDIAT) as a combination of metric values. The sensitivity of the MDIAT to organic and nutrient stressors supports the use of this index to classify the ecological status of Galician rivers. The MDIAT showed higher correlations with some variables and nutrients than the individual metrics. According to the MDIAT, 69% of the sites sampled in Galician coastal rivers achieve good ecological status. The MDIAT has been developed specifically for Galician granitic rivers (NW Spain), and has been intercalibrated at the European level in the Central Baltic Rivers GIG. Our study validates the application of this multimetric index to evaluate the water quality in coastal Galician rivers.     

Ability of phytoplankton trait sensitivity to highlight anthropogenic pressures in Mediterranean lagoons: A size spectra sensitivity index (ISS-phyto)

Size spectra exhibit common patterns of variation and predictable responses to pressures across ecosystem types, functional guilds and taxonomic groups. Here, we extend the size spectra approach to phytoplankton ecological status assessment in transitional waters by developing, testing and validating a multi-metric index of size spectra sensitivity (ISS-phyto), which integrates size structure metrics with others such as phytoplankton diversity, biomass and sensitivity of size classes to anthropogenic disturbance. The ability of various theoretical models of size spectra sensitivity to discriminate between disturbed and undisturbed ecosystems and levels of anthropogenic stress was evaluated. We used data on phytoplankton samples collected in 14 Mediterranean and Black sea transitional water ecosystems (coastal lagoons) from Italy, Albania, Greece, Bulgaria and Romania, and compared the models’ efficiency by looking at their pressure–impact response along salinity and enrichment gradients, the latter quantified as variations in dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP). Data from a fifteenth Mediterranean lagoon was used for external validation purposes. Right asymmetric models of size class sensitivity, implying higher sensitivity of smaller cell size classes, were found to contribute to the ISS-phyto multimetric tool more effectively than symmetric and left asymmetric models, distinguishing disturbed from undisturbed lagoons and disturbed from undisturbed stations within the same lagoon. When based on right asymmetric sensitivity models, i.e., those that were most efficient in identifying anthropogenic impacts, ISS-phyto also showed the best fit of pressure–response relationships along the salinity and enrichment gradients; at low to high levels of impact ISS response was driven by size class sensitivity and at very high impacts by phytoplankton biomass. A scheme for the classification of Ecological Quality Status based on ISS-phyto is proposed and validated. The validation procedure found that ISS-phyto is an effective and sensitive monitoring tool, robust, easy to apply and to inter-calibrate among laboratories.     

Application of an angiosperm-based classification system (BiPo) to Mediterranean coastal waters: using spatial analysis and data on metal contamination of plants in identifying sources of pressure

The Biotic Index based on Posidonia oceanica (BiPo) is a classification system for evaluation of the ecological status in Mediterranean coastal waters, developed in accordance with the EU Water Framework requirements. The aim of this study is to verify the applicability and reliability of the BiPo index to different geographical areas of the north-western Mediterranean (France, Spain and Italy), to understand whether such a classification system may be applied more extensively, as so far it has only been applied to coastal waters in Corsica. The ecological status determined for sites is verified against pressures revealed from satellite imagery and from trace metal contamination of plants, to identify the sources of pressure that may be responsible for a low ecological status. The results of this study indicate that: (i) the BiPo index responds reliably to pressures, in different areas of the Mediterranean; (ii) sites with an ecological quality ratio (EQR) close to the good/moderate boundary require particular attention to identify and reduce causes of deterioration; (iii) the support of chemical indicators, in this case metal contamination, is relevant to identify potential sources of pressure.     

Fine-Scale Cartography of Human Impacts along French Mediterranean Coasts: A Relevant Map for the Management of Marine Ecosystems

Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast) or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m). It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica) at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity) are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures at a relevant scale for biodiversity conservation.     

Ecological opportunities and specializations shaped genetic divergence in a highly mobile marine top predator

Environmental conditions can shape genetic and morphological divergence. Release of new habitats during historical environmental changes was a major driver of evolutionary diversification. Here, forces shaping population structure and ecotype differentiation (‘pelagic’ and ‘coastal’) of bottlenose dolphins in the North-east Atlantic were investigated using complementary evolutionary and ecological approaches. Inference of population demographic history using approximate Bayesian computation indicated that coastal populations were likely founded by the Atlantic pelagic population after the Last Glacial Maxima probably as a result of newly available coastal ecological niches. Pelagic dolphins from the Atlantic and the Mediterranean Sea likely diverged during a period of high productivity in the Mediterranean Sea. Genetic differentiation between coastal and pelagic ecotypes may be maintained by niche specializations, as indicated by stable isotope and stomach content analyses, and social behaviour. The two ecotypes were only weakly morphologically segregated in contrast to other parts of the World Ocean. This may be linked to weak contrasts between coastal and pelagic habitats and/or a relatively recent divergence. We suggest that ecological opportunity to specialize is a major driver of genetic and morphological divergence. Combining genetic, ecological and morphological approaches is essential to understanding the population structure of mobile and cryptic species.     

The suitability of the marine biotic index (AMBI) to new impact sources along European coasts

In recent years, several benthic biotic indices have been proposed to be used as ecological indicators in estuarine and coastal waters. One such indicator, the AZTI Marine Biotic Index (AMBI), was designed to establish the ecological quality of European coasts. The index examined the response of soft-bottom benthic communities to natural and man-induced disturbances in coastal and estuarine environments. It has been successfully applied to different geographical areas and under different impact sources, with increasing user numbers in European marine waters (Baltic, North Sea, Atlantic and Mediterranean). The AMBI has been used also for the determination of the ecological quality status (EcoQ) within the context of the European Water Framework Directive (WFD).In this contribution, 38 different applications including six new case studies (hypoxia processes, sand extraction, oil platform impacts, engineering works, dredging and fish aquaculture) are presented. The results show the response of the benthic communities to different disturbance sources in a simple way. Those communities act as ecological indicators of the ‘health’ of the system, indicating clearly the gradient associated with the disturbance.     

Landscape genetic structure of natural populations of Acacia caven in Argentina

Acacia caven is a South American species which shows remarkable climate tolerance and ecological adaptability; as such, this species is suitable for colonizing anthropogenically degraded sites. This species is widely distributed, and six varieties have been described based on both morphological traits and molecular markers. Moreover, Aronson (1992) suggests that, for this species, geographical separation could be associated with ecological differentiation. In this study, amplified fragment length polymorphisms were used to study genetic variation within and among 15 populations of A. caven from five eco-regions of Argentina and to investigate (1) whether the varieties are genetically coherent, (2) whether the varieties correspond consistently to a single eco-region, (3) the proportion of the species diversity explained within and among varieties and eco-regions. Eight of the 225 bands appear to be under positive selection. The remaining 217 neutral loci showed a high percentage of polymorphism (99.1%). The estimates of genetic diversity H _j were generally high. The F _ST (0.315) was highly significant, providing evidence for genetic structure among populations. Hierarchical analysis of molecular variance indicated that variation among eco-regions was 8.2% and highly significant. The higher component of variance was found within populations (67.5%). STRUCTURE analysis suggested that the optimal number of K?=?11. The results showed that, in most cases, geographic separation is associated with ecological differentiation. Since differentiation of A. caven populations studied here in eco-regions was highly significant, sampling should include a large number of trees within populations as well as covering the wide ecological diversity of the species.     

Comparison of two methods for quality assessment of macroalgae assemblages,under different pollution types

The selection of adequate methodologies for the assessment of different biological quality elements is urgently needed for the application of the water framework directive (WFD 2000/60/EEC). In the case of macroalgae in coastal waters of the North East Atlantic, two methodologies have been proposed: the reduced species list (RSL) index and the quality of rocky bottoms (CFR) index. Both methods use multimetric approaches to evaluate the quality of macroalgae assemblages, which are based on community characteristics (species/populations richness, cover, percentage of opportunistic species, ecological state groups ratio, etc.). In this paper the results of applying both indices on three different types of pollution gradients in the North coast of Spain (bay of Biscay) are presented, in order to test their usefulness and intercalibration possibilities. In general terms, the CFR index responded more accurately than the RSL index to the pollution gradients under study. With respect to the indicators used in the current evaluation, richness, opportunistic species and cover seemed to be the most accurate for quality assessment of macroalgal communities. While the first two indicators are taken into account in both indices, the latter (cover) is only considered in the CFR index, even though the abundance of macroalgae is one of the aspects to be included in the evaluation of this biological element, according to the WFD.     

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.     

Genetic differentiation and secondary contact zone in the seagrass Cymodocea nodosa across the Mediterranean–Atlantic transition region

Aim A central question in evolutionary ecology is the nature of environmental barriers that can limit gene flow and induce population genetic divergence, a first step towards speciation. Here we study the geographical barrier constituted by the transition zone between the Atlantic Ocean and the Mediterranean Sea, using as our model Cymodocea nodosa, a seagrass distributed throughout the Mediterranean and in the Atlantic, from central Portugal to Mauritania. We also test predictions about the genetic footprints of Pleistocene glaciations. Location The Atlantic–Mediterranean transition region and adjacent areas in the Atlantic (Mauritania to south‐west Portugal) and the Mediterranean. Methods We used eight microsatellite markers to compare 20 seagrass meadows in the Atlantic and 27 meadows in the Mediterranean, focusing on the transition between these basins. Results Populations from these two regions form coherent groups containing several unique, high‐frequency alleles for the Atlantic and for the Mediterranean, with some admixture west of the Almeria–Oran Front (Portugal, south‐west Spain and Morocco). These are populations where only one or a few genotypes were found, for all but Cadiz, but remarkably still show the footprint of a contact zone. This extremely low genotypic richness at the Atlantic northern edge contrasts with the high values (low clonality) at the Atlantic southern edge and in most of the Mediterranean. The most divergent populations are those at the higher temperature range limits: the southernmost Atlantic populations and the easternmost Mediterranean, both potential footprints of vicariance. Main conclusions A biogeographical transition region occurs close to the Almeria–Oran front. A secondary contact zone in Atlantic Iberia and Morocco results from two distinct dispersal sources: the Mediterranean and southernmost Atlantic populations, possibly during warmer interglacial or post‐glacial periods. The presence of high‐frequency diagnostic alleles in present‐day disjunct populations from the southernmost Atlantic region indicates that their separation from all remaining populations is ancient, and suggests an old, stable rear edge.