Characterization of the ecological quality of the coastal Gulf of Lions (NW Mediterranean). A comparative approach based on three biotic indices

European coastal monitoring programmes may fail to identify impacts on benthic macrofauna caused by bottom trawling

Bottom trawling (hereafter trawling) is the dominant human pressure impacting continental shelves globally. However, due to ongoing data deficiencies for smaller coastal vessels, the effects of trawling on nearshore seabed ecosystems are poorly understood. In Europe, the Water Framework Directive (WFD) provides a framework for the protection and improvement of coastal water bodies. It requires member states to track the status of 'biological quality elements' (including benthic macrofauna) using WFD-specific ecological indicators. While many of these metrics are sensitive to coastal pressures such as nutrient enrichment, little is known about their ability to detect trawling impacts. Here, we analysed a comprehensive data set of 5885 nearshore benthic samples - spatiotemporally matched to high-resolution trawling and environmental data - to examine how these pressures affect coastal benthos. In addition, we investigated the ability of 8 widely-used benthic monitoring metrics to detect impacts on benthic biological quality. We found that abundance (N) and species richness (S) were strongly impacted by bottom trawling. A clear response to trawling was also observed for the WFD-specific Benthic Quality Index (BQI). Relationships between N and S, and trawling were particularly consistent across the study area, indicating sensitivity across varying environmental conditions. In contrast, WFD indices such as AZTIs Marine Biotic Index (AMBI), multivariate AMBI (M-AMBI), and the Danish Quality Index (DKI), were unresponsive to trawling. In fact, some of the most heavily trawled areas examined were classified as being of 'high/good ecological status' by these indices. A likely explanation for this is that the indices are calculated using species sensitivity scores, based on expected species response to eutrophication and chemical pollution. While the BQI also uses species sensitivity scores, these are based on observed responses to disturbance gradients comprising a range of coastal pressures. Given the prominent use of AMBI and DKI throughout Europe, our results highlight the considerable risk that the metrics used to assess Good Ecological Status (GES) under the WFD may fail to identify trawling impacts. As trawling represents a widespread source of coastal disturbance, fishing impacts on benthic macrofauna may be underestimated, or go undetected, in many coastal monitoring programmes around Europe.

Tracing the impact and recovery trajectory of oil spill affected tropical rocky intertidal macrobenthic communities using the BOPA index

A yearlong study was conducted to assess the impact of an oil spill on macrobenthos of rocky intertidal zone of Uran, India and its recovery processes, by comparing impacted site with a reference. Immediate acute effects observed were elevated sediment hydrocarbons, absence of macroalgae and amphipods, mass mortality of macrofauna and dominance of the opportunistic nereid, Namalycastis senegalensis. As the hydrocarbons reduced at the impacted site by ~50 % within three months, gradual re-appearance of macroalgae and re-colonization of amphipods (51.4 %) and sensitive polychaetes (7 %) indicated that the recovery was well underway. The amphipod, Allomelita pellucida proved to be a potential indicator of oil contamination. BOPA correlated with sediment hydrocarbons and performed effectively as the extant macrobenthic communities had sufficient representation of Polychaeta and Amphipoda. Notwithstanding the distinct initial impacts of the oil spill, comparable macrobenthic assemblages comprised of sensitive species at both sites after a year confirmed complete recovery.

Response of marine amphipods to sediment variables (Chabahar Bay- Iran): A step toward localizing amphipod-based bioindices

Chabahar Bay will undergo industrial and coastal pressures according to the government plan to develop the Makran coasts. Therefore, knowing its biological community as well as their possible interactions with environmental variables, before and after coastal development, is important. The amphipod community structure and their response to the structural and contaminant parameters of the sediment include: granulometry, total organic matter (TOM) overloading, heavy metal contamination based on the Pollution Load Index (PLI) and polycyclic aromatic hydrocarbons (PAHs) during post monsoon season of 2017 were investigated from 19 stations. Traditional diversity and taxonomic distinctness indices were calculated. Multivariate analysis revealed the main role of sediment grain size and depth in shaping amphipod community structure. Consequently, two specific ecological niches were determined: species that prefer non-muddy substrates; and those dwelling in muddy or muddy sandy biotopes. No correlation was found between the Shannon diversity (H'), the average taxonomic distinctness indices (Δ+) together and both with contamination parameters. The Δ+ funnel plot well separated under-stressed stations from the healthy ones. The presence of only Ampelisca congeners in under-stressed stations revealed the tolerant nature as well as species-specific response of the genus to anthropogenic impacts. Considerable tolerant response (P > 0.05, r² = 0.4) of A. zamboangae to PAHs; A. persicus to TOM were observed. High concentration of nickel (Ni) in the studied area already stated due to erosion of ophiolite units from Makran Mountains. The significant correlation of the recently described Iranian species A. lowryi with Ni assumes that it is a native species that is well adapted to the geological conditions of the seabed. Instead Urothoe platydactyla can be considered as early warning signal for PAHs, TOM, Ni and cadmium (Cd) contamination particularly for non-muddy substrates. Our findings help to localize common biotic indices (e.g. AMBI, BENTIX, and BOPA) for studied area through correctly assignment of amphipods to the sensitive/tolerant ecological groups. Finally, we state that in the current situation of Chabahar Bay, in which no special industrial complexes have been established, any sediment-disrupting activity (i.e. sedimentation, dredging, trawling) affects its amphipod communities more than chemical pollutants.

Seasonality of macrobenthic assemblages and the biotic environmental quality of the largest monsoonal estuary along the west coast of India

This study deals with the macrobenthic assemblages and the biotic environmental quality of Kochi backwaters (KBW), India. Due to the heavy river discharge, extensive limnetic and turbid conditions prevailed in the KBW during the southwest monsoon (June to September). This exerted a profound adverse effect on the abundance, richness, and diversity of macrobenthic assemblages. Overall, mesohaline conditions with a clayey sand bottom substratum favored the high macrofaunal abundance during the southwest and northeast monsoon seasons. But mesohaline condition and sandy silt bottom were found to support high macrofaunal abundance in the KBW during the pre-monsoon season. Polychaete dominated the macrobenthic community, regardless of seasons. Capitella capitata, Heteromastus similis, Paraheteromastus sp., Prionospio cirrobranchiata, Minuspio cirrifera, Pagurapseudopsis kochindica, P. gymnophobia, Ctenapseudes indiana, C.chilkensis, Tanais sp., Villorita cyprinoides, Grandidierella sp., Ampelisca sp., and Littorina sp. were the dominant ones observed during the study. The sediment organic carbon, in general, showed a positive correlation with polychaete abundance during all three seasons. The ecological status of KBW during all three seasons was assessed as per BO2A index, which ranged from 0.05 to 0.18, suggesting a healthy to a moderately polluted bottom environmental condition.

Ecological quality status evaluation of a monsoonal tropical estuary using benthic indices: comparison via a seasonal approach

The use of biotic indices has garnered attention during the last decade due to its extensive application in evaluating ecological quality status (EcoQS) of marine waters and estuaries. Three seasonal surveys were conducted in the Kundalika estuary, India to evaluate the ecostatus using five benthic indices and comparing their effectiveness considering the estuarine salinity gradient and seasonality. All indices gave divergent results displaying a wide range of classes (good to bad) across salinity zones and seasons. Comparatively, M-AMBI discriminated the EcoQS suitably than other indices. Hence, a seasonally averaged approach for M-AMBI was proposed to obtain a final mean EcoQS which assigned moderate status to the euhaline and poly-mesohaline zones and poor status to the oligohaline zone. Considering the high degree of spatial heterogeneity and seasonality in the estuary, the monsoon data was found to lower the EcoQS due to natural stress in some cases; the exclusion of the monsoon season resulted in a more valid ecostatus. Therefore, this approach which combines information from the non-monsoon seasons stands out in providing a useful basis for ecological management by scrutinizing responses of macrobenthos. Also, we suggest salinity zone-wise evaluation for more effective classification chiefly in tropical monsoonal estuaries. An effort to establish a final EcoQS was performed; however, future in-depth studies are necessary to ascertain the reliability of the successful biotic index (M-AMBI) in estuaries with different stressors.

Comparative efficacy of benthic biotic indices in assessing the Ecological Quality Status (EcoQS) of the stressed Ulhas estuary, India

Ecostatus of Ulhas estuary, one of the most polluted estuaries along the industrialized and urbanized northwest coast of India, was evaluated by six widely accepted benthic indices viz. H'(log₂), AMBI, M-AMBI, BENTIX, BOPA and BO2A to test their efficiency in a tropical setting. The mesohaline zone, which presented eutrophic conditions, was classified as 'bad' by all indices due to the azoic status. Despite significant correlations obtained between indices, there were discrepancies in the accurate level of EcoQS assigned to each station. AMBI was observed to be most efficient in indicating a clear spatial variability from a 'poor' to 'bad' ecological quality status in the middle and upstream zones to an improved status in the downstream region. Limitations of all indices are discussed in light of their suitability for assessing the estuarine environmental condition. The present results could provide a fillip to environmental improvement initiatives currently being undertaken in the estuary.

Impacts of environmental and anthropogenic stresses on macrozoobenthic communities in Jinhae Bay, Korea

In this study, spatiotemporal dynamics of macrofaunal assemblages and their associations with environmental conditions were examined in Jinhae Bay (10 sites), where the obvious sources of pollution including industries, oyster farms (hanging cultures), and municipal discharges has surrounded. The survey had performed over five consecutive seasons in 2013-2014. Target sedimentary variables included grain size, organic content, C/N ratio, carbon and nitrogen stable isotope ratios, and some heavy metals. Five ecological quality indices (EcoQ) were calculated from the benthic community data to evaluate ecological qualities in site-specific manner. Jinhae Bay is a shallow (depths range, 11-24 m) and typical semi-enclosed bay. The benthic environments represented mud dominated bottoms (>70%) with fairly substantial organic content levels (>2%) over all five seasons. Seasonal patterns were observed with peak abundances in the spring and distinctive macrozoobenthos species shifts in the summer. The spring bloom could be explained by drastic increases of some polychaetes, mainly Capitella sp., at certain site, particularly near the shore. The oyster farms situated in the innermost locations seem to provide organic-rich bottoms being dominated by opportunistic species and/or organic pollution indicator species, such as Lumbrineris longifolia, Capitella sp., and Paraprionospio patiens. In general, the EcoQ indicators indicated that Jinhae Bay was moderately polluted, with exceptionally poor EcoQ in a few locations during the specific season(s). Overall, adverse effects on benthic community was broadly attributable to contaminations of heavy metals and nearby aquatic farm activities in Jinhae Bay, which requires a prompt action toward ecosystem-based management practice in the given area.

Structuring factors of the spatio-temporal variability of macrozoobenthos assemblages in a southern Mediterranean lagoon: How useful for bioindication is a multi-biotic indices approach?

The authors investigated the impact of the extension of the El Kantra Channel on the composition and structure of macrobenthic assemblages in Boughrara Lagoon (Gulf of Gabes, Tunisia along with the use of 4 biotic indices (AMBI, BENTIX, M-AMBI and TUBI). Thirteen stations were sampled seasonally in 2012-2013. Forty-one species were found in 2012-2013 not recorded in 2009-2010, including 20 species of polychaetes belonging to the trophic groups of deposit-feeders and carnivores which are expected to increase in areas disturbed by organic pollution. During the survey, we recorded a high fish mortality, essentially caused by the development of harmful algal blooms (HAB) which increased organic matter deposition, thus inducing polychaete development. This seems to weaken the bio-indicating power of biotic indices used here which, paradoxically, classified all sampled stations at a high ecological status. A review of these indices and their applicability to all marine environments is recommended.

Reducing spatial variation in environmental assessment of marine benthic fauna

The Benthic Quality Index, BQI, is widely used for benthic quality assessment. Here, we investigated if spatial variation in the BQI can be reduced by accounting for the environmental factors instead of having different boundaries for different salinity regimes between status classes in the EU Water Framework Directive and Marine Strategy Framework Directive. For this purpose we tested salinity, sediment structure, and depth in a regression model to test their contribution to variations in BQI. The spatial variation in BQI was better explained by depth than by salinity or sediment structure. The proposed assessment method uses the residuals from the regression model between BQI and depth. With this method the variance in BQI between samples was reduced by 50% to 75% in the majority of situations. A method to establish the boundary between good and moderate status and how to derive EQR-values according to the WFD is presented.

Long-term (1998-2010) large-scale comparison of the ecological quality status of gulf of lions (NW Mediterranean) benthic habitats

A comprehensive Mediterranean data set has been used to address 3 questions associated with the use of sensitivity/tolerance based biotic indices to infer the Ecological Quality status (EcoQs) of benthic habitats. Our results showed: (1) a significant effect of the reference database on derived sensitivity/tolerance measure (ES500.05) as well as associated Benthic Quality Index values and derived EcoQs; (2) a lack of correlation neither between BQI and AZTI Marine Biotic Index values nor between BQI and Multivariate-AZTI Marine Biotic Index values; (3) a lack of correlation between the values of the Benthic Habitat Quality Index (index derived from Sediment Profile Imagery) and those of either of the 3 tested biotic indices; and (4) a general agreement between the 3 tested biotic indices in describing the lack of global trend for the EcoQs of the Gulf of Lions despite the occurrence of significant changes in benthic macrofauna composition between 1998 and 2010.

Performance evaluation and validation of ecological indices toward site-specific application for varying benthic conditions in Korean coasts

Although several ecological indices have been developed worldwide to assess the ecological quality (EcoQ) status of coastal environments, their applicability remains in question. The present study evaluated the performance of 14 univariate and multivariate indices selected to provide a good description of benthic EcoQ status. We specifically investigated on i) spatial and regional variability, ii) (dis)similarity between ecological indices, and iii) the association of selected indices against heavy metal pollution. Benthic community data were collected from six coastal regions of Korea (n=365) that have varying land-use activity in adjacent inland areas (municipal, industrial, and rural). Abiotic sedimentary parameters were also considered as possible pressures associated with benthic community responses, including grain size, organic carbon content, and heavy metal pollution. The macrozoobenthic biodiversity and EcoQ results generally well reflected the geographical settings and the pollution gradient of heavy metals between regions. Among the six selected indices (H', AMBI, BPI, BQI, EQR, and M-AMBI), BPI appeared to be the most tolerant index, with >90% of locations being classified as "High" to "Good" while EQR showed the clear classification across the EcoQ status range. Significant disagreement between BQI vs. AMBI, BPI vs. M-AMBI, and AMBI vs. M-AMBI were found. Overall, single or limited indices seemed to over- or underestimate the given benthic conditions, warranting the use of site-specific indices at specific areas and/or locations. In conclusion, our study demonstrates the utility of applying different ecological or multivariate indices to infer the general ecological status of specific sites to gauge the extent of sedimentary pollution.

One Step forward: Benthic Pelagic Coupling and Indicators for Environmental Status

A large data set from the Eastern Mediterranean was analyzed to explore the relationship between seawater column variables and benthic community status. Our results showed a strong quantitative link between the seawater column variables (Chlorophyll a and Eutrophication Index) and various indicators describing benthic diversity and community composition. The percentage of benthic opportunistic species increased significantly in the stations with high trophic status of the seawater column and so did the strength of the coupling between values of seawater column and benthic indicators. The Eutrophication Index threshold level of 0.85, separating the “Bad and Poor” from “Moderate to High” conditions could serve as an acceptable critical value above which there is a readily observable change in benthic community composition.

Calculation of species sensitivity values and their precision in marine benthic faunal quality indices

A challenging aspect of benthic quality indices used for assessing the marine environment has been to compile reliable measures of the species' sensitivity to disturbances. Sensitivity values and their uncertainties can be calculated, but a problem to cope with is that the results may depend on the actual proportion of samples from disturbed and undisturbed environments. Here we calculated sensitivity values for each species along an artificial disturbance gradient created by bootstrapping varying numbers of samples from disturbed and undisturbed environments. The values were increasing, decreasing, or more or less constant along this gradient. The lowest value with the lowest uncertainty was adopted as the species sensitivity value. Analyses of the uncertainties indicated that the accuracy rather than the precision might be a concern. We suggest a method to exclude species for which the uncertainty is outside predefined limits as a precaution to reduce bias in the environmental status classification.

Objective classification of ecological status in marine water bodies using ecotoxicological information and multivariate analysis

Some relevant shortcomings have been identified in the current approach for the classification of ecological status in marine water bodies, leading to delays in the fulfillment of the Water Framework Directive objectives. Natural variability makes difficult to settle fixed reference values and boundary values for the Ecological Quality Ratios (EQR) for the biological quality elements. Biological responses to environmental degradation are frequently of nonmonotonic nature, hampering the EQR approach. Community structure traits respond only once ecological damage has already been done and do not provide early warning signals. An alternative methodology for the classification of ecological status integrating chemical measurements, ecotoxicological bioassays and community structure traits (species richness and diversity), and using multivariate analyses (multidimensional scaling and cluster analysis), is proposed. This approach does not depend on the arbitrary definition of fixed reference values and EQR boundary values, and it is suitable to integrate nonlinear, sensitive signals of ecological degradation. As a disadvantage, this approach demands the inclusion of sampling sites representing the full range of ecological status in each monitoring campaign. National or international agencies in charge of coastal pollution monitoring have comprehensive data sets available to overcome this limitation.

Offshore platforms: comparison of five benthic indicators for assessing the macrozoobenthic stress levels

Within the European Water Framework Directive, many studies have been conducted to evaluate the sensitivity/robustness of a variety of indices in relation to natural or anthropogenic disturbance events. However, these indices have rarely been applied to verify the impacts of disturbances in offshore environments, though the Marine Strategy Framework Directive recommends their use for assessing benthic community conditions and functionality. The aim of this paper was to determine which biotic indicator performed the best for detecting the impacts of offshore structures on benthic populations in the Adriatic Sea. The impacts of four rigs were investigated six months after their installation, and the H', AMBI, m-AMBI, BENTIX, and BOPA indices were assessed. Although these five indices delivered some contradictory results because of the differences in their structure and discrepancies in their assignment of species sensitivity, the BENTIX, H' and BOPA indices appear to evaluate stress levels better than the AMBI and m-AMBI indices, which tend to provide results that are slightly overly optimistic.

Seagrass burial by dredged sediments: benthic community alteration, secondary production loss, biotic index reaction and recovery possibility

In 2005, dredging activities in Arcachon Bay (France) led in burying 320,000 m(2) of Zostera noltii intertidal seagrass. Recovery by macrobenthos and seagrass was monitored. Six months after works, seagrass was absent and macrobenthos drastically different from surrounding vegetated stations. Rapidly and due to sediment dispersal, disposal area was divided into a sandflat with a specific benthic community which maintained its difference until the end of the survey (2010), and a mudflat where associated fauna became similar to those in adjacent seagrass. Macrobenthic community needs 3 years to recover while seagrass needs 5 years to recover in the station impacted by mud. The secondary production loss due to works was low. In this naturally carbon enriched system, univariate biotic indices did not perform well to detect seagrass destruction and recovery. Multivariate index MISS gave more relevant conclusions and a simplified version was tested with success, at this local scale.

Macrobenthic community for assessment of estuarine health in tropical areas (Northeast, Brazil): review of macrofauna classification in ecological groups and application of AZTI Marine Biotic Index

The aim of the present study was to investigate the ecological quality of tropical estuaries on the northeastern coast of Brazil using the AMBI. Macrofauna classification based on ecological groups was reviewed using the Indicator Value (IndVal) coefficient. The results indicate that the ecosystems exhibit some level of disturbance. Most sites are situated between slightly-moderately disturbed boundaries due to the higher proportion of Nematoda (assigned here as Ecological Group I) and of Oligochaeta and Tubificidae (both classified as Ecological Group V). The AMBI proved efficient in evaluating environmental status, although the applicability of this index requires adjustments regarding some species in ecological groups. The present study also highlights the merits of the IndVal method for examining the assignments of species/taxa to an ecological group and demonstrates the validity of this coefficient is an assessment tool. Moreover, the complementary use of different methods is recommended for the assessment of ecosystem quality.

Critical appraisal on the identification of Reference Conditions for the evaluation of ecological quality status along the Emilia-Romagna coast (Italy) using M-AMBI

According to the European Water Framework Directive, the ecological status (ES) of a water body is determined by comparing observation data with undisturbed Reference Conditions (RCs). Defining RCs is crucial when evaluating the ES of a water body as it strongly affects the final outcome of any index application. Identifying RCs by observing real sites is not feasible in many marine environments, such as the Emilia-Romagna coast (Italy, N-Adriatic Sea). We used a statistical approach on a large dataset to derive RCs for the application of the benthic index M-AMBI in this area. We then applied M-AMBI to samples collected along a gradient of presumed environmental disturbance. The results put 14.8% of the Emilia-Romagna samples in "High" ES, 60.2% in "Good", 23.0% in "Moderate" and 2.0% in "Poor", showing a spatial gradient of improving quality. These results are in agreement with the extensive ecological knowledge available for this area.

Ecological Quality Status of the soft-bottom communities on the Algerian coast: general patterns and diagnosis

Between 1995 and 2001, the soft-bottom communities along the 1180 km of the Algerian coast were sampled in nine gulfs and 12 harbours, providing a total of 655 samples. Eight macrozoobenthos-based biotic indices (S, N, H', BQI, AMBI, BENTIX, BO2A and ITI) were selected to describe the general patterns of the coastal water quality status and to establish a quality diagnosis for the different zones subjected to anthropogenic pressure (e.g., harbour construction, industrial and urban pollution). Reference values were determined for each of the eight indices selected by analyzing the indices' parameter distribution. The Ecological Quality Ratio (EQR) was estimated for each index, resulting in an EQR Mean Score and an EQR Bad Score. From these EQR, we defined an EQS for each sample. The agreement between these EQS was analysed using the Kappa method in order to propose a survey strategy for the Algerian coastal waters that would take into account the soft-bottom biological compartment. The results clearly indicate that high and good quality assessments are prevalent in the gulfs, while quality assessments in harbours vary greatly from bad to good. The effect of pollution observed in the harbours can be classified in two main groups, according to when they were constructed and their relative degree of openness to the sea, which permits better water circulation and probably dilutes the pollution.

Environmental quality of Korean coasts as determined by modified Shannon-Wiener evenness proportion

The coast of the Korean peninsula experiences a range of human impacts, including pollution, shipping, reclamation, and aquaculture, that have motivated numerous local studies of macrobenthic organisms. In this paper, 1,492 subtidal stations were compiled from 23 studies (areas) to evaluate environmental quality on a broader scale. A common index in biomonitoring, Shannon-Wiener evenness proportion (SEP), could not incorporate azoic or single-species samples. This shortcoming was overcome by developing an inverse function of SEP (ISEP), which was positively correlated with independent measures of water quality available for nine sites and was not biased by the size of the sampling unit. Additionally, at Shihwa Dike, where samples were collected before and after reinstating a tidal connection with the ocean, ISEP values improved over time, as expected. Thus, it is now possible to assign Korean subtidal sites to seven ISEP "grades" and to use their values and trends to guide coastal management.

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.

Effects of fish farming on the biological and geochemical properties of muddy and sandy sediments in the Mediterranean Sea

The aim of this paper was to test how benthic fauna and biogeochemical properties of sediment will vary in response to similar levels of organic enrichment (induced by fish farming) as a function of bottom-habitat type (i.e., mud versus seagrass/coarse sediments), distance from the enrichment source and depth. Our results showed that samples from silty sediments in the vicinity of fish farms have higher TOC and TON values, higher oxygen consumption, higher PO(4) release and lower benthic diversity. In this context muddy sites are more likely to be identified as impacted/critical, than coarse sediment ones.

An insight into the performance of benthic classification indices tested in Eastern Mediterranean coastal waters

This work evaluates four indices that have been used for benthic macroinvertebrate ecological quality classification in the Mediterranean Sea. Our study was based on the data obtained from the participation of Greece and Cyprus in the Mediterranean Geographical Intercalibration group. The indices AMBI, M-AMBI, MEDOCC and BENTIX were applied to the available benthic species data, and the succession of the ecological groups along the graded values of each index was plotted. The level of agreement among methods was calculated, and the performance of each method in estimating ecological quality status was evaluated. AMBI, based on the Atlantic model, and its derivative M-AMBI overestimated the statuses, while MEDOCC showed the best level of agreement with BENTIX. BENTIX gives equal weight to tolerant and opportunistic species groups, which correlates them more closely than the other indices and makes BENTIX the most sensitive in detecting ecological disturbances in the Eastern Mediterranean basin, where tolerant and opportunistic groups seem to play an equally important role in the response of benthic communities to stressors.

Ecological quality assessment of the lower Lima Estuary

Monitoring biotic factors is gaining in importance within Europe, due in large extent to the ecological approach of the European Water Framework Directive (WFD) and the importance attributed to biological elements in the assessment of quality status. Despite its ecological importance, the Lima Estuary is subjected to a range of perturbations, including urban, agricultural and industrial waste discharge, dredging activities, and introduction of non-indigenous invasive species. This work uses macrozoobenthic data to study the ecological status of the lower Lima Estuary where most disturbance factors are concentrated. We were able to verify consistent differences along space, and to identify different degrees of disturbance in the estuarine area. These results allow us to suggest cost-effective approaches to monitor this estuarine area, aiming on contributing to effective management actions.

Performance of some biotic indices in the real variable world: a case study at different spatial scales in North-Western Mediterranean Sea

The aim of this study was to analyse the variability of four different benthic biotic indices (AMBI, BENTIX, H', M-AMBI) in two marine coastal areas of the North-Western Mediterranean Sea. In each coastal area, 36 replicates were randomly selected according to a hierarchical sampling design, which allowed estimating the variance components of the indices associated with four different spatial scales (ranging from metres to kilometres). All the analyses were performed at two different sampling periods in order to evaluate if the observed trends were consistent over the time. The variance components of the four indices revealed complex trends and different patterns in the two sampling periods. These results highlighted that independently from the employed index, a rigorous and appropriate sampling design taking into account different scales should always be used in order to avoid erroneous classifications and to develop effective monitoring programs.

Influence of macrofauna long-term natural variability on benthic indices used in ecological quality assessment

An essential prerequisite for the assessment of the ecological quality of marine ecosystems is the understanding of the natural variability and its effect on the performance of quality indices. This study is focused on the long-term natural variability of diversity, biotic and multimetric indices by using long-term macrofauna data of a coastal area in the southern North Sea (1978-2005). The univariate and most biotic and multimetric indices respond significantly on specific natural disturbance events such as cold winters, but the strength of response varied between indices as well as between events. As a result, the ecological quality status can decrease over a range of 3 (out of 5) classification units. The overall ecological quality was good to high, but an increase of indices occurred from the mid 1980s onwards due to changes in the climate regime. This long-term variability has to be considered within ecological quality assessment schemes.

Quality assessment of benthic macroinvertebrates under the scope of WFD using BAT, the Benthic Assessment Tool

Assessing the health of ecosystems has become a focal point among researchers worldwide. Recently, the European Water Framework Directive intensified the development of approaches to assess ecosystems' ecological quality. The Benthic Assessment Tool (BAT) is a multimetric approach to evaluate condition of subtidal soft bottom macroinvertebrates of coastal and transitional waters. The effects of anthropogenic disturbances on benthic macroinvertebrate communities, from 1990 to 2006, allowed testing BAT performance in Mondego estuary (Portugal). The method was able to detect decrease on ecological quality, induced essentially by eutrophication and physical disturbances, and follow communities' subsequent recovery. It evidenced, nevertheless, some limitations associated with the unstable nature of estuaries. The ecological classification of key species in the community and the balance expected between ecological groups of estuarine communities had great influence in the final ecological assessment. Shortcomings of the method were discussed in the light of its suitability for assessing transitional waters' condition.

Monitoring strategies for re-establishment of ecological reference conditions: possibilities and limitations

The ecological status of an environment should be evaluated by comparison with local "reference conditions", here defined as the pre-industrial ecological status of the 19th century. This pilot study illustrates how micropalaeontological monitoring, using benthic foraminifera (protists) and associated geochemical parameters preserved in inner Oslofjord (Norway) sediments, characterise local reference conditions. In order to optimise the usefulness of the ecological information held by foraminifera and enable characterisation of temporal changes in environmental quality beyond time intervals covered by biological time-series, the Norwegian governmental macrofauna-based classification system is applied on fossil benthic foraminiferal assemblages. Quantitative comparisons demonstrate deteriorating ecological status in response to increased anthropogenic forcing (eutrophication, micropollutants), including a 73% loss in number of foraminiferal species. Despite reduced pollution during the past decades and, at one site, capping of polluted sediments with clean clay, the reference conditions are far from re-established. Micropalaeontological monitoring requires net sediment accumulation basins and careful considerations of taphonomic processes.

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.

An adjustment of benthic ecological quality assessment to effects of salinity

In the last decade a politically inspired marine protection movement arose in the European Union. This movement leads to an holistic strategy. Merging the Water Framework Directive (WFD) and the Marine Strategy Directive (MSD) along the European coastline demands sophisticated ecological classification procedures. The 'Benthic Quality Index' (BQI) is one of several indices created in view of the WFD. We used the dynamic species reference system ES(50)(0.05) to test the capability of BQI to exclude primary environmental factors including the salinity gradient and depth (a proxy for the oxygen regime) from the ecological quality (EcoQ) assessment. A macrozoobenthos dataset of the southern Baltic Sea spreading over more than 20 years and over 100,000 km2 was used for the EcoQ assessment. Quality assurance rules were applied to the record set and an analytical dataset of 936 sampling events with 20,451 abundance records was used in the analysis. We show that the natural salinity gradient has a severe impact on the BQI based EcoQ. We adapted the calculation procedure to reduce the salinity effects to a minimum. According to the adaptation 503 sensitivity/tolerance values for 87 species were computed. These values were calculated within seven salinity ranges from 0 to >30 PSU and two depth zones. These values can be used as a reference for further investigation in the Baltic and other areas with similar environmental conditions.

The robustness of ecological indicators to detect long-term changes in the macrobenthos of estuarine systems

Accurate and reliable benthic quality indicators are in great demand following the recent developments and the strict time schedule for implementing the European Water Framework Directive. The Mondego estuary has experienced a progressive deterioration during the 1990s, followed by a partial ecological recovery due to restoration measures in 1997/1998. We have used the estuary as a model system to test the performance and robustness of a set of ecological indicators in highlighting the changes in the ecological state of intertidal areas. Over a period of 17 years (1985-2002), we calculated Margalef, Shannon-Wiener, Berger-Parker, Taxonomic Distinctness measures, AZTI's Marine Biotic Index, Infaunal Trophic Index, and Eco-Exergy based indices and tested differences across periods characterised by different anthropogenic disturbance. We combined temporal data within three periods: before, during and after disturbance, based on progressive information on the changes in the extended type of anthropogenic disturbance. Indices were then compared with biological and abiotic descriptors (macroalgae, macrophytes, benthic macrofauna, nutrients concentration, sediment grain size and total organic carbon). We found great disparity in the indicators ability to capture temporal changes, showing distinct performances at each site. At the Zostera noltii site, only Margalef, Total Taxonomic Distinctness and the thermodynamically based indices captured temporal changes, despite giving higher values during the disturbance period. At the bare sediment site, Taxonomic Distinctness, ITI, Shannon-Wiener, Berger-Parker, AMBI and the TBI were able to distinguish between periods, in agreement with the differences observed analysing the macrobenthic assemblages. Furthermore, Taxonomic Distinctness was not robust enough to detect any temporal or spatial change. We thus suggest further research to understand the behaviour of ecological indicators, in view of their crucial importance for the management and protection of marine coastal areas.

Calibration and evaluation of five indicators of benthic community condition in two California bay and estuary habitats

Many types of indices have been developed to assess benthic invertebrate community condition, but there have been few studies evaluating the relative performance of different index approaches. Here we calibrate and compare the performance of five indices: the Benthic Response Index (BRI), Benthic Quality Index (BQI), Relative Benthic Index (RBI), River Invertebrate Prediction and Classification System (RIVPACS), and the Index of Biotic Integrity (IBI). We also examine whether index performance improves when the different indices, which rely on measurement of different properties, are used in combination. The five indices were calibrated for two geographies using 238 samples from southern California marine bays and 125 samples from polyhaline San Francisco Bay. Index performance was evaluated by comparing index assessments of 35 sites to the best professional judgment of nine benthic experts. None of the individual indices performed as well as the average expert in ranking sample condition or evaluating whether benthic assemblages exhibited evidence of disturbance. However, several index combinations outperformed the average expert. When results from both habitats were combined, two four-index combinations and a three-index combination performed best. However, performance differences among several combinations were small enough that factors such as logistics can also become a consideration in index selection.

Assessing ecological integrity in marine waters, using multiple indices and ecosystem components: challenges for the future

During the last decade, there have been substantial scientific advances in the development of indices that measure the condition of biological ecosystem elements in coastal and estuarine waters. Though successful, these advances were only the initial steps and a special session on use of indices in ecological integrity assessments was held at the Coastal and Estuarine Research Federation meeting to focus the field on the most appropriate directions for the next decade. The session identified four primary scientific challenges: (i) reduce the array of indices by identifying the index approaches that are most widely successful; (ii) establish minimum criteria for index validation; (iii) intercalibrate methods to achieve uniform assessment scales across geographies and habitats; and (iv) integrate indices across ecosystem elements. Where an explosion of indices characterized the last decade, the next decade needs to be characterized by consolidation. With increased knowledge and understanding about the strengths and weaknesses of competing index approaches, the field needs to unify approaches that provide managers with the simple answers they need to use ecological condition information effectively and efficiently.

Is it possible to assess the ecological status of highly stressed natural estuarine environments using macroinvertebrates indices?

Several biotic indices have been proposed for the assessment of the ecological status of benthic macroinvertebrates in marine waters, although none have been generally accepted. When it comes to assessing highly stressed natural environments, such as estuaries, the controversy and uncertainty is much higher than for any given normal index. In this article, we test the behavior and suitability of different biotic indices proposed under the perspective of the Water Framework Directive (S, H, AMBI, M-AMBI, BQI, W-statistic, Taxonomic distinctness) for the assessment of estuaries in northern Spain. The low species richness and dominance of a few tolerant species in the characteristic community of these estuaries presented a challenge to the application of the biotic indices tested. Combined approaches that integrate different aspects of water quality and ecosystem functionality could increase the reliability of the ecological assessment of these transitional waters.

Influence of oyster culture practices and environmental conditions on the ecological status of intertidal mudflats in the Pertuis Charentais (SW France): a multi-index approach

The ecological quality status (EcoQ) of intertidal mudflats constrained by Pacific oyster farming was assessed by single (H', AMBI, BENTIX and BOPA) and multimetric (M-AMBI and average score) index approaches in the Pertuis Charentais (SW France). Fifteen sampling stations were monitored seasonally for sedimentological features and macrozoobenthos in 2004. Sediments affected by oyster biodeposits showed organic matter enrichment, and sediments from off-bottom culture sites had higher organic matter contents and lower redox potentials than sediments from on-bottom culture sites. Biotic indices consistently registered responses of macrozoobenthos to organic enrichment but there was only partial agreement between single index-derived EcoQs. The average score was better than M-AMBI and single indices for determining EcoQs. Accordingly, oyster farming alters intertidal macrozoobenthic assemblages moderately, and off-bottom cultures cause more disturbance than on-bottom cultures. Hydrodynamics and seasons may interact with culture practices in smothering/strengthening biodeposition-mediated effects through dispersal/accumulation of biodeposits.

Use of multimetric indices to classify estuaries with different hydromorphological characteristics and different levels of human pressure

The assessment of estuaries based on benthic communities is widely used to determine impacts caused by human pressure and is one of the required tools for the implementation of the European Water Framework Directive (WFD). Our study compared multimetric approaches (B-IBI and TICOR) to assess the benthic condition of three Portuguese estuaries (Mondego, Tejo, and Mira rivers) with different levels of natural and human induced stress. Benthic community condition was classified into quality status categories of the WFD and compared for consistency with a priori status categories based upon physical-chemical criteria. Both multimetric indices discriminated equally well between locations classified above or below the good status category but were unable to provide good separation between other quality classes (high/good, moderate, poor/bad). Metrics included in these indices are greatly affected by natural stress and we recommend the development of habitat-specific thresholds to increase the discriminatory ability of any benthic condition index.

Assessment of the ecological quality status of soft-bottoms in Reunion Island (tropical Southwest Indian Ocean) using AZTI marine biotic indices

The ability of the two synthetic marine biotic indices, AMBI and M-AMBI, to account for changes in the ecological quality of coastal soft bottoms of Reunion Island according to disturbances was assessed from macrobenthic samples collected in five sectors between 1994 and 2004. Samples were collected under non-perturbed conditions and at two sites subjected to heavy organic enrichment. Both indices are based on a classification of macrofauna into ecological groups (EG), and their transfer to tropical waters required some adaptations. These indices proved efficient in detecting a degradation of habitat quality. Their use resulted in the classification of all sites sampled between 1996 and 1998 as "good" or "high". M-AMBI nevertheless tended to result in the attribution of a slightly worse ecological quality status than AMBI. Together with an update of the EG species list for the Indian Ocean area, our results support the extension of both indices for the assessment of tropical soft bottoms.

An intercalibration of classification metrics of benthic macroinvertebrates in coastal and transitional ecosystems of the Eastern Mediterranean ecoregion (Greece)

Three coastal and three lagoonal sites located in Greece (Eastern Mediterranean) were selected to test and intercalibrate classification methods developed for benthic invertebrates ecological quality assessments. These methods were developed for the purposes of the European Water Framework Directive which is a European legislation adopted for the protection and improvement of the coastal and transitional waters. However, through testing these methods, this work addresses in general the issue of determining and comparing the ecological status of the coastal and transitional macrobenthic communities in Eastern Mediterranean ecosystems. Among methods tested were the biotic indices AMBI and BENTIX, the multivariate method M-AMBI and the biomass size structure index ISD in lagoonal sites only. ISD index is a rather new method developed especially for transitional ecosystems and in this contribution its performance is intercalibrated with the other benthic classification metrics. Comparison and intercalibration of the indices results in assessing the ecological quality status (EQS) are presented graphically and statistically performing the Kappa analysis. Results of the comparison and the indices' performance are evaluated based on the knowledge of the sites' environmental condition and baseline studies. Based on an extended dataset of coastal and transitional ecosystems benthic invertebrates, an evaluation of each index performance and effectiveness is attempted through an insight and comparative analysis of each methods' structure and design. Results showed that in these Eastern Mediterranean coastal sites the BENTIX index seems to give a more biologically relevant classification and gives a higher confidence level regarding the classification compared to the other indices. In the coastal areas AMBI showed a tendency for the "good" class classification, while the factorial M-AMBI gave more consistent results with the BENTIX. In the lagoonal sites the biotic indices tested were not proved efficient enough and the biomass based ISD index proved more appropriate for these ecosystems. AMBI showed the highest agreement with the ISD which is due to the better performance of this index in the slightly and moderately polluted lagoons, compared to the other indices. However, AMBI failed to classify the polluted lagoon, in which case the BENTIX gave a more relevant classification.

Evaluation of the applicability of a fuzzy index of ecosystem integrity (FINE) to characterize the status of Tyrrhenian lagoons

The new index FINE, a multimetric, fuzzy-based index for the evaluation of environmental quality for Mediterranean transitional waters, was calculated using biotic data gathered between 2000 and 2006 at 15 stations in 4 Tyrrhenian transitional water ecosystems (Orbetello Lagoon, Padrongiano Delta, Stagno di S. Teodoro, and Stagno di Tortolì), i.e. in a different biogeographic sub-province respect to the one in which the index was developed and validated. The rationale of FINE is that certain attributes, selected on the basis of established principles of benthic ecology, are fundamental for lagoon ecosystem function. A set of other indices (Simpson's 1-lambda', the W-statistics, AMBI, and BOPA) was also calculated and compared to FINE outputs. FINE, 1-lambda', and the W-statistics were significantly correlated with sedimentary organic matter content. Some stations were unequivocally assigned to the same ecological status, independently from the index used; for others, some discrepancies were evident. Mediterranean transitional waters probably share ecosystem complexities which are not yet fully captured by indices developed and validated elsewhere.

Performance comparison of two biotic indices measuring the ecological status of water bodies in the Southern Baltic and Gulf of Lions

Two biotic indices, ATZI Marine Biotic Index (AMBI) and Benthic Quality Index (BQI) have been recently introduced within the EC Water Framework Directive to assess the quality of marine habitats: both are based on sensitivity/tolerance classification and quantitative information on the composition of soft-bottom macrofauna. Their performance, especially with regard to sampling effort was assessed based on two data sets collected in Southern Baltic and one from the Gulf of Lions Mediterranean. AMBI was not affected by sampling effort but BQI was. Two modifications were proposed for BQI (i.e., BQI) (1) the removal of the scaling term (i.e., BQI(W)), and (2) the replacement of the scaling term by different scaling term (i.e., BQI(ES)). Both modified BQIs were largely independent of sampling effort. Variability was slightly lower for BQI(W) than for BQI(ES). BQI was highly correlated with BQI(W) and with BQI(ES) both in the Southern Baltic and in the Gulf of Lions. However, the proportions of stations, which were not attributed the same ecological quality status (EcoQ) when using BQI and its two modified forms were always high. Differences in ecological classification were mostly due to the scales used to infer EcoQ. Based on this study we recommend to use BQI(ES) in future studies because it apparently constitutes the best compromise in (1) being independent of sampling effort, (2) limiting the variability in computation in relation with sampling effort, (3) being correlated with BQI and corresponding EcoQ.

Application of biotic indices and relationship with structural and functional features of macrobenthic community in the lagoon of Venice: an example over a long time series of data

In the context of the application of WFD, a scientific debate is growing about the applicability of biotic indices in coastal and transitional waters. In the present work, the question about the discriminating power of different biotic indices and the relationships with the structure and functioning of the macrobenthic community in a transitional environment is discussed. A time series of samples collected during the last 70 years in the lagoon of Venice, reflecting different environmental conditions (a sort of 'pristine state' in 1935, the distrophic crisis in 1988 and subsequent modifications in 1990, the invasion by an alien species and the developing of high impacting fishery in 1999) has been used. The comparison of results obtained by applying different biotic indices, such as AMBI, Bentix and BOPA, shows differences in the discriminating power of indices and a general overestimation of environmental conditions. Discrepancies between environmental status as indicated by biotic indices and the structure and functioning of the benthic community have been highlighted.

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.

Benthic biodiversity indices versus salinity gradient in the southern Baltic Sea

The need to assess the environmental status of marine and coastal waters according to the EU Water Framework Directive (WFD) encouraged the design of specific biotic indices to evaluate the response of benthic communities to human-induced changes in water quality. In the present study three of these indices, the traditional Shannon Wiener Index (H') and the more recently published AMBI (AZTI' Marine Biotic Index) and BQI (Benthic Quality Index), were tested along a salinity gradient in the southern Baltic Sea. The comparison of the three indices demonstrates that in the southern Baltic Sea the ecological quality (EcoQ) classification based on macrozoobenthic communities as indicator greatly depends on the biotic index chosen. We found a significant positive relation between species number, H', BQI and salinity resulting in EcoQ status of "Bad", "Poor" or "Moderate" in areas with a salinity value below 10 psu. The AMBI was less dependent on salinity but appear to partly overestimate the EcoQ status. Presently none of these biotic indices appear to be adjusted for application in a gradient system as given in the southern Baltic Sea. A potential approach describing how to overcome this limitation is discussed.

Ecological status in the Ligurian Sea: the effect of coastline urbanisation and the importance of proper reference sites

The assessment of the ecological status, as required by the Water Framework Directive (WFD), plays an important role in coastal zone management, but only a small number of ecological indices are applicable on rocky bottoms. In this study, we apply a previously defined ecological quality index based on the cartography of littoral and upper-sublittoral rocky-shore communities (CARLIT), based on the sensitivity of algae dominated communities to anthropogenic impacts along a moderate urban gradient. We also apply this index in four Marine Protected Areas (MPAs), proposed as reference sites at a regional scale. After comparing the outputs with water variables and other quality indices, we can affirm that (1) the CARLIT index is suitable to detect different kinds of anthropogenic pressures, that (2) the choice of proper reference sites is a focal point in the fulfilment of the WFD (Water Framework Directive) and that (3) historical data are important to define reference conditions and the degradation of ecological status.

Paradox of estuarine quality: benthic indicators and indices, consensus or debate for the future

The European Water Framework Directive will have instituted the concept of Ecological Quality Status (EQS) as a way to assess the biological quality of water masses. The EQS will be based mainly upon the composition of the different biological compartments in the ecosystem specially the benthos as compared to certain reference sites. Such management tools are already well established for freshwater (i.e. biotic indices), but not for coastal and estuarine (i.e. transitional) waters. In the framework of the Seine-Aval programme a workshop on benthic indicators was organized at Wimereux (France) in June 2005. The aim of this workshop and this paper is (1) to present the experiences of the Seine Aval researchers, and the French scientific approaches to benthic indicators, with those international experiences and approaches that have been published or are under development; and (2) to examine the existing benthic tools and their possible use in the characterization of the state of estuarine ecosystems. The debate during the workshop and the numerous recently published on the WFD are discussed in term of the implementation of the WFD in transitional water bodies using benthic indicators and indices. Some proposals for the future underline the needs to re-examine and adapt the different index thresholds, to take into account physical disturbances, to inventory the existing conditions vs reference conditions and to be as pragmatic as possible in using the WFD in transitional 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.

The ecological quality status of the Bay of Seine and the Seine estuary: use of biotic indices

Using recent indices developed, in part, for use under the European Water Framework Directive (AMBI, BENTIX, BOPA, BQI, I2EC and the trophic index ITI), the ecological quality status of two highly contaminated environments--the Bay of Seine and the Seine estuary (Eastern English Channel)--was determined on several spatial and temporal scales. Data from 604 observations gathered over a 14-year period (1988-2002) were analyzed, and the results used to show the relationship between biotic indices, environmental variables and classic descriptors (e.g., number of species, total abundance, dominance index, ES(50) and Shannon/Brillouin diversities). Though the specific ecological quality (EcoQ) values calculated with the various indices were different, the overall trend of the results was similar. Synthesizing the values produced by the six indices used in the study allowed attribution of a high to good EcoQ status to the Bay of Seine and a moderate EcoQ to the estuary. The mesh size used when processing samples was proved to have no effect in winter on the EcoQ values for either body of water.

The use of the marine biotic index AMBI in the assessment of the ecological status of the Obidos lagoon (Portugal)

This study reports the longitudinal distribution of sediment properties, including inorganic and organic contaminants, and the structure of the benthic community in Obidos lagoon, a coastal system permanently connected to the sea and with negligible freshwater sources. Sediments from the upper to central lagoon consist of fine particles (91%) and from the lower lagoon of sands (94%). Chemical composition is strongly correlated to the percentage of fine particles. Contamination is relatively low in those sediments suggesting the effect of diffuse sources. The increase in organic matter content from down- to upstream areas was associated with the dominance of opportunistic species, while sensitive and indifferent species to organic enrichment were mainly associated to the clean sandy downstream area. The marine biotic index (AMBI) was suitable for the discrimination of the biological and environmental gradients in the Obidos lagoon and was highly related with the gradient of organic matter content in this system.