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This study assessed the ecological health of waters within the Saudi Arabian Exclusive Economic Zone, by utilizing benthic biotic indices with a marine monitoring dataset covering the years 2013 to 2018. This comprehensive evaluation covered a vast expanse, encompassing 67 distinctive sampling locations characterized by a wide range of depth and salinity gradients. The study examined spatial fluctuations in the benthic community and assessed potential correlations with environmental variables, including salinity, depth, sediment texture, total organic carbon, and other relevant factors. The macrobenthic density varied across the study sites, with an average density of 566 ± 120 ind.m−2. The Shannon diversity index ranged from 3.21 and 5.90, with an average of 4.70 ± 0.52. Based on the average AMBI values, all the locations were categorized as either slightly disturbed or undisturbed. Additionally, the M-AMBI analysis indicated that 95.5 % sites were in good or high ecological status. • Studied 67 locations in the Arabian Gulf from 2013 to 2018, varying in depth and salinity, to assess benthic community changes. • Average macrobenthic density in the Arabian Gulf from 2013 to 2018 was 566 ± 120 ind.m², with a Shannon index of 4.70 ± 0.52. • AMBI values suggest slight disturbance or undisturbed conditions observed during the study period from 2013 to 2018. • M-AMBI analysis shows 95.5% of sites in the study areas are in good or high ecological status based on data from 2013 to 2018. • Continuous benthic monitoring is crucial due to the 'Shifting Baseline' trend, ensuring effective ecosystem management. [ABSTRACT FROM AUTHOR]

Abstract Increasingly environmental management seeks to limit the impacts of human activities on ecosystems relative to some 'reference' condition, which is often the presumed pre-impacted state, however such information is limited. We explore how marine ecosystems in deep time (Late Jurassic) are characterised by AZTI's Marine Biotic Index (AMBI), and how the indices responded to natural perturbations. AMBI is widely used to detect the impacts of human disturbance and to establish management targets, and this study is the first application of these indices to a fossil fauna. Our results show AMBI detected changes in past seafloor communities (well-preserved fossil deposits) that underwent regional deoxygenation in a manner analogous to those experiencing two decades of organic pollution. These findings highlight the potential for palaeoecological data to contribute to reconstructions of pre-human marine ecosystems, and hence provide information to policy makers and regulators with greater temporal context on the nature of 'pristine' marine ecosystems. Highlights • AMBI indices detected disturbance in fossil faunas that were similar to present-day. • Natural regional deoxygenation has analogous benthic impacts to organic pollution. • Palaeoecological data can be used to understand natural ecosystem change. • Fossil data could provide temporally-integrated references of good ecological status. [ABSTRACT FROM AUTHOR]

MicrogAMBI is a bacterial community-based index, recently developed to assess the ecological status of marine systems. The easy access to High Throughput Sequencing (HTS) technologies, allowing microgAMBI the quick taxonomic identification of bacterial assemblages, providing an early warning signal to assess impacts. MicrogAMBI was developed, applied to human pressures (organic and metal pollution), and validated, in estuaries and coasts of the Basque Country (northern Spain). Here, to test the efficiency of the index, six case studies have been selected, including different substrata and environments (sediment, water column, coral, and a sludge reactor), from polar to temperate and tropical locations. The pressures include a polluted sludge reactor, underground discharges, diffuse pollution, sedimentation, sewage outfalls and eutrophication, as well as two pristine areas, in some cases with spatial and temporal gradients. To calculate the index, the new taxa list includes 693 taxa. The list, being public, will allow to achieve a consensus in the assignation of taxa to ecological groups. This would facilitate the assessment of multiple human pressures, based upon bacteria composition. The study has demonstrated that microgAMBI has the potential to work reasonably well under very different environments and pressures. The index provides a single, clear and efficient way to establish the ecological status, based upon bacteria community composition, along spatial and temporal pressure gradients. [ABSTRACT FROM AUTHOR]

We compared the performance of abundance- and biomass-based M-AMBI in the 13 major Italian lagoons, using a benthic dataset constituted by 208 sampling sites. The relative importance of ecological groups changed when using abundance or biomass, sometimes leading to an improved ecological status classification. Being biomass more ecologically relevant than abundance, the adoption of a biomass-based index may better describe the ecological status of lagoons, where the community is naturally disturbed and dominated by tolerant and opportunist species. [ABSTRACT FROM AUTHOR]

Marine benthic ecosystems are difficult to monitor and assess, which is in contrast to modern ecosystem-based management requiring detailed information at all important ecological and anthropogenic impact levels. Ecosystem management needs to ensure a sustainable exploitation of marine resources as well as the protection of sensitive habitats, taking account of potential multiple-use conflicts and impacts over large spatial scales. The urgent need for large-scale spatial data on benthic species and communities resulted in an increasing application of distribution modelling (DM). The use of DM techniques enables to employ full spatial coverage data of environmental variables to predict benthic spatial distribution patterns. Especially, statistical DMs have opened new possibilities for ecosystem management applications, since they are straightforward and the outputs are easy to interpret and communicate. Mechanistic modelling techniques, targeting the fundamental niche of species, and Bayesian belief networks are the most promising to further improve DM performance in the marine realm. There are many actual and potential management applications of DMs in the marine benthic environment, these are (i) early warning systems for species invasion and pest control, (ii) to assess distribution probabilities of species to be protected, (iii) uses in monitoring design and spatial management frameworks (e.g. MPA designations), and (iv) establishing long-term ecosystem management measures (accounting for future climate-driven changes in the ecosystem). It is important to acknowledge also the limitations associated with DM applications in a marine management context as well as considering new areas for future DM developments. The knowledge of explanatory variables, for example, setting the basis for DM, will continue to be further developed: this includes both the abiotic (natural and anthropogenic) and the more pressing biotic (e.g. species interactions) aspects of the ecosystem. While the response variables on the other hand are often focused on species presence and some work undertaken on species abundances, it is equally important to consider, e.g. biological traits or benthic ecosystem functions in DM applications. Tools such as DMs are suitable to forecast the possible effects of climate change on benthic species distribution patterns and hence could help to steer present-day ecosystem management. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Good Environmental Status (GEnS) should be reached in European marine waters by 2020. [•] A clear understanding of what is GEnS and how to reach a holistic status assessment is missing. [•] GEnS needs to be measurable and consider biotic, abiotic and socio-economic elements. [•] The available options leading to an operational definition of GEnS are proposed. [•] Approaches for integrating assessment results are discussed. [Copyright &y& Elsevier]

Seagrasses are key components of coastal marine ecosystems and many monitoring programmes worldwide assess seagrass health and apply seagrasses as indicators of environmental status. This study aims at identifying the diversity and characteristics of seagrass indicators in use within and across European ecoregions in order to provide an overview of seagrass monitoring effort in Europe. We identified 49 seagrass indicators used in 42 monitoring programmes and including a total of 51 metrics. The seagrass metrics represented 6 broad categories covering different seagrass organizational levels and spatial scales. The large diversity is particularly striking considering that the pan-European Water Framework Directive sets common demands for the presence and abundance of seagrasses and related disturbance-sensitive species. The diversity of indicators reduces the possibility to provide pan-European overviews of the status of seagrass ecosystems. The diversity can be partially justified by differences in species, differences in habitat conditions and associated communities but also seems to be determined by tradition. Within each European region, we strongly encourage the evaluation of seagrass indicator-pressure responses and quantification of the uncertainty of classification associated to the indicator in order to identify the most effective seagrass indicators for assessing ecological quality of coastal and transitional water bodies. [ABSTRACT FROM AUTHOR]

The European Water Framework and Marine Strategy Directives relate to the assessment of ecological quality, within estuarine and coastal systems. This legislation requires quality to be defined in an integrative way, using several biological elements (phytoplankton, benthos, algae, phanerogams, and fishes), together with physico-chemical elements (including pollutants). This contribution describes a methodology that integrates all of this information into a unique quality assessment for 51 stations from 18 water bodies, within the Basque Country. These water bodies are distributed into four typologies, including soft-bottom coastal areas and three types of estuaries. For each station, decision trees were used to integrate (i) water, sediment and biomonitor chemical data to achieve an integrated physico-chemical assessment and (ii) multiple biological ecosystem elements into an integrated biological assessment. Depending on the availability of ecological quality ratios or global quality values, different integration schemes were used to combine station assessments into water body assessments on a single scale. Several examples from each element have been selected, to illustrate their responses to different pressures; likewise, to establish how the assessed integrated quality has changed, over time. The results made biological and ecological sense and physico-chemical improvements were often correlated with improvements in the quality of benthos and fishes. These tools permit policy makers and managers to take decisions, based upon scientific knowledge, in water management, regarding the mitigation of human pressures and associated recovery processes. [Copyright &y& Elsevier]

Abstract: The European Marine Strategy Framework Directive (MSFD) requires European states to maintain their marine waters in ‘Good Environmental Status’. The MSFD includes 11 descriptors of “Good Environmental Status” (GES), including “Sea-floor Integrity”. This descriptor is defined as: “Sea-floor integrity is at a level that ensures that the structure and functions of the ecosystems are safeguarded and benthic ecosystems, in particular, are not adversely affected.” This contribution briefly summarizes the main conclusions of an international expert group established to review the scientific basis for making this concept operational. The experts concluded that consideration of 8 attributes of the seabed system would provide adequate information to meet requirements of the MSFD: (i) substratum, (ii) bioengineers, (iii) oxygen concentration, (iv) contaminants and hazardous substances, (v) species composition, (vi) size distribution, (vii) trophodynamics and (viii) energy flow and life history traits. The experts further concluded that “Good Environmental Status” cannot be defined exclusively as “pristine Environmental Status”, but rather status when impacts of all uses were sustainable. Uses are sustainable if two conditions are met: [•] the pressures associated with those uses do not hinder the ecosystem components to retain their natural diversity, productivity and dynamic ecological processes [•] recovery from perturbations such that the attributes lie within their range of historical natural variation must be rapid and secure. No single specific suite of indicators is proposed, both because no single set of indicators will meet the needs of all EU countries in all regional seas, and because according to the MSFD indicator selection is the prerogative of individual states. However, the need for conceptual consistency in assessing GES throughout European seas should be served if the selection of indicators and the integration of their information content in assessing GES follow the guidance in the report of the TG on Seafloor Integrity. This guidance is presented here in summary form. Informed by this report European Commission selected as indicators for the Sea-floor Integrity: (i) type, abundance, biomass and areal extent of relevant biogenic substrate; (ii) extent of the seabed significantly affected by human activities for the different substrate types; (iii) presence of particularly sensitive and/or tolerant species; (iv) multi-metric indices assessing benthic community condition and functionality, such as species diversity and richness, proportion of opportunistic to sensitive species; (v) proportion of biomass or number of individuals in the macrobenthos above some specified length/size; and (vi) parameters describing the characteristics (shape, slope and intercept) of the size spectrum of the benthic community. [Copyright &y& Elsevier]

• Multiple stressor effects depend on sample size and stressor gradient length. • Dependence on gradient length increases with increasing trophic level. • Monitoring programmes need to provide sufficient stressor gradient coverage. • The findings highlight the importance of adaptive environmental management. Multiple stressors are continuously deteriorating surface waters worldwide, posing many challenges for their conservation and restoration. Combined effect types of multiple stressors range from single-stressor dominance to complex interactions. Identifying prevalent combined effect types is critical for environmental management, as it helps to prioritise key stressors for mitigation. However, it remains unclear whether observed single and combined stressor effects reflect true ecological processes unbiased by sample size and length of stressor gradients. Therefore, we examined the role of sample size and stressor gradient lengths in 158 paired-stressor response cases with over 120,000 samples from rivers, lakes, transitional and marine ecosystems around the world. For each case, we split the overall stressor gradient into two partial gradients (lower and upper) and investigated associated changes in single and combined stressor effects. Sample size influenced the identified combined effect types, and stressor interactions were less likely for cases with fewer samples. After splitting gradients, 40 % of cases showed a change in combined effect type, 30 % no change, and 31 % showed a loss in stressor effects. These findings suggest that identified combined effect types may often be statistical artefacts rather than representing ecological processes. In 58 % of cases, we observed changes in stressor effect directions after the gradient split, suggesting unimodal stressor effects. In general, such non-linear responses were more pronounced for organisms at higher trophic levels. We conclude that observed multiple stressor effects are not solely determined by ecological processes, but also strongly depend on sampling design. Observed effects are likely to change when sample size and/or gradient length are modified. Our study highlights the need for improved monitoring programmes with sufficient sample size and stressor gradient coverage. Our findings emphasize the importance of adaptive management, as stress reduction measures or further ecosystem degradation may change multiple stressor-effect relationships, which will then require associated changes in management strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

The AZTI Marine Biotic Index (AMBI) requires less geographically-specific calibration than other benthic indices, but has not performed as well in US coastal waters as it has in the European waters for which it was originally developed. Here we examine the extent of improvement in index performance when the Ecological Group (EG) classifications on which AMBI is based are derived using local expertise. Twenty-three US benthic experts developed EG scores for each of three regions in the United States, as well as for the US as a whole. Index performance was then compared using: (1) EG scores specific to a region, (2) national EG scores, (3) national EG scores supplemented with standard international EG scores for taxa that the US experts were not able to make assignments, and (4) standard international EG scores. Performance of each scheme was evaluated by diagnosis of condition at pre-defined good/bad sites, concordance with existing local benthic indices, and independence from natural environmental gradients. The AMBI performed best when using the national EG assignments augmented with standard international EG values. The AMBI using this hybrid EG scheme performed well in differentiating apriori good and bad sites (>80% correct classification rate) and AMBI scores were both concordant and correlated ( r s = 0.4–0.7) with those of existing local indices. Nearly all of the results suggest that assigning the EG values in the framework of local biogeographic conditions produced a better-performing version of AMBI. The improved index performance, however, was tempered with apparent biases in score distribution. The AMBI, regardless of EG scheme, tended to compress ratings away from the extremes and toward the moderate condition and there was a bias with salinity, where high quality sites received increasingly poorer condition scores with decreasing salinity. [ABSTRACT FROM AUTHOR]