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.

Realistic assessments of the ecological status of benthic habitats, as requested by European directives such as the Water Framework Directive and the European Marine Strategy Framework Directive, require biotic indices capable of detecting anthropogenic impact without having preliminary knowledge of the occurring pressures. In this context, a new general-purpose biotic index (GPBI) based on the deviation of benthic macrofauna community composition and structure from a valid reference (i.e., good ecological status) is proposed. GPBI is based on the assumption that as a site becomes impacted by a pressure, the most sensitive species are the first to disappear, and that stronger impacts lead to more important losses. Thus, it explicitly uses the within-species loss of individuals in the tested station in comparison to one or several reference stations as the basis of ecological status assessment. In this study, GPBI is successfully used in four case studies considering the impact of diversified pressures on benthic fauna: (1) maerl extraction in the northern Bay of Biscay, (2–3) dredging and trawling in the North Sea, and (4) hypoxic events at the seafloor in the Gullmarfjord. Our results show that GPBI was able to efficiently detect the impact of the different physical disturbances as well as that of hypoxia and that it performs better than commonly used pressure-specific indices (M-AMBI and TDI). Signal detection theory was used to propose a sound good/moderate ecological quality status boundary, and recommendations for future monitoring are also provided based on the reported performance of GPBI.

Bottom trawling affects seabed habitats, but its large‐scale impacts remain poorly quantified. Assessment of trawling impacts is essential to support monitoring and achieving sustainability objectives under international conventions, sustainable development goals, and seafood certification programs. We present a Europe‐wide quantitative assessment of bottom trawling impacts, accounting for regional seabed‐community sensitivity drivers, across the Baltic, Atlantic, Mediterranean and Black Sea continental shelves. Using two risk‐based indicators of seabed status—Relative Benthic Status determined as benthic community biomass relative to seabed fauna carrying capacity (RBS _tot ) and RBS _sen (biomass of the 10% most sensitive fauna relative to carrying capacity)—we found substantial regional and habitat differences. The Black, Baltic and Aegean‐Levantine Seas showed low trawling intensity and high seabed status across habitats. In contrast, the Western Mediterranean, Ionian and Central Mediterranean and Adriatic Seas were the most severely impacted. Trawling affected the sensitive species biomass fraction more strongly than the total community biomass. RBS _tot was in good condition (here chosen as RBS > 75% for epifauna) for over 79% of habitat‐ecoregion combinations. In contrast, RBS _sen met this threshold in only 46% of these. A strong correlation emerged between the mean trawling intensity and RBS _tot and RBS _sen , allowing the use of SAR to estimate ecosystem status. This relationship can support decisions on where, and by how much, SAR reductions are needed to achieve good environmental status in regions where no detailed assessment is available. Our approach provides a quantitative framework to balance fishery production with ecosystem sustainability, offering tools for environmental and fisheries management in Europe.

Benthic organisms are important ecological receptors, playing fundamental roles across seafloor ecosystems, delivering some of the most important functions in the marine environment. Some of these key benthic functions include nutrient cycling, food provision for higher trophic levels, and carbon storage. Over the past 6 years, benthic monitoring has faced growing complexity, driven by diminishing funding and the constraints imposed by the COVID-19 pandemic. These challenges underscore the pressing need to recognize the enduring value of benthic time series in supporting monitoring, management, and modelling efforts. These long-term data sets have been critical to advance our current understanding into the areas of cumulative effects, conservation, management of Marine Protected Areas (MPAs), development of indicators, and assessment of climate-driven changes in marine ecosystems. Ongoing expert group discussions consistently affirm both the relevance and necessity of continuing to collect these vital data sets. However, the focus on emerging technologies and so-called ‘cutting-edge’ approaches sometimes leads to the undervaluation and compromising some of these long-term series. We contend that a comprehensive understanding of benthic ecology, essential for robust marine management, reliable numerical analysis, and taxonomic consistency, cannot be achieved without the continuity provided by long-term data. Such time series are indispensable for tracking patterns of change and assessing responses across diverse human activities and seafloor ecosystems. While our research has concentrated on soft sediment environments, many of the key principles and recommendations outlined here are broadly applicable to other ecosystem types.