A general-purpose multivariate marine recovery index (MUMARINEX) for quantifying the influence of human activities on benthic habitat ecological status

Benthic ecosystems worldwide are increasingly exposed to multiple anthropogenic pressures. Ecological indices provide valuable tools for assessing the impacts of these activities and guiding mitigation strategies. While numerous indices have been developed, many show limitations in their applicability depending on habitat nature and pressure type. Here, we introduce the MUltivariate MArine Recovery INdEX (MUMARINEX), a new, generalist multi-metric index designed to assess benthic ecological quality. MUMARINEX is built on the assumption that ecological status can be described through the combined response of three components: preservation of species/taxonomic richness, preservation of community structure (no increase or decrease in abundances), and absence of change in opportunistic dominance. These three components are compared against a supposed unimpacted reference state. To evaluate its performance, MUMARINEX was compared with the widely used M-AMBI and two more recent and methodologically distinct indices, GPBI and EQA, using datasets from six case studies addressing distinct anthropogenic pressures: marine aggregate and carbonate sand extractions, eutrophication, experimental trawling, green tides and maerl bed exploitation. Across all case studies, MUMARINEX proved to be a simple, user-friendly (computable through an R package or a web interface), versatile, and sensitive tool capable of detecting impacts while providing insights into the ecological mechanisms underlying community changes. Its continuous scoring and explicit decomposition into complementary sub-indices make MUMARINEX a promising addition to the current toolbox for benthic monitoring. While no single index should be used alone, combining MUMARINEX with other dedicated indices offers a more robust framework for future environmental monitoring and impact assessment.