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.
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RBINS Staff Publications 2026
The geochemical cycles of iron and sulphur in marine sediments are strongly intertwined and give rise to a complex network of redox and precipitation reactions. Bioturbation refers to all modes of transport of particles and solutes induced by larger organisms, and in the present-day seafloor, bioturbation is one of the most important factors controlling the biogeochemical cycling of iron and sulphur. To better understand how bioturbation controls Fe and S cycling, we developed reactive transport model of a coastal sediment impacted by faunal activity. Subsequently, we performed a model sensitivity analysis, separately investigating the two different transport modes of bioturbation, i.e. bio-mixing (solid particle transport) and bio-irrigation (enhanced solute transport). This analysis reveals that bio-mixing and bio-irrigation have distinct—and largely opposing effects on both the iron and sulphur cycles. Bio-mixing enhances transport between the oxic and suboxic zones, thus promoting the reduction of oxidised species (e.g. iron oxyhydroxides) and the oxidation of reduced species (e.g. iron sulphides). Through the reoxidation of iron sulphides, bio-mixing strongly enhances the recycling of Fe and S between their reduced and oxidised states. Bio-irrigation on the other hand removes reduced solutes, i.e. ferrous iron and free sulphide, from the sediment pore water. These reduced species are then reoxidised in the overlying water and not recycled within the sediment column, which leads to a decrease in Fe and S recycling. Overall, our results demonstrate that the ecology of the macrofauna (inducing bio-mixing or bio-irrigation, or both) matters when assessing their impact on sediment geochemistry. This finding seems particularly relevant for sedimentary cycling across Cambrian transition, when benthic fauna started colonizing and reworking the seafloor.
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