Aquatic sediments are ecologically diverse and important environments, which shelter and support a variety of benthic animals and plants. Active reworking and ventilation by macrobenthic communities control the physical structure and biogeochemistry of sediment by redistribution of solids (e.g. organic carbon sources), solutes (e.g. oxygen), and microorganisms. Examples vary in scale and effect, including oxygen entrainment into riverbeds by nesting salmon, rapid bioirrigation of deep burrows by benthic invertebrates, large-scale sediment remodelling by tunnelling crustaceans (bioturbation), and oxidation of metals in the rhizosphere of macrophytes. Much of our knowledge on sediment biogeochemistry, hydrodynamics and geomicrobiology is derived from studies on undisturbed sediments, yet the majority of sediments are in some way affected by the macrobenthos. We therefore aim to gather novel research that links physico-chemical and microbial properties of the sediment to its (macro)biological community. This session invites contributions describing interactions between benthic fauna and the sediment, with emphasis on sediment biogeochemistry, hydrodynamics, geomicrobiology or molecular interactions. We aim to balance research that is field-, laboratory- and computational-focussed.