In shallow freshwater ecosystems, the functioning of the benthic compartment is driven by interactions between the physico-chemical environment and the communities of both micro- and macroorganisms. Such interactions are modulated by steep redox gradients across multiple interfaces, and the biological communities inhabiting these systems have developed specific physiological and behavioral adaptations, together with positive interactions as facilitation.
Among these communities, macrophytes play an important role in providing biogeochemical ecosystem services such as particulate matter retention, nutrient uptake, and oxygenation of water and sediments. Macrophytes stimulate microbial respiration via exudates and have adapted to anoxia via radial oxygen loss from their roots. Such adaptation results in positive feedback to aerobic and anaerobic microbial processes, coupled redox reactions and macrofauna, leading to increased nutrient recycling and reuse within the benthic system. Similarly, burrowing macrofauna provide important contributions to biogeochemical cycles by reworking and oxidizing sediments, stimulating mineralization, and promoting nutrient transformations and mobility. Bioirrigating and burrowing macrofauna can therefore be facilitated by and facilitate aquatic plants.
Biogeochemical interactions among microbes, macrophytes, and macrofauna in organic freshwater sediments were studied with manipulative experiments carried out in the light and in the dark. This study summarizes the results of such manipulative experiments and explores how multiple facilitative interactions between benthic organisms are influenced, among others, by light and by background nutrient levels and affect benthic nutrient cycling and the fluxes of greenhouse gas.