Plant-Microbe Interactions in Seagrass Meadows

Seagrass rhizospheres can form complex networks, typically deploying about half a kilometre of root and rhizome material and an active surface in excess of 1 m2 of root surface per m2 of seagrass meadow. These surfaces release oxygen and organic substrates, which, together with the enhanced sedimentary organic carbon and nutrient inputs associated with seagrass canopies, render seagrass sediments hot spots for microbial activity. Oxygen release through seagrass roots, mostly photosynthetically produced, promotes aerobic metabolism despite the enhanced microbial activities. However, reduced conditions, conducive to sulfate reduction and the accumulation of toxic metabolites, such as sulfides, may develop when photosynthetic activity is reduced or impaired. Seagrass photosynthesis affects both the activity and the metabolic pathways of the associated microbial benthic community, generating a coupling between water column conditions, notably the light environment, and microbial processes in seagrass sediments.