Cover loss in a seagrass Posidonia oceanica meadow accelerates soil organic matter turnover and alters soil prokaryotic communities

Abstract Carbon stocks in coastal vegetated ecosystems account for half of the carbon in marine sediments and soils. Disturbance in these ecosystems can release vast amounts of carbon through mineralization, depending on poorly understood factors such as soil organic matter (SOM) quality and environmental factors. The meadows of the seagrass Posidonia oceanica, the species with the larger carbon stocks, are currently under threat. The aim of this study was to determine the impact of cover loss on the SOM and microbial community composition in a P. oceanica meadow. For this purpose, soil cores were taken in dead, degraded and healthy areas in the same meadow. Cores were analyzed for total, inorganic and organic carbon and nitrogen contents, as well as for molecular SOM composition by analytical pyrolysis (