Seasonal variations of the diel carbon budget of a marine macrophytes ecosystem

Seasonal variation of the diel carbon budget of a Posidonia oceanica seagrass ecosystem was estimated in the Bay of Calvi (Corsica): the ecosystem served as a carbon sink from December to July and as a source from August to November. Comparison of these results with net primary production of the vegetation suggests that organisms associated with the seagrasses consume a quantity of oxygen, expressed as inorganic carbon, equal to about 55 % of net organic carbon production. The quantitative significance of the annual carbon sink constituted by P. oceanica seagrass beds when determined using only vegetative biomass and turnover is discussed.