Two research teams from the University of Liège studied the fate of the material produced by Posidonia seagrass meadows.
Two research teams from the University of Liège studied the fate of the material produced by Posidonia seagrass meadows. This study, carried out in the Mediterranean Sea at STARESO, shows that the dead leaves of what is commonly known as Neptune grass accumulate in shallow areas, where they break down like a compost, remineralising the organic matter. This has a previously underestimated effect on carbon fluxes in the Mediterranean coastal environments. Surprisingly, alongside this CO2 emission, oxygen production was also measured. This is linked to the presence of photosynthetic organisms living in this compost in the sea, which fundamentally differentiates it from compost on land.
Posidonia, a flowering plant emblematic of the Mediterranean Sea, commonly known as Neptune grass, forms vast meadows (underwater prairies) in shallow waters (less than 40m deep). “It is a terrestrial plant that recolonised the marine environment several million years ago, a small quirk of Evolution,” explains Alberto Borges, an oceanographer at ULiège. “Like most terrestrial plants in our regions, Posidonia loses its oldest leaves in autumn. These dead leaves accumulate as litter (like at the base of trees) in large patches near the seagrass meadows." It is these accumulations of dead leaves and their breakdown and transformation that interested Willy Champenois, Gilles Lepoint, and Alberto Borges, researchers in the FOCUS Research Unit (ISOTOPY Platform), who travelled to STARESO, ULiège's underwater and oceanographic research station located in Calvi, Corsica, to conduct a study on the primary production and degradation of organic matter in Posidonia litter.
Read more at University of Liège
Image: From left to right: View of the STARESO harbour entrance with Posidonia meadow islands and an accumulation of dead leaves. Close-up of litter accumulation. Experimental benthic incubation device (‘bell’) installed on accumulations of Posidonia dead leaves (10 m deep). (Credit: G.Lepoint & W. Champenois / ULiège)
