Since the 1960s, the seagrass meadows – endemic underwater grass in the Mediterranean – have declined between 13% and 38%, which is a real environmental calamity: the oceanic Posidonia contributes to preserving water quality, protecting the coast and to counteract the effects of rising sea levels, for example. Experts believe that these benefits would have been reduced by as much as 50% in the last twenty years.
A new international study prepared by the Higher Council for Scientific Research (CSIC), the Autonomous University of Barcelona and the Oceans Institute of the University of Western Australia has focused on one of the most serious consequences derived from the decline of the marine angiosperm. “Our results indicate that there is a significant decrease in carbon sequestration and storage capacity, ” explains Núria Marbà, researcher at the Mediterranean Institute for Advanced Studies and co-author of the report. In addition, the areas where the posidonia disappears not only stop capturing C02, but can also become sources of that gas when they erode and release the carbon that the prairie had accumulated for decades or centuries.
For his part, Pere Masqué, an expert at the Autonomous University of Barcelona and co-author of the research, recalls that this loss is not irreversible : “the potential area available to carry out replanting projects is enormous.”
The study was carried out in the coastal lagoon of Oyster Harbor, in the south of Western Australia, whose posidonia population suffered a very significant reduction between the 1960s and the late 1980s. From 1994, the prairie grew again, in much of it from replanting. By dating the sediments, experts have measured the accumulation of carbon in repopulated areas and its erosion in non-recolonized areas.
