SEMINAR: OI Seminar Series - Nuria Marba

Núria Marbà from Department of Global Change Research IMEDEA (CSIC-UIB)

Title: Warming triggers Mediterranean seagrass (Posidonia oceanica) loss

Abstract: The Mediterranean Sea, one of the regions warming fastest under climate change, harbors lush seagrass (Posidonia oceanica) meadows that form the basis for a key ecosystem in the Mediterranean coastal area. Recent field results have shown that increased maximum annual seawater temperature in the Mediterranean for the last 10 years has already led to increased seagrass mortaliy, mortality increasing by 2% by each ºC of warming. Using this empirically-derived functional relationship between temperature and P. oceanica shoot mortality and the temporal evolution of annual maximum seawater temperature projected for the 21st century under scenario SRES A1b with a multi model ensamble we examine the future trajectories of Posidonia oceanica meadows under climate warming. We also explore the capacity to increase their resistance to climate warming by acting on local pressures to alleviate additional disturbances contributing to mortality. This study reveals that warming, even under a relatively mild scenario, will lead to the functional extinction of Posidonia meadows by the middle of this century (year 2047 ± 8.4). Efforts to alleviate local stresses adding to the loss of Posidonia meadows will have a limited effect in conserving the meadows under climate change. Efforts to mitigate climate change are urgently needed to preserve this key ecosystem.