Will oysters be the next victims of climate change? While the Intergovernmental Panel on Climate Change (IPCC) recently sounded the alarm about the drastic consequences of climate change, especially due to the vulnerability of our planet’s species, a team of researchers from Université de Nantes, Institut de recherche pour le développement (IRD), Ifremer and CNRS have studied the mortality of oysters, the “sentinels of the sea”, on the French Atlantic coast in relation to climate variations. By analysing the IPCC’s climate scenarios, the researchers estimate that by 2035 oyster mortality risk will be equivalent to the worst episodes of mortality observed over the past 20 years.

Les huitres menacées par le chagement climatiqueThe study conducted by these French scientists and recently published in Environmental Research Letters shows that mild, wet winters dominated by atmospheric circulation patterns of the positive phase of the North Atlantic Oscillation (NAO+) generate environmental conditions leading to high adult oyster mortality throughout the following year. In winters dominated by the NAO+ regime, the increase in temperature favours pathogens, and a simultaneous increase in freshwater inflows from rivers after heavy rains weakens oyster populations.

"Marine resources are essential for humankind’s food supply. Among these resources, shellfish are of paramount social, economic and cultural importance," says Yoann Thomas, a former post-doctoral student at the Mer Molécules Santé (MMS) laboratory who is now a researcher at the Institut de recherche pour le développement (IRD). "[Oyster] production is vulnerable to anthropogenic pressures and global warming. There is an urgent need to reduce our energy consumption and greenhouse gas emissions to avoid further disruption of coastal ecosystems."