Climate change's effect on coastal ecosystems is very likely to increase mortality risks of adult oyster populations in the next 20 years.
That is the finding of a new study led by the University of Nantes, the LEMAR (the Marine Environmental Science Laboratory) in Plouzané and the Cerfacs (European center for research and advanced training in scientific computing) in Toulouse (France).
Published today in the journal Environmental Research Letters, the research highlights a novel and comprehensive relationship between climate variability and historical mortality of adult oysters on the French Atlantic coast from 1993 to 2015.
The team's results show oyster mortality usually increases after warm and wet winters over Northern Europe, affected by recurrent storms embedded in large weather circulation patterns covering the whole North Atlantic basin -- known as the positive phase of the North Atlantic Oscillation (NAO).
The study's lead author is Dr Yoann Thomas, from the French National Research Institute for Sustainable Development (IRD) at LEMAR. He said: "Benthic species like oysters are keystone species in coastal ecosystems. For example, they build reef habitats, which sustain a high biodiversity, and provide tremendous food source worldwide though fishing or aquaculture activities.
"But they are very sensitive to changes in climate and water quality, because they cannot move if a location becomes inhospitable. In this sense, oyster populations are sentinels of long-term climate fluctuations and climate trends, and more broadly of the 'health' of coastal ecosystems.
"We know the NAO is one of the key drivers of ecological variations like species individual growth rate, geographical distribution, phenology and survival. We show that recurrent positive NAO episodes in winter, leading to milder temperatures along the northern European coast, have a long-lasting effect on the biological and environmental factors influencing oyster mortality.
"We also show that the cumulative mortality rate over a year significantly increases after winters dominated by positive NAO. From a practical perspective, this lagged relationship can be used for potential predictability of annual mortality at several months lead-time."
The researchers linked this climate-related risk to several environmental factors like the unlocking of the winter cold-water barrier for pathogens, the shortening of the resting phase for oyster, and enhanced metabolic rates leading to higher vulnerability in spring and summer.
Published today in the journal Environmental Research Letters, the research highlights a novel and comprehensive relationship between climate variability and historical mortality of adult oysters on the French Atlantic coast from 1993 to 2015.
The team's results show oyster mortality usually increases after warm and wet winters over Northern Europe, affected by recurrent storms embedded in large weather circulation patterns covering the whole North Atlantic basin -- known as the positive phase of the North Atlantic Oscillation (NAO).
The study's lead author is Dr Yoann Thomas, from the French National Research Institute for Sustainable Development (IRD) at LEMAR. He said: "Benthic species like oysters are keystone species in coastal ecosystems. For example, they build reef habitats, which sustain a high biodiversity, and provide tremendous food source worldwide though fishing or aquaculture activities.
"But they are very sensitive to changes in climate and water quality, because they cannot move if a location becomes inhospitable. In this sense, oyster populations are sentinels of long-term climate fluctuations and climate trends, and more broadly of the 'health' of coastal ecosystems.
"We know the NAO is one of the key drivers of ecological variations like species individual growth rate, geographical distribution, phenology and survival. We show that recurrent positive NAO episodes in winter, leading to milder temperatures along the northern European coast, have a long-lasting effect on the biological and environmental factors influencing oyster mortality.
"We also show that the cumulative mortality rate over a year significantly increases after winters dominated by positive NAO. From a practical perspective, this lagged relationship can be used for potential predictability of annual mortality at several months lead-time."
The researchers linked this climate-related risk to several environmental factors like the unlocking of the winter cold-water barrier for pathogens, the shortening of the resting phase for oyster, and enhanced metabolic rates leading to higher vulnerability in spring and summer.
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