The temperature sensitivity of prokaryotic extracellular enzymatic activities implies expected shifts in the stoichiometry of organic matter in a warmer ocean

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainIn a context of global warming of surface marine waters, we determined the temperature sensitivity (Q10) of extracellular β-glucosidase, leucine-aminopeptidase and alkaline phosphatase activities in the euphotic layer of the Atlantic, Pacific and Indian Oceans, during the Malaspina 2010 Circumnavigation Expedition. We observed higher sensitivities in surface waters (3 m) than in DCM waters (23-170 m) for leucine-aminopeptidase and β-glucosidase activities, which suggest a gradient in the response to warming from surface towards deeper water layers. Sensitivity to temperature increased with latitude for the three activities. Remarkably, the Q10 were different for each activity being β-glucosidase activity more sensitive to temperature than leucine-aminopeptidase and alkaline phosphatase. Our data suggest that warming of the ocean surface will cause a greater increase in the hydrolysis of carbohydrates compared to that of protein and organic phosphorus materials, which would result in an increase in the C:N and C:P ratios of the products and, consequently, in an impoverishment of the nutritional quality of the organic matter accessible to the prokaryotic communityPeer Reviewe