Seagrass meadows are key blue carbon (C) ecosystems, storing large amounts of organic C over centuries. Their climate benefits may be reduced by methane (CH 4 ) emissions, whose microbial and environmental descriptors in Zostera noltii meadows, dominant seagrass in North‐Western Europe, remain poorly understood. We studied CH 4 fluxes, CH 4 ‐producing and consuming microbial communities and sediment physicochemical parameters...