High methane production and emission from tropical seagrasses through methylotrophic methanogenesis

durch Guiyuan Dai (FB2-CH)

Mittwoch 17.09.2025, 13:15 → 14:30 Europe/Berlin

8A-002 - Hörsaal Ostufer / Lecture Hall East (GEOMAR - Standort Ostufer / GEOMAR - East Shore)

Methane (CH₄) is a potent greenhouse gas that reduces the carbon sequestration capacity of seagrass meadows. However, our understanding of CH₄ production and emission from these important carbon sinks is limited. Here we conducted biogeochemical experiments to identify methylotrophic methanogenesis as the primary methanogenesis pathway in a tropical seagrass meadow. The production rate constant was 2.2-3.9 day^-1, significantly higher than those in temperate meadows (<0.02 day^-1). The CH₄ emission rate from the meadow was 835±124 μmol m^-2 day^-1. A global meta-analysis further revealed the CH₄ emission rate in tropical seagrass meadows is approximately 8 times higher than temperate meadows. Global seagrass meadows emit 0.3 Tg CH₄ yr^-1, with over 90% from tropical meadows and resulting in an 8.6% reduction of the seagrass carbon burial on a 20-year time horizon. These findings highlight the role of tropical seagrass meadows as CH₄ sources, which can offset the benefits of seagrass carbon sequestration.