Methanogens limited to lower rhizosphere and to an atypical salt marsh niche along a pristine intertidal mangrove continuum

Abstract Mangroves are valuable ecosystems that facilitate primary production, carbon sequestration, and regulation of greenhouse gas (GHG) cycles in coastal sediments, with microorganisms playing key roles. Specialized bacteria archaea compete for energy resources mangrove sediments to inhabit optimal ecological niches can produce or consume methane (CH 4 )—a potent GHG—in the process. CH cycling mangroves has gained growing attention, yet uncertainties regarding functional spatial distributions remain. Here, we demonstrate a pristine forest, concentrations methanogen communities concentrated within lower below rhizosphere depths. We also reveal atypical methanogens upper tidal salt marsh zone where vegetation is sparse highest abundances were detected at deepest depths (4715 reads g −1 ) despite relatively high redox potentials (> 250 mV). Pore water depth forest (max. 3.40 ± 0.21 μ M) coincided sediment fluxes (276.4 54.2 mol m −2 d methanotroph surface (1309 ). Sediment oxidation fractions between (60 cm) shallowest (5 estimated 18.8% 64.9%. Positive correlation crab burrows suggests from deeper be transported via conduits atmosphere. The data this study highlights importance investigating dynamics across estuarine ecosystem gradients better understand complex roles vital zones face changing climate.