Abstract

Introduction:  Methanogenic archaea (MA), participate in the anaerobic mineralization of organic matter in mangrove sediments, their activity is related to atmospheric warming due to the production of methane; several environmental variables can influence the presence of MA and methane production in these sediments.

Objective:  To analyze, through culture-dependent techniques, viable methanogenic archaea (VMA) in the sediments, and the production of methane from acetate in different climatic periods in the mangrove El Morro-La Mancha, Veracruz, Gulf of Mexico.

Methods:  From May to November 2019, following a salinity transect, sediment samples from El Morro-La Mancha mangrove were collected at three locations, in three different climatic seasons, dry (May), rainy (October) and northern (November) (N = 9). VMA in the sediments was quantified using the Most Probable Number (MPN) technique with acetate and methanol as substrates. The influence of sulfate on methane production was analyzed from acetate in microcosm by gas chromatography and the chemical variables of salinity, pH, Eh, carbohydrates, organic content, and carbonates in the sediments were evaluated.

Results:  The abundance of VMA was 10² to 10⁸ MPN/g of wet sediment, higher than that reported in other studies, this abundance was higher when methanol (10⁴-10⁸ MPN/g sediment) was used as substrate, compared to acetate (10²-10⁵ MPN/g sediment); methane production in the microcosms increased in sulfate-free conditions (29.78-929.75 nmol CH₄/month) and in the sediments of the rainy season.

Conclusion:  The influence of the chemical conditions of the mangrove sediments on the methanogenic dynamics is highlighted, determining that in the rainy season, the decrease in salinity, more electronegative Eh, and the increase in organic fractions favored the methanogenesis.

Key words: acetate; climatic season; mangrove; methanol; microcosms; viable methanogenic archaea; sulfate.