Kontribusi mangrove terhadap emisi metana global merupakan topik yang sedang diperdebatkan. Ini adalah kajian pustaka dari 154 makalah--yang diakses dari arsip daring, Web of Science– yang mendiskusikan tentang metana di ekosistem mangrove yang dikaji dari berbagai aspek. Namun demikian, hanya 35 makalah yang secara langsung melaporkan tentang volume emisi metana dari ekosistem mangrove. Selebihnya mengkaji tentang metana yang terlarut di dalam air poros (pore-water), mikrobioma dan organisme pembentuk metana, pemindahan gas metana melalui pasang surut, dan geokimia. Kajian emisis gas metana dari sedimen mangrove menunjukkan bahwa secara umum emisinya rendah. Namun, penilaian mendalam terhadap aspek-aspek kajian lainnya serta dikombinaiskan dengan informasi dari kajian-kajian di ekosistem lahan basah air tawar menunjukkan bahwa ekosistem mangrove mungkina menghasilkan emisi gas metana yang tinggi. Kondisi tertentu yang dapat menyebabkan tingginya emisi ini yaitu ketika ada polusi nutrisi di ekosistem mangrove. Hal ini menghasilkan kondisi lingkungan yang cocok bagi metanogen, yaitu kombinasi antara materi organik yang melimpah dan kondisi anerobik. Kemungkinan yang lain adalah ada jalur-jalur lain dalam pelepasan gas metana ke atmosfer. Hal ini disimpulkan dari aksioma bahwa emisi gas metana sedimen mangrove secara alami rendah tapi potensi produksi gas metana tinggi. Mengacu pada aksioma-aksioma ini, maka beberapa pertanyaan penelitian diajukan di sini untuk dijawab pada penelitian-penelitian di masa yang akan datang. Pertanyaan-pertanyaan penelitian ini diajukan untuk mendorong penelitian terkait gas metana di hutan mangrove Indonesia.

We examined the effect of mangrove, seagrass meadows, reef characteristics, and complexity of seascape heterogeneity on reef fish assemblages in Ternate, Natuna and Bintan-Indonesia. The analytical approach of seascape ecology was undertaken, using field survey data of reef fish community and maps of mangrove covers and habitat benthic. The fish data had been collected during reef health monitoring in 2015 through the Coral Reef Rehabilitation and Management Program-Coral Triangle Initiative. Map of benthic habitats and mangroves was provided by Indonesia’s data custodians in 2015-2016. Generalized Additive Models were performed to analyze non-linear and non-monotonic relationships. The results showed that mangroves and seagrasses were essential for reef fishes, and as expected, reef characteristics were also important. Accordingly, the conservations of coral reefs should consider mangrove and seagrass protection and vice versa. Therefore, this information could be considered for managers of marine protected areas (MPA) to better practice MPA management.

Methane (CH₄) emissions in mangrove ecosystems may complicate the ecosystem’s potential carbon offset for climate change mitigation. Microbial processes and the mass balance of CH₄ in mangrove sediment are responsible for the emissions from the ecosystems. This is the follow up of our previous research which found the super saturation of CH₄ in the pore water of mangrove sediment compared to atmospheric CH₄ and the lack of a correlation between pore water sulphate and CH₄ concentrations. This study is going to investigate methane production pathways in the sediment of overwashed mangrove forests. Two approaches were used to study methanogens here: (1) the spread plate count method and the quantitative polymerase chain reaction (qPCR) method, and (2) laboratory experiments with additional methanogenic substrates (methanol, acetate, and hydrogen) to determine which substrates are more conducive to methane production. According to the qPCR method, methanogen abundance ranged from 72 to 6 × 10⁵ CFU g⁻¹ sediment, while SRB abundance ranged from 2 × 10² to 2 × 10⁵ CFU g⁻¹ sediment. According to the plate count method, the abundance of methylotrophic methanogens (the only group of methanogens capable of competing with SRBs) ranged from 8.3 × 10² to 5.1 × 10⁴ CFU g⁻¹, which is higher than the abundance of the other group of methanogens (0 to 7.7 × 10² CFU g⁻¹). The addition of methanol to the sediment slurry, a substrate for methylotropic methanogens, resulted in a massive production of CH₄ (up to 9 × 10⁴ ppm) and intriguingly the control treatments with autoclaving did not kill methanogens. These findings suggested that mangrove ecosystems in the marine environment provide favourable conditions for methanogens and further characterisation of the methanogen involved in the process is required. As a result, future research in this ecosystem should include methane production in carbon offset calculations, particularly due to methylotropic methanogenesis.