Terrestrial inputs boost organic carbon accumulation in Mexican mangroves

• Published in: The Science of the total environment 2024-08, Vol.940, p.173440, Article 173440
• Main Authors: Jupin, J.L.J., Ruiz-Fernández, A.C., Sifeddine, A., Mendez-Millan, M., Sanchez-Cabeza, J.A., Pérez-Bernal, L.H., Cardoso-Mohedano, J.G., Gómez-Ponce, M.A., Flores-Trujillo, J.G.
• Format: Article
• Language: English
• Subjects: 210Pb radiochronology; Blue carbon; Burial rate; Environmental Sciences; Mangroves; MixSIAR; Stock
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.173440

Despite their ability to mitigate climate change by efficiently absorbing atmospheric carbon dioxide (CO2) and acting as natural long-term carbon sinks, mangrove ecosystems have faced several anthropogenic threats over the past century, resulting in a decline in the global mangrove cover. By using standardized methods and the most recent Bayesian tracer mixing models MixSIAR, this study aimed to quantify source contributions, burial rates, and stocks of organic carbon (Corg) and explore their temporal changes (∼100 years) in seven lead-210 dated sediment cores collected from three contrasting Mexican mangrove areas. The spatial variation in Corg burial rates and stocks in these blue carbon ecosystems primarily depended on the influence of local rivers, which controlled Corg sources and fluxes within the mangrove areas. The Corg burial rates in the cores ranged from 66 ± 16 to 400 ± 40 g m−2 yr−1. The Corg stocks ranged from 84.9 ± 0.7 to 255 ± 2 Mg ha−1 at 50 cm depth and from 137 ± 2 to 241 ± 4 Mg ha−1 at 1 m depth. The highest Corg burial rates and stocks were observed in cores from the carbonate platform of Yucatan and in cores with reduced river influence and high mangrove detritus inputs, in contrast to patterns identified from global databases. Over the past century, the rising trends in Corg burial rates and stocks in the study sites were primarily driven by enhanced inputs of fluvial-derived Corg and, in some cores, mangrove-derived Corg. Despite their decreasing extension, mangrove areas remained highly effective producers and sinks of Corg. Ongoing efforts to enhance the global database should continue, including mangrove area characteristics and reliable timescales to facilitate cross-comparison among studies. [Display omitted] •Burial rates and stocks of mangrove sediment organic carbon (Corg) are reported.•Highest Corg stocks was observed in sites with autochthonous-dominated Corg.•Global Corg patterns do not fully explain the local Corg variability in study sites.•Long-term rise in terrestrial Corg inputs led to higher Corg burial rates and stocks.•Despite cover loss, mangroves areas remained effective Corg producers and sinks.