Miguel Angel Mateo

Crucial for coastal carbon sequestration, global seagrass organic carbon (OC) burial rates remain uncertain as early estimates were derived from mixed methodologies across geographically and taxonomically biased datasets. Here, we present a data-driven reassessment from a synthesis of 332 sediment cores spanning the last century. Results show that seagrasses bury OC at 25 ± 3 g OC m ⁻² yr ⁻¹ (geometric mean), with an area-weighted global average of 33 ± 9 g OC m ⁻² yr ⁻¹ . Rates reflect a balance between sediment OC content and sediment accumulation, which share a negative exponential relationship driven by mineral dilution. Based on a revised mapped seagrass extent (247,700–366,400 km ² ), global burial scales to 6–15 Tg C yr ⁻¹ . Although one-fourth of earlier benchmarks, seagrasses account for 3–4% to 3–6% of total oceanic OC burial despite covering <0.1% of the seafloor. Combined with mangroves and tidal marshes, vegetated coastal ecosystems contribute 8–13% of oceanic OC burial.

Seagrass ecosystems are pivotal contributors to coastal carbon sequestration through the long-term burial of organic carbon (OC) in sediments. Yet global burial estimates remain uncertain, with early values of 138 ± 38 g OC m-2 yr-1 derived from a limited dataset biased toward highly depositional communities and indirect, production-based approaches. We call for a downward revision, supported by a data-driven assessment based on a global synthesis of 326 dated sediment cores integrating OC burial over the last century. We find that seagrass meadows bury OC at a geometric mean rate of 26 ± 2 g OC m-2 yr-1, with an area-weighted global average of 33 ± 10 g OC m-2 yr-1 accounting for bioregional differences in seagrass distribution. Globally, these rates scale to 6–16 Tg C yr-1, based on current mapped seagrass extent (247,800–366,200 km2), and reveal that ~15% of seagrass net community production is retained and buried locally. Although our estimate is roughly one-fourth of earlier values, seagrass sediments still account for 3–6% of total oceanic OC burial, despite occupying <0.1% of the seafloor. Combined with mangroves and tidal marshes, OC burial in vegetated coastal sediments represents an estimated 8–13% of total oceanic OC burial.

Seagrass meadows play a key role in the global carbon cycle through storing carbon in their biomass and soils. However, the lack of global assessments of carbon stocks in seagrass biomass and net primary production (NPP) limits our understanding of their role in the carbon cycle. Here, we provide global estimates of biomass carbon stocks and NPP encompassing seagrasses with different life-history strategies, across bioregions and 66 countries. Seagrass meadows show up to 800-fold differences in biomass across different life-history strategies and bioregions (mean ± SE; 1551 ± 40 kg C ha⁻¹), whereas seagrass NPP (5833 ± 557 kg C ha⁻¹ yr⁻¹) ranks among the highest within photosynthetic ecosystems. We estimate seagrass biomass carbon stocks at 24–40 Tg C and NPP at 83–137 Tg C yr⁻¹ within 160,387 to 266,500 km² of global seagrass extent. This study showcases the role of seagrasses in the global carbon cycle and provides the basis for their inclusion in carbon crediting schemes towards implementing conservation actions for climate change mitigation.

The variability in stocks and accumulation rates of organic carbon (C_org), nitrogen (N), and carbonate (CaCO₃) was studied in fifteen Posidonia oceanica meadows spread throughout the South Aegean Sea (Greece). In addition, the abiotic and biotic drivers determining the pattern of variability in the accumulation rates were assessed by exploring the influence of sediment characteristics, seagrass traits, and environmental settings. The meadows supported on average (±STDEV) 14.6 ± 5.0 kg C_org m⁻², 0.47 ± 0.17 kg N m⁻², and 249 ± 210 kg CaCO₃ m⁻² in the top meter of their sediments, with mean accumulation rates over the last 500 years of 33.6 ± 23.6 g C_org m⁻² yr⁻¹, 1.00 ± 0.62 g N m⁻² yr⁻¹, and 405 ± 336 g CaCO₃ m⁻² yr⁻¹ across sites. A redundancy analysis (RDA) explained 70% of the variation in C_org, N, and CaCO₃ accumulation rates, with three sediment characteristics (i.e., sediment C_org:N and C_org:C_inorg ratios and P. oceanica contribution to the sediment C_org pool) emerging as the primary set of factors shaping the accumulation of matter, followed by seagrass traits (i.e., leaf biomass and rhizome elongation) and environmental variables (i.e., suspended organic matter). The high degree of variability within the region emphasizes the need for fine‐scale assessments to understand the local conditions influencing sequestration. Our findings underscored the critical role of seagrass meadows in carbon and nitrogen sequestration in the region, urging conservation efforts to protect these ecosystems and prevent potential losses of stored carbon and nitrogen following seagrass degradation.

Introducción: Los pénfigos son enfermedades ampollosas autoinmunes, poco frecuentes, pero potencialmente graves y pueden asociarse a consecuencias catastróficas si no se realiza un abordaje diagnóstico y terapéutico apropiado. El servicio de Dermatología de la Universidad de Antioquia en sus sedes principales, Hospital Alma Mater de Antioquia y Hospital Universitario San Vicente Fundación, es centro de referencia para el estudio y manejo de estas enfermedades. Metodología: discusión de las pautas de manejo y revisión de la literatura en el grupo de docentes y residentes de la Universidad de Antioquia. Resultados: Se describen pautas en el diagnóstico y el tratamiento de pacientes con pénfigo vulgar y pénfigo foliáceo. Del mismo modo, se realiza una revisión narrativa de la evidencia científica que respalda lo recomendado en el presente artículo.

Seagrass meadows are effective carbon sinks due to high primary production and sequestration in sediments. However, methane (CH₄) emissions can partially counteract their carbon sink capacity. Here, we measured diffusive sediment‐water and sea‐air CO₂ and CH₄ fluxes in a coastal embayment dominated by Posidonia oceanica in the Mediterranean Sea. High‐resolution timeseries observations revealed large spatial and temporal variability in CH₄ concentrations (2–36 nM). Lower sea‐air CH₄ emissions were observed in an area with dense seagrass meadows compared to patchy seagrass. A 6%−40% decrease of CH₄ concentration in the surface water around noon indicates that photosynthesis likely limits CH₄ fluxes. Sediments were the major CH₄ source as implied from radon (a natural porewater tracer) observations and evidence for methanogenesis in deeper sediments. CH₄ sediment‐water fluxes (0.1 ± 0.1–0.4 ± 0.1 μmol m⁻² d⁻¹) were higher than average sea‐air CH₄ emissions (0.12 ± 0.10 μmol m⁻² d⁻¹), suggesting that dilution and CH₄ oxidation in the water column could reduce net CH₄ fluxes into the atmosphere. Overall, relatively low sea‐air CH₄ fluxes likely represent the net emissions from subtidal seagrass habitat not influenced by allochthonous CH₄ sources. The local CH₄ emissions in P. oceanica can offset less than 1% of the carbon burial in sediments (142 ± 69 g CO_2eq m⁻² yr⁻¹). Combining our results with earlier observations in other seagrass meadows worldwide reveals that global CH₄ emissions only offset a small fraction (<2%) of carbon sequestration in sediments from seagrass meadows.