Northern Gulf of Mexico Seagrass Sediment Blue Carbon and Isotope Inventory

This multi-tiered coastal dataset quantifies surficial (top 10 cm) sedimentary blue carbon and nitrogen stocks, bulk dry density, loss on ignition (LOI), and stable isotope signatures ($\delta^{13}\text{C}$ and $\delta^{15}\text{N}$) across seagrass and unvegetated estuarine habitats in the Northern Gulf of Mexico. Designed for spatial blue carbon accounting and Bayesian stable isotope mixing models (MixSIAR), the collection couples empirical core measurements with generalized additive model (GAM) stock predictions and organic matter source end-members. Geographic & Temporal Scope Spatial Range: Covers 19 estuarine and bay systems across 4 Gulf States—Texas, Louisiana, Mississippi, and Florida (Latitude $24.48^\circ\text{N}$ to $30.42^\circ\text{N}$, Longitude $-97.75^\circ\text{W}$ to $-80.21^\circ\text{W}$). Sampling Window: Field collections conducted between 2022 and 2023 across 931 unique monitoring stations. Habitat Coverage: Vegetated seagrass beds (Halodule wrightii, Thalassia testudinum, Syringodium filiforme, Halophila engelmannii, Ruppia maritima), benthic macroalgae, and bare sediment controls. Methodological Overview Sediment dry bulk density was determined via standard volumetric subsampling ($4.5\text{ cm}^3$). Organic matter and carbonate contents were measured via sequential loss-on-ignition at 550°C ($\text{LOI}_{550}$) and 1000°C ($\text{LOI}_{1000}$). Elemental carbon/nitrogen concentrations and stable isotope ratios ($\delta^{13}\text{C}$ vs. VPDB, $\delta^{15}\text{N}$ vs. Air) were quantified using Elemental Analyzer–Isotope Ratio Mass Spectrometry (EA-IRMS). GAM regression models trained on LOI metrics provided full-dataset coverage of organic carbon, inorganic carbon, and nitrogen stocks ($g\cdot\text{m}^{-2}$ and $\text{Mg}\cdot\text{ha}^{-1}$).