Spatial Variation of Blue Carbon Stored in Seagrass T. hemprichii Meadows along the Coasts of Mainland Tanzania.

Dataset and R Codes for Seagrass Sediment Organic Carbon Analysis in Coastal Tanzania This repository contains the dataset and R scripts associated with a study investigating sediment organic carbon, carbon stocks, and environmental characteristics of Thalassia hemprichii seagrass meadows and adjacent unvegetated sediments along the coast of mainland Tanzania. The study was conducted across nine coastal sampling sites distributed among three regions: Mtwara, Lindi, and Tanga. Sediment samples were collected from seagrass-vegetated and unvegetated habitats at different sediment depths to assess spatial and vertical variation in sediment organic carbon and associated environmental characteristics. The dataset includes measurements of sediment organic carbon concentration, sediment physical and chemical properties, and selected seagrass structural characteristics. Variables include organic carbon concentration, sediment nitrogen, fine sediment fraction, grain size, porosity, sediment bulk density, seagrass biomass, shoot density, seagrass cover, and water depth. The repository also provides R scripts developed to reproduce the statistical analyses, including: Principal Component Analysis (PCA): To investigate multivariate patterns in sediment characteristics and their associations with habitat type. Permutational Multivariate Analysis of Variance (PERMANOVA): To evaluate differences in multivariate sediment characteristics between seagrass and unvegetated habitats while accounting for sampling sites. Multivariate dispersion was also assessed using PERMDISP. Partial Least Squares (PLS) Regression: To assess relationships between sediment organic carbon concentration and environmental predictors. Variable Importance in Projection (VIP) scores and regression coefficients were calculated, and predictive performance was evaluated using leave-one-site-out cross-validation. Organic Carbon Analysis: To evaluate variation in sediment organic carbon concentration across habitats, sampling sites, and sediment depths using descriptive statistics and mixed-effects modelling. The R scripts generate statistical summary tables, model outputs, and publication-quality figures. They are provided to support transparency, reproducibility, and further research on seagrass-associated blue carbon ecosystems in the Western Indian Ocean. Software: R statistical software (version 4.5.2). Principal packages include vegan, mixOmics, ggplot2, lme4, lmerTest, emmeans, and readxl. Geographical coverage: Coastal mainland Tanzania, Western Indian Ocean. Keywords: Seagrass; Thalassia hemprichii; Sediment Organic Carbon; Blue Carbon; Carbon Stocks; PCA; PERMANOVA; PLS Regression; Tanzania; Western Indian Ocean.