Compiled δ15N isotopic data of macrophytes used for nitrogen pollution monitoring in tropical oligotrophic coastal waters

Studies were identified through a structured literature search targeting tropical coastal systems. Only field studies reporting δ15N in macroalgae or seagrass in relation to a clearly defined nitrogen source (e.g., wastewater, sewage, groundwater, fertilizer, atmospheric deposition, particulate organic matter, aquaculture) were included. For each article, δ15N values were extracted as reported by the authors, usually as site-level means. Additional metadata (species, exposure conditions, methodology) were systematically recorded. The dataset does not contain raw individual measurements when these were not provided by the original studies; instead, it reflects the summary metrics used in the accompanying review.