Dataset: Sediment organic carbon of the Cape Dwarf-Eelgrass <i>Zostera capensis</i> in six South African estuaries

This dataset comprises sediment organic samples from seagrass meadows of the Cape dwarf-eelgrass (<i>Zostera capensis</i>), collected from six South African estuaries—Olifants, Berg, Breede, Knysna, Swartkops, and Mngazana—spanning approximately 1,800 km of coastline. At each estuary, two plots were sampled, and four sediment cores were collected using a Russian peat corer (50 cm depth, 5 cm diameter). Each core was sectioned into five intervals: 0–5 cm, 5–10 cm, 10–20 cm, 20–30 cm, and 30–50 cm. Samples were acidified with hydrochloric acid to remove inorganic carbon, and organic carbon content was measured using an Elementar Vario EL Cube CHNS analyzer.