Researchers found that 5,000-year-old submerged forests off Mozambique's coast are acting as reefs for fish. The peat beds, exposed by rising seas, support 26 to 36 fish species per site, including juvenile snappers and grunts that usually depend on coral. The study in Scientific Reports is the first ecological survey of tropical peat reefs. Unlike coral reefs, these peat reefs have no living coral. Seagrass and seaweed grow directly on the peat, and its crevices shelter lobsters, oysters, and barnacles. The reefs sit only a few meters deep, so tides and storms constantly reshape them, and many are lost to erosion and moving sand. The carbon question remains open. Peat can hold up to 2,000 metric tons of carbon per hectare on land, but the researchers say they do not yet know whether these submerged peat layers are storing or releasing carbon today. They call for more measurements before deciding if peat reefs qualify as blue carbon habitats. Coastal planners rarely map or protect these areas, and similar habitats may exist across Southeast Asia, the Caribbean, and West Africa.
