Researchers in Mozambique's Bazaruto Archipelago have documented ancient coastal forests, flooded by rising seas thousands of years ago, that now exist as underwater peat reefs. These reefs host seagrass, seaweeds, lobsters, juvenile fish, sharks, rays and turtles, with fish diversity comparable to nearby coral reefs despite having no living coral. The study, published in Scientific Reports, is the first ecological look at tropical peat reefs from a biodiversity standpoint. The peat contains up to 40% organic carbon by dry weight, but the researchers say it is not yet clear whether these systems are storing or releasing carbon today. Measuring peat thickness, carbon stocks, erosion rates and greenhouse-gas fluxes is needed before classifying them as blue carbon habitats like mangroves or seagrass. The authors argue peat reefs should be added to coastal habitat maps, conservation plans and assessments of legacy coastal carbon. Similar submerged forests could exist along coastlines in Southeast Asia, the Caribbean and West Africa, making this a starting point for broader marine policy and potential carbon credit considerations.
