Researchers in Mozambique found that ancient coastal forests submerged by rising seas now form peat reefs on the seafloor near the Bazaruto Archipelago. Radiocarbon dating puts the peat between roughly 300 and 5,000 years old. The material contains up to 40% organic carbon by dry weight, and its isotopic signature points to a terrestrial plant origin. Unlike nearby coral reefs, these peat reefs have no living corals. Instead, seagrass, macroalgae, and sponges grow on the peat, and the reefs support a distinct mix of fish and invertebrates. Biodiversity surveys showed the peat reefs are ecologically connected to coral reefs, with dozens of shared species, even though habitat composition is different. The authors argue these relict ecosystems should be included in coastal habitat mapping, conservation planning, and assessments of legacy coastal carbon. The study does not calculate total carbon stocks or erosion rates, so the full climate significance remains an open question.
