New rhodolith species found off Japan store carbon as living pink rocks on the seafloor

Scientists at Hiroshima University discovered four new species of rhodoliths, also known as living pink rocks, in the waters off Tanegashima Island, Japan. Rhodoliths are calcifying red algae that form pebble-like nodules on the seafloor. They create essential habitats for marine life and contribute to long term carbon storage in marine sediments, making them relevant to blue carbon and climate change mitigation. The study found at least 12 coralline algae species in a small patch of seafloor 35 to 38 meters deep. Only three of those species also appeared in nearby shallow waters, showing that deeper habitats host completely different biological communities. The researchers used DNA sequencing and microscopy to identify four new species and revised the descriptions of two algal genera. Understanding rhodolith diversity helps scientists measure how much carbon these ecosystems actually store. The next step is to confirm whether the new species are unique to this area and to map the coverage of rhodolith beds off Tanegashima. This work strengthens the foundation for marine biodiversity research and blue carbon accounting.