Carbon burial in cold-water coral mounds across time and space

Scleractinian cold-water corals (CWCs) are ecosystem engineers that build three-dimensional carbonate frameworks and if suitable environmental conditions are met, may create large reefs. Over geological timescales and cycles of reef growth and extinction, CWC reefs with sufficient sediment supply develop into coral mounds. Coral mounds are biogenic structures on the seabed composed of CWC framework and stabilised by sediments that can be more than two million years old and over 300 m high. Due to the difficulty to explore these remote deep-sea ecosystems, significant knowledge gaps remain, especially with regards to their functional role and spatial distribution. Coral mounds are considered marine carbonate (CaCO3) factories that can exhibit relatively high aggradation rates. With an increasing number of mounds being discovered around the Atlantic, it has been suggested that they play a vital role in long-term carbon burial (i.e., accumulation) processes. Yet, quantitative studies about carbon accumulation on coral mounds are scarce, hindering the establishment of representative accumulation rates and their adequate integration into marine carbon budget calculations. Therefore, the present study aims to quantify total carbon accumulation, encompassing both organic and inorganic carbon fractions, in coral mounds across time and space.