Cold-water corals are widely distributed across the global oceans. Their skeletons form the fundamental infrastructure of a diverse ecosystem within and below the ocean’s twilight zone. Previous work found that the spatiotemporal distribution of certain cold-water coral species seem to respond to environmental factors such as oxygen levels and the saturation state of calcium carbonates (CaCO₃), making them sensitive indicators of the ocean environment. Here we further investigate the environmental factors controlling the spatial distribution of cold-water corals with multiple global databases. We find a systematic difference in coral taxonomy between different ocean basins: calcitic gorgonian corals are generally more widespread and particularly dominant in the Pacific Ocean, while aragonitic stony corals prefer the Atlantic Ocean due to its higher CaCO₃ saturation. While coral abundance generally decreases with depth, there is an abundance minimum around 1000 m for different types of corals possibly related to oxygen levels and food supply. Statistical analysis shows that both calcitic and aragonitic corals have abundance peaks at saturation states of 1 for calcite and aragonite respectively, suggesting their co-evolution with the environment that constrains their particular ecological niche in the ocean. Calcitic corals and corals with only organic skeletons both have abundance peaks at high phosphate concentrations, suggesting the importance of nutrients to the prosperity of these types of corals. Under the framework of the metabolic index, we find that cold-water corals seem to live in environments with metabolic indexes slightly above 1, suggesting minimal extra energetic constraints on survival. Understanding these environmental controls on the distribution of cold-water corals can help us better use them as archives for the long-term evolution of the deep ocean environment through different climate states in geological history.

 

Cold water corals,Spatial distribution,Oxygen,Nutrients,Saturation,Metabolic Index