36 Growth Patterns of Mediterranean Calcifying Cold-Water Corals

Skeletal growth is a key physiological function, which in the case of calcifying organisms, provides support for the general colony structure together, whilst simultaneously providing protection for internal soft tissues. Given this fundamental importance, growth patterns can therefore reflect the health status of organisms. Additionally, engineer species forming 3D structures, such as scleractinian cold-water corals, enhance local biodiversity through the provision of new structural and hydrodynamic habitats. Furthermore, cold-water corals may be used as paleoclimate indicators, and act as sources for novel pharmaceutical compounds as well as represent significant sinks for CO₂ sequestration. At time of writing, cold-water coral reefs are facing several serious threats, particularly in the Mediterranean Sea, where the combined effects of climate change and other anthropogenic environmental disturbances are interacting in regions of coral colonisation. The characterisation of the Mediterranean cold-water coral growth patterns is thus a crucial step for accurate forecasting of reef resilience under environmental change and for the establishment of adequate conservation strategies. From the organisation of soft tissues to the resulting mineralogical structures formed from the polyp to the reef scale, this chapter gives an overview of the state of the art of the current understanding of scleractinian cold-water coral growth patterns. The main environmental parameters that control calcification and their influence on cold-water corals in the context of ongoing global environmental change are illustrated with examples from studies conducted with different calcifying species from the Mediterranean Sea, utilising both aquaria and in situ experimental studies.