Deciphering the composite morphological diversity of Lophelia pertusa, a cosmopolitan deep-water ecosystem engineer

Cold-water coral reefs constitute important biodiversity hotspots in aphotic waters around the world. The complex, highly variable morphology of the reef habitat-forming species has important implications for the communities they harbor and for the physical processes occurring therein. Lophelia pertusa (Desmophyllum pertusum) is one of the most common reef-building cold-water corals, but its morphological diversity has never been characterized on a broad scale. We qualitatively and quantitatively explored the patterns of morphological variation of this species over a wide geographic and ecological range, addressing corallite and colony traits and their interrelation. Geographic variation is evident at both corallite and colony level, although with distinct trends. By linking branching patterns to colony morphology, we identified three main morphotypes (asymmetrical, bushy, and columnar) with substantial geometric and architectural differences, which suggest high functional diversity of cold-water coral reefs across regions. Colony morphology appears strongly governed by asexual budding of individual polyps, but largely decoupled from corallite morphology. We hypothesize that colony morphology is primarily driven by local hydrodynamic conditions and associated food supply.