Abstract. In contrast with a general decline of Caribbean reef corals, a previously rare sun coral is increasing in abundance within shallow coral communities on Curacao. This azooxanthellate scleractinian was identified as Cladopsammia manuelensis, which has an amphi-Atlantic distribution. Over the last decade, C. manuelensis has increased abundance along the leeward coast of Curacao (southern Caribbean) between depths of 4 and 30 m. This species was initially not noticed because it resembles the invasive coral Tubastraea coccinea, which was introduced to Curacao from the Indo-Pacific around 1940. However, in contrast to T. coccinea, C. manuelensis was previously only present on deeper reef sections (>70 m) of Caribbean reefs. Our observations illustrate how the sudden increase in abundance of a previously unnoticed, apparently cryptogenic species could result from natural dynamics on present-day reefs, but also could easily be mistaken for an invasive species. The finding that deep reef sections can harbor species capable of colonizing shallower reef zones highlights the importance of thorough inventories of reef communities across large depth ranges, which can help us to discriminate between range increases of native species and the arrival of invasives.
Key words: bathymetric distribution; Cladopsammia; coral reefs; cryptogenic; deep water; Dendrophylliidae; invasive; native; Rhizopsammia; Tubastraea;.