Enigmatic coral recorded for first time from Malta

The Mediterranean Sea is notorious for invasion by non-native biota, resulting in an ever-increasing number of alien species recorded from this sea, including in Maltese waters. Nevertheless, when a new species is recorded, it is not always due to a recent introduction: many species are small and inconspicuous, and therefore may have been present for a long while but simply went unnoticed. This is less likely to happen with large colourful species such as corals, which are more striking and hence more readily detected, making the story of Oculina patagonica all the more remarkable.

Oculina patagonica is a large stony coral, colonies of which can reach more than a metre in diameter. As its name suggests, it was first described from Argentina ( SW Atlantic); this was back in 1908 and the original description was based on fossil specimens. For a few decades no living individuals of this species could be found. Fast forward to 1966 and a living specimen was finally recorded… but not from Argentina or anywhere close! The living individual was found in Savona Harbour, Italy, and since then the coral has been observed in several other places in the Mediterranean, including Spain, France, Algeria, Tunisia, Croatia, Greece, Turkey, Egypt, Lebanon and Israel. Researchers from the Marine Ecology Research Group at the Depart- ment of Biology of the University of Malta have now also documented its presence in Maltese harbours, where sizeable colonies were observed on jetties.

The origin of this coral in the Mediterranean remains enigmatic. No fossils of the species are known from the Mediterranean, which has been taken to indicate that it is not native in the area and must have been introduced from somewhere else. At the same time, no living individuals are known from anywhere outside the Mediterranean, and recent genetic analysis suggested that it may have been present in this sea for much longer than previously thought. In the case of Malta, however, the situation is clearer. Given the number of snorkelers, divers and other sea users in our seas, a large, yellow coral is unlikely to have gone unnoticed if it were present here for a long time, which, together with the fact that it was discovered from artificial substrata in harbours, points to a recent introduction. Given that this coral seems to be acting invasively elsewhere in the Mediterranean, the Maltese researchers are actively monitoring its status in Maltese waters. The Marine Ecology Research Group welcomes reports of any unusual or new marine organisms. Please contact the group leader, Prof. Patrick J. Schembri at the Department of Biology, University of Malta on +356 2340 2272.