Microhabitat specialisation and ecological consequences for coral gobies of the genus Gobiodon in the Gulf of Aqaba, northern Red Sea

The microhabitat selection and distribution of 6 coral-associated species of Gobiodon were examined in the Gulf of Aqaba, northern Red Sea, including 3 recently discovered species. A total of 1626 fishes were counted visually using 10 x 1 m belt transects in 1731 colonies of 13 species of Acropora. Niche segregation was observed at the level of coral species. Gobiodon sp. 2 was the most specialised, occupying only A. hyacinthus; Gobiodon sp. 1 was most generalised (occupying 3 species of Acropora more frequently than expected). G. reticulatus was a zone specialist that preferred deeper water regions. Less specialised species were able to use substitute host corals, which enabled them to maintain extraordinarily high abundance. G. histrio, for example, preferred the rare A. digitifera, but was common in the very abundant A. acuminata, although proportionally fewer breeding pairs were established in the latter. When compared to the western Pacific, G, histrio showed a more generalised behaviour in the northern Red Sea, and different coral species served as host corals; the latter also holds true for the even more generalised G. rivulatus. Hence, species of Gobiodon appear to alter host-use and degree of specialisation on a global scale.