THE TIES THAT BIND - INTER-CLONAL COOPERATION MAY HELP A FRAGILE CORAL DOMINATE SHALLOW HIGH-ENERGY REEFS

In Belize, shallow fore-reef buttresses are dominated by Agaricia tenuifolia Dana. The ecological importance of this fragile coral in such a high-energy environment may be explained in part by an unusual cooperative interaction between adjacent clones of A. tenuifolia. The shallow buttresses are often composed primarily of many clones of A. tenuifolia growing in close proximity. Surveys conducted at Carrie Bow Cay, Belize, in 1986 and 1987 showed that intraspecific contacts between different clones are common and occur far more frequently than interspecific encounters with other sessile taxa. In contrast to many other corals, contacts between non-clonemates of A. tenuifolia do not result in competitive interactions, tissue bleaching or death, or significantly altered patterns of colony growth. Instead, inter-clonal contact stimulates localized morphological changes in the skeletons of both corals directly beneath the contact interface, which tend to anchor the two corals against each other, making them more resistant to breakage and detachment. By mechanically stabilizing clusters of otherwise fragile corals, these cooperative interactions potentially enhance the long-term survivorship and hence the fitness of interacting A. tenuifolia clones.