13:00-15:05 Session IVa Coral Reef and Human Existence
Regenaration processes in scleractinian corals
Y. Loya and U. Oren
Department of Zoology, The George S. Wise Faculty of Life Sciences
Tel Aviv University, Tel Aviv 69978, Israel
Convergence of form and function has accompanied the evolution of modular growth in colonial marine invertebrates. Part of this convergence is related to optimal exploitation of resources (space and light) and the ability to translocate energy products from sources to sink sites. Hermatypic corals, the major organisms constructing tropical reefs, contain photosynthetic algae (zooxanthellae), whose energetic products are translocated towards sink sites located at the coral's growing tips and regenerating areas. Because of their colonial structure, whole corals may survive the death of individual modules, a phenomenon known as partial mortality. Previous studies have already shown that corals are prone to damage by a multitude of agents and that their recovery capability is species-specific. Furthermore, that the regeneration process affects colony growth, reproduction, resistance to diseases and competitive abilities.
We have studied energetic pathways involved in the regeneration processes of damaged scleractinian corals in Eilat (Red Sea). We have recorded the recovery dynamics of coral tissue in experimentally inflicted lesions and in lesions caused by predatory snails.
Using a localized 14C labeling technique, we documented an oriented intra-colonial translocation of photosynthetic products towards regenerating areas in two scleractinian corals, Favia favas and Platygyra lamellina.
We found that 14C labeled materials originating in distant areas of the coral colony are translocated towards large regenerating lesions and that the size of the coral lesion affects the magnitude of this translocation. It is also concluded that energy allocation to recovery is prioritized over energy allocation to reproduction. In addition, we found that colony margins of the stony coral Porites function as major energy sinks. When corallivorous snails inhabited these sites (causing local tissue lesions), they incorporated significant amounts of 14C, indicating that they had fed on photosynthetic products translocated from the inner parts of the colony.
Our results indicate that an important consequence of modularity may be reflected in the ability of a colony to continually re-allocate priority of resource transport among its units in response to stress. Furthermore, that regeneration from injury may require an extended magnitude of energy integration throughout the colony. The extent of this integration is regulated by the colony in accordance with lesion characteristics.
