Complexity of Coral Interactions: Influence of Time, Location of Interaction and Epifauna

Bak, R.; Termaat, R.; Dekker, R.

The potential role of competition for space in a community depends on the arrangement of interaction relationships. A survey (255 m^2) of the interactions between corals (Scleractinia) on a Caribbean reef (depth 10-30 m) indicated the outcome of 17-35% of the aggressive and defensive interactions to be unpredictable. Experiments on the reef (depth 7-13 m) with pairs of interacting corals - Madracis mirabilis (Duchassing & Micheloutti), Agaricia agaricites (L), Montastrea annularis (Ellis & Solander), Eusmilia fastigiata (Pallas) - showed that, after the initial contest through extracoelentric digestion, there are at least two additional processes which can result in a reversal of dominance: interference by epifauna and sweeper tentacle development. Moreover, the impact of extracoelenteric digestion and the extent of sweeper tentacle development varied over the surface of the corals. Employing laboratory and field experiments to distinguish between the impact of extracoelenteric digestion, epifauna behaviour and sweeper tentacles, we show the three processes combined to explain the coral interaction process in toto. The outcome of the interaction process on the reef depends on numerous, partly unpredictable variables, including mode of contact and effects of position. Consequently, patterns of community organization resulting from spatial competition will be slow to emerge and easily erased prematurely by disturbances,

Complexity of Coral Interactions: Influence of Time, Location of Interaction and Epifauna

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