How Episodic Coral Breakage Can Determine Community Structure: A South African Coral Reef Example
Episodic disturbance, Coral community structure, Coral reef, South Africa, Scleractinia, Alcyonacea, Fragmentation, Regeneration
Africa's southernmost coral reefs are situated in Natal Province, South Africa. The Natal coast is exposed to open Ocean swells and episodic storm swell conditions. Benthic communities on these reefs differentiated into three community types: shallow reefs (8–18 m) were dominated by alcyonacean corals and low-growing, massive Scleractinia; intermediate reefs (18–25 m) were dominated chiefly by branching and tabular Scleractinia of the genus Acropora (A. austera, A. clathrata); deep reefs were not dominated by corals but by sponges. Breakage and recovery experiments indicated that the difference in Acropora dominance between shallow and intermediate sites was caused by breakage in high swell conditions. Survival of experimentally produced A. austera fragments was significantly higher in intermediate than in shallow sites, where higher surge made re-attachment and regeneration unlikely. Also, colony morphology was adapted to differential surge conditions: colonies on the shallow reefs were smaller with shorter branches, while on intermediate reefs they were much bigger with long, widely spreading branches. Episodic breakage and low fragment survival due to high water-motion thus excluded branching corals from shallow reef sites.
Bernhard Riegl and Andrea Riegl. 1996. How Episodic Coral Breakage Can Determine Community Structure: A South African Coral Reef Example .Marine Ecology , (1-3) : 399 -410. https://nsuworks.nova.edu/occ_facarticles/343.