Phoenix from the Ashes? Repetitive Mass Mortality and the Biogeology of Southern Arabian Gulf (United Arab Emirates) Coral Systems

Biogeological dynamics consist of a combination of community-ecological responses based on individual-species physiological tolerance limits to a dominant environmental stressor and their consequences on carbonate sedimentological properties. This interplay was investigated in coral carpet systems (biostromal coral frameworks) in the southern Arabian Gulf in Abu Dhabi and Dubai (UAE). Five coral assemblages occur in the area: (A) low coral cover, widely spaced Porites lutea (B) high coral cover (biostromal framework), dense Acropora spp. (C) low coral cover, widely spaced faviids (D) low coral cover, individual Siderastrea savignyana only (E) high coral cover (biostromal framework), dense Porites harrisoni. Coral community dynamics and the potential for the accretion of reefal limestones was found to be controlled by recurring sea-surface temperature anomalies. The effects of these heating or cooling events are mass mortality of all Acropora species. COADS data and time-series of AVHRR satellite data suggest potential recurrence periods of 11-17 years. Extreme positive SST anomalies only appeared after 1986. These events result in large areas of dead framework with only interspersed live corals (the non-Acropora members in the assemblages). Dead frameworks are intensely biocorroded and break down rapidly. Thus the next generation of framebuilders has to settle on the same substratum as the previous Bright, M., P.C. Dworschak & M. Stachowitsch (Eds.) 2002: The Vienna School of Marine Biology: A Tribute to Jörg Ott. Facultas Universitätsverlag, Wien: 137-159