Abstract: Coral reefs are becoming seriously degraded in many regions of the world, including the Great Barrier Reef. However, while many studies have documented a steady decline in coral cover, few have provided sufficient information on important population demographic processes to allow the causes of these declines to be identified. In this study, I document spatial and temporally variation in mortality, growth and reproduction in the scleractinian coral, Acropora millepora, at two sites each three regions separated by 5° latitude along the Great Barrier Reef: the Palm Islands (18°N), the Whitsundays (20°N) and the Keppels (23°N). In the course of my study, there were three major disturbances that affected a number of sites: Cyclone Ului, Cyclone Yasi and Fitzroy River flood, and clearly had a profound effect on overall patterns of mortality. Of 180 colonies tagged in April 2009 only 36 were alive Tat the end of the study in April 2011. Of these 144 whole colony events 67.4% followed these acute disturbances. For example, the flood of the Fitzroy River in January 2011 killed all 59 living colonies in the Keppels. Nonetheless, background rates of mortality were higher in the Palm Islands; suggesting difference among region population dynamics, possibly as a result of difference in environment, such as temperature. Size transitions also varied spatially and temporally. In particular, increases in colony size were restricted to the winter months in the Palms and Whitsundays: in summer colonies in these regions shrank on average. In contrast, colonies in the Keppels increased in size in both winter and summer. In contrast, to spatial and temporal variation in mortality and growth, neither per polyp fecundity not egg size varied consistently among years, site or regions. This suggests that coral fecundity is a much less plastic trait than colony growth or mortality. In conclusion, the population dynamics of A. millepora varied dramatically among regions, possibly in response to environmental differences among these regions. These results imply that population resilience is also likely to vary among regions and that therefore different strategies may be required to manage them.
Biography: James Tan comes from Malaysia and completed his Bachelor and Master degree in Marine Biology at the Universiti Malaysia Terengganu. He is currently a Ph.D. candidate in the ARC Centre of Excellence for Coral Reef Studies supervised by Assoc. Prof. Andrew Baird, Prof. Morgan Pratchett and Dr. Line Bay