Abstract: Central to understanding how coral reef ecosystems will cope with future global climate change is knowledge of how coral communities persist in marginal environments. Coral communities in the southern Persian Gulf already exist in a naturally extreme environment with average summer temperatures well in excess of those predicted to occur on most tropical coral reefs by 2100. However, few studies have examined key ecological processes (e.g., reproduction, recruitment and population size structure) that determine coral population dynamics in the Gulf. Furthermore, considerable changes to coral reef community structure have occurred in the southern Persian Gulf over the past two decades. Most dramatic are the apparent changes from Acropora dominated to poritids and faviids dominated communities. Despite extreme temperatures and high levels of bleaching, surveys showed that corals in the Gulf are reproductively active and continue to recruit. Reproduction was seasonal, with spawning occurring mainly in April and May just prior to summer maximum temperatures. The proportions of colonies spawning and per polyp rates of fecundity were similar to other regions. Further, the overall density of recruits (≈ 121 recruits m-2 year-1) was similar to sub-tropical reefs in the Indo-Pacific. Recruitment was highly seasonal with peak recruitment in the summer (June–August) when maximum summer temperatures can exceed 35°C. Elsewhere, survivorship and/or development of coral larvae would be severely reduced at these temperatures indicating marked capacity for local adaptation of corals in the Gulf. While corals in the Gulf appear adapted to the extreme environment, spawning and recruiting at temperatures that would inhibit these process in other regions of the world, increases in sea surface temperatures and recurrent bleaching events are having a marked effect on the population size structure of corals within the southern Gulf. Results showed that locally abundant coral species in the southern Gulf were significantly smaller, and their size structure positively skewed and more leptokurtic compared to coral populations in other parts of the Gulf, suggesting that increasing climate change will lead to persistent declines in the size of coral colonies and vulnerability to future disturbances.

Biography: Andrew is originally from the United States and obtained his bachelor’s degree in marine biology from the University of South Carolina in 1997. Shortly thereafter, he moved to Palau in Micronesia where he served as a US Peace Corps marine resource volunteer. Following his work in Palau, he attended James Cook University where he completed his master’s degree in tropical marine ecology in 2003. After hopping around the globe for another several years, back in Micronesia, the Middle East and Southeast Asia he decided to pursue his PhD at the ARC Centre of Excellence for Coral Reef Studies under the supervision of Prof Morgan Pratchett and Dr. Andrew Baird. His current research focuses on the ecology and dynamics of coral reef communities in extreme marginal reef environments, specifically reef communities in the Persian/Arabian Gulf and Gulf of Oman. He is most interested in basic processes that determine population dynamics of reef communities, including: reproduction, recruitment and colony growth, and how these processes will likely be impacted by future climate change.