Abstract: Disturbances on coral reefs may cause changes in both the composition of ecological communities and topographic complexity of the reef structures themselves. The increasing frequency and severity of disturbances in recent decades has resulted in declines in both structural complexity and coral abundance and diversity, which in turn influences other coral-dependent taxa such as fishes and mobile invertebrates. Despite widespread recognition of the importance of quantifying both community composition and structural complexity for understanding the health of coral reefs, quantitative methods for assessing changes in these two key indicators remain elusive. Recent advances in underwater 3D imaging technology have facilitated new techniques for simultaneously and quantitatively assessing changes in structural complexity over multiple spatial and temporal scales. Here, I use 3D imagery collected from the Houtman Abrolhos Islands, Western Australia, to examine changes in community composition and structural complexity over a 4-year period spanning the 2011 ‘marine heatwave’ in Western Australia. The response of benthic assemblages to the bleaching event was highly variable across relatively small spatial scales (tens of metres), and shifts in community composition did not result in consistent changes in structural complexity. Understanding the relationships between community composition and structural complexity across scales will provide new understanding of the response of coral reef ecosystems to increasing frequency and severity of disturbances.

Biography: Tom is originally from Sydney and completed a B.Sc (Honours) at the University of Sydney. His honours thesis examined the influence of environmental variation on the distribution of juvenile black marlin off eastern Australia. After spending time travelling and in the diving industry, Tom moved to Townsville in 2007 to begin his PhD in the School of Earth and Environmental Science at JCU, studying mesophotic coral reefs on the GBR. His major field work comprised a 3-week expedition on board the RV Southern Surveyor, which conducted the first detailed study of the biology of the Great Barrier Reef outer-shelf. Completing his PhD in 2011, Tom has continued his research on mesophotic coral reefs at the ARC Centre of Excellence for Coral Reef Studies, JCU. He is currently a joint-postdoc between the ARC Centre of Excellence and the Australian Institute of Marine Science.