Climate change and projections for net annual growth rates: The objective has been expanded from that of 'improving our ability to detect coral stress and predict coral mortality risks in the future' to take account of the observation that mortality in clonal organisms is essentially negative growth that can be counteracted by rapid positive growth. The newly stated goal is to 'improve our ability to detect coral stress and predict sustained downturns in coral cover resultant from future climate scenarios'. The new aspect of this goal is to develop new models that incorporate knowledge about how key environmental factors affect coral growth, specifically the balance between rates of polyp mortality and fission, in addition to calcification rates. The models will be calibrated using seasonal data and controlled laboratory experiments in which the responses of acroporid corals, from several GBR latitudes, to temperature, CO₂ and water quality will be determined. Experiments will seek to determine physical conditions that led not only to mortality (negative coral growth), but also to rapid coral growth.  Additionally, they will seek to determine the role that variations in carbon translocation from symbiont to host have on host growth rates to improve our understanding of the relationship between bleaching and coral growth. This later feature is added due to the fact that data collected to date suggest that corals can be significantly bleached without necessarily compromising net photosynthesis with remnant symbionts working harder, and based on the observation in Berkelmans and van Oppen (2006) that corals that don't bleach can be equally susceptible to polyp mortality at elevated temperature as corals that do bleach. Resultant predictors for net annual growth rates will be incorporated into projection models of how reefs might change as seas warm (and acidify) (Project 2.5i.1: Regional climate scenarios (see Annual Research Plan for 2008/2009) and Project 2.5i.4: Tools to support resilience-based management in the face of climate change). An important outcome is the development of an expanded framework for how climate-change stressors impact on coral communities at levels ranging from cell biology to community ecology.

Heritability and genetics: The identity of coral symbionts (Symbiodinium) is of importance because physiological differences between Symbiodinium types partly determine the response of their host to increased water temperatures and bleaching. Substantial variability in Symbiodinium has been revealed in studies by the Hoegh-Guldberg and van Oppen laboratories and collection efforts by LaJeunesse et al. (2003, 2004) at a southern and central Great Barrier Reef site. In the first stage of this project, we documented existing information on Symbiodinium identity and expanded the collection with targeted sites and host genera. Parts of these collections are being analysed while some targeted sites still need to be included. Understanding abundance and tolerance ranges across the extent of host species present under a wide range of sites along the GBR, each with distinct environmental conditions, will have significant outcomes for management strategies designed to minimize climate impacts.