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Project 2.5i.2 - Early warning and assessment system for thermal stress on the Great Barrier Reef

Project Leader and Host Organisation

Professor Ove Hoegh-Guldberg, The University of Queensland

Project Description and Objectives

For detailed descriptions of the outputs for this project for Year 4 (2009/2010) of the MTSRF Research Programme, see the Annual Research Plan.

In Year 4 (2009/2010) Project 2.5i.2 has three main objectives:

  • 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.

  • Oceanography, bleaching and higher trophic effects: The role of mesoscale oceanographic patterns and variability will be investigated to better understand their link to, and influence on, mass coral bleaching and higher trophic animals, especially sea birds. MODIS sea surface temperature (SST) and chlorophyll remote sensing data will be used to explore the GBR oceanography and it influence on biological systems. SST and chlorophyll climatologies have been generated as a 1 km resolution baseline essential for future studies, showing distinct 'bio-geographic provinces' across the GBR region. The higher resolution time series have provided unique insights into coral bleaching patterns in the southern GBR, particularly for the inshore Keppels Islands reefs. Further to this, we will investigate how broad-scale climate change phenomena translate into changes within the GBR ecosystem and impact reefs on the meso- and smaller-scale. Key environmental variables will be mapped in space and time to improve our understanding 'of climate change impacts across the scale of the GBR ecosystem. The spatial-temporal variability of the physical dynamics will be investigated to determine the biological response, and also whether particular reef systems may be heated or cooled (flushed) and hence likely to experience coral bleaching and mortality or not.  Seabird foraging and reproductive success is explicitly linked to both local and large-scale oceanographic variation. We will investigate the relationships between prey availability/ accessibility and specific physiochemical oceanographic parameters at different scales. These data will be combined with satellite and hydrodynamic information on meso-scale oceanographic variability to better predict how seabirds will respond to projected increases in both SST and other ENSO associated phenomena. Further, we will aim to assess both behavioral and developmental plasticity in multiple seabird species under fluctuating resource availability. These project components will allow determination of the likely range of oceanographic and climatic conditions within which seabird reproduction on the GBR will remain viable.

Further Information

Dr David Souter
GBR Program Research Manager
Reef and Rainforest Research Centre Limited
Tel: (07) 4781 6013


Coral Bleaching

Other Resources

BleachWatch is a community-based coral reef monitoring initiative developed by the Great Barrier Reef Marine Park Authority. 

Information from the Bleachwatch program is published via the Authority's Condition Reports.

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Major Project Outputs

The Annual Research Plans, or ARPs, outline the specific tasks, products, budgets and staff for each research project within each of the Research Themes and Programs of the MTSRF.  The ARPs also outline the key deliverables, or 'project milestones' (e.g. major reports, journal articles, communications products) to be achieved.

An ARP is developed for each operating year of the MTSRF (2006-2010).

Details of this and previous years' outputs from this project are included in each of the Annual Research Plans

All Content © Reef & Rainforest Research Centre 2006