Recommendations on monitoring Reef carbonate budget discussed under Reef 2050 Plan
Conservation of biodiversity has historically been the focus of ecosystem-based management on the GBR, but it is increasingly recognised that some species may be more important than others in maintaining critical ecological functions on coral reefs. Recommendations for maintaining functioning of the Great Barrier Reef is the first study to make a comprehensive assessment of reef functioning across a diverse range of taxonomic and functional groups on the GBR – from microbes to predatory fishes.
To determine these key groups, the project team assembled an expert scientific panel to identify various knowledge gaps on ecosystem functioning in the GBR. Researchers addressed these gaps with case studies which highlight key species at various levels of GBR ecosystem functionality, including the role of several hard coral species in determining carbonate budgets.
A reef’s ‘carbonate budget’ refers to the balance between calcification (construction of new coral structures by polyps) and bio-erosion (destruction of coral structures). If a reef’s carbonate budget is positive, this indicates the reef is healthy and growing. If negative, it indicates a loss of coral structure which likely indicates overall health decline for that reef.
Up until now, carbonate budgets have been determined for limited areas of the Great Barrier Reef and it is critical to upscale this information to provide a baseline carbonate budget at a whole-of-reef stage. The project developed a carbonate budget for the entire Great Barrier Reef with results divided into northern, central and southern sectors.
This case study found that Acropora (staghorn) corals had the fastest calcification rates while grazing parrotfishes accounted for nearly all the bio-erosion. The northern sector of the Great Barrier Reef was found to have a negative carbon budget (with the assumption that this was driven by poor carbonate production in the aftermath of severe mass bleaching events) while the central and southern GBR had positive carbon budgets.
In early March 2020, the use of current and future carbonate budgets was discussed as a key reef health indicator by an expert panel meeting at the Great Barrier Reef Marine Park Authority under a specific objective of the Reef 2050 Plan, “Coral reef habitats maintain good condition and resilience”.
Photo: Peter J. Mumby