This project will engage coral taxonomic experts to annotate existing Reef Life Survey photoquadrats taken across northern Australia before and after major disturbances, to allow:
- Quantification of the spatial and species-level responses of Australian corals to the 2016 and 2017 marine heatwave and mass bleaching events (and cyclones that occurred during this period).
- Identification of the species most threatened by warming and cyclones, and species likely to respond best to restoration efforts.
- Contribution to a coral-specific analysis to the next national State of the Environment report, through project D5
Extensive coral losses have been observed in northwestern WA, Coral Sea, and along the GBR following the 2016 and 2017 marine heatwaves and mass bleaching events. Reports of surveys undertaken at local and regional scales indicate particular coral species have been badly affected by bleaching mortality, while other species exhibited considerable resistance (e.g. Hughes et al 2018 Nature). Indeed, previous studies have identified ‘winners’ and ‘losers’ from such disturbances amongst species in the coral community (e.g. Loya et al 2001 Ecology Letters) or made predictions based on simulation models or traits for which species would be winners and losers (e.g. Kubicek et al 2019 Scientific Reports; Darling et al 2012 Ecology Letters). However, generalisation from such studies has been difficult due to their limited geographic and taxonomic scope. In most cases where empirical data have been collected, it has been impossible to determine whether the responses of species were associated with the species or the impact that occurred at that location. To determine any taxonomic consistency in responses of corals to bleaching events or cyclones, empirical data on species level trends are needed that span many locations and impacts of different intensities.
Photoquadrats taken by Reef Life Survey divers represent a unique potential source of standardised data for identifying species-level responses of corals, allowing a general understanding of coral responses to heatwaves at a scale greater than previously considered possible. Archived photoquadrats are available from RLS surveys undertaken before and after the 2016 bleaching event at all major coral reef systems in Australia (e.g. Ningaloo, Rowley Shoals, Scott, Ashmore, Hibernia, Lord Howe, Elizabeth/Middleton and along the full spans of the GBR and Coral Sea). Most have not previously been scored, and were not otherwise going to allow assessment of coral cover for project D5 (coral cover was not an indicator possible for the national reefs case study for the last SoE either, due to the added expense required to score imagery). Images are typically used only for classifying biota into coarse functional and taxonomic classes, but with expert taxonomic assistance, many taxa (~150) could be accurately classified to species, allowing impacts on populations of these species to be assessed nationally. Such data would provide an invaluable input to the 2021 SOE report, added to the analyses of fishes and mobile invertebrates already underway (including trends for 600-1000 species), and form the basis for multiple scientific analyses (bioregionalization, threatened species assessment, impact assessment). The project will be able to test predictions based on species responses reported from particular locations and those made based on simulation studies or species traits.
To date, RLS photoquadrats have been annotated using coarse functional groupings, with the primary purpose of providing estimation of total live hard coral cover. Many images have not yet been annotated. This project specifically involves the annotation of available images by experts in coral identification (primarily Emre Turak, with input from James Gilmour, AIMS), with points scored to the highest possible taxonomic resolution. Not all coral species can be identified to species-level from images, but with Emre’s experience and arguably un-matched capacity to contribute, many species will be scorable (and those that aren’t can be flagged as such). While all scoring data will be valuable, the high-confidence species will be the focus of species-level analyses to be undertaken as part of project D5.
Specific Australian Marine Parks to be included are Ashmore Reef, Mermaid Reef and Coral Sea.