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Marine heatwaves in the Great Barrier Reef and Coral Sea, their mechanisms and impacts on shallow and mesophotic coral ecosystems

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Created 20/01/2025

Updated 20/01/2025

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The Great Barrier Reef (GBR) World Heritage Area and adjacent Coral Sea Marine Park are under serious threat from global climate change. This study used sea surface temperature (SST) data to identify major marine heatwaves (MHWs) occurring in this region over the last three decades (1992–2022) and to map significant MHW events that have occurred between 2015 and2022. We investigated the mechanisms of the MHWs and identified potential coral refugia. MHWs in this region have increased in frequency, intensity and spatial extent. El Niño, especially when it is in phase with positive Indian Ocean Dipole, was the key remote driver leading to intense MHWs. However, the more recent strong MHWs (e.g., 2017 and 2022) occurred without these climatic events, signifying the impacts of long-term climate change and local drivers. We also found that reduced wind speed and shoaling mixed layer depth, often together with reduced cloudiness, were the main local drivers pre-conditioning these MHWs. Anomalous air-sea heat flux into the ocean, mainly controlled by shortwave solar radiation (cloudiness) and latent heat flux (wind), was the most constant contributor to the 2015–16 and 2019–20 MHW events. However, local oceanographic dynamics, especially horizontal advection and turbulent mixing, played important roles in MHW heat budgets. This study confirmed that shallow-water coral bleaching severity was positively related to the cumulative MHW intensity in these two MHWs. We identified the shallow reefs along the path of the North Queensland Current as potential coral refugia from bleaching because of the cooler waters upwelled from the ocean current. We also found that, except during abnormal weather events such as tropical cyclones, the mesophotic reefs in the Coral Sea Marine Park may be less susceptible to severe bleaching as the MHWs are more confined within the shallow mixed layer. Presented at the 30th Conference of the Australian Meteorological and Oceanographic Society (AMOS) 2024

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Title Marine heatwaves in the Great Barrier Reef and Coral Sea, their mechanisms and impacts on shallow and mesophotic coral ecosystems
Language eng
Licence notspecified
Landing Page https://devweb.dga.links.com.au/data/dataset/e54c1d09-60e6-46a1-9e35-62c0928e5b9f
Contact Point
Geoscience Australia
clientservices@ga.gov.au
Reference Period 01/08/2024
Geospatial Coverage {"type": "Polygon", "coordinates": [[[112.92, -54.75], [159.11, -54.75], [159.11, -9.2402], [112.92, -9.2402], [112.92, -54.75]]]}
Data Portal data.gov.au

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This dataset was originally found on data.gov.au "Marine heatwaves in the Great Barrier Reef and Coral Sea, their mechanisms and impacts on shallow and mesophotic coral ecosystems". Please visit the source to access the original metadata of the dataset:
https://devweb.dga.links.com.au/data/dataset/marine-heatwaves-in-the-great-barrier-reef-and-coral-sea-their-mechanisms-and-impacts-on-shallo1

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