This dataset contains bathymetry products from the Lord Howe Rise 2D Seismic Survey undertaken by Geoscience Australia (GA) and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) during the period from8 of November 2017 to1stJanuary 2018 onboard the RV Kairei (Survey KR1715C). The Lord Howe Rise (LHR) is a submerged plateau that extends from southwest New Caledonia to the west of New Zealand. Much of the LHR lies within the Australian marine jurisdiction at water depths of 1000-3000m. The Commonwealth conducted a scientific seismic survey over the Lord Howe Rise in 2017 in collaboration with JAMSTEC. This collaboration contributes to a larger research proposal submitted to the International Ocean Discovery Program (IODP) that would provide the first deep stratigraphic record for the Cretaceous Eastern Gondwana Margin. The IODP proposal, if funded, is to drill a deep stratigraphic well to a depth of 2-3 km below the seabed, possibly in 2020. In order to select the drill sites, GA and JAMSTEC are conducting site assessments that involve a seismic survey in 2016 and a geotechnical survey in 2017. Multibeam bathymetry data were acquired during the survey covering an area of 69,190 km2. Five bathymetry grids of 70 to 90m resolution were produced using the shipborne 12 KHz sonar system.<p><p>This dataset is not to be used for navigational purposes.

This resource includes bathymetry data acquired during the Visioning the Coral Sea Marine Park bathymetry survey using Kongsberg EM302 and EM710 multibeam sonar systems. Visioning the Coral Sea Marine Park bathymetry survey (FK200429/GA4861) was led by Dr. Rob Beaman (James Cook University) and a team of scientists from Geoscience Australia, The University of Sydney, and the Queensland Museum, aboard the Schmidt Ocean Institute’s research vessel Falkor, from the 29th of April to 11th of June 2020. The primary objective of the survey was to map in detail the Queensland Plateau, including the steeper reef flanks and target the enigmatic seabed features, like the numerous drowned reef pinnacles and long meandering channels on the plateau surface. The second objective of this survey was to investigate the extent of the bleaching on the mesophotic or deeper reef, and if these reefs could act as a potential refuge for the Great Barrier Reef. The survey also aimed at providing insights into the geological evolution and biodiversity of Australia’s marine frontier. This dataset is not to be used for navigational purposes. This dataset is published with the permission of the CEO, Geoscience Australia.

This flythrough video highlights deep and mesophotic seabed environments within the Coral Sea Marine Park, offshore northeastern Australia. The mesophotic zone, commonly referred to as the ‘twilight zone’ represents the depth range below the brightly lit shallow waters down to the maximum depth that sunlight can penetrate for photosynthesis to occur (~ 30 to 150 meters beneath the sea surface). The featured Malay and North Flinders Reefs represent mid-ocean platform reefs and Cairns Seamount hosts a thriving coral reef community atop what is likely an extinct volcanic cone. These locations represent a range of benthic communities, which vary with depth and substrate type. Soft-sediments (sands, muds and oozes) dominate the deep seafloor, with evidence of water currents that produce bedforms showing active sediment transport at these depths. The walls and flanks of the platform reefs are very steep, with evidence of slope failure where rocky head walls have collapsed and deposited large blocks and boulders on the seafloor, which provide important habitat for sessile and mobile invertebrates including soft corals and sponges as well as cryptic octopus. Typical mesophotic habitats included vast Halimeda algal meadows and rhodolith beds interspersed with soft corals and sponges on soft-sediment. Hard substrates were typically colonised by plate and encrusting hard Scleractinian corals (e.g. Leptoseris and Montipora species), sponges and ascidians. Many large black corals (Antipatharia) and gorgonians (Octocorallia) also featured, with several black coral and carnivorous sponge observations representing new species. The reef community atop Cairns Seamount was highly diverse and included many demersal and pelagic fish species. A high abundance and diversity of gelatinous zooplankton were observed in the deep waters between reefs in the Coral Sea, with several new range extensions recorded. Bathymetry data and seafloor imagery for this flythrough were collected on RV Falkor, owned and operated by the Schmidt Ocean Institute (SOI), during surveys FK200830 and FK200902 in August and October 2020. These surveys were led by Geoscience Australia and James Cook University. Collaborative research partners included the Japan Agency for Marine-Earth Science and Technology, The University of Tokyo, Queensland University of Technology, Queensland Museum, The University of Sydney, University of Tasmania and the University of Wollongong.

<div>The iconic Great Barrier Reef (GBR) World Heritage Area and adjacent Coral Sea Marine Park are under serious threat from global climate change. Given the increase in the frequency, intensity and severity of mass coral bleaching events associated with marine heatwaves (MHWs) in this region it is essential that we improve our understanding of the drivers and mechanisms underlying&nbsp;MHWs and the extent to which they impact both shallow and deeper coral reef ecosystems. This study used coarse-resolution and high-resolution sea surface temperature (SST) data to identify all major MHWs occurring in the GBR and Coral Sea region over the last three decades (1992-2022) and map significant MHW events over the past seven years (2015-2022), respectively. We then investigated the mechanisms of these MHWs in relation to both remote and local drivers through statistical and heat budget analyses. Finally, we identified potential coral reef refugia in this region using aerial-survey coral bleaching data and Autonomous Underwater Vehicle (AUV) images, and examined their underlying mechanisms using ocean model and <em>in-situ</em> oceanographic data. The results confirmed that MHWs in this region indeed increased in frequency, intensity and extent over the past three decades. El Niño, especially when it is in phase with positive Indian Ocean Dipole, was found to be the key remote driver leading to significant MHWs. However, the more recent strong MHWs also tend to occur without these climatic events, signifying the impacts of long-term climate change. We also found that reduced wind speed and shoaling mixed layer depth, often together with reduced cloudiness, which can occur with or without the influence of remote drivers, were the main local drivers pre-conditioning these MHWs.&nbsp;Anomalous air-sea heat flux into the ocean, which is 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 local MHW heat budgets. Importantly, this study confirms that shallow-water coral bleaching severity was indeed positively related to the cumulative MHW intensity in the 2015-16 and 2019-20 MHWs. We identified the shallow reefs in the northern GBR along the path of the North Queensland Current as potential coral reef refugia from bleaching because of the up to 2 oC thermal relief that the ocean current provides. We also found that, except during abnormal weather events such as tropical cyclones, the mesophotic reefs in the Coral Sea Marine Park may also act as potential coral reef refugia from bleaching because of the thermal protection provided by the shallow mixed layer depth.</div><div> <b>Citation:</b> Zhi Huang, Ming Feng, Steven J. Dalton, Andrew G. Carroll, Marine heatwaves in the Great Barrier Reef and Coral Sea: their mechanisms and impacts on shallow and mesophotic coral ecosystems, <i>Science of The Total Environment</i>, Volume 908, 2024, 168063, ISSN 0048-9697, https://doi.org/10.1016/j.scitotenv.2023.168063.