AUSTRALIAN MESOPHOTIC
CORAL EXAMINATION

#TwilightCoral

04/09/2021 – 04/27/2021

Darwin, Australia

Chief Scientist: Dr. Karen Miller

Co-Chief Scientist: Dr. Nerida Wilson

Australian Institute of Marine Science, Western Australian Museum, University of Western Australia, Curtin University

Expedition objectives

Understand connectivity between mesophotic coral populations

Improve understanding of the biodiversity and biology of mesophotic reefs

Test new methods and technologies for monitoring the health of mesophotic coral ecosystems

While the waters of Australia are famous for shallow coral systems like the Great Barrier Reef, the deeper mesophotic (or twilight) coral ecosystems remain largely unknown and undocumented. Mesophotic coral ecosystems exist in depths between 50 and 200 meters and are hard to study without advanced technology like Remotely Operated Vehicles (ROVs). Mesophotic coral ecosystems are important as they hold unique biodiversity, provide ecosystem services and are a potential refuge for shallow water-species when they are facing stressors such as climate change.

The primary goal of the voyage was to learn more about mesophotic reefs on Australia’s NW shelf, particularly in Ashmore Reef Marine Park. The research conducted by Dr. Miller and collaborators helped scientists and park managers better understand the diversity and significance of the mesophotic reef Ecosystems. A better understanding of these ecosystems will help inform managers of the importance of protecting and managing the naturally valuable ecosystems of the park.

R/V Falkor circumnavigated Ashmore Reef Marine Park, fully mapped its entire mesophotic zone, and ROV SuBastian captured 4K imagery of the incredible ecosystem diversity including Halimeda beds, coral habitats, sponge gardens, and sand banks. The team conducted 148 hours of ROV surveys and tested the use of hyperspectral and 3D model imaging systems to assess the health of the mesophotic communities and assist in identification of marine species. Additionally, the team obtained and filtered 56 water samples for eDNA and collected over 100 mesophotic coral samples for onshore genetic and physiological studies.

Several new species may have been documented at Ashmore Reef and new records were made in Australia for several other species. One such record was a range extension for the Great Spotted Cowrie (Perissersoa guttata).