Perth Canyon is Australia's second largest submarine canyon, and its elongate and continental shelf-incising morphology contrasts with Australia's more prolific slope-confined canyons. The canyon's sinuous course extends for 120 km from the continental shelf break (~180 m depth, only 50 km offshore from Perth) to its fan at the foot of the continental slope (~4500 m). This seminar will describe the application of a new, internationally-collaborative mapping approach to capture the complexity of the canyon and to link its modern morphology to subsurface data and thereby reconstruct its geological evolution. Infilled incised valleys found in seismic data beneath the canyon headwall suggest that the canyon initially incised in the Late Cretaceous (around 70 million years ago), and subsequent incisions and canyon activity have since declined in scale. Repeat surveys of the canyon headwall following two relatively large earthquakes in 2018 reveal minimal instability of the seafloor and suggest that the canyon is now less active than in it has been in its geological past.

Survey FK200308 on the R/V Falkor undertook detailed mapping within two significant and biologically unexplored submarine canyons (Cape Range and Cloates Canyon) in the Gascoyne Marine Park. The Gascoyne Marine Park covers 81, 766 km2 adjacent to the Ningaloo Marine Park. The canyons form part of the habitat protection and multiple use zones of the marine park and are identified as Key Ecological Features. The canyons provide an important connection between the abyssal plain environments and the Commonwealth waters adjacent to Ningaloo Reef on the continental shelf. High productivity aided by upwelling through the canyons has been related to aggregations of whale sharks, manta rays, humpback whales, sea snakes, sharks, large predatory fish and seabirds. In addition, the hard canyon walls provide habitat for a range of sessile invertebrates, while the soft sediments on the canyon floor support a range of mobile invertebrates. The data from this survey will provide a comprehensive taxonomic survey to characterise the marine biodiversity of the canyons or to understand the distribution of canyon habitats in relation to the seabed morphology. The SuBastian ROV was used to acquire high-resolution video and collect samples. SuBastian is a custom-built work class ROV that conducts scientific work down to 4500m. It is equipped with a Sulis Subsea Z70 deep sea science camera with 4K UHD 2160p optics and sensors for temperature, depth, conductivity and oxygen. Twenty ROV dives were completed across 16 stations, and these included 12 quantitative imagery transects within the Cape Range Canyon. No quantitative transects were conducted in the Cloates Canyon. The quantitative transects were run for 500 m upslope, ideally at a speed of 0.3 knots and an altitude of 2 m above the seafloor or rock walls.