Post-survey report: CANYONS - Cape Darnley paleoceanography from sediment cores IN2023_V01

The CANYONS voyage on R/V Investigator aimed to investigate past and present processes governing the flow pathways, formation and geochemical signatures of Antarctic Bottom Water (AABW) off Cape Darnley, East Antarctica. The proposed survey area was focussed on the Wild and Daly canyons and the adjacent sediment drifts - the Daly and ‘Armand’ drifts. The survey aimed to collect systematic multibeam bathymetry and sub-bottom profiles across the region to support collection of long sediment cores (up to 24 m), kasten cores and multicores, CTDs and deep towed camera transects. Due to a medical evacuation 5 days after arriving in the survey area we were only able to partially map the northern part of Wild Canyon and the ‘Armand’ Drift, collect 1 piston core (15.2 m), 2 kasten cores and 2 CTDs. Some seafloor images were also obtained from a camera system mounted to the CTD frame. Sediment cores were sampled for physical properties, microfossil content, biostratigraphic markers, ancient DNA and various geochemical signatures. Water samples from the CTDs were collected for hydrochemistry, biogeochemistry and environmental DNA. Analysis of these datasets is currently underway and forms part of several PhD projects. Underway water samples were collected during transit and within the survey area for hydrochemistry, biogeochemistry and environmental DNA (eDNA). In addition, a magnetometer was towed on the southward transit and a continuous plankton recorder on the northward transit. Aerosols were sampled throughout the survey for trace elements and bio-aerosols. Several Argo floats, including 2 biogeochemical Argo floats were deployed during the transit and in the survey area. We undertook two days of opportunistic science within Two Peoples Canyon offshore Albany following the medical evacuation. This work focussed on characterising the seafloor biota of this poorly known region by undertaking 2 deep tow camera transects and 1 biological dredge. We also collected 3 CTDs and 1 kasten core to understand the modern and past oceanography in the context of previous work in the region. Outreach was conducted throughout the voyage by our Sea2School program to Primary and High school students across Australia and internationally. We undertook public outreach via regular blogs, podcasts, posts to our CANYONS Twitter, Facebook and Instagram accounts and through media interviews. Many of the science team were early career researchers and post-graduate students. They gained not only first-hand experience and skills in undertaking marine science at sea, but also in responding and adapting to rapidly changing situations with grace and resilience.