Research Vessel Tangaroa 2025 Ross Sea Antarctic “ACTUATE” Voyage, 15 January - 23 February 2025

In January-February of 2025 Aotearoa New Zealand’s RV Tangaroa completed the 40-day “ACTUATE” voyage - its 16th to Antarctica and the Southern Ocean. ACTUATE (AntarCTic soUthern oceAn scienTific rEsearch) was supported by funding from the Ministry of Business, Innovation, and Employment (MBIE), the Antarctic Science Platform (ASP), NIWA Strategic Science Investment Funds, University of Auckland, University of Otago, Victoria University Wellington, and overseas funding agencies (India’s CMLRE - Centre for Marine Living Resources & Ecology; U.K. NERC). The science objectives for the 2025 RV Tangaroa Voyage included hydrography, benthic ecology, fish eDNA, oxygen budgets and zooplankton. The voyage plan was designed to deliver research consistent with the Research and Monitoring plan for the Ross Sea region Marine Protected Area. The voyage succeeded in samping 253 stations, with more than 1100 water sample bottles, 72 DTIS camera deployments, 15 Hydrographic/biophysical mooring and 220 km ocean Glider mission. Notably, the voyage enabled RV Tangaroa’s farthest south science at 77° South in order to recover the RISIPE ice shelf cavity moorings deployed last year by a NZ team aboard the Italian RV Laura Bassi. In addition, the sea ice conditions meant we were able to map new benthic ecology distributions at Franklin Island, Ross Island and Coulman Island. There is growing interest in robotic monitoring and, along with the ocean glider mission, ACTUATE deployed 12 Argo profiling floats. Two of the floats were BGC-Argo units, funded by the ASP, with biological and biogeochemical sampling capability. There is at least one future RV Tangaroa voyage scheduled (January 2027) as part of the phase two of the ASP. International scientists interested in participating or collaborating on these future voyages are welcome to contact the authors of this paper for more information.