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| Tasmanian Abyssal Plain | |
|---|---|
| Name | Tasmanian Abyssal Plain |
| Location | Southern Ocean |
| Type | Abyssal plain |
| Countries | Australia |
Tasmanian Abyssal Plain is an extensive deep-sea feature south of Tasmania within the Southern Ocean and adjacent to the Tasman Sea and Indian Ocean. The plain lies seaward of the Continental shelf and continental slope off Tasmania and is influenced by major currents such as the Antarctic Circumpolar Current, the Bass Strait outflow systems, and the East Australian Current. As a locus for seabed sedimentation, deep-water fauna, and mineral prospectivity, it figures in scientific programs led by institutions like the CSIRO, Commonwealth Scientific and Industrial Research Organisation and universities including the University of Tasmania and the University of Melbourne.
The Tasmanian Abyssal Plain occupies a sector south of Tasmania bounded to the west by the continental margin near King Island and to the east by the Tasman Fracture and features approaching the Heard and McDonald Islands projection. Neighboring marine provinces include the Southeast Indian Ridge corridor, the Macquarie Ridge, and the deeper troughs that connect with the Antarctic Basin and the Kerguelen Plateau. Bathymetric mapping by vessels from the Australian Antarctic Division and programs funded by the National Oceanic and Atmospheric Administration has refined limits where the plain grades into abyssal hills, submarine canyons linked to the Derwent River and Huon River drainage, and the geomorphic transition toward the Lord Howe Rise. Political proximity to the Australian Exclusive Economic Zone frames management discussions involving agencies such as the Department of Agriculture, Water and the Environment and the International Seabed Authority.
Basement beneath the plain comprises stretched Gondwana-derived continental fragments and oceanic crust emplaced during the breakup events recorded in plate tectonics between the Indian Plate and the Australian Plate. Volcanic highs and seamounts related to the Tasman Fracture Zone and Macquarie Triple Junction punctuate sediment drifts that include pelagic clay, turbidites sourced from the Tasmanian Gateway episodes, and glacially derived tills tied to Pleistocene sea-level cycles. Geological surveys by teams connected to the Geological Survey of Tasmania and the Geoscience Australia have identified manganese nodules, authigenic mineral deposits, and phosphatic horizons analogous to those documented at the Kerguelen Plateau and Southeast Indian Ridge. Structural frameworks reference paleogeographic reconstructions developed by researchers at the Smithsonian Institution and the Australian National University.
Circulation over the plain is dominated by the Antarctic Circumpolar Current and modified by eddies generated from the East Australian Current retroflection and interactions with the Macquarie Ridge. Water masses present include Antarctic Intermediate Water, Circumpolar Deep Water, and relics of North Atlantic Deep Water pathways, with thermohaline signatures measured in programs sponsored by the International Geophysical Year legacy projects and modern initiatives led by the CSRIO and the Bureau of Meteorology. Seasonal and interannual variability links to phenomena such as the El Niño–Southern Oscillation, the Southern Annular Mode, and teleconnections recognized by researchers at the CSIRO. Deep-ocean mixing, nutrient fluxes, and particle transport have been quantified in collaborative campaigns involving the Monash University oceanography groups and instruments deployed from research platforms like RV Investigator.
Benthic communities on the Tasmanian Abyssal Plain include suspension feeders, deposit feeders, and chemosynthetic assemblages associated with seeps and hard substrata around seamounts; taxa recorded mirror those cataloged in surveys by the Australian Museum and include representatives from the Porifera, Cnidaria, Echinodermata, Mollusca, and Arthropoda phyla. Megafauna observations documented by remote-operated vehicles from institutions such as the National Oceanography Centre reveal abyssal echinoderms, holothurians, deep-sea corals related to genera studied at the Smithsonian National Museum of Natural History, and endemic species likened to fauna from the South Tasman Rise. Microbial assemblages mediating biogeochemical cycles have been characterized by researchers at the Scripps Institution of Oceanography and the University of Tasmania, showing links to methane cycling and nitrification processes also studied around the Kermadec Arc and Juan de Fuca Ridge.
The plain has attracted interest for resources including polymetallic nodules, phosphorite, and potential hydrocarbon seeps, prompting assessment by companies registered with the Australian Securities Exchange and regulatory review by the Commonwealth Scientific and Industrial Research Organisation advisory panels and the International Seabed Authority. Fisheries interactions involve deep-water demersal species connected to licensed operations under frameworks influenced by precedents from the United Nations Convention on the Law of the Sea administered by the International Maritime Organization-linked regimes. Anthropogenic impacts include rising deposition of microplastics traced in studies involving the CSIRO and contamination signals comparable to those reported in the Southern Ocean Persistent Organic Pollutants research coordinated by the World Health Organization partner networks. Conservation measures reflect assessments by the Australian Government and proposals to include zones under protections akin to those designated by the Convention on Biological Diversity and the Commission for the Conservation of Antarctic Marine Living Resources.
Exploration of the Tasmanian Abyssal Plain follows a history of voyages by ships such as early 20th-century expeditions influenced by the Discovery Investigations and postwar surveys by the Australian Antarctic Division and international collaborations involving the National Science Foundation and the UK Natural Environment Research Council. Modern mapping and sampling use multibeam echosounders, ROVs, and autonomous vehicles developed at institutions like the Woods Hole Oceanographic Institution, Ifremer, and the Institute of Marine Research (Norway), and data contribute to global compilations coordinated by the Intergovernmental Oceanographic Commission and the Global Ocean Observing System. Key researchers and institutions involved include teams from the University of Tasmania, Geoscience Australia, the Australian Antarctic Division, Monash University, and international partners such as the Smithsonian Institution and the Scripps Institution of Oceanography.