Straits of the Southern Ocean

Straits of the Southern Ocean
Name	Straits of the Southern Ocean
Location	Southern Ocean
Type	Straits and channels

Contents

Straits of the Southern Ocean are the network of narrow marine passages, channels, and sounds that connect basins within the Southern Ocean and link the Southern Ocean with adjacent seas such as the South Atlantic Ocean, South Pacific Ocean, and Indian Ocean. These passages include named straits around Antarctica, the Subantarctic Islands, and along the southern margins of South America, Africa, Australia, and New Zealand. Many of these waterways have been central to the routes of explorers like James Cook, Roald Amundsen, and Ernest Shackleton, and have influenced climatic, ecological, and geopolitical patterns involving entities such as the Commission for the Conservation of Antarctic Marine Living Resources and the International Maritime Organization.

Geography and definitions

Geographical definitions of straits and channels in the Southern Ocean vary among cartographers from institutions like the British Admiralty, the United States Board on Geographic Names, and the Scientific Committee on Antarctic Research, with delineations influenced by features catalogued in the GEBCO atlas and mapping projects by Australian Antarctic Division and Instituto Antártico Argentino. Prominent regional groupings include straits adjacent to Antarctic Peninsula, passages between South Georgia and the South Sandwich Islands, and channels among the Kerguelen Islands, Prince Edward Islands, and Heard Island and McDonald Islands. Hydrological definitions reference bodies recognized by the International Hydrographic Organization, while maritime jurisdictions invoke conventions such as the United Nations Convention on the Law of the Sea administered by the United Nations.

Major named passages that form part of Southern Ocean navigation include the Drake Passage between Cape Horn and the South Shetland Islands, the Falkland Sound near the Falkland Islands, the Bransfield Strait separating South Shetland Islands from the Antarctic Peninsula, the Gerlache Strait and Lemaire Channel along the Antarctic Peninsula coast, the Prince Gustav Channel and George VI Sound, the McMurdo Sound adjacent to Ross Island and McMurdo Station, and the Scotia Sea passages linking to South Georgia. Additional corridors include the waters around Bouvet Island, the passages between Kerguelen and Crozet Islands, channels near Macquarie Island, and routes among the Auckland Islands, Campbell Island, and Chatham Islands of New Zealand.

Geological formation of Southern Ocean straits reflects plate tectonic processes involving the Antarctic Plate, the South American Plate, the African Plate, the Australian Plate, and the Pacific Plate, with seafloor spreading at features such as the Antarctic Ridge and fracture zones like the Southwest Indian Ridge and Pacific-Antarctic Ridge. Glacial and interglacial cycles tied to events recorded at Vostok Station and EPICA cores carved troughs and fjords, producing isostatic adjustments documented by research from Scott Polar Research Institute and Lamont–Doherty Earth Observatory. Sedimentological studies by expeditions of the RV Nathaniel B. Palmer and RV Polarstern show submarine channels formed by turbidity currents similar to deposits studied in the Weddell Sea and Ross Sea basins.

Oceanographic regimes in Southern Ocean straits are dominated by the Antarctic Circumpolar Current, with mesoscale eddies, frontal systems like the Subantarctic Front and Polar Front, and interactions with gyres such as those influencing the South Pacific Gyre and South Atlantic Gyre. Exchanges across straits affect thermohaline circulation components connected to research from Scripps Institution of Oceanography and Woods Hole Oceanographic Institution, while observational programs by ARGO floats and SOCCOM profilers track variability in properties noted by Intergovernmental Panel on Climate Change assessments. Wind forcing from systems such as the Southern Annular Mode drives upwelling in channels studied in work affiliated with British Antarctic Survey and the National Oceanic and Atmospheric Administration.

Ecological communities in and around these straits support fauna recorded by the Commission for the Conservation of Antarctic Marine Living Resources, including populations of Antarctic krill (Euphausia superba), minke whales, antarctic fur seals, king penguins, and Adélie penguin colonies connected to islands like South Georgia. Benthic habitats host taxa monitored by programs from Monterey Bay Aquarium Research Institute collaborations and protected areas under regimes such as the Convention on the Conservation of Antarctic Marine Living Resources. Phytoplankton blooms influenced by iron inputs studied in SOFeX and JGOFS programs underpin trophic webs involving seabirds tracked by BirdLife International and mammal surveys conducted by IUCN evaluations.

Exploration history of these passages involves voyages by Ferdinand Magellan (Atlantic–Pacific precursors), Francis Drake (circumnavigation precedents), James Cook (first southern crossings), polar expeditions by Roald Amundsen, Ernest Shackleton, and Robert Falcon Scott, and scientific voyages such as the Discovery Investigations and Operation Tabarin. Sealers and whalers from United Kingdom, Norway, Argentina, and Chile exploited routes near South Georgia and South Shetland Islands in the 19th and 20th centuries, prompting cartographic efforts from institutions like the Hydrographic Office. Modern navigation uses ice forecasts from National Snow and Ice Data Center and satellite services provided by European Space Agency and NASA.

Human uses include scientific research from stations such as McMurdo Station, Mawson Station, and Palmer Station, tourism operations regulated by the International Association of Antarctica Tour Operators, and limited fisheries managed through the Commission for the Conservation of Antarctic Marine Living Resources. Environmental protection frameworks include the Antarctic Treaty System, the Madrid Protocol (Protocol on Environmental Protection to the Antarctic Treaty), marine protected areas proposed under CCAMLR, and global agreements like the Convention on Biological Diversity. Stakeholders such as Argentina, Chile, United Kingdom, Australia, and New Zealand engage in governance, while scientific collaboration involves networks including the Scientific Committee on Antarctic Research and universities such as University of Cambridge, University of Tasmania, and University of Cape Town.