The Western Bass Strait Shelf Transition is a

biogeographic Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

region of

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

's coastal and

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

waters. It is a transitional region between the cold-temperate Bass Strait Shelf and Tasmanian Shelf provinces and the warm-temperate Spencer Gulf Shelf Province. It is a provincial bioregion in the

Integrated Marine and Coastal Regionalisation of Australia The Integrated Marine and Coastal Regionalisation of Australia (IMCRA), formerly the Interim Marine and Coastal Regionalisation for Australia, is a biogeographic regionalisation of the oceanic waters of Australia's exclusive economic zone (EE ...

(IMCRA) system."A Guide to the Integrated Marine and Coastal Regionalisation of Australia Version 4.0". Department of Environment and Heritage, Government of Australia. June 2006. ISBN 0 642 552274. It is the southern portion of the Western Bassian

marine ecoregion A marine ecoregion is an ecoregion, or ecological region, of the oceans and seas identified and defined based on biogeography, biogeographic characteristics. Introduction A more complete definition describes them as “Areas of relatively homogen ...

in the

World Wildlife Fund The World Wide Fund for Nature Inc. (WWF) is an international non-governmental organization founded in 1961 that works in the field of wilderness preservation and the reduction of human impact on the environment. It was formerly named the Wo ...

's (WWF) Marine Ecoregions of the World system.

Geography

The Western Bass Strait Shelf Transition extends from

Cape Jaffa Cape Jaffa is a headland in the Australian state of South Australia located at the south end of Lacepede Bay on the state's south east coast about south west of the town centre of Kingston SE. The cape is described as being "a low sandy point" ...

in South Australia to the western end of the

Bass Strait Bass Strait () is a strait separating the island state of Tasmania from the Australian mainland (more specifically the coast of Victoria, with the exception of the land border across Boundary Islet). The strait provides the most direct waterwa ...

. It includes the southern

Limestone Coast The Limestone Coast is a name used since the early twenty-first century for a South Australian government region located in the south east of South Australia which immediately adjoins the continental coastline and the Victorian border. The ...

of South Australia, the western coast of

Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...

east to

Cape Otway Cape Otway is a cape and a bounded locality of the Colac Otway Shire in southern Victoria, Australia on the Great Ocean Road; much of the area is enclosed in the Great Otway National Park. History Cape Otway was originally inhabited by the Gadub ...

, and the waters around King Island as far as Tasmania's northwestern tip. The continental shelf is generally narrow, and the coast is subject to high-energy waves. It at the eastern end of the warm

Leeuwin Current The Leeuwin Current is a warm ocean current which flows southwards near the western coast of Australia. It rounds Cape Leeuwin to enter the waters south of Australia where its influence extends as far as Tasmania. Discovery The existence of the ...

, which weakens during the summer months, allowing nutrient-rich cold water

upwelling Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface. It replaces the warmer and usually nutrient-depleted surface water. The nutr ...

along the coast. During the winter the Leeuwin Current's influence makes the transition's waters warmer than those of the adjacent Bassian and Tasmanian provinces.

Ecology

The biota includes many cold-temperate species from the Bass Strait and Tasmanian provinces. Smaller numbers of species are shared with the warm-temperate Central Eastern Province further east, and the Southwest Shelf and Spencer Gulf Shelf provinces to the west.

Meso-scale bioregions

In IMCRA version 4.0, the transition contains a single meso-scale bioregion, Otway. In version 3.3 of the IMCRA, the Coorong bioregion to the northwest was also part of the transition, but version 4.0 includes it in the Spencer Gulf Shelf Province. The Western Bassian marine ecoregion, as delineated by the WWF, includes both the Coorong and Otway bioregions.

References

{{reflist Biogeography of South Australia Biogeography of Victoria (state) Biogeography of Tasmania Ecoregions of Australia Marine ecoregions IMCRA provincial bioregions Temperate Australasia Coastline of South Australia Coastline of Tasmania Coastline of Victoria (state)