South-west Marine Atlas

The South-west Marine Atlas is an interactive mapping tool that displays information about the biodiversity and physical characteristics of the South-west Marine Region and the human activities which occur in the area. It will enable you to search for, and view information in your specific area of interest. It is not intended as a primary source of data for research purposes.

The maps below are a selection from the South-west Bioregional Profile. Further detail about the information contained within these maps is available from the South-west Bioregional Profile.

Bioregions

Australian waters have been classified into 41 provincial bioregions, comprising 24 provinces and 17 transitional areas. Bioregions provide a spatial framework that represents broad-scale distribution patterns of seafloor features, marine life and ocean conditions. They are large areas of ocean, considered to be ecologically similar, compared to other similarly sized areas. For further information see the brochure on Integrated Marine and Coastal Regionalisation of Australia.

The Government recognises 7 provincial bioregions in the South-west Marine Region, from the cool, temperate waters of the Great Australian Bight to the warm waters of the mid-Western Australian coast around Shark Bay. For more information about the bioregions of the South-west Marine Region, refer to the Chapter 2 of the Bioregional Profile.

Southwest Shelf Transition

(PDF - 608 KB)

The Southwest Shelf Transition is a near-shore bioregion that covers the area of continental shelf from Perth to Kalbarri, and extends out to the edge of the shelf. The Leeuwin Current has a significant influence on biodiversity here, as it pushes subtropical water southward along the western edge of the bioregion. Ridges and inshore lagoons characterise the seafloor of the continental shelf. The bioregion has high biodiversity and contains a large number of species that are found nowhere else in the world.

The Houtman Abrolhos Islands, off Geraldton, are renowned for their high species diversity, coral reefs and unique mix of temperate and tropical species. They are also important breeding sites for seabirds, and are the northernmost breeding site for the Australian sea lion. The western rock lobster is an iconic species of the bioregion with an important trophic role for a range of inshore species that prey on juvenile lobsters.

Central Western Province

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The Central Western Province extends offshore from the Southwest Shelf Transition to the limit of the Exclusive Economic Zone (EEZ).

It is characterised by a narrow continental slope incised by many submarine canyons and the most extensive area of continental rise in any of Australias marine regions. A significant feature within the bioregion is several eddies, hundreds of kilometres in diameter, that form off the Leeuwin Current at predictable locations. The eddies are ecologically important because they are associated with enhanced productivity in surface waters.

The bioregion includes the Perth Canyon, the largest of Australia's submarine canyons, which marks the southernmost boundary for numerous tropical and sub-tropical species. Perth Canyon also appears to be an important area for blue whales and other deep-diving whales that feed around the rim of the canyon. The demersal fish communities on the continental slope of the bioregion are characterised by relatively high biodiversity and include at least 31 endemic species.

Southwest Shelf Province

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The Southwest Shelf Province is a nearshore bioregion that extends from Rottnest Island to Point Dempster, approximately 185 km east of Esperance. Around the southwest corner of Australia, the Leeuwin Current changes direction from a southbound to an eastbound current. The bioregion is characterised by sub-tropical species in the north and temperate species along the southern extent. Species diversity of seagrasses and macro-algae is very high.

A small upwelling of nutrient-rich water off Cape Mentelle increases productivity locally, and this attracts aggregations of marine life. The sheltered waters of Geographe Bay support extensive seagrass beds that in turn provide important nursery habitat for a range of marine species. Further east, the Recherche Archipelago supports high species diversity of fish, molluscs, sponges and macro-algae. The islands provide shelter for marine communities and important haul-out and breeding sites for Australian sea lions and New Zealand fur seals. The sheltered bays along the south coast are important southern right whale calving areas.

Southwest Transition

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The Southwest Transition is a deepwater bioregion that extends offshore from the Southwest Shelf Province to the limit of the EEZ. The main features of the bioregion are the Naturaliste Plateau (the deepest submarine plateau along Australia's continental margins), and the deep water mixing that results from the dynamics of major ocean currents when these meet the seafloor.

Unusually deep eddies are known to form offshore of Cape Leeuwin, where some interact with the shallower parts of the Naturaliste Plateau. There is little available information on biological communities of the bioregion however, information on demersal fish communities indicates that it is an area of transition between those communities found in the Central Western Province and those of the Southern Province. Scientists also speculate that the marine communities associated with the Naturaliste Plateau may have high species diversity and endemism.

Great Australian Bight Shelf Transition

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The Great Australian Bight Shelf Transition, from Point Dempster (185 km east of Esperance) to Ceduna, includes a particularly wide area of continental shelf. Ocean currents flowing through the bioregion display marked seasonal patterns, particularly on the inner shelf. Marine life in this bioregion predominantly comprises temperate species of flora and fauna. The benthic invertebrate communities found on the inner shelf are among the worlds most diverse in soft sediment ecosystems. The inner shelf is also an important area for Australian sea lions that rest and breed on the rocky shores of the Bight and on numerous small islands in the eastern parts of the bioregion.

The Head of Bight represents a hot-spot of productivity and is an important calving area for southern right whales. Ecosystems representative of this bioregion are protected in the Great Australian Bight Marine Park, which extends across state and Commonwealth waters and is one of the largest Commonwealth marine reserves.

Spencer Gulf Shelf Province

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The Spencer Gulf Shelf Province extends over the continental shelf between Ceduna and Cape Jaffa. The bioregion straddles the South-east and South-west Marine Regions. A complex coastline of gulfs, peninsulas and islands characterise the bioregion. Ocean currents flowing through display marked seasonal patterns, particularly on the inner shelf.

Marine life comprises a mix of warm and cold temperate species, including New Zealand fur seals, Australian sea lions, little penguins and pygmy blue whales. The bioregion also features a number of local, seasonal upwellings of nutrient-rich water. Pygmy blue whales feed on krill aggregations associated with an upwelling west of Kangaroo Island, known as the Kangaroo Island pool a hotspot for marine productivity. Spawning aggregations of a number of commercially fished species are also found in this area. The shield islands, characteristic of the bioregion, provide shelter for marine life.

Southern Province

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The Southern Province extends from the continental shelf break south of Kangaroo Island to the southern edge of the Naturaliste Plateau. It is the largest bioregion and has the deepest waters in the Australias EEZ reaching a depth of 7390 metres. The bioregion is characterised by a long continental slope incised by many well-developed submarine canyons, two extensive mid-slope terraces and the Diamantina Fracture Zone.

The Diamantina Fracture Zone is a rugged area of deep seafloor consisting of numerous ridges and troughs. The submarine canyons in the area south of Kangaroo Island appear to be important for biological productivity, spawning and aggregation for a range of marine species.

The Albany Group of submarine canyons are also considered important for biological productivity that attracts feeding aggregations of fish and mammals. A representative transect of the seafloor environment of this bioregion has been captured in the Benthic Protection Zone of the Great Australian Bight Marine Park.

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