Marine Protected Areas

South-east Commonwealth Marine Reserves Network

Geomorphology of the South-east Marine Region of Australia

The environment in the South-east Marine Region is exceptionally diverse. It encompasses shallow shelf, slope and deep water ecosystems that provide important habitats for a variety of bird and sea life.

Geologically the South-east Marine Region has been partly shaped by the catchments of Australia's major river systems from Victoria, Tasmania and the Murray-Darling Basin which take in a land area in excess of 1.2 million square kilometres. These river systems provide inputs into coastal ecosystems and have helped to shape underwater features at times of lower sea levels.

Map of Geomorphic features in the South-east Marine Planning Region

Examples of this are the canyon structures at the eastern end of Bass Strait and the spectacular Murray Canyons, a geological marvel bigger than the Grand Canyon. The water depth in the region varies from the vast shallow expanse of Bass Strait, averaging 60 metres deep, to the Hjort Trench, near Macquarie Island, where the sea floor lies 6700 metres below the surface.

Other key geological features of the Region include the upper continental shelf, where water depths are generally less than 200 metres, seamount structures off southern Tasmania, the sunken continental shelf known as the South Tasman Rise south of Tasmania, and the steep continental slope.

The South-east Marine Region has many unique and fascinating geomorphological features that shape the landscape, alter the currents and create places where animals and plants can live. These features include submerged mountains, canyons and ridges set against the vast, flat expanse of ocean floor. Much is yet to be discovered within this underwater 'landscape'.

Geomorphic features

The following table illustrates the geomorphic features in South-east Commonwealth Marine Reserve Network.

Geomorphic feature Total area in South-east Marine Region (Commonwealth waters) (km2) Area in new Commonwealth Marine Reserves (km2) % of feature in the new network
Shelf 91 107 6599 7.24%
Slope 249 986 68 001 27.20%
Abyssal-plain/deep ocean floor 539 335 92 768 17.20%
Bank/shoals 1341 0 0.00%
Basin 23 693 1761 7.43%
Canyon 40 195 8399 20.89%
Deep/hole/valley 21 010 1732 8.24%
Escarpment 5809 330 5.68%
Knoll/abyssal hills/hills/mountains/peak 7173 2673 37.27%
Pinnacle 733 381 51.98%
Plateau 98 570 17 706 17.96%
Ridge 5845 4959 84.84%
Saddle 30 443 5712 18.76%
Seamount/guyot 9088 7396 81.39%
Sill 2629 1315 50.04%
Terrace 22 335 3978 17.81%
Tidal-sandwave/sand-bank 5740 454 7.91%
Trench/trough 2088 2088 100.00%
Total area (km2) 1 157 119 226 458 19.57%

See also

Also in this section

Existing Commonwealth reserves under the EPBC Act

Marine Protected Areas

Temperate East Marine Region

Coral Sea

North-west Marine Region

South-east Marine Region

South-west Marine Region