Biodiversity

The amount of diversity that is seen among global marine environments is also reflected in Australia’s own coastal regions.  

In the tropical north of Australia, coral reefs are in abundance across western, northern and eastern coasts. The Great Barrier Reef, located along the north eastern coastline of Australia, is the world's most famous tropical reef, and is the largest living structure on the planet. In fact, the Great Barrier Reef is over 340,000 square kilometres in size and supports an abundance of marine life, and plays an important role in providing vital ecosystem services.

In contrast, the temperate southern coastal regions of Australia are quite different to that of the tropics. While not as famous, the Great Southern Reef extends 8000km across the southern Australian coastline, and is home to an incredible diversity and abundance of life. Kelp and rocky reefs form the structure of this incredible reef system, which includes a huge amount of diversity including weedy and leafy seadragons, giant Australian cuttlefish, nudibranchs, blue ringed octopus, and many species of fish and echinoderms. Many species of marine mammals, including the southern right whale, humpback whale, Australian fur seal and Burrunan dolphins can all be found within this reef system. In fact, it is estimated that there is a higher rate of endemic species found within the Great Southern reef than in the Great Barrier Reef.

Currents of the Australian Ocean

There are four major currents found within the oceans of Australia. Local ocean currents are important for driving life within Australia’s coastal environments.

The East Australian Current (EAC) carries warm, tropical water southward along Australia’s east coast from Queensland to Tasmania. The EAC is approximately 100km wide, flows at depths of up to 500m, and is strongest during the summer moving at a flow of 5 knots (compared to 2 – 3 knots in winter). The Leeuwin Current carries warm tropical water southward along the Western Australian coastline and east along southern Australia, where it meets the Zeehan Current and continues south-east along the east coast of Tasmania. In far southern Australian waters, the Antarctic Circumpolar Current (ACC) is the largest current in the world, and flows in an easterly direction around the Antarctic continent connecting the Southern, Pacific, Atlantic, and Indian Oceans. Along the northern Australia coastline, the Indonesian Flowthrough moves westward carrying water from the Pacific Ocean into the Indian Ocean. 

Along with transporting water, the interaction between ocean currents and landforms create oceanic upwellings, bringing colder nutrient rich water to the surface which drive productivity and biodiversity. Ocean currents also promote the dispersal of life within coastal environments. While driving climate, ocean currents are also expected to change in response to climate change, with the movement and strength of oceanic currents changing as ocean temperatures increase.