Our marine environment

The South East marine environment consists of some of the most fertile waters along southern Australia’s coastline, supporting an amazing array of animal and plant communities and a diversity of intertidal and subtidal reef systems.

These communities thrive due to the annual Bonney Upwelling – an oceanic phenomenon which provides one of the richest marine ecosystems in Australian waters and supports local fishing communities. The upwelling occurs between December and May each year. South-easterly winds force shallow water out to sea and allow cold, nutrient rich water from the deep to move close to the shore. These nutrients are the foundation of a complex food chain and ecosystem.

It is also where two marine bioregions meet - the Otway and Coorong Bioregions.

The Coorong bioregion is a complex stretch of coastline which consists of a diversity of habitats including algal dominated reef interspersed with sandy habitats.

The Otway bioregion also contains a variety of unique environments with semi-enclosed bays containing seagrass, kelp beds, calcareous reefs and soft sediment environments.

The Otway and Coorong Bioregions are distinct marine environments, each with a rich and distinct ecology and biodiversity. For example, the algal diversity is one of the most diverse in the world and the marine flora and fauna in the cold temperate waters of the Otway Bioregion are unique in South Australia.

The marine habitats include calcarious platform reef systems at various depths, forms and covers. The reef’s abundant crevices provide microhabitats for a variety of organisms and invertebrate animals. Other marine habitats like the vast sea grass meadows, tall kelp forests and sandy bottomed expanses of the South East near-shore marine environment provide a mix of habitats, rich with marine species of all shapes and sizes.

Amazing diversity can be seen in the reef environments where octopus, molluscs (mussels and abalone), algae, squid, fish, crustaceans (e.g. crabs, rock lobster), invertebrates such as sponges, soft coral, star fish and urchins call home. Even South Australia’s own marine emblem, the Leafy Sea Dragon, can be found hiding behind kelp stands. These attributes are what makes the South East such a popular spot for diving, boating and fishing. This environment is extremely important to the region’s tourism and commercial fishing industries.

The karst rising springs, close to the border at places like Piccaninnie Pond, Eight Mile Creek or Ewans Ponds, pour mega-liters of freshwater into the sea creating a rare ecosystem of great diversity that is of international importance and is protection.  Migratory birds exploit these resources each summer, feeding and fattening up for their return journey to the northern hemisphere where they nest and raise their young.


Did You Know?

  • The largest single seagrass meadow in the South East (25,062 ha) is located in Lacepede Bay opposite the township of Kingston. Seagrass communities are very important as they provide key nursery, breeding, feeding and shelter environments for species such as King George Whiting, garfish, and snapper.
  •  Piccaninnie Pondsis now a RAMSAR site. This means it is a wetland of international importance and is protected.
  • Female Leafy Sea Dragons lay 100 to 250 eggs onto a special brood patch under the males tale where they are fertilised and incubated for 4 to 6 weeks. Baby sea dragons are independent from the day they hatch.

Issues and threats

  • Marine debris and wastes such as plastics, fishing lines and fish offal generated from fishing activities and general beach litter from the public can have a severe impact on marine species.
  • Seabirds can become entangled in discarded tackle and marine mammals can mistake floating plastics for food.
  • Introduced marine species threaten the regions local biodiversity but also the social and economic benefits received from the
  • Some pest species include the European Shore Crab, Asian Date Mussel and the Pacific Oyster.
  • Recreational activities such as boating (anchoring on reefs), harvesting for food and bait, walking and trampling, turning
    boulders over, spear fishing, collecting and netting in the intertidal zones also has a detrimental affect to this environment.
  •  Climate changeis a challenge the whole world faces. An increase in water temperature will change breeding cycles (i.e. timing,
    success rate and gender) of marine organisms. This will affect the survival of species and therefore shape the future of the fishing
    industry in the South East.
  • Discharge and industrial runoff release excess nutrients and pollutants into the marine environment. There is significant
    evidence of this where seagrass loss has been recorded opposite Drain M which flows into Rivoli Bay, at Southend.
  • Physical changes such as coastal development i.e. housing and marinas, breakwaters, boat ramps and other constructions which
    are positioned incorrectly can cause habitat degradation by disrupting the natural flows of sand and water.


Natural Resources South East is strongly committed to protecting, enhancing and learning about our marine life Further information on our coastal projects can be found in the left hand menu.

Related links

More information

  • Coast and Marine Officer
    08 87351177