Marine environment

Marine environment

With responsibility for an area of ocean larger than our land mass and a coastline stretching 70,000 km, Australia has the world’s greatest marine habitat and species diversity of any single nation. Among our marine treasures is the Great Barrier Reef – the world’s largest coral reef – with over 3,000 individual reef systems and coral cays.

Healthy oceans are essential to life on our planet. According to some estimates, green algae and cyanobacteria provide 45-70% of the oxygen produced on Earth.

$25 billion in value every year

While industries such as fishing, oil, gas and shipping profit from the oceans, the marine environment also provides an unrecognised $25 billion in value every year to our national economy in ecosystem services produced ‘free of charge’. These include carbon storage, fish nurseries and pest and disease control.

Coastline condition

Although the health of offshore waters and remote coastlines is generally good, inshore ecosystems near developed coastlines are in poor condition. Algal blooms occur regularly, levels of sediment and nutrients are high and in waters near intensive agriculture there are concerning levels of pesticides.


Many Australian fisheries are far from sustainable. Intensive fishing in the past and continued fishing practices mean most sought-after species are at low numbers and not recovering. Overfished species include southern bluefin tuna, orange roughy, gemfish, swordfish and some sharks. Destructive fishing techniques such as trawling – which ‘clear fells’ the seafloor of animals and plants – continue.

Habitat destruction

Other causes of marine habitat destruction include accelerating coastal urbanisation as well as infrastructure associated with mining, oil and gas extraction, and shipping.

Climate change

Climate change poses huge risks to the future health of the marine environment through rising ocean temperatures, acidification, sea level changes and an increase in extreme weather. Rising ocean temperatures lead to coral bleaching, which can cause the death of coral has already occurred on the Great Barrier Reef and been recorded on reefs at Ningaloo, Lord Howe Island and Rottnest Island.

Ocean acidification reduces the ability of some marine organisms to make shells. This can pose a risk to marine food chains, coral reefs, and the production of oxygen by microscopic marine organisms.


Tonnes of litter and debris end up in the oceans each year, killing and maiming birds, turtles and mammals such as dolphins, whales and seals. Animals are often killed by swallowing or becoming entangled in plastic.


Solutions to the challenges faced by our marine environment are diverse. The following is not an exhaustive list but rather a sample of the more important responses.

Protect marine ecosystems by:

  • creating a system of marine national parks or sanctuaries free of extractive uses – just like national parks on land. (This system should include each type of habitat and protect critical breeding, feeding and resting areas for our ocean life.)

Reduce and manage impacts on the marine environment by:

  • strengthening enforcement of laws and regulations
  • reducing land-based sources of ocean pollution, including agricultural chemicals and debris
  • stopping water quality decline by repairing land along nearby riverbanks, maintaining ground cover in river catchments and minimising agricultural run off
  • tightening controls on shipping in particularly sensitive areas such as the Great Barrier Reef and identifying solutions to other shipping issues such as ocean noise, increased turbidity and invasive species
  • limiting coastal development, including new port facilities in particularly sensitive areas
  • reducing carbon emissions
  • minimising the threats posed by invasive species.

Manage the impacts of oil, gas and mining by:

  • improving the way we manage accident risk including establishment of baselines, spill monitoring, modelling, forecasting, emergency response and environmental risk assessment
  • connecting oil and gas industry planning and regional environmental management
  • assessing and potentially stopping risks such as seabed mining for ores and heavy metals
  • assessing and managing risks associated with the expansion of shipping.

Manage the impacts of fishing and aquaculture by:

  • changing Australian fisheries so there are fewer boats but improved sustainability and profitability
  • banning destructive fishing techniques such as trawling
  • limiting destructive fishing by buying fishing licences
  • ending targeted shark fishing
  • addressing the impacts of recreational fishing as part of the overall management of Australian fisheries
  • creating a movement for sustainable fishing with information and tools for consumers and seafood suppliers
  • supporting the establishment of sustainable aquaculture focused on species that can be produced through lower impact systems and provide consumer advice on this.

Further the knowledge base on the marine environment by:

  • investing in marine sciences and research that improves management and builds our understanding of temperate and tropical marine systems.

Further reading