- South Australia has the highest number of known sea squirts in the world?
- South Australia has some of the largest seagrass meadows in the world?
 |
| Sea squirt colony from Pearson Isand |
- South Australia is home to 85% of the population of endangered Australian sea lions?
- Whyalla has the world's only known cuttlefish breeding aggregation? And the giant Australian cuttlefish (Sepia apama) that gathers here to breed, are the world's largest cuttlefish species? And the upper Spencer Gulf population is probably a separate species?
Southern Australia's marine environment is unique with many more species than comparable areas elsewhere in the world. For some types of plants and animals there is a greater variety of species in southern Australia than can be found on tropical reefs or rain-forests around the world.
Up to 85% of the species found in southern Australia are endemic (only found here). If we do not protect these species in our own backyard then they will not be protected elsewhere.
Threats to the marine environment are ever increasing including impacts from climate change, invasive species, mining, dredging, over fishing and pollution from storm water and waste water discharge.
Undisturbed environments are known to be more resilient in the face of impacts and this highlights the need to act now if we are to protect our fragile marine resources.
For a recent overview of Australian marine biodiversity, this report provides an excellent summary of the knowledge of marine life in Australia's EEZ.
What makes South Australia so special?
There are four key conditions that contribute to making South Australia a marine biodiversity hotspot:
- It is in the middle of the longest south-facing coastline in the world, with ocean currents that have isolated marine life in SA for a long period of time (unlike the Great Barrier Reef, which shares most of its marine life with the Pacific Ocean).
2. South Australia has more than 150 offshore islands, most of which have nearshore ecosystems that are almost pristine.
3. We are privileged to have two of only three ‘reverse’ estuaries in the world: Spencer Gulf and Gulf St. Vincent. This term refers to the fact that these gulfs are more saline at their tips than they are at their open ends, due to no freshwater input at the top of either gulf. This gives the gulfs very special marine conditions, heating and cooling at their tips and margins to great extremes, much more so than open oceanic water. A variety of animals and plants have evolved to survive in these harsh conditions and some of them can live nowhere else.
4. Southern Australian waters are relatively low in nutrients when compared with similar temperate ecosystems around the world. Intuitively it would seem that low nutrient conditions would develop low species diversity, but on the contrary it is the opposite. This is so on land and in the sea. South-west WA is renowned for its unique and diverse plant life, which is due largely to the very low nutrient conditions in that part of Australia. The same is true for southern Australian marine life. To respond to low nutrient conditions, life evolved many millions of times over to cope with the enormous variety of conditions present in southern Australian waters.
