The Great Southern Reef

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The Great Southern Reef is the catalyst for many of Australia’s most famous underwater experiences and encounters 

The Great Southern Reef

Ask any interstate diver about South Australia and they will probably mention one of three things to you that they know about diving here – Great White Sharks, Leafy Sea Dragons and Giant Cuttlefish.

While each of these remarkable creatures varies wildly to the next in form and function, they all owe their uniqueness and specialization to one powerhouse of an entity: The Great Southern Reef. However, until recently the importance, dynamics, beauty and richness of this huge reef system was largely unrecognized and much still, remains undiscovered.

The Great Southern Reef

So, what is the Great Southern Reef and why dive it here in South Australia? While Australia is famed for its spectacular tropical coral reef systems, found in places like Ningaloo in Western Australia, and the Barrier Reef in Queensland, to the South of these destinations lies cooler waters that are rich in nutrients which feeds one of the most powerful, productive temperate ecosystems on the planet.

Consequently, its full of unique lifeforms. So, for divers, this huge natural powerhouse gives ample opportunity to discover new destinations and animals not seen anywhere else in the world. So, where do you start!? Let’s look at what makes The Great Southern Reef so…well, GREAT!

The Great Southern Reef

Bordering almost half of Australia’s land mass the Great Southern Reef covers approximately 71,000 square kilometers and rivals the Great Barrier Reef for size and diversity. Its 8000-kilometer network of reefs reach along Australia’s southern coastline and see it encompass five different states, from New South Wales on the east coast, right around to Kalbarri, 500kms north of Perth, in Western Australia.

Geographically, as far as ice-free coastlines go, it’s the longest continuous temperate coastline in the southern hemisphere and because it runs east to west, the average mean temperature difference is relatively small across the whole length of the reef. The range of habitats that adjoin the Reef also vary from protective mangroves and mudflats, to exposed, energetic rocky coastlines, sheltered reefs, towering kelp forests and sandy beaches.

The Great Southern Reef

Within this temperate ocean reef system, bioregions have also formed. In South Australia, this is due to two distinct currents and its geography. The most dominant is the Leeuwin current.  Warm waters forge their way south, along Western Australia’s coast, turning at Cape Leeuwin to head east across the Great Australian Bight. Covering a significant length of the overall Great Southern Reef, these warm temperate waters reach all the way to Kangaroo Island and the west coast of Tasmania.

Here it meets the cool temperate upwelling waters of the Flinders current from the south-eastern oceans of Australia. Pushed up from the continental shelf off the coast, it brings cold nutrient rich water to this area. Both these currents mix around Kangaroo Island making this area a very, productive and distinct marine environment. Testament to this is the well-known Lobster, Abalone and fishing industries that have developed, and the Sea Lion colonies of the Neptune and Pearson Islands. All supported by the abundant fish life found there.

The Great Southern Reef

The most unique region of South Australia’s portion of the Great Southern Reef are the two Gulfs: Spencer Gulf, the home of the Giant Cuttlefish migration and the Gulf of St Vincent of which the capital city Adelaide overlooks. What is unique about these Gulfs, is that during the warmer parts of the year, they effectively become isolated marine environments.

Water, warming and evaporating, raises the salinity, water density and average temperature, creating a boundary where the open ocean currents don’t mix as easily. This seasonal ‘isolation’ as well as the relative geographical isolation of the Gulfs has meant flora and fauna, often found nowhere else, have continued to evolve and exploit this area. This makes it a mecca for macro photographers looking for something different to add to their experiences.

The Great Southern Reef

Here in the Gulfs, fantastic shore diving exists from Jetties that reach out into these Southern Temperate Waters. As well, there are many reef and wrecks that scatter the coastlines, easily accessible by boat. The wrecks act as artificial extensions of the Rocky Reef system and allow divers to explore the life that settles in the deeper reaches of the Great Southern Reef.

Despite these varying bioregions when you drop under the surface at any one of the shore, or off-shore dive sites, apart from the temperature difference to the tropics, there is one main feature consistent with the entire reef and underpins its entire ecology. The blue-green waters are beautifully contrasted with one of my favorite Kelps, the Golden Kelp, Ecklonia radiata.

The Great Southern Reef

This key species of Kelp is the backbone of The Great Southern Reef and is also its most visually identifiable feature. It creates shelter, food and habitat for breeding for a huge range of species in the ecosystem. Ecklonia radiata is a species that is found the entire length of the Reef, working like a forest canopy for the life that resides under it. If you are not one for packing the macro camera or searching for the tiny things, these kelp beds offer up some ruggedly beautiful underwater landscapes to immerse yourself in.

If the marine micro world doesn’t appeal and swaying landscapes of Kelp aren’t your thing and you need even more variety you can also choose between many accessible Wrecks encrusted with sponges, offshore Sponge Gardens and shallow Seagrass Meadows. All these diverse landscapes make up the Great Southern Reef.

The Great Southern Reef

Fortunately for divers, depending on what you are looking for much of the Great Southern Reefs productivity, color and energy exists in the relatively shallow coastal waters, less than 30 meters deep, allowing many easy opportunities to discover and explore what resides in this significant reef. With so much variety and uniqueness to be found, how do you go about diving this magical part of the Great Southern Reef?

When I can escape from my daily grind and look to recharge, I am fortunate that I can easily immerse myself in this dynamic world and what it has on offer. Most of the diving is within an hour of my home in Adelaide, either by car to a shore dive, or by boat to one of the many Wreck or Reef systems. Accessibility is a big reason for visitors to dive the Great Southern Reef while here. It’s a huge drawcard having such an amazing Reef system, and the variety of habitats not found in the tropics, right here on your doorstep.

The Great Southern Reef

Flying or driving into Adelaide you want to make your first port of call a dive shop. Most shops offer Boat Schedules, Group Shore dives and Personal Guiding services to get you to where you want to go. You only need to bring your wish list, and what you want of your dive gear as hiring what you need can be easily arranged. My personal preference would be to get yourself a professional guide and talk to them about what you want to see. They will be best informed to make the pick of the best sites and conditions to match your wish list.

The next big question to ask yourself is what do you want to see?! Kelps Reefs, Sponge Gardens, Grass Meadows or Wrecks? The variety of life and dive sites that the Great Southern Reef supports is amazing.

The Great Southern Reef

If you are here for the Kelp reefs that are home to the iconic Leafy Sea Dragon, you might head down to dive the beautiful kelp wall of Victor Harbors “The Bluff” dive site. While there don’t miss seeing the beautiful serpentine male Herring Cale sliding through the kelp or sneak a peek at a Crayfish or two.

Perhaps what you prefer is color, so some offshore sponge walls are in order? My pick being the Aldinga Drop Off, a beautiful wall located in the Encounter Marine Park Sanctuary Zone. Here you will find Blue Devils, Nudibranchs, Gorgonian Fans and a rainbow of colorful sponges all vying for access to the nutrients in the passing current.

The Great Southern Reef

Maybe you have read about South Australia’s treacherous maritime history and you wish to explore one or more of the many historic wrecks sitting just offshore? Encrusted with beautiful sponges and home to schooling and pelagic fish you can get your fill of wide-angle and macro on many of these dives whilst indulging your thirst for some maritime history.

Top of the list here for many is diving the ex-HMAS Hobart. A 133-meter missile destroyer that saw active service with the Royal Australian Navy until it’s decommission in 2000. Sitting in 30 meters and exposed to strong nutrient rich currents means it’s covered in anemones and sponges and a refuge for Reef Fish, large Snapper and Wrasse that hang out with you on your safety stop.

The Great Southern Reef

For something more relaxed and family inclusive, you might prefer the shallower dives that let you explore the vibrant green Seagrass Meadows that edge the shallower parts of the Great Southern Reef. Wool Bay, Port Victoria and Port Hughes are perfect destinations for a trip away and some slow diving in the grasses where Sting Rays are found foraging for crabs and Pipefish watch your every move.

There is so much to explore of this reef system that I have hardly scratched the surface. As divers wanting to explore a new world, to see something different, or add something to their ‘bucket list’, these cooler temperate waters, in my opinion, couldn’t be more enticing and so ruggedly beautiful. The more I dive into the Great Southern Reef, the more I learn and discover. It’s why I fell in love with diving here.

The Great Southern Reef

Whatever your desire, well-equipped dive shops have boats, schedules and knowledgeable, passionate professionals to introduce you to South Australia’s part of the Great Southern Reef and now there couldn’t be a better time to do it.

With overseas travel restrictions looking set to be in place for some time to come, and divers needing to get their intrepid fix of nature, this rugged, challenging and beautiful reef will get more visitors and the attention and appreciation it deserves – and very much needs. Thankfully through science, diving, photography and tourism it’s profile is lifting and it’s getting more protection.

The Great Southern Reef

In a strange turn of events COVID has had some positive impact. By turning people to look to their own backyards for adventure and new experiences, more and more people are discovering that there is more than one Great Reef system in Australia. Come down and explore it sometime.

Written by Chelsea Haebich

Photo Credit: Chelsea Haebich

For the latest issue of Scuba Diver click here Scuba Diver ANZ issue 30

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