PARK WATCH September 2019 |

ReefWatch Project Officer Nicole Mertens takes us for a dive with a temperate twist.

Our other reef

There is no denying the cultural, environmental and economic benefits of the Great Barrier Reef – just as there is no denying the threats it is facing. But while most of us can conjure up a clear picture of the expansive, overlapping bright corals reefs teeming with colourfully patterned fish in tropical waters, many Victorians don’t realise that we have our very own beautiful and highly valuable reef system right here at our doorstep – in our cooler, or temperate, waters along our coast.

The Great Southern Reef is not a single, unbroken line of reef – rather a collection of thousands of kilometres of rocky substrate covered in habitat-forming organisms, and interconnected through currents and ecological processes. If this sounds less impressive, remember that the same goes for the Great Barrier Reef. In the case of our Great Southern Reef system, these rocky reefs are dominated by kelp forests that shelter a myriad of molluscs, some crustaceans and fish, as well as supporting other seaweeds, sponges and bryozoans. 

The Great Southern Reef has an exceptionally high percentage of unique species (endemic). Remarkably, somewhere in the range of 80 per cent of species (depending on their taxonomic group) found here are not found anywhere else in the world. 

An underwater wonderland anyone can visit

Unlike the Great Barrier Reef, the Great Southern Reef is easily accessible along most of the coastline it surrounds (see map opposite) and there are many places to see it even within the shallow waters of Port Phillip Bay. You’ll find amazing reef habitats and animals just offshore in the Ricketts Point, Jawbone and Point Cooke marine sanctuaries, and many other areas that can be accessed via swimming or a short boat ride. 

Outside of Port Phillip Bay, the Great Southern Reef is on display right along the Victorian coast –  in Merri Marine Sanctuary in the west of the state, fringing the Great Ocean Road, down around Phillip Island, Bunurong Marine Park and Wilson’s Promontory, and right across to Beware Reef in the state’s far east. Wherever you are on our magnificent coast, you’re never very far from the Great Southern Reef.

Along with temperate reefs, coastal Victoria is home to other important marine habitats seagrasses, sandy bottoms, mangroves and mudflats. While most would not consider these sites their ‘go-to’ for coastal exploration, you might be surprised at how many species they support; it can be fascinating to observe the differences in species using these varying habitats along the coast. 

Lack of awareness

Low levels of public knowledge of the very existence of this reef system may be putting it in peril. While the effects of climate change on the Great Barrier Reef are well publicised, the kelp forests of southern Australia are beginning to suffer in relative silence. A marine heatwave in 2011, combined with warmer than average water temperatures in the years that followed, caused massive losses to kelp forests in Western Australia and saw movement of tropical species into areas that once supported the state’s abalone and rock lobster habitats and industries. Kelp further to the south are surviving, for now, but researchers fear that this could change as ocean temperatures continue to rise. 

With 70 per cent of the Australian population living near the Great Southern Reef, it is also at risk of impacts from urban development and population growth. 

The Great Southern Reef is estimated to be worth 10 billion dollars in direct tourism alone – compared to estimates of 5.7 billion dollars for the Great Barrier Reef (of course, the real value of both ecosystems is worth more than can be assigned in dollar terms). Despite this, temperate reef studies receive a meagre fraction of the amount of funding spent researching threats to the Great Barrier Reef, and though there have been recent efforts to raise its profile, public awareness of the Great Southern Reef is still relatively low. 

Our marine life is spectacular

Southern marine species are often just as colourful and interesting as their coral reef-dwelling cousins. I’ve seen children and adults alike mistake a white-barred boxfish for a clownfish, unable to fathom that something so colourful (and made famous by the character Nemo) could be from anywhere other than the iconic Great Barrier Reef.

Taking part in our Great Victorian Fish Count is an exciting way to join the community of people who love and care for the Great Southern Reef and learn about the wonderful fish that live amongst it. 

This will be the 15th year of the state’s biggest marine citizen science event that sees divers and snorkelers hit the water to gather a snapshot of the fish, shark and ray species that live in Victoria’s coastal environment. Data from field surveys is uploaded to the Atlas of Living Australia to support citizen scientists, ecologists and natural resource managers in monitoring these largely understudied species. 

The 2019 Great Victorian Fish Count will be held from 16 November – 15 December. Groups with appropriately qualified snorkel or dive instructors may register with VNPA’s ReefWatch program to conduct a survey at their favourite patch. While many spectacular fish species can be found sheltering under jetties and piers that are often popular dive sites, it’s worth remembering natural coastal habitats are likely to be home to a different assemblage of species, such as fiddler rays, Port Jackson sharks, blue devils, and cowfish. The Fish Count data lets us compare the species that are found in natural and artificial habitats, as well as in protected and unprotected areas, so it’s important that we get a fair share of surveys from both. 

The fishy faces that call our Great Southern Reef home

The ornate cowfish, Aracana ornata, is the face of the 2019 Great Victorian Fish Count. This colourful fish (pictured on page 33) has a box-like shape and three sets of horns running along its head and body. They are covered in a rigid carapace of bony plates. Males are easily recognisable with their bright blue spots and stripes, orange tail, and a large yellow bump on their snout, while females have brown and yellow-white stripes. Another species on the Fish Count list, Shaw’s cowfish (Aracana aurita), looks quite similar, but the stripes on the heads of Shaw’s cowfish are more or less horizontal, while the stripes on the heads of ornate cowfish are more diagonal. The horns of ornate cowfish are also taller and narrower than Shaw’s cowfish. 

You can find both species on reefs and in seagrass beds in sheltered coasts throughout southern Australia – and searching for a glimpse is an excellent excuse to discover, explore and connect with our Great Southern Reef

 

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