Patagonia NZ

One of the key species that calls the GSR home is Macrocystis pyrifera, known to you and me as giant kelp. It’s a remarkable organism, growing in dense stands, converting sunlight and nutrient rich water into colossal forests. Individual strands can grow to 45 metres or more, and when conditions are perfect, the giant kelp can grow up to 60cm a day. The giant kelp is a foundation species of the GSR, creating a unique ecosystem in which countless other species thrive. The kelp creates a three-dimensional underwater habitat, providing sustenance and shelter for a complex interconnected web of life. They are critical hatcheries, protectors from coastal erosion and are powerful and prolific sequesters of carbon. Their presence underpins enormous cultural, environmental and economic value.

But after millennia of relative stability, change is afoot.

Back to my dive, enraptured by this miniature universe of life, I fin around the deepwater side of a large reef. Where the cold water failed to take my breath away, the scene before me succeeds. Where moments ago, there was a rich web of life, now there is endless white rock disappearing down into the blue void of the open ocean.

An urchin barren.

The white rock is dotted with black, spiny shapes. They are the globular bodies and spiny, protective shells of Centrostephanus rodgersii, commonly known as the long-spined sea urchin or ‘centros’. On closer inspection, the centros have inky, dark-red bodies and radiating, needle-like, iridescent green spines. When seen tucked amongst healthy reef they are beautiful, but here in a barren, they are tragic.

Native to inshore waters of northern NSW, centros can happily coexist with other species of the reef. Herbivores, they use their long spines to secure themselves into cracks and crevices in the reef where they graze on the seaweeds they cohabitate with. Their populations are controlled by predators such as the crested horn shark, the Port Jackson shark and the Eastern rock lobster. However, when centro populations grow unchecked, they can eat so much that they strip the reef of all seaweed and then maintain the urchin barren by grazing on any algae that tries to take a foothold on the rock.

So how did this native species of echinoderm go from reef resident to kelp clear cutter?

In the case of the disappearing giant kelp forests of the GSR – particularly those along the east coast of Tasmania, where it’s estimated only 5 per cent of the original giant kelp forests remain – shifting environmental conditions caused by anthropogenic climate change is altering the ecology at a rate the marine life of the GSR is struggling to keep stride with.

Oceans drive our climates around the world, with the East Australia Current (EAC) being a major force along the east coast of Australia. The EAC is like an oceanic river, collecting warm, nutrient poor water from the Coral Sea, before flowing down the east coast where it meets the cold, rich waters of the Southern Ocean. It historically diverts from its southward journey around 200 nautical miles north of Sydney, creating eddies and flows that stir up deep water nutrients, creating the rich oceanic conditions that support the biodiversity of the Tasman Sea.

The waters of the Tasman however have become warmer and saltier over the past 70 years. It’s actually one of the fastest warming places on earth, with a strengthening EAC thought to be the main driver. As the water temperature and intensity of the EAC increases, it pushes further south than its traditional limits, bringing warmer water and delivering new species to new regions, such as the east coast of Tasmania. The larvae of the urchins have been highly successful at riding this southbound current, landing in new habitat and then proliferating.

After wrapping up my dive, I get on the phone to get a better understanding of the collapse of biodiversity that’s taking place out of sight, under the waves.

My first call is to Wally Stewart, a Walbunja man from Narooma and a long-term campaigner for the recognition of native title over Sea Country in southern NSW. I catch him on a Saturday morning and ask about his memory of how the reef has changed over the course of his life.

Wally first started diving these waters with his father and uncles when he was just 10 years old. Swimming amongst the reef before school, searching for abalone and crays, he would then spend the day in the classroom, sitting there in wet undies, looking out the window towards the sea. He said that the waters were rich, unbelievable, and that there was kelp everywhere. The old men would tell him; you need to look after your water. He tells me that now when his nephews go diving there’s mostly nothing there. Where there were secret cray holes tucked into kelp covered reef, their location passed down through the generations, there are now urchin barrens. He says the young men laugh at the old men when they sit around the fire telling stories of how easy and abundant the fishing was in their time. He laments that the abundance may never be seen again and that it’s not just the physical loss of the kelp habitat, but a loss of a cultural way of life, the loss of connection from the community to the ocean.

After fighting so hard to have native title over their Sea Country recognised, Wally now also sees the need to fight for the preservation of the remaining kelp habitat. He says his people have endured climate change once, with stories recounting how the old people would walk to Barranguba, an island now 9km off the coast of Narooma, and they will survive it again. I’m left wondering what change to the reef I will witness in my lifetime and my kids in theirs.

Next, I call up a mate, Steve Bunney, who has been a commercial ab diver on the NSW South Coast for nearly 40 years and is the current Chair of the Abalone Association of NSW. He tells me that because of the underwater nature of their work and the reef systems they cover, the abalone divers were among the first to raise the alarm.

Steve tells me of a project undertaken in conjunction with Ocean Watch and the NSW Department of Primary Industries. Three areas were selected to trial the culling of urchins, to see if that would lead to natural restoration of kelp. Divers had a target to cull 200,000 urchins, covering eight hectares. In the end they culled approximately 270,000 urchins. Nine months after the cull, seaweeds and kelp had repopulated from anywhere between 70 to 100 per cent of the reef. A further 12 months later, macroalgal assemblages (communities of seaweed/kelp etc) had dominated the reef again.

It was an encouraging result, but it took considerable time and human resource to cull the urchins from even this tiny fraction of the GSR and would require ongoing harvesting or culling to keep the barrens at bay. When asked if commercial urchin harvesting could be the answer, Steve tells me the NSW commercial fishery harvests more than 150 tonnes of urchins a year, only a miniscule fraction of the state's urchin population.

I’m keen to learn more about the solutions and get a better understanding of the work involved in reducing urchin pressures on the GSR. I reach out to the Great Southern Reef Foundation, who connect me with Dr John Keane, a senior research fellow in dive fisheries with the University of Tasmania’s Institute for Marine and Antarctic Studies. Over the phone, John tells me that the centro was first reported, just two of them, in Tasmanian waters in 1978, but the population has now exploded to an estimated 30 million, a number that continues to grow. Over the nearly 50 years since they were first discovered in Tasmanian waters, urchins have turned 15 per cent of the reefs along Tasmania’s east coast to urchin barren, with modelling showing that number growing to 50 per cent if the spread continues unchecked.

I ask John what the tipping points for the creation of urchin barrens are and he tells me that if there are two large urchins per square metre, they can create a barren. Alternatively, if the conditions for kelp recovery are to be restored, then that density needs to be decimated by direct human involvement to one urchin per four-to-five square metres. Once that lower density is achieved, then within 18 months kelp and other algae can repopulate the reef. The catch, again, is that urchin numbers need to be kept in check by predators (most importantly humans) to prevent them from reforming barrens.

The message I understand from Wally, Steve and John, is that immediate action must be taken to halt the spread of urchin barrens, and that if we are to succeed then it needs to be a coordinated effort from First Nations people, the scientific community, commercial fishos and government. There’s currently a Senate Enquiry open with the Federal Government that has stakeholders from around the coast lobbying for $55 million in funding to implement control measures and to boost the number of urchins coming out of the water.

But progress is slow.

I ask John what can the average punter do? Is there anything that I can do while diving on my tiny patch of reef? He tells me there has been past success with community groups targeting their favourite patches of reef and manually removing or culling urchins, reversing barrens and allowing kelp to reestablish. He says that while the efforts of community-driven management are to be celebrated and can be effective in isolated patches, it’s a drop in the ocean compared to the 2000km of reef currently at risk of becoming urchin barren.

While government funding will be essential in the short to medium term, like the culling itself it’s only a temporary measure. To support ongoing management of urchin populations what is really needed is a culinary culture shift. The urchins are edible, delicious in fact and are already celebrated in places like Japan, where the numbers of their native urchins have plummeted thanks to centuries of consumption. Here in Australia, you’d be hard pressed to find a person in a crowd that has eaten urchin. Along the Tasmanian East Coast, a 400-tonne commercial harvest is only just keeping the urchins at bay, preventing the dam wall from breaking. The urchin fishery is in desperate need of further significant investment if it is to prevent largescale impact to valuable kelp habitat, as well as abalone and lobster fisheries, the most valuable in Australia.

The damage happening to the Great Southern Reef is playing out beneath the waves, out of sight and out of mind for most people. If anything is to change and this heartbreaking loss of one of the world’s great underwater ecologies is to be halted, even reversed, then it needs support.

The First Nations mob, commercial fishos and scientists have been sounding the alarm for years. But now it needs the support of the millions of people who live along the coast bordering the GSR. Support from surfers, fishos and divers. Support from people who don’t want to take their grandkids diving across barrens of white rock, while telling them stories of ecological richness, of life, that they will never know.

Back at home, it’s another perfect spring day.

No wind, blue sky and the crystal-clear water beckoning. I’m back in the water, but this time, with a purpose. I still take in the kaleidoscope of life on the healthy reef, listening to the clicking and chattering, a language that eludes me, but whose meaning I understand… the undeniable sound of life. I pass the reef that marks the boundary of the urchin barren, take a deep breath and kick my way to the bottom. My gloved hand works the reef, finding the pockets of the white rock where the urchins sit, pulling them from their stronghold and stuffing them into a catch bag. I work up an appetite, moving in the cold water, but the hunger pleases me. Lunch is in the bag.