The great southern reef: Australia's other great reef

What is the Great Southern Reef?

The Great Southern Reef is the interconnected system of temperate rocky reefs and kelp forests that runs around the southern coast of Australia — roughly from New South Wales, down around Tasmania, and along Victoria and South Australia to Western Australia. Rather than a single reef, it is a chain of cool-water reefs linked by shared species and ocean currents, stretching across thousands of kilometres of southern Australia kelp reef.

The system is dominated by golden kelp (Ecklonia radiata), a fast-growing brown seaweed that forms dense underwater canopies. The name "Great Southern Reef" was coined by scientists (Bennett et al., 2015) to give this overlooked temperate reef in Australia a single identity — and, with it, a fighting chance at the attention and funding it has long missed.

Why the great southern reef matters

For a system most Australians have never heard of, the Great Southern Reef does an extraordinary amount of work:

• Fisheries: its reefs underpin major fisheries — including abalone and rock lobster — that scientists and industry report to be worth billions of dollars to the Australian economy.
• Endemism: the cool temperate waters support a remarkably high number of species found nowhere else on Earth, from seaweeds to fish and invertebrates.
• Carbon and coastlines: fast-growing kelp draws down carbon as it grows and helps buffer the coast from wave energy — a large but under-recognised natural asset.
• Tourism and culture: the reef supports diving, fishing and coastal tourism, and is woven into the identity of southern coastal communities.

In other words, this is not a niche concern for marine biologists. It is a working part of southern Australia's economy and environment, hidden just below the surface.

The threats it faces

The Great Southern Reef is under growing pressure, and the central driver is a warming ocean. As sea temperatures rise and marine heatwaves become more frequent and intense, kelp forests that evolved for cool water are pushed beyond what they can tolerate.

The clearest example is eastern Tasmania, where the spectacular giant kelp forests have been reduced to a small fraction of their former extent as warm water has moved south. Warming also helps the long-spined sea urchin spread into new waters, where it can graze kelp down to bare rock — creating urchin barrens that lock the reef into a degraded state. Together, heat and grazing can strip a thriving forest in a matter of years.

The reef no one talks about

Despite its scale and value, the Great Southern Reef receives a fraction of the attention given to the Great Barrier Reef. Part of the reason is simple: it is temperate, not tropical, and its forests are muted greens and golds rather than vivid coral. It is also harder to see — cooler, deeper and less inviting to the average snorkeller.

That low profile has real consequences. A system this important should not be invisible in public debate or in funding decisions. Naming it was a first step; restoring it is the next.

How restoration helps — and where Ocean Greens works

The hopeful part is that kelp forests can be rebuilt. Where reefs have tipped into barrens, reducing urchin numbers and re-establishing native kelp can allow a forest to return. The challenge is doing it at meaningful scale, and funding the work over time.

That is where Ocean Greens begins. We start along the Great Southern Reef, clearing urchin barrens and rebuilding kelp through engineered seaweed farms, then harvesting a sustainable share of that seaweed to help fund the next stretch of reef. You can read the full method on our kelp restoration page, and see how it fits the national picture in our work to rewild Australia's coasts. The outcomes we describe across this site are 2030 goals and projections, not results — this is an early-stage effort to restore a reef most people don't yet know exists.