Australia has recycled 150,000 wheelbarrows of shells, and fish are coming back fast

Oyster shells dropped into Port Phillip Bay are helping to restore reefs off the coast of Australia.

According to a news release from the United Nations Environment Programme, or UNEP, the shell drop was part of the Shellfish Reef Rebuilding Program, which has restored 62 hectares (a little over 150 acres) of reef at 21 sites. Researchers say the rebuilt habitat is already helping marine life recover and benefiting nearby communities.

What's happening?

Intensive harvesting of oyster and mussel reefs began as early as the arrival of European settlers. But before that, these reefs were widespread in bays and estuaries around Australia. Many of those reefs have since been destroyed.

In these areas, less than 10% now remain, and the reefs that survive are still under pressure from pollution, coastal development, and climate change, according to the UNEP release.

To rebuild them, conservationists place rock and recycled shells on the seafloor to form the base of new reefs. The material settles over rubble, creating a hard surface where young shellfish can attach and grow.

"What we're really doing is sort of kick-starting that recovery process," Simon Branigan, Marine Restoration Lead at The Nature Conservancy Australia, told UNEP. "Since 2014, we've recycled like 150,000 wheelbarrows of shells."

Why does it matter?

The agency said the restoration program is aiming to cover 300 hectares (over 700 acres) across 60 locations by 2030. Reaching that goal could make Australia the first country to recover a critically endangered marine ecosystem.

According to UNEP, the restored reefs are already increasing fish stocks by an estimated 50 tonnes (around 110,000 pounds) each year. Researchers have also recorded about 250 species of fish and mobile invertebrates — including crabs and sea stars — on restored reefs, compared with 175 in nearby areas.

The reefs are also improving water quality. UNEP said they filter up to 125 billion liters of seawater a year and remove as much as 14 tonnes of nutrient pollution, which can help limit harmful algal blooms.

The recovery effort can also directly benefit nearby communities by improving water quality, strengthening fisheries, boosting ecotourism, and making coastlines more resilient.

UNEP said the project could also create thousands of jobs, support hundreds of local businesses, and deliver nearly 14 million Australian dollars (nearly $10 million) in ongoing annual benefits.

What are people saying?

"They may not be as famous as Australia's Great Barrier Reef, but these ecosystems are just as important for maintaining the health of our oceans," UNEP's Natalia Alekseeva said in the news release.

Alekseeva added, "This initiative shows that when nature is given a helping hand, it can come roaring back, for its own sake and for ours."

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