Sea cucumber poo to save Great Barrier Reef

Sea cucumbers and their faeces could save coral reefs from the impacts of climate change, say experts.

A sea cucumber creeps past healthy coral. (Credit: Getty)

SCIENTISTS AT ONE TREE ISLAND, the University of Sydney's research station on the Great Barrier Reef, say sea cucumbers could reduce ocean acidification affecting coral growth. The experts argue that we need to think more carefully about commercially harvesting these animals that could help mitigate the impacts of climate change.

"When they ingest sand, the natural digestive processes in the sea cucumber's gut increases the pH levels of the water on the reef where they defecate," says One Tree Island deputy director, Professor Maria Byrne. This works to counter the negative effects of ocean acidification, which is caused by carbon dioxide pollution dissolving in sea water.

One of the by-products when sea cucumbers digest sand is also calcium carbonate (CaCO₃), which is a key component of coral.

"To survive, coral reefs must accumulate CaCO₃at a rate greater than or equal to the CaCO₃ that is eroded from the reef [by ocean acidification]," Maria says. "The research at One Tree Island showed that in a healthy reef, dissolution of calcium carbonate sediment by sea cucumbers and other bioeroders appears to be an important component of the natural calcium carbonate turnover."

Daily dose of calcium

Testing the effects of ocean acidification at One Tree Island Research Station on the GBR. (Credit: Getty)

The ammonia waste produced when sea cucumbers digest sand also serves to fertilise the surrounding area, providing nutrients for coral growth. Sea cucumbers are among the largest invertebrates found on tropical reefs.

Some 30 species are commercially harvested by the fishery industry along the Great Barrier Reef and throughout the tropics.

Given this Maria says, "we urgently need to understand the impact of removing sea cucumbers and other invertebrates on reef health and resilience at a time when reefs face an uncertain future."

Home to a warm climate and the crystal clear waters of the Whitsunday Islands, Queensland is a tropical paradise. Off the coast lies the Great Barrier Reef, a breathtaking coral system abounding in exotic fish and spectacular colours. The lush World Heritage-listed Daintree forest in the far north provide some relief from the heat, while further inland, the Simpson Desert’s earthy red dunes offer a stark change of scene.