Australasian Science: Australia's authority on science since 1938

Value in Seagrass Beds

By Stephen Luntz

The carbon stored in the seagrass beds that fringe our coast could be worth billions of dollars if trading schemes to protect forests are extended to the oceans, according to a report in PLOS ONE.

Researchers at Edith Cowan University’s Centre for Marine Ecosystems analysed data from 17 locations to estimate that 150 million tonnes of carbon were stored in a combined area of 92,500 km2.

While this is well down on the estimate of 14,000 tonnes/km2 in one previous study (AS, September 2012, p.15), it would still be worth more than $5 billion at a price of $35/tonne projected for 2020.

Moreover, the Centre’s Director, Prof Paul Lavery, says the team only had equipment to measure to a depth of 30 cm, while some southern beds are metres deep.

Trading schemes now exist to protect the carbon in endangered tropical forests, and Lavery says there have been suggestions these could be applied to the oceans as well. Moreover, these beds lay down around a million tonnes of carbon per year, three times as fast per square metre as tropical rainforests.

While the expansion of meadows from their relatively small areas would make a major impact on climate change, Lavery says seagrass has proved very difficult to propagate. “What is imperative at the moment is that we preserve what we have,” he says.

Little is known about how much carbon is released when seagrass beds are disturbed. “We are not sure if it floats to the surface or is released to the atmosphere,” Lavery says. “We are taking soil cores and taking the carbon into an oxygenated environment and looking to see if it escapes into the atmosphere. This might depend on the temperature and amount of nutrients.”