Scientists see link between loss of marine life and disappearing seagrass

Seagrass grows underwater in the ocean, forming thick underwater meadows that sea creatures live on and depend on as a source of food. Seagrass acts like a barrier along the coast, stopping waves and erosion. Coastal seabeds can store up to 83,000 metric tons of carbon per square kilometre in the soil beneath them.

The World Bank reported that one hectare of mangrove could store five times more carbon than a similar area of forest on land. Stopping the destruction and degradation of seagrass worldwide could save up to 650 million tons of CO2 emissions annually, roughly equivalent to the entire annual emissions of the global shipping industry.

Discussing the seagrass crisis

At the 11th Westpac International Marine Science Conference on Wednesday about “Seagrass Crisis: Call for Solutions and Collaborations”, scientists banded together to find out how to solve the issue of seagrass restoration and how Thailand can find a way out.

Dr. Kongkiat Kittiwattanawong, an expert in resources and environments in marine and coastal ecosystems with the Department of Marine and Coastal Resources, showed his findings in the hope that Thai scientists could come together and prevent seagrass from dying off.

His findings showed that seagrass had decreased since 2019, specifically on Muk Island and Libong Island. There has been damage to the seagrass, and locals had observed that the grass was shorter than usual. Up until last year, the problem hadn't spread to many other islands. Apart from the shorter seagrass, other types of seagrass have appeared, but they disappeared over time, and there has been an increase in sediments, such as mud, that limit the growth of seagrass.

“What can be done now is to find a clear cause so that we can take appropriate action,” Kongkiat said. “However, it's expected that the research will show the apparent cause of these changes is global warming, leading to abnormal water levels. As the water levels change, the seagrass is exposed to the sun for longer periods.”

But there are also other contributing factors, such as the accumulation of sediment. It has still not been determined where it came from, he said.

Paying the price

Another alarming factor is the impact on dugongs that feed on seagrass. They now look smaller and have gotten sicker from diseases. Nearly 40 per cent of these mammals disappeared from Muk Island and Libong Island, once the largest seagrass habitats in Thailand. Dugongs often gathered in these areas. But when seagrass decreases, dugongs may either try to stay in the same place and adapt or move to find new sources of food, he said. It was determined that some of these mammals may have migrated about 15-30 kilometres to islands like Koh Sriborya and Koh Pu. However, it's important to monitor how much the seagrass habitat, even if not in perfect condition, can support them, he added.

Seagrass and mangrove have similar coastal environments, as they both thrive in flooded conditions. However, seagrass has the advantage of lower biomass compared to mangroves, taking up less space. Therefore, seagrass beds should be considered an alternative source for future blue carbon initiatives.

However, Dr.Kongkiat said that “Seagrass may not be perceived as a priority if the current global issues are not recognised. It is worth aiming towards utilising seagrass for blue carbon in the future.”

Growing seagrass in Thailand

The current hope for seagrass in Thailand is lab grown.

Assoc Prof Chatcharee Kaewsuralikhit from the Faculty of Fisheries, Kasetsart University, led the research lab, testing out different methods of growing seagrass. He said the project was going well. Testing will still be carried out in different temperatures and locations. The current hot April weather, however, was not the best condition to grow the grass. He said further research on growing seagrass in the sea would be continued during the rainy season.

The research team is hoping to study the conditions to improve the survival rate of seagrass, and is developing a methodology to assess suitable seagrass transplant techniques from different environmental factors.