11 July 2024

Seagrass, a major food source for dugongs, has been steadily disappearing from the seas off Thailand’s southern province of Trang, raising concerns among marine scientists and conservationists over the fate of the sea mammals.

The accumulation of sediment, from the dredging of the Kantang waterway for navigation and business development, is assumed to be a cause of the steady dying off of the seagrass, but further studies are needed to pinpoint the exact cause or causes, according to Santi Nilawat, director of the marine and coastal resources research centre (southern Andaman Sea).

He said that a survey, conducted in Ao Kham in front of Pak Meng pier in 2021, found seagrass covered more than 80 hectares of the seabed, but another survey last year found a depletion of seagrass in six areas, he added.

He added, however, that the gradual loss of seagrass may not, for the time being, pose a threat to the 188 dugongs in the seas off Trang, because seagrass is still available, covering an area of 3,200 hectares, as each dugong consumes an average of 1.5kg of seagrass per day.

Another potential cause of the gradual disappearance of seagrass is the increasing number of green sea turtles in the area, prompting the Andaman Foundation to propose, a year ago, an end to the release of the young turtles from hatcheries into the sea.

Seagrass wasting disease is also believed to be a contributor to the gradual depletion of seagrass, but the disease has not yet been found in the Thai waters and a team of scientists from the Faculty of Fisheries at Kasetsart University are conducting research to find the answer.

According to Associate Professor Chatcharee Kaewsuralikhit, of the Department of Fisheries Biology, seagrass increases and decreases seasonally, adding that seagrass wasting disease has been found in Australian waters.

She noted that, if sediments continue to be dumped onto the seabed, seagrass will die and cannot grow again.