RAMANATHAPURAM
The invasive Kappaphycus alvarezii seaweed, which smothers and kills coral reefs, has spread its wings to coral reef areas in Valai island in the Gulf of Mannar (GoM) and set to invade new coral colonies in the marine national park.
After invading Shingle, Kurusadai and Mulli islands in Mandapam cluster of the GoM, the red algae invaded Valai island along Kilakarai coast following its cultivation in south Palk Bay. A 2005 Government Order had restricted cultivation of the exotic seaweed only to the seawaters north of the Palk Bay and South of Thoothukdi coast.
The Reef Research Team (RRT) of Suganthi Devadason Marine Research Institute (SDMRI), Thoothukudi, after an elaborate underwater survey, observed that the destructive algae had invaded the reef areas of Valai Island and sounded an alarm bell in its report submitted to the Ministry of Environment, Forest and Climate Change (MoEFC) on February 21, details of which were made available to The Hindu .
The institute undertook the four-year project, ‘Studies on the impact of the exotic seaweed, Kappaphycus alvarezii on corals, and the associated resources, and management measures in the Gulf of Mannar Marine National Park’, funded by the MoEFC.
The research team counted 32 coral colonies of Acropora nobilis affected by Kappaphycus algae and the area of impact was 15-20 square metres, J.K. Patterson Edward, Director, SDMRI, said. The algae was firmly attached to the coral colonies and started forming mat over them, he said, adding it would eventually smother and kill corals.
“It is most likely that Kappaphycus alvarezii would spread to new live coral colonies and cause significant coral mortality in Valai Island,” he said. Detached mats of the algae were also seen along the shores of the island and nearby Thalaiyari island, he said.
“Yes, the destructive seaweed has invaded coral colonies in Valai island and posed a threat to other coral colonies,” said T.K. Ashok Kumar, Wildlife Warden, GoM Marine National Park, who inspected the island area along with SDMRI researchers recently.
The Forest department would take up the issue with agencies, which promoted cultivation of the seaweed. The department had been carrying out manual removal of the seaweed every year since 2014 to protect coral reefs, he said.
Macrofaunal and fish density decreased when Kappaphycus cover increased, the SDMRI report said.
