The cabinet's recent decision to approve construction of a 4.48-billion-baht bridge across Songkhla Lake is causing alarm among environmental activists and authorities.

The bridge will link tambon Koh Yai in Songkhla's Krasae Sin district to tambon Jong Thanon in Phatthalung's Khao Chaison district.

Yet many have questioned if the project will displace the last pod of 14 Irrawaddy dolphins, an endangered species, living in the lake.

Addressing concerns about the bridge's impact on the dolphins' survival, the Department of Rural Roads and the Department of Marine and Coastal Resources says it will launch a scheme to protect the rare mammals as plans for the bridge move forward.

The move was announced by Natural Resources and Environment Minister Varawut Silpa-archa on his Facebook page. In a post on Friday, he said he had talked to the deputy dean of Kasetsart University's Faculty of Fisheries, Thon Thamrongnawasawat, along with other members of the university's Department of Marine Science to discuss a grant for dolphin conservation studies that will be funded by some of the budget for the bridge.

"I assigned the Marine and Coastal Resources Department to study a sustainable solution to protect the habitat of [Songkhla Lake's] last pod of 14 dolphins," he wrote.

Mr Varawut added he will propose his conservation plan to the permanent secretary of the Ministry of Natural Resources and Environment (MNRE) and work with others involved to conduct further research.

Mr Thon, however, had previously made known his concerns that the bridge's construction might affect the dolphins.

"The freshwater Irrawaddy dolphins can only be found in five places around the world. The 14 dolphins that live in Songkhla Lake are the smallest pod," he wrote.

"Even though the bridge is not built over the dolphins' habitat, there might be some other consequences from food, machine noise and changes to the underwater environment," he added.