At a meeting with the authority's representatives yesterday, members of the advisory body asked if the proposed 2,400-hectare park could be set up earlier, or if a temporary conservation area could be set up during construction, expected to begin in 2016.

"Can we set up a shelter so the dolphins will not be disturbed during construction," board member Ng Cho-nam asked.

Other members expressed concern about whether the authority's experts had assessed if there were undamaged habitats the dolphins could move to.

Airport Authority executive director John Chai Sung-veng said: "It's not like a swimming pool being occupied and we need to open another pool. It's a big sea and there's enough space for the dolphins' activities."

He added that the authority would consider the suggestions.

Professor Bernd Würsig, one of the authority's dolphin experts, said he believed there would be a net gain in having both the new runway and the marine park.

As marine parks come under the Agriculture, Fisheries and Conservation Department, board members also asked whether the department or the authority would be held responsible if the park failed to mitigate the negative impact brought about by the third runway.

Board member Tennessy Hui Mei-sheung was unhappy that the authority would profit from the runway while the government paid for the marine park.

Public consultation on the authority's environmental impact assessment report will be open until July 19, after which the Environmental Protection Department will decide whether to approve it. The government and authority have yet to agree on how the runway will be funded.