When Parliament on Tuesday passed laws designating the areas around Sisters' Islands Marine Park as a public park, it was a clear signal that built-up Singapore still has wild spaces worth protecting.

The move will better protect the organisms living in Singapore's murky, but thriving, waters.

Singapore's waters are home to more than a third of the world's total coral species. Most of the country's coral reefs lie to the south of the mainland, where the marine park is located.

Singapore's waters are home to rare marine life, such as the Neptune's cup sponge - a marine organism once thought to be globally extinct.

With the latest change to the Parks and Trees Act, the marine and foreshore areas of the marine park are to be safeguarded too. The terrestrial areas of the islands are already protected under the law.

Among other things, it would now be illegal for people to fish, collect corals or moor boats within the marine park without the approval of the National Parks Board. The stepped-up protection is laudable, but more can be done to give the park the maximum protection under the law.

There are more rules governing behaviour in a nature reserve than at marine parks. For instance, people cannot disturb land, dump things, or carry nets, traps or hunting devices in nature reserves.

Singapore has four nature reserves and more than 300 public parks, including the marine park.

Senior Minister of State for National Development Desmond Lee said the Government has sent a number of signals to demonstrate the importance of the areas around Sisters' Islands Marine Park.

These include the recent legislative amendment and announcements in 2014 that highlighted the marine park as a place for the conservation of marine biodiversity.

As the marine park already meets all the criteria for a nature reserve - it is used for conservation and research, as well as for recreational and educational purposes - upgrading its status should only be a matter of time.