HAIKOU -- Schools of small fish swam freely in the turquoise water, while various types of corals softly fluttered. Such vibrant underwater sights are closely monitored on screens by the keepers of the local marine ranch.

With the help of underwater cameras and 5G signals, Wuzhizhou Island in south China's Hainan Province is building a modernized marine ranch to monitor and restore the local marine ecosystem.

The butterfly-shaped Wuzhizhou Island, located in the city of Sanya, is a national-level tourist attraction. Around 2010, the island began building China's first tropical marine ranch to restore the underwater ecology damaged by typhoons and fishing activities.

Wang Fengguo, who heads the island's office on ocean management, has spent about a decade restoring corals and placing artificial reefs under seawater to attract marine life. His work is now aided by an information-based monitoring system.

"We've set 14 underwater cameras in seven spots. We are using both wired transmission and wireless 5G signal to send the information back," said the veteran coral keeper.

The system can display all the hydrological data and review the video playback from the past one or two months, which has played a big role in monitoring the complex marine ecosystem, Wang said.

"Sometimes there can be red tides or high temperatures at certain spots. When we have accumulated enough information, we can better prepare for possible disasters. We can even predict catastrophic situations," said Wang Aimin, former professor of oceanic science at Hainan University.

Since its launch, the marine ranch has transplanted more than 35,000 corals and placed 2,571 cement-type artificial reefs and 21 old iron boats to attract fish and other marine life to rest, hide, live, and breed. The improved eco-environment has attracted hundreds of species to the marine ranch.

The island is also working to contribute to China's "dual carbon" goal with its biodiversity advantages.

"We can now combine the marine ranch construction with the 'blue carbon system,' a marine carbon sink system. There are a lot of shellfish living on the artificial reefs, and these shellfish actually sequester carbon," said Wang Aimin.

While not in diving missions, Wang Fengguo enjoys watching the fish and coral on a large screen or on his phone. This reminds him of the early days when he worked as a diving instructor and personally witnessed the largely pristine coral system.

"In the future, I hope to see fish and corals everywhere in waters off Wuzhizhou Island," he said.