A CENSUS of corals was launched on the Pearl Island in Dongshan, Dapeng New Area on last Friday. Volunteer divers and experts from Beijing, Guangzhou and Zhuhai are participating in the census, Shenzhen Economic Daily reported.

Over the past few years, with water temperatures rising, coral bleaching has become an issue. This will be a key focus of this year’s census, according to Liao Baolin, senior engineer with the Shenzhen Institute of Guangdong Ocean University.

Coral bleaching refers to corals releasing algae (zooxanthellae) living in their tissues causing its color to turn completely white. This happens because the water is too warm. However, when a coral bleaches, it is not dead. Corals can survive a bleaching event, but they are under more stress and are subject to mortality.

In addition, the group will check on more than 60,000 corals planted in the city’s eastern sea. Four teams conducted a survey at sea areas in Dalajia, Huizhou and Yangmeikeng, Shenzhen on Sunday, said the report.

In 2007, Guangdong introduced Hong Kong environmentalists to help conduct the census. In 2018, Guangdong’s coral census sites were upgraded as a national census station.

The coral reef monitoring project in Guangdong has been held for 15 consecutive years, with more than 3,000 volunteers participating.

Coral reefs, one of the most complicated ecosystems on earth, are often called the “tropical rainforests of the sea” for their astounding richness of life.

South China Sea has some 2.57 percent of the world’s coral reef resources, ranking eighth in the world. Shenzhen’s coral reefs are mainly located in the city’s eastern sea areas.

This year’s event attracted two volunteers from Beijing. They are students from Tsinghua University and members of their university’s diving club.

Affected by recent typhoons, only 30 sites were designated for this year’s census of coral reef ecosystems in Guangdong, with 12 sites in Shenzhen, according to Liao.  (Wang Jingli)