Professor Zhang Peidong from the Ocean University of China has devoted the past 15 years to one thing: planting "grass" in "undersea prairies" to restore lush habitats to protect coasts, boost wildlife and store carbon.

The "prairies" are seagrasses, widely recognized to be one of three typical marine coastal ecosystems in the world, along with mangroves and coral reefs.

Growing in coastal bays, seagrasses used to be abundant, but the beds became barren due to coastal development and pollution from sewage and artificial sea farming.

"Seagrasses are the only flowering plants that grow in marine environments and provide habitats for marine creatures," Zhang said.

"Seagrasses are as meaningful to marine life as prairies are to cows and sheep," said the 46-year-old professor, adding that they also function as important carbon sinks.

The decline of seagrasses is a common issue worldwide. In coastal bays around cities such as Qingdao, Yantai and Weihai in Shandong province, eelgrasses are one of the major plants in seagrass beds, and more than 80 percent of them have disappeared, according to a research team led by Zhang.

Zhang launched the team at the Qingdao-based OUC in 2006 for a seagrass restoration project.

The team's first step was to acquire basic knowledge of how eelgrasses grow, including flowering, fertilization, seed formation and the reasons behind its degradation.

The team developed technology to breed eelgrasses and found ways to restore seagrass beds.

Swan Lake in Rongcheng, a county-level city in Weihai, was the first place for the team's research.

Cai Bing used to run an aquaculture business around the lake, which is now a nature reserve.

He said more seagrasses greatly improved water quality and increased the number of birds and shellfish around the lake.

China Central Television reported that nearly 10,000 swans spend the winter there every year, creating amazing scenes for tourists and photographers.

"The swans used to eat crops near the lake, but as more seagrasses grew, they mainly inhabited the lake and do not disturb the crops anymore," Cai added.

Zhang said the biggest difficulty in restoring seagrass beds is planting the seeds in the right place.

"We usually put the seeds at 1 to 1.5 centimeters deep in the soil," said Zhang. "If the seeds are placed deeper, they can't germinate easily, while if shallower, they are likely to be washed away."

The team's footsteps have now reached major coastal cities in Shandong and in Tangshan, Hebei province, with over 1,300 hectares of coastal bays now blanketed with eelgrass.