THE receding tide at the mouth of the Yellow River in Kenli District of the city of Dongying, East China’s Shandong Province, revealed a vast seagrass bed on a fall morning.

Dozens of workers walked back and forth, gathering Japanese eelgrass seeds to be sown next spring. The seeds, which were about the size of sesame seeds, were not ripe yet, and the workers put them in mesh bags and then soaked them in water to allow the eelgrass to continue growing.

"Seagrass seeds are too light and will be easily washed away by the waves when they are fully ripe, so collecting is best done around the time of the Mid-Autumn Festival," said Zhou Yi, a researcher at the Institute of Oceanology, Chinese Academy of Sciences.

Zhou, who has been engaged in seagrass research for more than 20 years, visits the “grassland” in the Yellow River estuary every other month.

“This seagrass bed covers about 30 hectares, and most of it has been restored in the past three or four years,” he explained. Once the largest Japanese eelgrass bed in China and a native habitat, the Yellow River estuary cradles this vast underwater meadow, resembling a luxuriant terrestrial grassland when the tides recede.

Regrettably, the onslaught of Typhoon Lekima in 2019 resulted in the destruction of over 10,000 mu (approximately 667 hectares) of seagrass beds. Standing amidst the devastation, Zhou Yi bore witness to extensive stretches of barren shores.

Zhou Licheng, director of the scientific research center of the management committee of the Shandong Yellow River Delta National Nature Reserve, compared seagrass beds to terrestrial forests, because they “provide support to benthic organisms and indirectly nourishing a diverse range of avian species.“

Attributing substantial damage to invasive species such as Spartina alterniflora and recurrent typhoons, Zhou Licheng underscored the consequential breaches in the local intertidal ecosystem. Classified as one of the 100 most perilous invasive alien species globally by the International Union for Conservation of Nature, Spartina alterniflora was among the earliest invasive alien species officially recognized as a threat by the Chinese authorities.

To revive the ailing ecosystem, the reserve, in collaboration with the Institute of Oceanology, Ocean University of China, and allied institutions, has actively promoted seagrass bed restoration since last year. Growing seagrass underwater is different from growing grass on land and much more difficult.

“We have tried direct planting, direct seeding and other methods, but due to the influence of submarine sediment, ocean currents and other factors, the plants and seeds sown can be easily washed away or eaten by marine organisms,” Zhou Yi said, adding that after many attempts, the team finally developed a combination of transplanting seedlings and planting “rolled clay balls.”

Zhou Yi explained the “rolled clay ball” approach, likening it to making dumplings: encapsulating the seeds in soil with necessary nutrients and then using machines to sow these “balls” on the shores. The reserve has spearheaded four major projects, including Spartina alterniflora management and seagrass bed restoration, culminating in a noteworthy 12.3% year-on-year expansion, increasing the total wetland area by 188 square kilometers as of September’s end.

A somber reality emerges from research indicating the loss of one-third of the world’s seagrass beds due to a confluence of human activities and global climate change. Consequently, the propagation of seagrass beds underwater stands as a critical contribution to global marine ecosystem preservation.

On Tuesday, the Dongying City government announced that more than 99% of the Spartina alterniflora had been eradicated, while a total of 1,500 mu of seagrass beds had been restored.

(Xinhua)