An aerial view of the Ailun Bay Marine Ranch in Rongcheng, East China's Shandong province. [Photo/Dazhong News]

In Rongcheng's Ailun Bay Marine Ranch, Shandong province, a harvest of kelp is underway. Using a multi‑trophic integrated aquacultural model known locally as "stacking", the ranch has turned the sea into a highly productive "blue granary".

At the surface of the sea, kelp and other seaweeds act as purifiers. In the middle waters, shellfish such as abalone and scallops filter plankton. On the seabed, artificial reefs and seagrass beds host sea cucumbers, urchins, and fish.