Potential of achieving sustainable development through integrated optimization of mariculture species based on the food-energy-water nexus in China

The sustainability of mariculture possesses substantial enormous potential in food security and the mitigation of global warming. Based on the food‑carbon-water nexus, this study assessed the carbon and water footprints of mariculture in China, identified key drivers, and constructed a multi-objective optimization model of mariculture structure. Results showed that the carbon and water footprints of mariculture in China increased continuously from 2008 to 2020, with the intensity of carbon footprint increasing from 0.08 to 0.14 t CO2/t and that of water footprint increasing from 5436.72 to 6169.01 m3/t. Shellfish showed lower intensity of footprints than fish and crustaceans. The carbon footprint intensity of mariculture was high in Tianjin and Hainan but resulted in negative carbon emissions in Shandong and Liaoning. Hainan, Hebei, and Liaoning provinces had the highest average annual water footprint intensity. Provincial population and total mariculture production significantly impacted the carbon and water footprints of mariculture. Optimizing mariculture species structure can reduce carbon and water footprints while increasing protein production. However, a large gap still exists between the current development and optimization scenarios for mariculture structure in China. A targeted increase in the production of mariculture species such as plaice in Tianjin, American redfish in Guangxi, oysters and scallops in Guangdong, wakame in Liaoning, and gracilaria in Fujian, can help promote low carbon and water-saving practices, thus achieving sustainable mariculture development. Therefore, China's mariculture should continuously optimize its structure and enhance carbon sink capacity in the future.