The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

Since the Industrial Revolution, the anthropogenic carbon dioxide emissions have significantly exacerbated global climate change, leading to various environmental and social issues. The ocean acts as the largest active carbon reservoir on Earth, and therefore plays a crucial role in mitigating climate change. Macroalgae cultivation, as one of the measures to enhance the ocean's capacity of carbon sequestration and uptake, is an effective approach to achieving carbon neutrality and addressing regional marine environmental problems. Current research primarily focuses on the positive effects of macroalgae cultivation on carbon cycling and ecosystems, such as carbon sequestration through primary production, carbon storage, and biodiversity feedbacks. However, the potential negative impacts of intensive cultivation activities, for instance, eutrophication, hypoxia, and acidification in subsurface waters, have not received sufficient attention and comprehensive evaluation. Our study investigates the ecological effects of the marine environment in the intensive macroalgae cultivation area of Xiapu, Fujian Province. We found that during spring (the later stages of macroalgae cultivation), the water exhibited high dissolved inorganic carbon levels and low dissolved oxygen. We further demonstrate that nearly all oxygen-consuming organic matter originates from mariculture, with isotope compositions very similar to the δ¹³C values of organic matter in macroalgae. To ensure the sustainability and long-term benefits of macroalgae cultivation as a marine carbon sink, our study emphasizes the need for a comprehensive assessment of the cultivation process, providing scientific support for the national "dual carbon" strategy.

macroalgae cultivation, marine carbon sink, ecological and environmental effects, acidification, hypoxia