The Role of Seaweed Cultivation in Integrated Multi-Trophic Aquaculture (IMTA): The Current Status and Challenges

Abstract

Global mariculture production has witnessed sustained growth, yet intensive monoculture practices (primarily fish aquaculture) have generated increasingly severe environmental externalities, driving demand for sustainable solutions. Integrated Multi-Trophic Aquaculture (IMTA), leveraging species synergy to recycle nutrients, emerges as a promising strategy. Seaweed plays a critical role as inorganic extractive species in IMTA. However, current large-scale seaweed farming remains predominantly concentrated in Asia. Through literature review and synthesis, this paper mainly reveals the significance of seaweed in maintaining the ecological balance of the marine environment and improving co-cultured species' production quality within IMTA. We also discuss the challenges faced by seaweed cultivation in IMTA, which include the following three parts: seaweed selection, IMTA setting and seaweed utilization, while highlighting emerging pressures from climate change. Analysis reveals greater controllability in land-based IMTA systems versus open-sea systems, where marine environmental complexity necessitates multidimensional considerations of seaweed species selection, cultivation area allocation, and temporal management. While envisioned as an eco-economic “win-win” solution, over-optimistic projections of seaweed cultivation coupled with inadequate risk assessment may lead to short-term successes followed by long-term failures. For instance, although IMTA reduces environmental governance costs, hidden challenges—including seaweed's low market valuation, potential ecosystem perturbations, infrastructure requirements, and specialized labor demands—could paradoxically elevate systemic production costs. Future research requires dual assessment frameworks that concurrently evaluate ecological services and economic viability of seaweed cultivation in IMTA. More research and practical adjustments are needed to develop a long-term, sustainable IMTA system.