What evidence exists for the environmental outcomes of nature-based aquaculture systems? a systematic map protocol

BACKGROUND: Nature-based solutions (NbS) are defined as actions that protect, conserve, restore, and sustainably use natural or modified ecosystems. These actions aim to deliver environmental services, enhance biodiversity, and support societal well-being. NbS are increasingly promoted across a wide range of sectors, including agriculture, coastal management, and civil engineering. However, despite being introduced almost twenty years ago, NBS appear not to have been widely and explicitly adopted in aquaculture production systems policies and practices, arguably because there is little evidence of their efficacy in improving environmental outcomes and production. This systematic map therefore seeks to address the primary review question: What evidence exists in the literature on reported environmental outcomes associated with nature-based approaches in aquaculture? To answer this question, the study will identify, collate, and characterize the available evidence on nature-based approaches applied within aquaculture systems. METHODS: This systematic map will follow a structured evidence-synthesis approach to identify and characterize literature on nature-based solutions in aquaculture. Comprehensive searches will be conducted across established scientific databases using carefully developed search strings, and these will be complemented by targeted grey literature searches across specialist aquaculture and NbS platforms, as well as Google Scholar. Retrieved records will be screened at title, abstract, and full-text levels against predefined eligibility criteria. Studies will be included if they focus on aquaculture systems, examine interventions framed as or consistent with NbS, report outcomes related to environmental performance, socio-economic value, or policy relevance, and are based on empirical evidence from peer-reviewed or credible grey literature sources. Data from eligible studies will be extracted and summarized descriptively, followed by a narrative synthesis to identify thematic clusters, geographical patterns, and gaps in the evidence base. The outputs will provide a structured knowledge base to inform researchers, practitioners, and policymakers seeking to expand the application of NbS in aquaculture.