Nature-based solutions for freshwater conservation and equitable adaptation in the Amazon basin: a case study review

Abstract The Amazon region is recognized internationally for its role in providing global ecosystem services, as one of the most important biodiversity hotspots on Earth, and as home to millions of indigenous people whose livelihoods are tightly coupled with ecosystem processes. Efforts to counter anthropogenic pressures on Amazonian ecosystems have largely excluded freshwater ecosystems despite their central role in supporting biodiversity and human communities. Nature based solutions (NbS) are garnering attention as a holistic strategy that address ecological and human dimensions of resilience, offering a promising approach to couple freshwater biodiversity conservation and equitable adaptation in the Amazon. The extent to which NbS projects in the Amazon are incorporating freshwater biodiversity objectives and aligning with principles of equitable adaptation is unresolved. Synthesizing across existing NbS cases is key to distilling lessons learned and identifying remaining gaps to inform current and future project implementation. We evaluate four cases of implemented NbS projects in the lowland Amazonian basin to assess three themes: freshwater biodiversity impacts, equity considerations, and guiding policies of each case. Freshwater biodiversity outcomes are evaluated by assessing against Couto (Couto et al 2024 Conserv. Sci. Pract. 6 e13241)’ five themes for freshwater biodiversity conservation; equity implications evaluated by comparing project documents to the Stockholm Environment Institute’s Principles for Just and Equitable NbS; and the degree to which freshwater biodiversity is prioritized by relevant policies is assessed through a search for keywords. The case studies demonstrate alignment with principles of equitable and just NbS in the Amazon basin, but links to freshwater biodiversity are minimal, suggesting an oversight of the importance of sustaining and protecting freshwater biodiversity, particularly among vulnerable local communities. We provide recommendations to expand freshwater NbS-A project implementation, monitoring and data sharing, and policy in the region with the aim of safeguarding freshwater ecosystems and local communities in the face of environmental change.