Molluscs in a Changing Amazon: Ecological Importance, Climate-Crisis Vulnerability, and Taxonomic and Funding Constraints in Brazil

Molluscs contribute to food webs, nutrient cycling, food production and environmental reconstruction across Amazonian forests, inland waters and coastal habitats. This critical narrative review examines climate-impact pathways and the limits of regional evidence, while distinguishing biological vulnerability from the institutional capacity to assess and manage it. A targeted literature update links regional case studies with explicitly identified evidence from other Neotropical and extra-regional systems. Studies from the Caeté basin, the Amazon mangrove coast and a floodplain lake near Iquitos document habitat associations, reproductive seasonality and shell-isotope signals, respectively; they do not establish basin-wide climate-driven declines. Drought-associated mortality outside Amazonia and marine physiological experiments identify plausible mechanisms requiring regional tests. National catalogue and specialist assessments indicate knowledge gaps but cannot quantify transboundary Amazonian richness or climate risk. Priorities include voucher-based inventories, monitoring of recruitment and adult survival, habitat-specific experiments, and protection of hydrological connectivity and moist refugia. A staged ten-year programme is proposed, with conservation outcomes assessed separately from research outputs. Sustained taxonomic and institutional capacity can reduce identification uncertainty and delays in management; its effects should not be conflated with a population’s intrinsic tolerance or adaptive capacity.