Climate change may increase the suitable habitats for invasive freshwater Cichlids in a Neotropical basin

Climate change is considered a driver for the spread of invasive alien species (IAS); nevertheless, research assessing this link remains limited. Recognizing suitable habitats where IAS have been introduced is crucial for biodiversity conservation and ecosystem management. Here, we integrated online, museum, and laboratory occurrence databases with local ecological knowledge (LEK) on IAS fishes from semi-structured interviews and georeferenced Instagram posts from traditional and recreational fishers to model the habitat-suitability of three voracious IAS Cichlids introduced in the Brazilian part of the Upper Paraguay River Basin (the Pantanal wetland and its tributaries). Our goal was to locate areas (regions, sub-basins, and reservoirs) most at risk from the spread of these IAS fishes in the basin. Our findings reveal extensive suitable habitats for these IAS fishes throughout the study basin, currently covering half of the Pantanal wetland and up to 90% of the upstream sub-basins. Under future climate scenarios, these suitable habitats are projected to expand further, encompassing 85% of the Pantanal floodplain - one of the most fish-rich basins in the Neotropical region (~ 300 spp). These findings underscore a potential IAS Cichlid range expansion in the Pantanal floodplains in the upcoming decades. Our study emphasizes the value of integrating Ecological Niche Models (ENMs) with Citizen Science data to identify high-risk areas during early invasion stages, inform preventive strategies, and support conservation efforts to mitigate the impacts of IAS on native biodiversity.