Non-native freshwater molluscs in the Neotropics: what can be learned from Brazilian reservoirs?

Habitat modification and the establislunent of non-native species are two major causes of biodiversity loss. Reservoirs modify habitat, can restrain the occurrence of native species, and allow the establislunent of non-native undesirable organisms. Non-native species are widespread. However, the status and distribution of some invaders in these man-made systems remains unclear, especially in the Neotropics. In this study, we surveyed digital databases to determine the distribution of nonnative molluscs in Brazilian reservoirs. Studies on non-native molluscs in Brazilian reservoirs had been increasing steadily until they reached their peak in 2015. Eight non-native mollusc species were recorded in reservoirs in all river basins except for the Amazonas River. Non-native molluscs were reported in 74 reservoirs, mostly located within the Parana River basin. The co-occurrence of multiple non-native molluscs was common. Time lapsed since first introduction of species was not correlated with their distribution in Brazilian reservoirs. This study was a first step toward understanding the distribution of non-native molluscs, and their possible impacts, in Neotropical reservoirs.