Small in size but rather pervasive: the spread of the North American rotifer Kellicottia bostoniensis (Rousselet, 1908) through Neotropical basins

Kellicottia bostoniensis is a North American limnetic zooplankter and the single rotifer species within the group of 163 non-native species recorded in Brazilian inland waters by the Brazilian Environmental Ministry in 2016. This species is also the only non-native rotifer of the genus Kellicottia recorded in Brazilian basins. This paper reports the first occurrence of K. bostoniensis in thirteen Brazilian hydroelectric reservoirs with varying trophic levels and throughout two freshwater ecoregions. The abundance of K. bostoniensis was higher in oligotrophic reservoirs, indicating a possible preference of this species for clear waters. The distribution pattern detected in this study suggests a great spread potential within Brazilian basins, which could be due to water birds or fish gill transportation, but the exact vectors are still unknown. Moreover, its small-sized body, the presence of dormant eggs, long spines to avoid fish predation, and apparent tolerance to variable trophic conditions are the major life-history traits that might contribute to its spread and potential establishment. The high dispersal ability and overabundance of K. bostoniensis reported in our study, stress the invasive potential of this microzooplankton species and the importance of assessment programmes to evaluate possible deterioration of water quality and impacts on native plankton fauna.