Why are they here? Local variables explain the distribution of invasive mollusk species in neotropical hydropower reservoirs

Abstract

Reservoirs are a common sight in most rivers systems in the world and a frequent problem related to them is the introduction of non-native invasive mollusk species. We aimed to determine which local variables (near-site land use, physical habitat structure, water quality) were most strongly associated with the local distribution of invasive non-native mollusks in neotropical hydropower reservoirs. We used data from three neotropical reservoirs to calculate which local variables most influenced the presence or absence of the three non-native invasive mollusk species (i.e., Corbicula fluminea, Limnoperna fortunei and Melanoides tuberculata) found in them. We found that the presence of both C. fluminea and L. fortunei were positively correlated with local anthropogenic disturbances, likely because it was associated with more frequent human access to the water body and increased introductions of larval mollusks. Conversely, M. tuberculata was negatively correlated with total phosphorus concentration, which is linked to agriculture and urbanization in the reservoir catchments. Additionally, we found that C. fluminea and M. tuberculata presence was positively related to each other, implying a biological facilitation process between these two species. Our findings suggest that anthropogenic disturbances are important for the local distribution of invasive non-native mollusks in neotropical reservoirs and can be used by environmental managers and decision-makers to help manage invasive mollusk populations in neotropical hydropower reservoirs.