Can effects of invasive non-native species on ichthyofauna be predicted by their trophic level? an evaluation of Plagioscion squamosissimus and Geophagus sveni in Neotropical reservoirs

Abstract

One of the threats to biodiversity is biological invasion, which can result in taxonomic and functional losses and important ecosystem services, harming economic and ecological sectors. In Neotropical reservoirs there are gaps on the effects of invasion of nonnative species such as Geophagus sveni and Plagioscion squamosissimus, on fish assemblages. Thus, the present proposal will test the following hypotheses: (1) the structure and composition of the fish assemblage in the reservoirs were altered after the invasion of P. squamosissimus; (2) the structure and composition of the fish assemblage in the reservoirs were altered after the invasion of G. sveni; (3) the loss of local native species and the invasive potential vary according to the position in the trophic dynamics of the invasive species. Will be used data from long-term ichthyological monitoring performed at 17 sites in the reservoirs of Ilha Solteira, Três Irmãos, Jupiá, Porto Primavera and Jaguari, in Southeastern Brazil. For each reservoir, the temporal variations of the composition and abundance of the ichthyofauna and the taxonomic and functional diversity indices will be analyzed. Correlations will be made between the taxonomic and functional ecological indexes with the predictors of the invader and habitat conditions, as well as the abundance of the invaders with the total local abundance and of its possible competitors. The invasive potential of the two species and the fluctuations in the richness of fish species in each reservoir will also be measured after the invasion. The expected results of this research may contribute to management plans and mechanisms to mitigate the negative impacts of biological invasions. (AU)