Taxonomic loss and functional reduction over time in the ichthyofauna of the Taquaruçu Reservoir, lower Paranapanema River, Southern Brazil

Abstract

We evaluated the fish composition and ecological attributes of the ichthyofauna collected in a limnological zone of the Taquaruçu Reservoir, lower Paranapanema River. Information about the fish community was updated when compared to the previous study (2006). Non-metric multidimensional scaling (NMDS) showed differences in species composition between periods and community weighted means (CWMs) exhibited changes in functional composition over time. Four functional indices were used in the principal coordinate analysis (PcoA) to measure changes in the functional space of species, whereas functional β-diversity inspected differences in the traits composition between the periods. 1,203 individuals were sampled of 43 species, being 16 non-native and 14 new records. Compared to 2006, 27 species were absent, most of them native to Loricariidae and Anostomidae, while Curimatidae and Pimelodidae decreased in abundance. Functional indexes showed a reduction in functional diversity, whereas new species records exhibited functional redundancy. It might have occurred a simplification of the fish community over time, excluding the migratory and specialists species such as the herbivores and detritivores. Accordingly, we concluded that the ichthyofauna of the Taquaruçu Reservoir might have been undergoing a process towards biotic homogenization.

Keywords:
Biological invasion; Damming; Homogenization; Long Term Changes; South America