Abstract
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.
Highlights
Large artificial lakes formed from damming large rivers cause a series of impacts which affect chemical, physical and specially biological components in the area of impoundment (Bianchini Jr., 1994), promoting considerable alterations in theActa Limnol
The Taquaruçu Hydro-electrical Plant is located at 22o32 - 22o42’ S and 52o01’ 5 1 o2 2 ’ W, inthelowcourseofthe Paranapanema River, between the States of São Paulo and Paraná, Brazil
We verified that the 73 species registered in the Taquaruçu reservoir are inserted among the 221 already catalogued for the Upper Paraná Basin (Agostinho & JúlioJr. , 1 9 9 9 )
Summary
Large artificial lakes formed from damming large rivers cause a series of impacts which affect chemical, physical and specially biological components in the area of impoundment (Bianchini Jr., 1994), promoting considerable alterations in theActa Limnol. Britski (1994) states that damming river has severe implications on fish community. In this aspect Agostinho & Gomes (2005) argue that the degree of impacts relates mainly to the characteristics of local fauna, location of the dam in relation to the area of population distribution, basin morphometry, the existence of other impoundments, the design of the dam and operational procedures of the plant. Local processes and factors, mainly the limnological and structural characteristics of the aquatic ecosystem and the interactions among species, are regarded as responsible for the composition and structuring of fish communities (Agostinho & Gomes, 2005)
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