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Trophic categories of the native and introduced species in the reservoirs and tributaries of the Middle and Lower Tietê River.
Source publication
Aim: We investigated the use of food resources throughout the reservoirs and tributaries of the Middle and Lower Tietê River. Methods The samplings were made in July 2000 (dry period) and January 2001 (rainy period). The fish samples were collected using two batteries of gill nets consisting of 8 nets with 10 meters in length and 1.5 meters wide wi...
Contexts in source publication
Context 1
... predominant items in the reservoirs were debris, filamentous algae, crustaceans, scales and fish, and in tributaries were the plant material, debris, Odonata, aquatic insect (for which it was not possible to identify at the highest level) and aquatic Hemiptera (Figure 2). The fish species were grouped into 13 trophic categories, according to the prevailing food ( Figure 3). In the reservoirs the omnivorous category was prevailing for native species while the invasive ones presented insectivorous and carnivorous categories. ...
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Citations
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.
