Estrutura das assembleias de peixes em reservatórios receptores e não-receptores de transferências de águas interbacias

Abstract

Interbasin water transfers (TAIB) represent an important strategy in water allocation, and can cause the transport of nutrients, parasites and exotic species to the receiving basin. In the semi-arid region, the hydrography is made up of intermittent rivers, where TAIB's can cause their perennialization, changing the seasonal dynamics of these rivers, which can alter the structure of aquatic organisms, such as fish. It is not known how TAIB's influence the taxonomic and functional dynamics of fish assemblages, especially in the semi-arid region. Therefore, this work aims to evaluate the seasonal structure of fish assemblages in TAIB-receiving and non-receiving reservoirs in a semi-arid region. The study was carried out in six receiving and non-receiving reservoirs of the São Francisco TAIB in the Paraíba River basin. Active and passive devices were used in the dry and rainy seasons to collect individuals. The taxonomic analysis was carried out by identifying the species and functional analysis, based on 15 functional characteristics. Limnological variables were collected to evaluate their effects on the dynamics of fish assemblages. Taxonomic and functional indices were used to measure the structure of fish assemblages. Environmental heterogeneity was calculated to capture the local environmental profile of each reservoir. Mantel correlation tests were used to measure the effects of limnological variables on the dynamics of fish assemblages. The dry season and the receiving reservoirs showed greater species richness. Both groups of reservoirs showed seasonal variations in taxonomic composition. The drought was marked by greater functional dispersion and Rao index. Greater beta diversity was found in rain. Limnological variables explained the taxonomic composition in drought in both groups of reservoirs, and the functional composition of both groups of reservoirs. The non-receiving reservoirs presented taxonomic and functional patterns expected for semi-arid reservoirs. Taxonomically, there was no change in the structure of fish assemblages. Functionally, the change in the structure of fish assemblages may be associated with the impacts promoted by TAIB’s. Environmental filtration shapes the dynamics of fish assemblages in receiving and non-receiving reservoirs.