Levantamento taxonômico e padrões de distribuição da fauna de peixes em ambientes antropizados: estrutura, composição e fatores ambientais

Abstract

Abstract (Chapter one) The increasing anthropogenic activities on the water network urgently require measures of conservation and restoration of aquatic environments. In addition, fish inventory, in general, are scarce in the Middle Amazon region. Thus, the objective of this study was to conduct a survey of the ichthyofauna in anthropic environments in the Middle Amazon region, Brazil. The samples were collected at six sampling points located in the system at the Urubu and Canaçari lake in the June, September, November, 2018 and March, 2019. For the capture of the specimens, were used gillnets and seine. A total of 67 species were captured, distributed in 12 orders, 7 families and 43 genera. The orders with the greatest number of species were Characiformes, Cichliformes and Siluriformes. The most representative families in relation to the number of species were Cichlidae, Characidae and Lebiasinidae. Species tolerant to anthropic environments were captured, the main example being the representatives of the family Cichlidae, where the common species in all the sampling points were the Acarichthys heckelii, Acaronia nassa, Biotoecus opercularis, Cichla monoculus, Geophagus altifrons, Laetacara thayeri, Mesonauta festivus e Satanoperca litith. Among the common cichlids at all sampling points the most abundant was Acarichthys heckelii. The most abundant species in our study was Hemigrammus levis. The point with lower relative abundance and number of species were point 2, visually the most impacted body of water with deforestation and surrounding pasture. Species of economic interest were collected, as well as species recently described and one that still awaits formal description, identified here as Moenkhausia aff. colletii. In this way, we emphasize the importance of cataloging and get to know fish fauna in modified environments, to investigate the potential impacts of fish fauna composition, maintenance and survival in these environments directly affected by human activities, and to generate conservation measures and information on local ichthyofauna.

ABSTRACT (Chapter two) One of the factors that affect fish fauna is the habitat conditions that are increasingly suffering from intense anthropogenic activities. The objective of the present study was describe the structure of the fish fauna (number of species, ecological indices), and evaluate differences in the structure of the fish fauna between anthropic environments of black and white water and different collection periods, and to test the influence of environmental factors (water type, collection periods and physicochemical variables) on species composition. The samples were collected at six sample points located in the system at Urubu and Canaçari lake. Three were of black water and three of white water unnatural with different situations of anthropization to the environment. The collections were carried out in the full, leakage, dry and flood period. For the capture of the specimens, were used gillnets and seine. Sixty three species were captured in black water and forty eight in white water. The relative abundance was (62.6%) for black water and (34.4%) for white water. The higher number of species for the order Characiformes were found in black water. While, the number of species for the Cichlidae family was close to both types of water. Nineteen exclusives species were captured in black water, the most abundant being Curimatopsis macrolepis, Moenkhausia aff. colletii (species not described), Curimatopsis cryptica and Metynnis melanogrammus. Five exclusives species were captured in whitw water, the most abundant being Apistogramma pertensis, Brachyhypopomus brevirostris, Rhamdia quelen e Hypophthalmus edentatus and forty four species were captured in both types of water. The structure and composition of the fish fauna were strongly influenced by the water difference (black and white), whereas only one ecological descriptor (number of species) had a statistical difference between the collections. Thus, we emphasize the importance of verifying the factors that can influence the fauna of fish in a positive or negative way to take measures of conservation of aquatic nets and their resources in the future.