Contribuição de espécies ornamentais para a estrutura funcional de assembleias de peixes de igarapés do médio rio negro, Amazônia Brasileira

Abstract

The study of biodiversity through its functional facet brings advantages related to the understanding of the structuring mechanisms, the relationships between the species and their respective ecosystemic roles, and the prediction of changes in biological services in the face of environmental changes. One of the main sources of pressures on natural fish populations in the Amazon is fishing, which has been more intensively carried out over the last decades. Seeing that the ornamental fishery carried out in the middle portion of the Negro River basin is an extractive activity focused on certain species, it is possible that the pressure exerted by the activity generates disturbances in the functional structure of the communities and suppresses specific ecological functions. With this scenario, the present study sought to estimate the effects of ornamental fishing on the functional structure of streams fish assemblages, through the elaboration of hypothetical scenarios of subtraction of abundances of ornamental and non - ornamental species. Through the evaluation of three complementary functional indexes (Redundancy, Divergence and Functional Dispersion) we found that the assemblies studied have high functional diversity related to the use of the environment and food resources. The species exploited by ornamental fisheries contribute significantly to the functional redundancy of the assemblages, and the simulated withdrawal of the Tetra cardinal Paracheirodon axelrodi causes greater losses to the assembly than the removal of non-ornamental species. These results indicate that the activity should be performed in an orderly manner and with adequate management, in order not to spoil the functional structure of local fish assemblages. As the activity does not generate significant changes in the physical and chemical conditions of the environment, and that economic unfeasibility decreases the chances of local extinction, ornamental fishery in the Barcelos region is prone to remain viable without altering the stability of the ecosystem.