Riqueza e diversidade de peixes avaliação da influência do ciclo hidrológico na composição ictiológica de um lago de várzea amazônica no município de TonantinsAM, microrreg

Abstract

Amazonian aquatic environments are one of the richest and most diverse in the world, this richness and diversity is reflected in the complexity of community structures and their relationships with the abiotic components that make up these ecosystems. The hydrological phenomenon that occurs in the Solimões/Amazonas River is responsible for shaping the physical and chemical structures of aquatic habitats, with a period of high water (flood) that floods the marginal forest connecting rivers and lakes and expands the trophic area for fish and other of low water (dry) that isolates water bodies and submits species to extreme variations in temperature and oxygen and increases the constancy of interspecific relationships. Therefore, this study aimed to evaluate the influence of the hydrological cycle on the ichthyological composition of a floodplain lake in the upper Solimões, in the municipality of Tonantins/AM. The collections were carried out during the wet and dry season using mesh nets with mesh 25, 30, 40, 45, 50, 55, 65, and 80mm between opposite nodes, the collected specimens were identified using identification guides through photographs. We calculated the Shannon Diversity (H’), Berger-Parker Dominance and Equitability indices for the two periods of the hydrological cycle. Our results showed that there was greater richness in the flood (43 spp.) than in the drought (27 spp.), with the order Characiformes being the most abundant in number of individuals and species in the flood and drought, followed by Perciformes. The family Curimatidae was dominant in terms of relative abundance in both flood and drought, with Potamorhina altamazonica being the most representative species in both periods. Lake Papucu's diversity index was considered low, as Shannon's diversity index was 2.73 and did not vary much between flood (H=2.8) and drought (H=2.2), and evenness demonstrated a greater dominance in drought than in flood. We conclude that the hydrological cycle is responsible for influencing the composition of fish communities in the Amazon floodplain, mainly because it modifies the physical-chemical patterns of water and reduces the diversity of habitats.