BANCOS DE MACRÓFITAS AQUÁTICAS COMO LOCAIS DE DESENVOLVIMENTO DAS FASES INICIAIS DE PEIXES EM VÁRZEA DO BAIXO AMAZONAS

Abstract

The study describes the composition and structure of the larval and juvenile fishes’ community associated with aquatic macrophyte stands and it evaluates the importance of this vegetation for the development of early life stages of the ichthyofauna in an alluvial island in the Lower Amazon River, state of Pará, Brazil. The sampling was conducted during the phases of full flood/receding water of 2017 (cycle I) and rising water of 2018 (cycle II) in aquatic macrophyte stands using a fishing sieve (500 µm mesh). In the laboratory, specimens were identified and classified for their development stage and verified the species composition, abundance and similarity between the sampling cycles. Variance analysis and t-test were used to identify possible differences in the density between the development stages and the hydrological cycles, respectively. There were captured 2,193 individuals, from which 87.91 % were at the larval stage and 12.08 % at the juvenile, classified in 84 taxa and identified in nine orders, 24 families, 50 genera and 72 species. During the cycle I, there was a higher predominance of juvenile individuals of small species, which have an important role in energy transferring in the aquatic ecosystem, while in the cycle II the highest values of abundance were recorded from the medium-sized species with economic importance, captured in the early development stages. No significant difference was observed in the density of individuals among the sampling cycles however, the similarity analysis registered a variation on the composition of species between the cycles. The higher species richness, dominance and density of individuals were recorded during the rising water, while the full flood/receding water presented higher values of evenness and species diversity. Thus, larval and juvenile fishes’ community in aquatic vegetation in varzea in the Lower Amazon region is shown to be influenced by the hydrological cycle, ensuring the maintenance and renewal of the ichthyofauna.