Peixes do rio Manicoré: uma abordagem taxonômica, molecular e ecológica sobre a ictiofauna dos igarapés

Abstract

The Amazon is home to one of the planet's greatest fish diversities, with many species yet unknown, especially in underexplored areas. The Manicoré River basin, a tributary of the Madeira River, exemplifies this biological richness, currently threatened by deforestation and fires. In response to environmental pressures, local communities, supported by Greenpeace Brazil, requested the creation of a Conservation Unit. To bolster this demand, Greenpeace, in partnership with the National Institute of Amazonian Research (INPA), organized the "Amazon We Need" expedition, aiming to conduct a biological survey of the basin. Fish were collected from streams on both the right and left banks of the Manicoré River using sieves and gillnets. Muscle fragments were preserved in absolute ethanol for subsequent genetic analysis. At the Animal Evolution and Genetics Laboratory (LEGAL-UFAM), DNA was extracted using the CTAB 2% method, and the mitochondrial genes COI and 12S were amplified with specific primers for molecular identification and diversity analysis. In Chapter 1, the application of multiple species delimitation methods (GMYC, bGMYC, mPTP, locMin, ABGD, ASAP, and morphological) revealed discrepancies among the delimitations, reflecting different aspects of the evolutionary process. However, congruence between two or more methods indicated the existence of evolutionarily significant lineages, some with signs of cryptic speciation. The COI marker demonstrated sensitivity in detecting fine population variations, even between opposite banks. In Chapter 2, the ecological structure of fish communities between the river banks was evaluated. Individual abundance was significantly higher in streams on the right bank, while species richness showed no statistical difference. Diversity indices were also higher and more consistent on this bank, suggesting greater ecological stability. The left bank showed greater variability in diversity patterns, indicating possible influence from heterogeneous environmental factors or differentiated anthropogenic impacts. The results emphasize the importance of the Manicoré River basin as a key area for the conservation of Amazonian ichthyofauna, highlighting the need for integrated research, management, and protection strategies.