Avaliação dos efeitos de monocultura de palma de dendê na estrutura do habitat e na diversidade de peixes de riachos amazônicos

Abstract

In the Amazon, oil palm plantation has been growing exponentially in recent years, altering the landscape natural characteristics and being a possible threat to biodiversity. This environmental impact extends to aquatic ecosystems, which because they are highly related to the adjacent vegetation, also suffer the impacts resulting from this agricultural action, such as habitat structure alterations, affecting the species distribution and ecosystem processes. Thus, studies to test the impact of this monoculture in the Amazon are important to support more efficient strategies for reducing impacts and maintaining biodiversity. Therefore, this thesis aims to answer the following questions: I) How the presence of oil palm cultivation around the streams affect their habitat structure and fish assemblage structure in relation to streams that drain through forested areas present along of this anthropogenic landscape? II) What are the effects of the substitution on landscape of primary forest on the oil palm in the habitat physical structure and on the taxonomic diversity of neotropical stream fish? III) How do the patterns of taxonomic and functional diversity of Amazon stream fish assemblages responds to the habitat and landscape changes caused by oil palm plantation? To answer these questions, we sampled and analyzed 39 streams in the Eastern Amazon. For the habitat characterization, an extensive protocol of the evaluation was applied, resulting in 238 habitat variables, besides that, was used landscape characteristics based on the percentage of land uses adjacent to the streams. For fish collection was used hand net for six hours in each stream. Morphological measures and ecological information of fish species were taken for later calculation of the functional attributes related to the third chapter. The results showed that oil palm plantation affect the stream habitat structure, modifying mainly the channel morphology, the substrate structure and shelter availability, such as woods and roots, for fish assemblage. Consequently, the fish species distribution was affected, resulting in changes in the assemblage structure. On the other hand, no changes were registered in the functional structure of these assemblies. Finally, we showed that the oil palm plantation modifies the stream habitat natural characteristics, as well as the distribution of the species, however the functional structure of the fish assemblages is maintained.