Influência da alteração do pulso de inundação sobre as comunidades arbóreas e as cadeias alimentares ictíicas na área da hidrelétrica de Balbina, Amazônia Central

Abstract

The productivity of floodplain forest ecosystems and the services they provide depend largely on the complex interactions of species with the environment and between species. The relationships between fish species and the use of resources from the flooded forest are embedded in a diverse network of trophic interactions, which is dependent on a cascade of seasonal events, such as the magnitude of the flood pulse, and the consequent availability of various allochthonous resources, including fruits and seeds from flooded forests, which are abundant during the flood period. In Chapter 1 we investigated how resource consumption shapes the structure of a fish food web. We hypothesize that the most important element that contributes to the structuring of food chains in igapó areas is the supply of allochthonous items through the flooded forest itself. We also assess which are the core fish species of the network, since their activities, in part, determine the structure of the community. Our results show that the structure of the food web is strongly shaped by the number of individuals, the size of the fish and the species composition of the flooded forest. In Chapter 2 we evaluated the consumption and dispersal of seeds by fish through two Quantitative Components (QC), using the Dispersion Effectiveness (SDE) approach. We found that fish that are more specialized in the consumption of fruits and seeds are more effective in seed dispersal when compared to fish that are considered trophic generalists. In summary, the results of this study indicate that possible changes in the trophic structure of the networks caused by increasing anthropic interventions in the landscape can lead to the loss of certain functional characteristics in relation to the fish community and the floodable forest, thus being able to affect the environmental services provided by both groups and jeopardize the functionality of the ecosystem of oligotrophic rivers.