A influência dos componentes da paisagem sobre a abundância de pirarucu (Arapaima gigas) em áreas de manejo

Abstract

In addition to overfishing, the degradation of floodplain environments by anthropic activities, the use of wild individuals in aquaculture, climate change and the construction of hydroelectric dams also threaten pirarucu populations in the Amazon. It is well known the importance of knowing the effects of environmental heterogeneity on fish assemblages, as there is an intrinsic relationship between the ichthyofauna and their habitats, since they derive the resources necessary for their survival, growth and reproduction. The development of new methodological approaches provide other ways of assessing environmental variables. Landscape components enable the characterization of the environment and can be studied in space and time through remote sensing. The present study seeks to verify if the landscape components of the Amazonian floodplain lakes influence the abundance of pirarucu. The abundance was measured by the pirarucu counting method, performed during the dry season (September), estimated in 7 floodplain lakes with management category. Pirarucu abundance was correlated with landscape components: (i) open water, (ii) macrophytes, (iii) flooded forest and (iv) non-flooded forest, estimated during the flood (May/July). It was identified the spectral response of each target, which assisted in the supervised classification using the maximum likelihood algorithm, allowing the elaboration of the land use and occupation maps between 2013 and 2018. The area of each landscape component was measured. After the creation of an area of influence that corresponded to a buffer of 100 meters distance, between the water and vegetation threshold, for each lake studied. Data were analyzed using a generalized linear model, considering total pirarucu abundance as the dependent variable and open water area, macrophyte, flooded forest and non-flooded forest as independent variables. Our analysis identified the influence of landscape components on pirarucu abundance in lakes of the Amazon floodplain. In the adjusted model (pseudo-R² 0.64; p <0.05) explains 64% of the influence of the variables, open water, macrophyte and flooded forest on the abundance of pirarucu. Finally, the conservation of landscape components of the floodplains of the Amazon floodplain is extremely important for the maintenance of pirarucu populations. Our results can corroborate the participatory zoning and the adequacy of the current environmental legislation that establishes guidelines for the sustainable management of pirarucu in the Amazon.