Influência de variáveis antrópicas e ambientais sobre a distribuição de ariranhas (Pteronura brasiliensis) em uma área protegida de uso sustentável na Amazônia oriental

Abstract

Historic anthropogenic impacts affecting the distribution and ecology of Giant otters are well documented, however little is known regarding the factors affecting the current distribution of the species. Our objective was to determine the relative importance of temporal (seasonal river levels), and anthropogenic (presence of houses, boats and fishing nets) factors on the distribution of Giant otters around a sustainable-use protected area in the eastern Brazilian Amazon. We conducted a total of 6836.1 km of motorized boat surveys to record locations of both direct observations and indirect signs of Giant otters along 150 km Araguari and Falsino River, in National Forest of Amapá, Amapá State, Brazil. To understand the importance of the factors at different spatial scales we conducted analysis using data summarized at two spatial scales: 50 km river “zones” and 5.1 km river sections. Our results showed contrasting spatial and temporal patterns resulting from direct and indirect signs. However, anthropogenic disturbances were the most important determinants of the presence of both direct and indirect signs, with Giant otters rarely detected within 40 km of the nearest town. Giant otters were present in the waterways throughout the annual water cycle (high, decreasing, low and increasing river levels), with direct observations positively related with the number of fishing nets present in the waterways. Our results suggest considerable spatial and temporal overlap between Giant otters and the activities of local fishers which must be considered for the effective management of conservation conflicts in this rapidly developing region.