A large scale analysis of threats to the nesting sites of Podocnemis species and the effectiveness of the coverage of these areas by the Brazilian Action Plan for Amazon Turtle Conservation

Abstract

We evaluated the vulnerability of nesting sites (sandbanks) available to Podocnemis expansa, P. unifilis and P. sextuberculata to human threats and the coverage of these areas by a public policy created to conserve turtles. Species distribution models were used to identify potential nesting areas in the Brazilian Amazon, where sandbanks were mapped through satellite imagery. Values of threats (deforestation, mining, dams and density of human communities) were normalized from 0 to 1 and summed in each 100 km2 pixel. We calculated the mean value of threats and sandbanks area for each basin. Basins with the greatest values for those variables were considered as the most vulnerable. We calculated the coverage of turtle nesting sites that have conservation actions in relation to the sandbanks available and if they are located in the most vulnerable basins. The areas of greatest gaps in conservation actions and vulnerability are located in the Tocantins-Araguaia basins and in rivers such as: Branco, Guaporé, Amazonas, Solimões, Madeira, Tapajós and Xingu. Nesting sites included by the public policy covered 15.17 % of the number of basins and about 21 % of total sandbank areas, encompassing 11 % of the most vulnerable basins and 43 % of their sandbanks. We suggest the prioritization of conservation actions in areas of greatest gaps in conservation activities and vulnerability. In addition, we propose the articulation among institutions and the increase of initiatives of community-based conservation management to increase the geographical coverage of the greatest impacted regions.