Navegando por Autor "Marco Júnior, Paulo De"

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Artigo
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.
(Journal for Nature Conservation,, 2021-06) Fagundes, Camila Kurzmann; Fath, Franciele; Cortes, Lara Gomes; Uhlig, Vívian; Andrade, Paulo C´esar Machado; Vogt, Richard Carl; Pezzuti, Juarez Carlos Brito; Marco Júnior, Paulo De
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, Guapor´e, Amazonas, Solimoes, ˜ Madeira, Tapajos ´ 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.
Artigo
Assessing Brazilian turtles’ vulnerability BY USING species distribution models AND dispersal constraints
(Biodiversity and Conservation, 2024-01-27) Pinto, Hugo Bonfim de Arruda; Valadão, Rafael Martins; Andrade, André Felipe Alves de; Batista, Flavia Regina de Queiroz; Marco Júnior, Paulo De
Most assessments of the conservation status of Brazilian turtles use the IUCN geographic range criteria performed by the Minimum Convex Polygon (MCP). This technique often leads to over- or under-estimating the geographic distribution of rare, vulnerable, or endangered species. We aimed to demonstrate that using Species Distribution Models (SDM) on the geographic range assessment of turtles could be more accurate than using the minimum polygon convex. We reduced overestimation of species’ extent of occurrence by adding dispersal constraints, which avoids under- or over-estimating the impact of threatening events. The extent of occurrence derived from MCP was 31% higher than SDM on average, ranging from 4 to 311% higher. Using remaining habitat variables, we found that habitat loss within the predicted extent of occurrence increased by 79% from 1985 to 2019, and inferred population fragmentation increased by 161%. The distribution of turtles Acanthochelys radiolata, Acanthochelys spixii, Hydromedusa maximiliani, Hydromedusa tectifera, Mesoclemmys vanderhaegei, Phrynops williamsi, and Ranacephala hogei is severely fragmented, with most of their extent of occurrence being split into patches that are unavailable to the species persistence. Our findings highlight the importance of using SDM combined with dispersal constraints, which may further benefit from future information about the dispersal capacity of turtles. Furthermore, adding environmental layers to this combination makes it possible to discuss processes affected by habitat fragmentation, such as the fragmentation of species populations, an aspect essential to evaluate population viability and local extinctions.