Livros e Publicações
URI permanente para esta coleçãohttps://bdc.icmbio.gov.br/handle/cecav/1481
Navegar
2 resultados
Resultados da Pesquisa
Item 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 DeWe 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.Item Vulnerability of Giant South American Turtle (Podocnemis expansa) nesting habitat to climate-changed-induced alterations to fluvial cicles.(Tropical Conservation Science, 2016) Eisemberg, Carla Camilo; Balestra, Rafael Antônio Machado; Famelli, Shirley; Pereira, Fernanda Freda; Bernardes, Virgínia Campos Diniz; Vogt, Richard CarlA change in seasonal flooding cycles in the Amazon may negatively impact nesting success of the Giant South American Turtle (Podocnemis expansa). Our aim was to devise a technique that could be replicated in the entire Amazon basin, for monitoring alterations in fluvial cycles and their effects on turtle nest mortality. We mapped the spatial distribution and height of P. expansa nests and tested the effects of different inundation scenarios within the Trombetas River Biological Reserve, Para state, Brazil. We also used historical data on water level and hatchling production to test whether the sharp decline in the Trombetas River P. expansa population over the past thirty years was related to detected changes in the flood pulse. Our models indicate that an increase of 1.5 m in the water level is sufficient to decrease the time of exposure to less than the minimum required for incubation and hatching (55 days above the water) in 50% of the nesting area. This model explains the low hatchling production in dry seasons when the total nesting site exposure was less than 200 days. Since 1971, there was na average decline of 15 days per decade in sandbank exposure during the nesting season (a total of 62 days from 1971 to 2015). However, the decrease in sandbank exposure was not significantly correlated with the sharp decline in hatchling production. Changes to the water cycle in combination with the main sources of decline (overharvest, construction of dams, and dredging of riverbeds) might have an accumulative effect on P. expansa populations.