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URI permanente desta comunidadehttps://bdc.icmbio.gov.br/handle/cecav/1401
Centro Nacional de Pesquisa e Conservação de Répteis e Anfíbios
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2 resultados
Resultados da Pesquisa
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.Item Don’t put all your eggs in one basket(Biological Conservation, 2019-10) Eisemberg, Carla Camilo; Vogt, Richard Carl; Balestra, Rafael Antônio M.; Reynolds, Stephen J.; Christian, Keith A. A.The Brazilian Government established the Amazon Turtle Project (Projeto Quelônios da Amazônia – PQA) in 1975 to monitor and protect the main nesting sites of Amazon River turtles. The PQA has become the largest-scale and longest-term wildlife conservation initiative in the Brazilian Amazon. We evaluated the outcomes of the PQA across 11 protected localities over 30 years (1977–2008). Inside the protected localities, one population of Podocnemis expansa has declined and four have seen an increase in numbers. The PQA conservation efforts for P. unifilis were not as successful as those of Podocnemis expansa, but were sufficient to stabilize or increase populations. These results suggest that there is a minimum effort necessary for positive conservation outcomes, which was not achieved for Podocnemis sextuberculata. Given the lack of correlation between initial nesting numbers and positive population trends, the current level of success in a given locality cannot be used as a tool to prioritize future protection efforts. We recommend that the PQA should maintain or increase its coverage due to the high levels of local unpredictability. If current harvest trends are maintained, it is likely the only surviving populations of P. expansa will be within protected areas. Considering the scope of the PQA and the period that it has been operational, it is surprising how little recognition it has received; the lack of national and international awareness of its achievements may be one of the main reasons behind the lack of support from the Brazilian Government. © 2019 Elsevier Ltd