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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 Mercury biomagnification in the food chain of a piscivorous turtle species (Testudines: Chelidae: Chelus fimbriata) in the Central Amazon, Brazil(2024-05-03) Cunha, Fábio Andrew G; Forsberg, Bruce R; Vogt, Richard C; Domingos, Fabíola X V; Marshall, Bruce G; Brito, Brendson C; Sousa, Otávio P de; Kasper, Daniele; Santos, Ana Laura P; Ândrade, MarceloDue to their natural history and ecological attributes, turtles are excellent organisms for studies of heavy metal contamination. Turtles have a large geographical distribution, occupy different aquatic habitats, and occupy various trophic levels. The present study investigated mercury bioaccumulation in the carnivorous chelonian Chelus fimbriata (Matamata turtle) and Hg biomagnification in relation to its aquatic food chain in the middle Rio Negro, AM-Brazil. Tissue samples of muscle, carapace and claws were collected from 26 C. fimbriata individuals, as well as collections of autotrophic energy sources found in the turtle's aquatic habitat area. The samples were collected in February-March/2014 and analyzed for THg concentrations and carbon (δ13C) and nitrogen (δ15N) stable isotopes. The highest THg levels were found in claws (3780 ng.g-1), carapace (3622 ng.g-1) and muscle (403 ng.g-1), which were found to be significantly different [F(2.73) = 49.02 p < 0.01]. However, THg concentrations in muscle tissue were below the consumption threshold indicated by the WHO and Brazilian Health Ministry. The average δ13C and δ15N values in Matamata samples were -31.7‰ and 11.9‰, respectively. The principal energy source sustaining the food chain of C. fimbriata was found to be terrestrial shrubs, with smaller contributions from emergent aquatic herbaceous plants and algae, while δ15N values showed its trophic position to be two levels above the autotrophic energy sources. There was a positive correlation between THg and turtle size, while a significant relationship was found between THg and δ15N, showing strong biomagnification in the food chain of C. fimbriata: y = 0.21x + 0.46; r2 = 0.45; p < 0.001, for which the slope presented a value of 0.21.Item Diet of invasive cats, rats and tegu lizards reveals impact over threatened species in a tropical island.(Perspectives in Ecology and Conservation, 2020) Gaiotto, Juliana Vallim; Abrahão, Carlos Roberto; Dias, Ricardo Augusto; Bugoni, LeandroVertebrates introduced in non-native habitats have contributed to several extinctions in the modern era, with direct effects mainly over birds, mammals and reptiles on islands. Fernando de Noronha Archipelago, in tropical Atlantic Ocean, is a World Heritage natural site, holding the most diverse breeding seabird community off Brazil, in addition to endemic landbirds and reptiles. It also holds invasive black rats (Rattus rattus), tegu lizards (Salvator merianae) and feral cats (Felis catus), among the 26 exotic species reported in the archipelago, all of which are species with potentially high impact upon native fauna. Aiming to assess the role of exotic vertebrates on the fauna, we investigated their diets through stomach content and scat analysis, and stable isotope analysis (SIA) followed by isotopic mixing models. The main food items for tegu lizards were fruits, with relative importance (Prey-specific Index of Relative Importance – %PSIRI) of 41.3%, and the endemic Noronha skink (Trachylepis atlantica; 19.6%) and for black rats was Noronha skink (30.3%). The diet of feral cats was composed by rodents (31.6%), birds (28.6%) and Noronha skink (18.8%). SIA and Bayesian mixing models provided evidences that invasive species use marine matter to synthesize tissues, probably derived directly or indirectly from seabird colonies. This study demonstrated that exotic species feed on other exotic, as well as endemic species. The most heavily impacted species was the endemic Noronha skink. We demonstrated the predation pressure of exotic fauna upon endemic vertebrates, and strongly recommend the implementation of an invasive species control and eradication plan.