Navegando por Assunto "Ecossistemas - Amazônia"

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Acesso aberto (Open Access)
Uma abordagem funcional das savanas amazônicas: atributos de anuros em um mosaico de paisagens naturais
(Universidade Federal do Pará, 2018-02-28) PASCHOALINO, Rosana Campos; PINHEIRO, Leandra de Paula Cardoso; http://lattes.cnpq.br/1114107627897774; SANTOS-COSTA, Maria Cristina dos; http://lattes.cnpq.br/1580962389416378
The structure of natural assemblages may result from selection of species and functional traits, according to their tolerance to certain environmental factors, which are related, for example, to vegetation type and water availability, may influencing functional diversity in ecosystems. We investigated the influence of different phytophysiognomies of Amazonian savannas on functional diversity of anurans, in the Carajás National Forest, Brazil. We also investigated a possible divergence of functional traits among the phytophysiognomies due to environmental differences using a null model. Three field expeditions were conducted in 2008 and 2010, during rainy season, dry season and the transition period between rainy and dry seasons. We sampled 32 sample units distributed in three sites: North highland, South highland and Tarzan highland. Each sample unit was distant at least 200 m from each other. Surveys for the presence of anurans were based in active visual and acoustic searches. We calculated functional diversity using the MPD index, considering the occurrence of anurans in each assemblage. Functional diversity of anurans did not differ among the vegetation types. According to null model, there was a functional convergence, that is, the sites are similar in species and functional traits. Our results suggest that despite the mosaic distribution and environmental differences, the landscapes are surrounded by Amazonian savanna matrix, which, due to some factors (historic, spatial, and environmental), did not differ in the functions performed by anurans in each phytophysiognomy. In any case, we found that anurans play important roles in local ecosystem functions.
Acesso aberto (Open Access)
Ecologia populacional de Clibanarius symmetricus (Anomura: Diogenidae) em uma praia exposta da Costa Amazônica Brasileira
(Universidade Federal do Pará, 2017-06) DANIN, Ana Paula Ferreira; SANTOS, Cleverson Ranieri; PETRACCO, Marcelo; http://lattes.cnpq.br/6834814201680920; https://orcid.org/0000-0001-6501-0099
The hermit crab Clibanarius symmetricus has a wide geographical distribution along the Western Atlantic where is a conspicuous species in intertidal and shallow waters of several ecosystems as sandy beaches, tidal flats, mangroves and rocky shores. However, information on the life history traits of this species is in general limited to the subtropical regions. Here, we access the population structure and dynamics, and the shell occupation pattern of a C. symmetricus population inhabiting a rocky outcroup of an exposed sandy beach on the Amazon coast. For this purpose, monthly samplings were carried out from October 2015 to September 2016. Higher density of C. symmetricus occurred in the drier season and the frequent presence of ovigerous females suggests continuous reproduction. The overall sex-ratio was skewed toward females (0.6:1, M:F) and sexual dimorphism was recorded. Males and females had similar curvature, but smaller growth performance index than others subtropical populations. The turnover rate (P/B) was also similar between sexes as a consequence of similar growth constant. Thaisella coronata was the most occupied (97.1%) gastropod shell and the overlap in shell utilization by hermit crabs of same size may reflect competitive interactions. Also, some difference in occupation between sexes was documented, suggesting that males can occupy larger and more suitable shells.