Navegando por Autor "BARTHEM, Ronaldo Borges"

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Acesso aberto (Open Access)
Diet of the freshwater stingray Potamotrygon motoro (Chondrichthyes: Potamotrygonidae) on Marajó Island (Pará, Brazil)
(2010-02) ALMEIDA, Mauricio Pinto de; LINS, Paulo Marcelo de Oliveira; CHARVET, Patrícia; BARTHEM, Ronaldo Borges
The stomach contents of 137 examples of Potamotrygon motoro caught in 3 locations (Muaná, Afuá and Lake Arari) on Marajó Island were analysed. The values of the Index of Relative Importance (IRI) and its respective percentage (%IRI) were calculated. The level of repletion 1 (¼ full) was the most representative for both sexes, as well as for immature and mature specimens. Most of the food items found were well-digested. The food items identification indicated the presence of 15 orders, including insects, mollusks, crustaceans, annelids and fish. Differences in diet were observed among the locations studied when comparing %IRI, crustaceans being the most preferred in Afuá, fish in Lake Arari and mollusks in Muaná.
Acesso aberto (Open Access)
Distribution, feeding and ecomorphology of four species of Auchenipteridae (Teleostei: Siluriformes) in Eastern Amazonia, Brazil
(Universidade Federal do Pará, 2017) FREITAS, Tiago Magalhães da Silva; MONTAG, Luciano Fogaça de Assis; BARTHEM, Ronaldo Borges
Fish exhibit morphological, physiological and behavioral specializations which enable them to display diff erent ways to explore the environments and resources. Thus, the aim of this study was to verify how four Auchenipteridae species diff er in the distribution, feeding habits and morphological traits: Auchenipterichthys longimanus (Günther, 1864), Auchenipterus nuchalis (Spix & Agassiz, 1829), Tatia intermedia (Steindachner, 1877) and Trachelyopterus galeatus (Linnaeus, 1766). This study was conducted in rivers and bays of the Anapú Basin, Pará State (Brazil), where these species are abundant. Specimens were collected using gillnets, and after caught the stomachs were removed for the contents analyzes. Eighteen morphometric measurements from ten adult specimens of each species were taken, combined into fi fteen ecomorphological attributes. The species distribution showed that A. longimanus was restricted to rivers, while the others were exclusively caught in the bays. All four species had their diet composed of allochthonous insects, but A. longimanus also exhibited a great frugivorous habit. The most important ecomorphological attributes were relative to the consumption of larger food items (for A. longimanus and T. galeatus) and to the longer swimming capacity (for A. longimanus and T. intermedia). These morphological diff erences and the trophic diversity presented in this study highlighted some important information about how ecomorphological similar species behave and share resources, which may play a signifi cant role on the coexistence of these species in the Anapú Basin.
Acesso aberto (Open Access)
Feeding ecology of immature Lithodoras dorsalis (Valenciennes, 1840) (Siluriformes: Doradidae) in a tidal environment, estuary of the rio Amazonas
(Sociedade Brasileira de Ictiologia, 2015-06) BARBOSA, Thiago Augusto Pedroso; BARTHEM, Ronaldo Borges; MONTAG, Luciano Fogaça de Assis
Studies of feeding ecology are important for the evaluation of interactive processes in fish communities. This study evaluated the feeding ecology of Lithodoras dorsalis (Doradidae) from streams within the Amazon estuary delta (Brazil), a macro-tidal area, on different pluviometric periods. A total of 371 young specimens was collected during 12 months of sampling (July 2010 to June 2011). The species diet was composed of 28 food items analyzed by Repletion Index, Alimentary Index and Niche Breadth. Young L. dorsalis was classified as herbivore with a frugivory tendency due to the high importance of fruit and seeds in its diet. Food intake varied among sampled months, with the lowest intake being recorded during the rainy-dry season transition period, and the highest at the beginning of the dry season. The importance of food items and the composition of the diet were different throughout the year, probably due to the daily tides that allow fish to access new environments and the pluviometric periods. These results provide important data on the feeding ecology of Amazonian doradids. The study also emphasized the importance of allochthonous resources, derived from the riparian forest, which reinforces the importance of this habitat for the conservation of Neotropical freshwater fishes.