Navegando por Assunto "Lithodoras dorsalis"

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Acesso aberto (Open Access)
Aspectos ecológicos do bacu-pedra Lithodoras dorsalis (Valenciennes, 1840) (Siluriformes: Doradidae) na foz amazônica, Brasil
(Universidade Federal do Pará, 2012) BARBOSA, Thiago Augusto Pedroso; MONTAG, Luciano Fogaça de Assis; http://lattes.cnpq.br/4936237097107099
The aim of this study was investigate the ecological aspects related to the rock-bacu Lithodoras dorsalis (Siluriformes: Doradidae) from streams next to the city of Abaetetuba, Pará, Brazil. The aspects investigated were: feeding ecology and dispersal of plant diaspores (seeds). The study of feeding ecology and seed dispersal are important because they provide essential information for understanding the relationship between ichthyofauna and environment, allowing the taking of effective measures in the conservation of species and ecosystems. The samplings were carried out monthly from July 2010 to June 2011. In this period, 371 specimens of L. dorsalis were collected and through analysis of the gonads was found that all were immature. The average standard length was equal to 15.40 cm (SD ± 4.87 cm) and average total mass equal to 94 g (SD ± 149.45). The diet of the species was composed by 28 food items (16 allochthonous origin and 12 autochthonous origin) and Lithodoras dorsalis was classified as herbivore with a strong tendency to frugivory due to the high importance of fruits and seeds in your diet. With regard to the intensity of obtaining food by the rock-bacu, there were differences between the pluviometric periods, where the end of the transitional period wet-drought and early drought periods represented the lowest and highest feeding activity, respectively. However, there were no significant difference to the importance of the items consumed between the pluviometric periods, the diet of species was similar throughout the sampling period. About the dispersal of seeds, 268 (74.93%) of 371s pecimens of Lithodoras dorsalis showed fruit and vegetable seeds in their stomachs, the main being the assai Euterpe oleracea Mart., the aninga Montrichardia linifera (Arruda) Schott and the buriti Mauritia flexuosa Mart. For analysis we used the assai seeds Euterpe oleracea Mart. and aninga Montrichardia linifera (Arruda) Schott for reaching enough samples. From the analysis of the digestive tract of the rock-bacu was found that all plant diaspores of Euterpe oleracea Mart. were found intact, with an increase in performance of this plant germination, but this did not occur to aninga Montrichardia linifera (Arruda) Schott, because the digestion process destroyed some seeds. Thus it was concluded that Lithodoras dorsalis is a potential disperser of assai Euterpe oleracea Mart. in the Amazonian mouth, because in addition to increasing the performance of the seeds germination, there is an increase in the amount of fruits and seeds consumed by the individuals with the increasing of their body size. Finally, given the high consumption of material of allochthonous origin for Lithodoras dorsalis, we highlight the importance of riparian vegetation by providing items such as fruit and seeds, essential in the diet of Neotropical fishes and we emphasize the importance of ictiocoria for plants since many have sessile habit of life and cannot move from one location to another without the aid of dispersers.
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.
Acesso aberto (Open Access)
The role of Lithodoras dorsalis (Siluriformes: Doradidae) as seed disperser in Eastern Amazon
(Sociedade Brasileira de Inctiologia, 2017) BARBOSA, Thiago Augusto Pedroso; MONTAG, Luciano Fogaça de Assis
Ichthyochory is an important process responsible for the high diversity of plant species in tropical flooded forests. Thus, this study aimed to investigate the role of a catfish species, Lithodoras dorsalis, as seed disperser in the flooded forests at the Amazon River mouth, Brazil. Analyzing the stomach contents of 371 individuals of Lithodoras dorsalis, the Germination Potential (GP%) and Germination Speed Index (GSI) of seeds that were removed intact were investigated. This allowed us to evaluate the germination performance of two important species of plants in Amazonia, Euterpe oleracea (Açaí) and Montrichardia linifera (Aninga), after passage through the digestive tract of this catfish species. Given that digestion by L. dorsalis reduced the germination viability of M. linifera and that seeds were often destroyed during consumption, we suggest that L. dorsalis may have a limited role as seed disperser of M. linifera and instead mostly act as seed predator. However, for the species E. oleracea, L. dorsalis was a potential disperser, since the performance of germination of these seeds was improved after digestion. In addition, the number of seeds consumed was directly proportional to the catfish’s body size, reinforcing the role of doradids as potential seed dispersers in tropical forests.
Acesso aberto (Open Access)
Utilização de peixes nativos da Amazônia como biomarcadores na avaliação da qualidade da água de uma área industrial no rio Pará - PA - Brasil
(Universidade Federal do Pará, 2011) MONTES, Caroline da Silva; FERREIRA, Maria Auxiliadora Pantoja; http://lattes.cnpq.br/1832728101486131; ROCHA, Rossineide Martins da; http://lattes.cnpq.br/4371300451793081
Indiscriminate dumping of toxic substances impairs and deteriorates the water quality. Fish gills have a large surface area; they remain in close contact with the external environment and are particularly sensitive to changes in water quality, for this reason they are quite relevant for environmental monitoring. This study analyzes the gill structure of the fish species Plagioscion squamossissimus and Lithodoras dorsalis from two different sites located an Amazon estuary. A total of 324 specimens were used, this total 176 were P. squamossissimus and 148 L. dorsalis, removing the second gill arch for histological, ultrastructural and immunohistochemical analyses. The histological changes were analysed semiquantitatively according to the histopathological evaluation. The sampled sites differ regarding the rate of occurrence of altered animals, only site A showed healthy animals, 84% of L. dorsalis and 77% of P. squamossissimus had normal gill structure, with the lamellae lined by simple squamous epithelial, composed of pillar, mucous and chloride cells. However, all the specimens collected in sites B revealed tissue changes in the gill lamellae such as: aneurysm; epithelial lifting; cell proliferation; lamellar fusion and cell hypertrophy, this result was also confirmed by scanning electron microscopy. TUNEL analysis indicated that only animals captured on site B showed apoptotic cells. The presence of injury in gill tissues in the animals captured on site B emphasizes the need for more effective pollution control measures with regards to discarding pollutant loads as well as the need for urban planning in this region.