Navegando por Assunto "Rio Xingu (Bacia do Amazonas)"

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Acesso aberto (Open Access)
Artisanal fisheries of the Xingu River basin in Brazilian Amazon
(Universidade Federal do Pará, 2015-08) NAHUM, Victoria Judith Isaac; ALMEIDA, Morgana Carvalho de; CRUZ, Rivetla Edipo Araujo; NUNES, José Leocyvan Gomes
The present study characterises the commercial fisheries of the basin of the Xingu River, a major tributary of the Amazon River, between the towns of Gurupá (at the mouth of the Amazon) and São Félix do Xingu. Between April, 2012, and March, 2014, a total of 23,939 fishing trips were recorded, yielding a total production of 1,484 tons of fish, harvested by almost three thousand fishers. The analysis of the catches emphasizes the small-scale and artisanal nature of the region’s fisheries, with emphasis on the contribution of the motorised canoes powered by “long-tail” outboard motors. Larger motorboats operate only at the mouth of the Xingu and on the Amazon. Peacock bass (Cichla spp.), croakers (Plagioscion spp.), pacu (a group containing numerous serrasalmid species), aracu (various anostomids), and curimatã (Prochilodus nigricans) together contributed more than 60% of the total catch. Mean catch per unit effort was 18 kg/fisher–1.day–1, which varied among fishing methods (type of vessel and fishing equipment used), river sections, and time of the year. In most cases, yields varied little between years (2012 and 2013). The technical database provided by this study constitutes an important resource for the regulation of the region’s fisheries, as well as for the evaluation of future changes resulting from the construction of the Belo Monte dam on the Xingu River.
Acesso aberto (Open Access)
Biologia reprodutiva e dinâmica populacional de Hypancistrus zebra Isbrücker & Nijssen, 1991 (Siluriformes, Loricariidae), no rio Xingu, Amazônia brasileira
(Universidade Federal do Pará, 2011-05-25) ROMAN, Ana Paula Oliveira; ROCHA, Rossineide Martins da; http://lattes.cnpq.br/4371300451793081; ISAAC, Victoria Judith; http://lattes.cnpq.br/3696530797888724
Hypancistrus zebra is a specie used with ornamental purposes, endemic and rare in the Middle - Lower Rio Xingu, which has strong demand from the international ornamental fish market, which created a strong pressure of exploitation associated with this species. H.zebra is included on the list of Brazilian fauna threatened with extinction and their capture is prohibited. It is known that even prohibited, it continues to be captured and exported illegally, together with the construction of this hydroelectric Belo Monte in his patch of distribution, which threatens their geographical distribution and lack of information on its biology and ecology make it difficult planning actions for this species. So, if this work aimed to study aspects of reproductive biology and population dynamics to contribute to conservation measures for this species. Specimens of H. zebra were taken monthly from March 2009 to February 2010, by diving with a compressor, on the Xingu River, between the location of the weevil and Rita village of Belo Monte. The captured individuals were weighed and measured (total weight and total length). The gonads were removed and immediately fixed in Bouin solution. This was followed by routine histological techniques and the slides were stained with hematoxylin-eosin (HE). The stages of gonadal maturation were described based on the presence of germ cells at different stages of development. Through the length frequency data, estimates of population parameters such as growth models, recruitment, mortality, yield per recruit and size of first gonadal maturity. The species showed a seasonal spawning peaks between the two transition seasons of drought and flood (and vice versa) of the river, and two periods of recruitment, with different growth rates. It was estimated that the species has a lifespan of five years, and is at the limit of maximum sustainable yield, which is characterized as a dangerous situation for the species, because any increase in effort will compromise the stock and it is not known impacts that occur as a result of changes in their habitat caused by dam construction.
Acesso aberto (Open Access)
Ecologia e etnoecologia de Hypancistrus zebra (Siluriformes: Loricariidae) no rio Xingu, Amazônia brasileira
(Universidade Federal do Pará, 2011-08-05) GONÇALVES, Alany Pedrosa; NAHUM, Victoria Judith Isaac; http://lattes.cnpq.br/3696530797888724
H. Zebra is a fish species of the Loricariidae family, Ancistrinae subfamily, endemic of the Xingu River, with distribution from Belo Monte to the confluence of the Xingu and Iriri rivers. Being a species with great market value aquarist ornamental his capture became rampant, making it an endangered species. Despite strong pressure on H. zebra, there are still few studies on the species. Thus, given the scarcity of basic information and the constant threats, knowing the biology and ecology of H. zebra, aggregating the results of scientific research, also the local ecological knowledge of fishermen ornamental trade about this species becomes an essential tool for the conservation of the species. The distribution of H. zebra is restricted to a small stretch of the Xingu River, between Gorgulho da Rita and Itaubinha, and does not occur evenly, it depends on the presence of boulders. A total of 283 individuals of H. zebra were visualized in the rocky outcrops of the study area, of which 232 were captured. The lowest average abundance was Gorgulho da Rita, as opposed to the site Jericoá with the greatest abundance. Between periods, there was a greater abundance in dry river and lowest value for the period of filling. Environmental factors had no significant influence on the abundance of H. zebra. H. zebra is a generalist species, feeding mainly of periphytic algae, debris, plant debris and sponges, while nematodes and millipedes were considered occasional items. Diet composition and abundance of H. zebra showed no significant differences for collection sites, periods of the year and ontogeny. Considering the composition and abundance of the diet, H. zebra can be considered an iliophagousomnivorous, and ability to adapt changes in food availability in the construction of the Hidroeletric Belo Monte. Ornamental trade fishermen demonstrate expert knowledge concerning the distribution and abundance, habitat, feeding, predation and reproduction of the H. zebra, which can be used to optimize work and to facilitate future management measures. The construction of the Hydroeltric Belo Monte Hydroelectric is a threat to the survival of H. zebra and future studies and monitoring of the species are needed, either as mitigation of impacts, either as to captive breeding as an alternative income coastal communities who depend on fishing on the Xingu river ornamental.
Acesso aberto (Open Access)
Influência do ambiente de nidificação sobre a taxa de eclosão, a duração da incubação e a determinação sexual em Podocnemis (Reptilia, Podocnemididae) no Tabuleiro do Embaubal rio Xingu, Pará
(Universidade Federal do Pará, 2012-05-14) CARNEIRO, Cristiane Costa; PEZZUTI, Juarez Carlos Brito; http://lattes.cnpq.br/3852277891994862
In turtles, the characteristics of the nesting environment have a strong influence on the incubation temperature of eggs and, consequently, on the reproductive success. The effects of the enviroment of nesting on the hatching rate, the duration of incubation and the sexual determination of the nestlings of Podocnemis expansa, Podocnemis unifilis and Podocnemis sextuberculata in the Embaubal nesting beach, Xingu River, Pará State, Brazil, in 2007, 2008 and 2010 were investigated. Nesting beaches were continuously visited between September and January, in order to monitoring nests marked in the first day after oviposition, in each reproductive season. The following features measured: day of spawning, depth to the first egg, The nest’s height in relation to the river level, granulometry and temperatures of inubation. The hatching rate differed between years for the three species. The duration f incubation varied only between years P. sextuberculata. The sex ratio of P. expansa in 2007 was 0.08 and in 2008 and 2010 all the nestlings were females. In P. sextuberculata sex ratio in 2007 was 0.34, and in 2008 and 2010 was 0.06. The sex ratio of P. unifilis in 2007 was 0.41, 0.65 in 2008 and 0.02 in 2010. All of these differences were significants statistically. The nest’s height in relation to the river level presented positive correlation with the hatching rate of the three species in 2008 and a negative relation with the hatching rate of P. sextuberculata in 2010. The number of days after the beginning of the spawnings influenced the duration of incubation of P. sextuberculata and P. unifilis in 2008. The average temperature, the number of hours/degree above of 32°C and the size of the sediment influenced the sex ratio of P. expansa. The results attest to the variation in hatching success, embryo development and sex ratio produced between years. Still, it was observed that the influence of microclimatic variables of the selected sites for nesting in nesting success and sex ratio varied between years, which is a clear evidence that climatic conditions plays a major role and causes changes in the parameters examined thorough a nesting season and between nesting seasons in subsequent years. It is recommended the continued monitoring of the related parameters in the main areas which is invest the protection the reproductive sites of turtles.
Acesso aberto (Open Access)
Mercury concentration in different tissues of Podocnemis unifilis (Troschel, 1848) (Podocnemididae: Testudines) from the lower Xingu River – Amazonian, Brazil
(Universidade Federal do Pará, 2015-08) ARAUJO, Juliana de Souza; GIARRIZZO, Tommaso; LIMA, Marcelo de Oliveira
Studies using chelonians as biosentinels of environment quality or health risks associated with turtle consumption are very rare, especially in the Amazon basin. This study aims to measure Mercury levels (Hg) in muscle, liver, fat and blood of Podocnemis unifilis from the lower Xingu River, assessing the possible difference in concentration between sexes and also evaluating the potential bioaccumulation along different body sizes. Samples were collected during the dry season (October 2012) and Mercury (Hg) concentrations were analysed by Cold Vapor Atomic Absorption Spectrometry (CVAAS). A total of 29 specimens of P. unifilis of different sizes showed low levels lower than 0.2 mg/Kg). Higher Hg concentrations were found in the liver, and significant correlations between Hg concentrations in the different tissues were also detected. There was no difference between males and females and a negative correlation was found between Hg concentration and body size.
Acesso aberto (Open Access)
Population and biological parameters of selected fish species from the middle Xingu River, Amazon Basin
(Universidade Federal do Pará, 2015-08) CAMARGO-ZORRO, Mauricio; GIARRIZZO, Tommaso; NAHUM, Victoria Judith Isaac
This study estimates the main biological parameters, including growth rates, asymptotic length, mortality, consumption by biomass, biological yield, and biomass, for the most abundant fish species found on the middle Xingu River, prior to the construction of the Belo Monte Dam. The specimens collected in experimental catches were analysed with empirical equations and length-based FISAT methods. For the 63 fish species studied, high growth rates (K) and high natural mortality (M) were related to early sexual maturation and low longevity. The predominance of species with short life cycles and a reduced number of age classes, determines high rates of stock turnover, which indicates high productivity for fisheries, and a low risk of overfishing.