10 results on '"Araújo, Francisco Gerson"'
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2. Fish Assemblages as Indicators of Water Quality in the Middle Thames Estuary, England (1980-1989)
- Author
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Araújo, Francisco Gerson, Williams, W. Peter, and Bailey, Roland G.
- Published
- 2000
3. Evidence of morphological differences between Astyanax bimaculatus (Actinopterygii: Characidae) from reaches above and below dams on a tropical river
- Author
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Santos, Alex Braz Iacone and Araújo, Francisco Gerson
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- 2015
- Full Text
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4. Heavy Metal in Tissues of Three Fish Species from Different Trophic Levels in a Tropical Brazilian River
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Terra, Bianca Freitas, Araújo, Francisco Gerson, Calza, Cristiane Ferreira, Lopes, Ricardo Tadeu, and Teixeira, Tatiana Pires
- Published
- 2008
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5. Effect of the wave exposure gradient on juvenile fish community in sandy beaches of the Rio de Janeiro City, Brazil
- Author
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Vasconcellos,Ruan Managna, Santos,Joaquim Neto de Sousa, Silva,Márcio de Araújo, and Araújo,Francisco Gerson
- Subjects
fish ,ichthyofauna ,surf zone ,Rio de Janeiro ,zona de arrebentação ,sandy beach ,ictiofauna ,praia arenosa ,peixe - Abstract
A distribuição e abundância da ictiofauna na zona de arrebentação de praias arenosas do Município do Rio de Janeiro, Brasil, foram estudadas objetivando detectar variações sazonais ou influências do grau de exposição na estrutura da comunidade de peixes jovens. Amostras trimestrais foram realizadas em 10 praias sendo agrupadas de acordo com o nível de exposição (abrigada, exposta e muito exposta), entre Janeiro e Novembro de 2004, com os arrastos tendo sido efetuados perpendiculares à linha de costa. Foram registrados 6.464 peixes, distribuídos em 38 espécies e 22 famílias, com o predomínio de formas juvenis ou de pequeno porte. As famílias Clupeidae, Carangidae e Sciaenidae representaram 79% do número total de indivíduos e 61% da biomassa total. As espécies de maior participação na biomassa, representando 81% do peso total, foram Harengula clupeola (36%), Orthopristis ruber (14%), Mugil liza (10%), Trachinotus goodei (8%), Trachinotus carolinus (7%) e Umbrina coroides (6%). Três espécies apresentaram maior abundância relativa, tendo cada uma, contribuído acima de 10% do número total (Harengula clupeola, Umbrina coroides e Trachinotus carolinus), mas somente T. carolinus apresentou um padrão bem definido, sendo mais abundante nas zonas abrigadas. As maiores CPUEs (número de indivíduos e biomassa) e o número de espécies foram encontradas nas zonas abrigadas (p < 0,05); sazonalmente nenhum destes indicadores apresentou diferença significativa (p > 0,05). O grau de exposição às ondas foi confirmado como um fator primário na estruturação da comunidade de peixes, com os locais mais abrigados provavelmente associados à maior disponibilidade de organismos planctônicos, menores turbulências e maior estabilidade do substrato. Distribution and abundance of the ichthyofauna of surf zone in sandy beaches of the Rio de Janeiro Municipality, Brazil, were studied aiming to detect seasonal and wave exposure gradient influences on the fish community structure. Quarterly samplings were performed at 10 sites according to the exposure degree (sheltered, exposed and very exposed) between January and November 2004, by using beach seines with hauls carried out perpendicular to the coastline. A total of 6,464 fishes in 38 species and 22 families were identified, mainly juveniles or small sized individuals. The families Clupeidae, Carangidae and Sciaenidae amounted to 79% of the total fish number and 61% of the total biomass. The following species amounted to 81% of the total weight were: Harengula clupeola (36%), Orthopristis ruber (14%), Mugil liza (10%), Trachinotus goodei (8%), Trachinotus carolinus (7%) and Umbrina coroides (6%). Three species showed the highest relative abundance, contributing each one more than 10% of the total number (Harengula clupeola, Umbrina coroides, e Trachinotus carolinus); but only T. carolinus showed a clear pattern, being more abundant in the sheltered beaches. The highest CPUEs (number of individuals and biomass) and number of species values occurred in the sheltered beaches (p < 0.05); none of these indicators showed significant seasonal differences (p > 0.05), although some trends were detected. The wave exposure degree was confirmed as a primary factor influencing the fish community structure, with sheltered sites probably associated to higher plankton availability, lesser turbulence and more substrate stability.
- Published
- 2007
6. Variações temporais e espaciais na composição e estrutura da comunidade de peixes jovens da Baía de Sepetiba, Rio de Janeiro
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Pessanha, André Luiz Machado, Araújo, Francisco Gerson, Azevedo, Márcia Cristina Costa de, and Gomes, Iracema David
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Sepetiba Bay ,fish ,ichthyofauna ,bioecology - Abstract
A year-long beach seine survey at the continental margin of Sepetiba Bay, Rio de Janeiro State, Brazil, catching mainly young-of-the-year and juvenile fishes was carried out from July 1983 to June 1984, in order to describe the community structure and their spatial and seasonal variations. Fifty-five monthly samplied carried out in five sites in the marginal surf zone waters yielded 11,463 fishes in 82 species, 59 genera and 31 families. Gerreidae, Engraulidi-dae, Atherinidae and Ariidae families amounted 87.01% of the total catch in number, and 81% in weight. Cerres aprion Cuvier, 1829, Anchoa januaria (Steindachner, 1879), Anchoviella lepidentostole (Fowler, 1911), Atherinella brasiliensis (Quoy & Gaimard, 1824) and Neluma barba (Lacépède, 1803) were the most numerous species, each one contributing more the 4% of total catch. Overall, both spatial and seasonal changes in fish were not evident although most individuais were more abundant in the outer Bay. The high number of fish species in this area, suggest the important role played by the Sepetiba Bay in the fish community to where many species probably migrate from the nearby sea and stay in the Bay during part of their life cycle. Decreasing diversity and high dominance of a few number of species seem to indicated a trend of environmental deterioration in the Sepetiba Bay over the last decade, as this date are compared whith similar sampling program carried out in 1993/94. It same to indicated that changes in fish populations which use this area as rearing grounds, occurred during their early life history.
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- 2000
7. Evaluation of Heavy Metals in Fish of the Sepetiba and Ilha Grande Bays, Rio de Janeiro, Brazil
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de Souza Lima Junior, Roberto Guião, Araújo, Francisco Gerson, Maia, Marilza Farias, and Seda da Silveira Braz Pinto, Andréa
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POISONOUS fishes , *HEAVY metals - Abstract
Muscles, gonads, and liver tissues of fish caught in Sepetiba and Ilha Grande Bay were analyzed to assess levels of heavy metal concentrations of Cd, Fe, Zn, Pb, Ni, Cu, and Cr. Levels of Cr surpassed the maximum permissible concentration in muscle, followed by Zn in some species. Pb, Cu, and Cd presented concentrations above maximum permissible levels in gonads and liver only. Fe presented concentrations in viscera comparable to those of highly polluted areas, although there are no standards available for this metal. Ni was the only metal that did not present contamination in the fish tissues examined. Overall, fish caught in Sepetiba Bay showed higher metal concentrations than those from Ilha Grande Bay, but the latter also presented high metal concentrations in several samples. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
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8. Trophic connectivity and basal food sources sustaining tropical aquatic consumers along a mangrove to ocean gradient.
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Claudino, Marlucy Coelho, Pessanha, André Luiz Machado, Araújo, Francisco Gerson, and Garcia, Alexandre Miranda
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CONSUMERS , *STABLE isotopes , *ESTUARINE ecology , *FOOD chains , *ISOTOPE geology - Abstract
Variations in the relative importance of autotrophic sources to aquatic consumers along environmental gradients and the trophic role of mangrove-derived detritus to marine coastal food webs are still poorly investigated in tropical systems. In this study, we employed stable isotope analyses to investigate the relative importance of basal food sources to macroconsumers (decapod crustaceans and fishes) in a tropical estuary along an environmental gradient extending from the mangroves to the ocean. Additionally, we evaluated the ‘outwelling hypothesis’, which hypothesizes that mangrove-derived detritus exported to the adjacent marine area is a food source for marine macroconsumers at open and reef-protected sandy beaches. Primary producers and macroconsumers (62 and 214 samples, respectively) were collected at five locations across the main longitudinal axis of the Mamanguape estuary, a tropical Southwestern Atlantic estuary. There were marked shifts in carbon and nitrogen isotope values for both food sources and consumers along the estuarine-marine gradient, and the mixing model results revealed similar patterns of assimilation of basal food sources by decapod crustaceans and fishes. In the inner section of the estuary, consumers tended to assimilated nutrients derived mainly from mangrove and macroalgae, whereas nearer the mouth of the estuary and in the adjacent marine area they assimilated nutrients derived mainly from macroalgae, seagrass and organic matter in the sediment (SOM). These findings support the hypothesis that the relative importance of basal food sources to macroconsumers in this tropical estuarine system reflects the dominant autochthonous primary production at each location. In contrast, our results did not support the outwelling hypothesis that mangrove-originated detritus, in the form of senescent mangrove leaves, makes a significant contribution as a primary source of carbon to high-order consumers inhabiting adjacent ocean sandy beaches. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
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9. Effects of a nuclear power plant thermal discharge on habitat complexity and fish community structure in Ilha Grande Bay, Brazil
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Teixeira, Tatiana Pires, Neves, Leonardo Mitrano, and Araújo, Francisco Gerson
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THERMAL pollution of rivers, lakes, etc. , *NUCLEAR power plants , *FISH communities , *BAYS , *HABITATS , *BIOINDICATORS , *SARGASSUM , *STEGASTES - Abstract
Abstract: Fish communities and habitat structures were evaluated by underwater visual censuses a rocky location impacted by thermal discharge (I) and at two control locations, one in a Sargassum bed (C1) and the other in a rocky shore with higher structural complexity (C2). Habitat indicators and fish communities exhibited significant differences between the impacted and control locations, with the impacted one showing a significant decrease in fish species richness and diversity, as well as a decrease in benthic cover. At the I location, only 13 fish species were described, and the average water temperature was 32±0.4°C, compared with 44 species at C1 (25.9±0.3°C) and 33 species at C2 (24.6±0.2°C). Significant differences in fish communities among locations were found by ANOSIM with Eucinostomus argenteus, Mugil sp. and Haemulon steindachneri typical of location I, while Abudefduf saxatilis, Stegastes fuscus and Malacoctenus delalandi were typical of the control locations. Our study shows that thermal pollution alters benthic cover and influences fish assemblages by altering composition and decreasing richness. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
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10. Hierarchical partitioning of fish diversity and scale-dependent environmental effects in tropical coastal ecosystems.
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Camara, Ellen Martins, Costa de Azevedo, Márcia Cristina, Franco, Taynara Pontes, and Araújo, Francisco Gerson
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SPECIES diversity , *ECOSYSTEMS , *LAND use , *FISH communities , *RANDOM variables , *FISH diversity , *COASTS - Abstract
The spatial structure of the fish diversity and site-scale and landscape-scale environmental effects were investigated across hierarchical levels in tropical coastal ecosystems. Total diversity (γ) was hierarchically partitioned into α and β components using both the additive and multiplicative methods. A model selection based on the AICc was applied to generalized linear mixed models relating diversity measures to environmental variables and including random effects for hierarchical levels and season. Short-term seasonal effects were negligible. Spatial effects were more relevant at the site level and negligible at the subregion level, due to the high spatial heterogeneity and the natural pooling of ecosystems, respectively. Site-scale environmental effects were more relevant at the subregion level, with eutrophic conditions (continental influence) favoring the species richness (α and γ) and higher absence of species (βA) in oligotrophic conditions (marine influence). At the system level, the positive effect of the distance from the ocean on γ and higher βA in oligotrophic conditions reinforced the positive continental influence on fish diversity. Environmental homogenization processes were most likely associated with the negative effect of the pasture cover on α at the system level, and γ and βA at the site level. The negative effect of the forest cover on the later diversity measure evidenced its relevance to maintain richer but more similar assemblages, whereas the positive continental influence was most likely due to the loss of stenohaline marine species. This study evidenced that disentangling spatial, land use, and marine vs. continental effects on diversity components is critical to understand the primary determinants of the fish diversity in tropical coastal ecosystems. • Spatial and environmental effects were critical for coastal fish diversity. • At the site level, diversity was primarily associated with land use effects. • Multi-scale continental influences affected positively fish diversity within systems. • Diversity was primarily driven by site-scale environmental effects within sub-regions. • The α and additive β components were the major determinants of changes on γ diversity. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
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