Impactos ecológicos das represas hidrelétricas na bacia amazônica brasileira&lt;A NAME="top1"&gt;&lt;/A&gt;

Junk, Wolfgang J.; Mello, José Alberto Sampaio Nunes de

doi:10.1590/s0103-40141990000100010

Cited by 99 publications

(68 citation statements)

References 10 publications

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“…Initial deoxygenation of the lake was much less pronounced than that expected from information from other tropical reservoirs (Van der Lingen, 1973;Van der Heide, 1982;Barrow, 1987;Junk & de Mello, 1987;Tundisi et al, 1993) and oxygen concentrations on the water surface never dropped below 63% saturation (Table 1). However, during stratification, deoxygenation of water occurred at lacustrine regions, and oxygen concentrations in the lower layer dropped to < 1 mg.L -1 .…”

Section: Resultsmentioning

confidence: 78%

Prediction of colonization by macrophytes in the Yaciretá reservoir of the Paraná River (Argentina and Paraguay)

Neiff

Patiño

et al. 2000

Rev. Bras. Biol.

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The potential colonization by anchored plants (PCAP) and the potential areas for initial colonization of free floating plants were estimated during the early filling phase for the Yaciretá reservoir. In order to obtain the PCAP, the observed maximum depth of colonization of the anchored macrophytes before impoundment and the hypsographic curves were used. The species inhabiting the preimpoundment area were classified according to the different bioforms before the inclussion in the analysis. The areal extent of PCAP (from depths between 0-4 m) could reach 275 km 2 at 76 m above sea level (current water level), whereas at 82 m above sea level (final filling level) the littoral zone will be increased by about 21.5%. The potential area for geophytes was estimated to be 99 km 2 ; 131 km 2 for root-floating leaved plants and 120 km 2 for submerged plants, at 76 m above sea level. At 82 m above sea level, the geophytes could reach 271 km 2 . The data for wind frequency, velocity and fetch, together with depth were used to calculate shallow and sheltered areas in which free floating plants could find favourable conditions to initial colonization. Physical and chemical features recorded at eight stations during the early filling phase are discussed in relation to potential plant development.Key words: tropical rivers, impounding reservoirs, South America, potential macrophytes colonization, reservoirs. RESUMO Predição da colonização por macrófitas no reservatório de Yaciretá do Rio ParanáA colonização potencial por plantas enraizadas (CPPE) e as áreas potenciais de colonização por plantas fluentes livres foram calculadas durante a fase de enchimento do reservatório de Yaciretá. Para obter o CPPE, a máxima profundidade de enraizamento observada previa o fechamento do rio e as curvas ipsográficas foram utilizadas. As espécies presentas na área pré-represamento foram classificadas de acordo com as diferentes bioformas antes da inclusão na análise: A extenção de CPPE (para profundidades entre 0-4 m) poderia alcançar 275 km 2 a 76 m acima do nível do mar (nível de água atual), enquanto na cota de 82 m acima do nível do mar (nível de recheio final) a zona litorânea será aumentada em aproximadamente 21,5%. A área potencial para macróficas emersas foi calculada em 99 km 2 , para as plantas enraizadas com folhas flutuantes em 131 km 2 , e para as plantas enraizadas submersas em Rev. Brasil. Biol., 60(4)

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Section: Resultsmentioning

confidence: 78%

Prediction of colonization by macrophytes in the Yaciretá reservoir of the Paraná River (Argentina and Paraguay)

Neiff

Patiño

et al. 2000

Rev. Bras. Biol.

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“…According to Junk & Nunes de Mello (1990), the construction of dams causes a huge impact leading to losses of both fauna and flora, including some completely or relatively unknown species such as Brycon gouldingi, studied in the present work. This species was recently described by Lima (2004) as an endemic fish from Tocantins-Araguaia River Basin that feeds mainly on fruits and insects, inhabiting tropical benthopelagic freshwater environments.…”

Section: Introductionmentioning

confidence: 97%

Brycon gouldingi(Teleostei, Characidae): aspects of the embryonic development in a new fish species with aquaculture potential

Faustino

Nakaghi

Neumann³

2010

Zygote

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SummaryBrycon gouldingi is an endemic species from Tocantins-Araguaia basin, used as a food source by riverine communities and relevant to aquaculture. Information about the initial morphology of B. gouldingi, a recently described species, is absent. In the present study, we analysed the fertilization and the embryonic development of this species based on light and scanning electron microscopy. After collection of adult specimens in Mortes River -Mato Grosso, Brazil, adaptation to captivity and induced spawning at Buriti Fishculture, Nova Mutum -Mato Grosso, Brazil, in December 2007 and January 2008, samples were collected at pre-defined periods from egg extrusion up to larval hatching, which occurred at 13.9 ± 0.06 h post-fertilization (hpf) in average. At the moment of extrusion, the eggs were slightly ovoid bearing a single micropyle per oocyte with a funnel-shaped micropyle canal and vestibule covered with longitudinal folds, typical of the genus Brycon. The embryonic development of B. gouldingi was characterized by six stages with distinct features: zygote (from fertilization up to formation of egg-cell); cleavage (cell divisions resulting in blastomeres, including the morula phase); blastula (several embryonic cells in a cup shape, without distinction of cell boundaries); gastrula (cell movement); histogenesis/organogenesis (formation of tissues and organs); and hatching (larval chorion rupture). Right after hatching, the larvae presented neither swimming abilities nor visual accuracy, and the digestive trait was undifferentiated. The present study is the first report on biological features of embryogenesis in B. gouldingi, providing relevant information to several approaches, mainly related to taxonomy, ecology, conservation and captive rearing of this new Brycon species.

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“…This would result in the permanent loss of connectivity between the fish assemblages located up-and down-stream of these falls, as well as a marked change in the types of habitat available for the different species, which would affect species composition, as well as reproductive patterns and the recruitment processes of the majority of taxa (Agostinho et al, 2004). The impacts of the construction of hydroelectric dams are well documented (Junk and Mello, 1990;Agostinho et al, 2008;Mims and Olden, 2013;Sakaris, 2013;Freedman et al, 2014) and are related primarily to processes such as the loss and homogenization of habitats, and the replacement of species. This emphasizes the need for the systematic collection of data on the characteristics of local fish assemblages prior Table 3.…”

Section: Discussionmentioning

confidence: 99%

Effect of waterfalls and the flood pulse on the structure of fish assemblages of the middle Xingu River in the eastern Amazon basin

et al. 2015

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The structure of fish assemblages in Neotropical rivers is influenced by a series of environmental, spatial and/or temporal factors, given that different species will occupy the habitats that present the most favourable conditions to their survival. The present study aims to identify the principal factors responsible for the structuring of the fish assemblages found in the middle Xingu River, examining the influence of environmental, spatial, and temporal factors, in addition to the presence of natural barriers (waterfalls). For this, data were collected every three months between July 2012 and April 2013, using gillnets of different sizes and meshes. In addition to biotic data, 17 environmental variables were measured. A total of 8,485 fish specimens were collected during the study, representing 188 species. Total dissolved solids, conductivity, total suspended matter, and dissolved oxygen concentrations were the variables that had the greatest influence on the characteristics of the fish fauna of the middle Xingu. Only the barriers and hydrological periods played a significant deterministic role, resulting in both longitudinal and lateral gradients. This emphasizes the role of the connectivity of the different habitats found within the study area in the structuring of its fish assemblages.Keywords: natural barriers, connectivity, hydrological periods, community ecology, impacts of hydroelectric dams. Efeito das cachoeiras e do pulso de inundação na estrutura das assembleias de peixes do Médio Rio Xingu, Amazônia oriental ResumoA estrutura da ictiofauna em rios neotropicais é constantemente influenciada por fatores ambientais, espaciais e/ou temporais, uma vez que as espécies tendem a ocupar ambientes com condições favoráveis à sua sobrevivência. Dessa forma, esta pesquisa tem como objetivo responder qual o principal fator responsável pela estruturação das assembleias de peixes no Médio Rio Xingu, testando a influência dos fatores ambientais, espaciais e temporais, além da presença de barreiras naturais (cachoeiras

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Impactos ecológicos das represas hidrelétricas na bacia amazônica brasileira<A NAME="top1"></A>

Cited by 99 publications

References 10 publications

Prediction of colonization by macrophytes in the Yaciretá reservoir of the Paraná River (Argentina and Paraguay)

Prediction of colonization by macrophytes in the Yaciretá reservoir of the Paraná River (Argentina and Paraguay)

Brycon gouldingi(Teleostei, Characidae): aspects of the embryonic development in a new fish species with aquaculture potential

Effect of waterfalls and the flood pulse on the structure of fish assemblages of the middle Xingu River in the eastern Amazon basin

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