Zooplankton abundance in the lower Orinoco River, Venezuela

Saunders, James F.; Lewis, William M.

doi:10.4319/lo.1989.34.2.0397

Cited by 66 publications

(56 citation statements)

References 23 publications

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“…Compared to mean density of zooplankton in the Orinoco main stem (Saunders & Lewis 1989, Vâs-quez & Rey 1989, mean density in the lakes was -100 times higher than in the river. A similar value was reported by Hamilton et al (1990) from ano ther Orinoco fioodplain lake.…”

Section: Discussionmentioning

confidence: 99%

“…A similar value was reported by Hamilton et al (1990) from ano ther Orinoco fioodplain lake. Considering the extension of the fioodplain and the high abundance of zooplankton found in these areas, the contribu tion of zooplankton biomass from fioodplain areas to the river is very small (Saunders & Lewis 1989). Hamilton et al (1990) ascribed the absence of a significant export of zooplankton as a consequence of retention of planktonic organisms by aquatic macrophytes.…”

Section: Discussionmentioning

confidence: 99%

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Composition, abundance and biomass of zooplankton in Orinoco floodplain lakes, Venezuela

Vasquez¹,

Rey

1992

Ann. Limnol. - Int. J. Lim.

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Zooplankton samples were collected over a 21-month period in five fioodplain lakes of the Orinoco River in order to establish zooplankton species composition, abundance patterns, and biomass and their relationships with the patterns of inundations and lake morphometry. 60 rotifer taxa were identified. This group was generally more abundant than copepods and cladocerans (mean : 73,4 % of total zooplankton). spinulosum. Most frequent and abundant zooplankton species were euplanktonic with a dominance of filter feeders and microphagous detritivores. Mean zooplankton density in all lakes ranged from 340 ind./l to 3 486 ind./l. Biomass ranged from 71,1 ^g.l (dw) to 432,8 ^g/l. Rotifers accounted for 64,7 % of the total mean zooplankton biomass in three lakes while copepods accounted for 57,8 % of the biomass in two lakes. Both density and biomass were markedly seasonal with highest mean values at low waters. Mean density in the lakes was 100 times higher than in the Orinoco main stem. Lakes with highest variabilities in surface area and water depths showed highest zooplankton densities. The type of connection (direct or indirect) established between the lakes and the major source of the water also seemed important to interpret the productivity of fioodplain lakes.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Composition, abundance and biomass of zooplankton in Orinoco floodplain lakes, Venezuela

Vasquez¹,

Rey

1992

Ann. Limnol. - Int. J. Lim.

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“…Another littoral species common on the floodplain is Ilyocryptus spinifer. The pelagic species B. deitersi, B. hagmanni, C. cornuta, and M. minuta are also frequent and often dominant on other floodplains (Brandorff et al, 1982;Robertson & Hardy, 1984;Saunders III & Lewis-Jr., 1989;Paggi & José de Paggi, 1990;Bozelli et al, 1992;Sendacz, 1997).…”

Section: Bosmina Tubicen Brehm 1939mentioning

confidence: 99%

Cladocera fauna composition in a river-lagoon system of the upper Paraná River floodplain, with a new record for Brazil

et al. 2003

Braz. J. Biol.

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Cladocera communities were studied in lotic and lentic environments of the Upper Paraná River floodplain, State of Mato Grosso do Sul, Brazil. A total of 63 species of Cladocera were identified in 108 samples. Of these, 24 species are considered new records for that floodplain, and one is a new record for Brazil. Chydoridae was the most representative family with 19 genera and 39 species.Key words: Cladocera, species richness, floodplain, Upper Paraná River. RESUMO Composição de cladóceros em um sistema rio-lagoa na planície de inundação do alto rio Paraná, BrasilA comunidade de cladóceros foi estudada em ambientes lótico e lêntico na planície de inundação do alto rio Paraná, Estado do Mato Grosso do Sul, Brasil. Foram identificadas 63 espécies em 108 amostras. Deste total, 24 espécies são consideradas novos registros para essa planície de inundação e uma espécie é um novo registro para o Brasil. Chydoridae foi a família mais representativa, com 19 gêneros e 39 espécies.Palavras-chave: Cladocera, riqueza de espécies, planície de inundação, rio Paraná.

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“…According to RZOSKA (1978), zooplankton reproduction is unlikely at water velocities > 0.4 m/s (THORP and CASPER, 2003). SAUNDERS and LEWIS (1989) reported an inverse relationship between egg rations of rotifers and water velocity. The above authors observed no egg-carrying individuals at current velocities > 1.5 m/s (RECKNDORFER et al, 1999).…”

Section: Taxonomic Compositionmentioning

confidence: 99%

Impacts of a Small Dam on Riverine Zooplankton

Zhou

Tang

et al. 2008

International Review of Hydrobiology

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In order to explore the temporal impacts of a small dam on riverine zooplankton, monthly samples were conducted from November 2005 to June 2006 in a reach of Xiangxi River, China, which is affected by a small hydropower plant. A total of 56 taxa of zooplankton were recorded during the study and rotifers were the most abundant group, accounting for 97% of total taxa, while the others were copepod nauplii and copepod adults. This study indicated that: (1) the small dam in the Xiangxi River study area created distinct physical and ecological conditions relative to free-flowing lotic reaches despite the constrained channel and small size of the dam; (2) the existence of the plant's small dam had a significant effect on the zooplankton community. In long periods of drought or dry seasons the effect of the dam on potamoplankton was more pronounced (e.g., November, February, March, and May). But the downfall or the connectivity of channel appeared to decrease the effect of small hydropower plants on riverine zooplankton (e.g., April). The present observation underscores the need for additional studies that provide more basic data on riverine zooplankton communities and quantify ecological responses to dam construction over longer time spans. IntroductionZooplankton are commonly referred to as 'passive drifters' based on the accepted notion that they are unable to swim against water currents and are thus transported passively in the horizontal plane by the flow field (WIAFE and FRID, 1996). In comparison to lentic systems, much less is known about the factors structuring zooplankton communities in lotic systems (streams and rivers) (JACK and THORP, 2002). Possible factors regulating plankton biomass in rivers may be physical (light), chemical (nutrient concentrations), hydrological, and biotic. The main factors regulating zooplankton biomass or abundance in lotic water are hydrological factors such as discharge or water residence time and suspended sediment (BASU and PICK, 1996;THORP and CASPER, 2003). Plankton in rivers is only important when residence time allows enough time for growth and reproduction (LAIR and REYES-MARCHANT, 1997). However, several studies suggest that zooplankton in river systems occupy an important status in food webs, contributing to secondary production and enabling flow of energy from algal primary producers to higher trophic levels (e.g., MWEBAZA-NDAWULA et al., 2005 All parts of a river ecosystem are inter-connected. Any disturbance to one part will create a greater or lesser response over much of the system. For instance, an in-channel dam can disrupt the river's natural course and flow, alter the water temperature, redirect the river channel, stop the migration of fish to spawning grounds, cut the circulation of organic matter and nutrients, increase the fragmentation of habitat with associated isolation of populations (WINSTON et al., 1991), and ultimately disrupt the composition of the river continuity. Ecological connectivity underpins the transfer of materials and products of e...

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Zooplankton abundance in the lower Orinoco River, Venezuela

Cited by 66 publications

References 23 publications

Composition, abundance and biomass of zooplankton in Orinoco floodplain lakes, Venezuela

Composition, abundance and biomass of zooplankton in Orinoco floodplain lakes, Venezuela

Cladocera fauna composition in a river-lagoon system of the upper Paraná River floodplain, with a new record for Brazil

Impacts of a Small Dam on Riverine Zooplankton

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