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Zooplankton body-size structure and biomass in tropical floodplain lakes: relationship with planktivorous fishes
Bonecker, Claudia Costa;Azevedo, Fábio de;Sim?es, Nadson Ressyé;
Acta Limnologica Brasiliensia , 2011, DOI: 10.1590/S2179-975X2012005000005
Abstract: aim: this study evaluated whether the size structure of the zooplankton community, as analyzed from density and biomass, would be influenced by bottom-up and/or top-down mechanisms in isolated lakes from the upper paraná river floodplain during dry and rainy periods. methods: zooplankton individuals were classified as: smaller-sized (<300 μm), intermediate-sized (301 to 600 μm) and larger-sized (greater than 601 μm). fish abundance was indexed by the capture per unit effort (cpue; number of individuals.100 m-2). productivity was measured as chlorophyll-a. results: the size structure of the community did not show significant relationship with chlorophyll-a concentration (p > 0.05), but it was associated to the increase in fish density during the dry season. the percentage of individuals with intermediate sizes (301 to 600 μm), in both biomass and density, was positively related to the fish density (r2 = 0.78 for biomass, p < 0.001; r2 = 0.58 for density, p = 0.02), indicating an increase numerical and mass of this size class with fish density. the percentage of larger-sized individuals (>600 μm), in both biomass (r2 = 0.86, p < 0.001) and density (r2 = 0.69, p = 0.02) was negatively associated to the fish density, reflecting a decrease of this size class with the increase of fish in the environment. conclusions: this can implicate a direct and negative effect of the predation on larger-sized individuals, as well as indirect and positive effect on the intermediate-sized individuals, but it occurred only on dry season. thus, different mechanisms act on the size structure of the zooplankton community between dry and rainy season.
Intra and inter-annual structure of zooplankton communities in floodplain lakes: a long-term ecological research study
Nadson R. Sim?es,Fábio A. Lansac-T?ha,Luiz F. M. Velho,Claudia C. Bonecker
Revista de Biología Tropical , 2012,
Abstract: Water flow management has significantly changed the natural dynamic of floods, which are responsible for the structure and dynamic of aquatic communities in river-floodplain systems. With the aim to elaborate a conceptual framework that describes the main ecological factors associated with zooplankton community structure in the Upper Paraná River, we investigated the mechanisms that regulate the communities structure and their response to inter-annual and hydro-sedimentological variations in the floodplain and the biological factors associated with species abundance in those communities. For this we conducted samplings every six months (potamophase in March and limnophase in September) to characterize intra and inter-annual variations in community structure between 2000 and 2008. The intra-annual differences on the species richness, abundance, Shannon diversity index, and evenness, were conducted using Bayesian procedures to show probabilistic predictions of the data fit to main variation sources. Non-metric multi-dimensional scaling (NMDS), multi-response permutation procedure (MRPP), and indicator species analysis (IndVal) were run to assess and characterize the seasonality of the community structure. During high water (potamophase), hydrologic connectivity favoured exchange and dispersal of species in some lakes, increasing local diversity; during low water (limnophase), higher local productivity favoured opportunistic taxa, increasing species dominance and decreasing local diversity. Food resources and density of small-size fish were biological factors associated with the seasonal dynamic of the zooplankton community; these factors were dependent on hydrosedimentological phase (potamophase or limnophase). Water levels and limnological modifications related to water flow management have promoted replacement and impoverishment of aquatic biota in affected lakes and have indicated the ecological importance of a natural dynamic flood, which displays regular flood pulses. The conceptual model presented encompassed interactions between diverse environmental variables to more understandable mechanisms of the main sources of community variation. El manejo del régimen de inundación ha cambiado de manera significativa la dinámica natural de las inundaciones, que son responsables de la estructura y dinámica de las comunidades acuáticas en sistemas río-planicie de inundación. En este sentido, investigamos cómo la estructura de las comunidades zooplanctónicas responde a variaciones estacionales e interanuales en los sistemas de llanura de inundación, y los factor
Biodiversity of zooplankton communities in the Upper Paraná River floodplain: interannual variation from long-term studies
Lansac-T?ha, FA.;Bonecker, CC.;Velho, LFM.;Sim?es, NR.;Dias, JD.;Alves, GM.;Takahashi, EM.;
Brazilian Journal of Biology , 2009, DOI: 10.1590/S1519-69842009000300009
Abstract: we investigated the effect of interannual variation of hydrosedimentological regime and connectivity on the zooplankton biodiversity in the upper paraná river floodplain. zooplankton samplings were undertaken between 2000 and 2007, in different environments of the floodplain, including connected and isolated floodplain lakes, backwaters, rivers and channels. the zooplankton included 541 species. rotifers showed the highest species richness and abundance. among the zooplankton species, 71 represent new occurrence records for the floodplain. the species accumulation curve showed a continuous increase in gamma diversity, demonstrating the importance of long-term research for accurate knowledge of biodiversity in heterogeneous and dynamic ecosystems, such as the floodplains. interannual beta diversity among studied years indicated a lesser alteration in community composition in 2001, when a long limnophase period was observed. in most of the environments, the highest species richness values were related to the greatest flooding amplitudes. flooding amplitude, which is associated with connectivity, favors faunal exchange amongst the environments and between the pelagic and littoral zones. this explains the occurrence of both planktonic and non-planktonic species within the community. on the other hand, mean zooplankton abundance values were higher when a long isolation period occurred. differences between the potamophase and limnophase amplitude associated with connectivity among the environments were the most important factors for the structure and dynamics of the zooplankton community in the upper paraná river floodplain.
Zooplankton body-size structure and biomass in tropical floodplain lakes: relationship with planktivorous fishes Estrutura de tamanho do corpo e biomassa do zooplancton em lagos tropicais de planície de inunda o: rela es com peixes planctívoros  [cached]
Claudia Costa Bonecker,Fábio de Azevedo,Nadson Ressyé Sim?es
Acta Limnologica Brasiliensia , 2011,
Abstract: AIM: This study evaluated whether the size structure of the zooplankton community, as analyzed from density and biomass, would be influenced by bottom-up and/or top-down mechanisms in isolated lakes from the Upper Paraná River floodplain during dry and rainy periods. METHODS: zooplankton individuals were classified as: smaller-sized (<300 μm), intermediate-sized (301 to 600 μm) and larger-sized (greater than 601 μm). Fish abundance was indexed by the capture per unit effort (CPUE; number of individuals.100 m-2). Productivity was measured as chlorophyll-a. RESULTS: The size structure of the community did not show significant relationship with chlorophyll-a concentration (p > 0.05), but it was associated to the increase in fish density during the dry season. The percentage of individuals with intermediate sizes (301 to 600 μm), in both biomass and density, was positively related to the fish density (R2 = 0.78 for biomass, p < 0.001; R2 = 0.58 for density, p = 0.02), indicating an increase numerical and mass of this size class with fish density. The percentage of larger-sized individuals (>600 μm), in both biomass (R2 = 0.86, p < 0.001) and density (R2 = 0.69, p = 0.02) was negatively associated to the fish density, reflecting a decrease of this size class with the increase of fish in the environment. CONCLUSIONS: This can implicate a direct and negative effect of the predation on larger-sized individuals, as well as indirect and positive effect on the intermediate-sized individuals, but it occurred only on dry season. Thus, different mechanisms act on the size structure of the zooplankton community between dry and rainy season. OBJETIVO: Este estudo avaliou se a estrutura de tamanho da comunidade zooplanct nica, analisada a partir da densidade e da biomassa, seria influenciada por processos ascendentes e/ou descendentes em lagos da planície de inunda o do Alto Rio Paraná durante um período seco e outro chuvoso. MéTODOS: o zooplancton foi classificado em: pequeno porte (<300 μm), porte intermediário (301 a 600 μm) e maior porte (maior que 601 μm). Abundancia de peixes foi estimada em captura por unidade de esfor o (CPUE; número de indivíduos.100 m-2). Produtividade foi definida como a concentra o de clorofila-a. RESULTADOS: A estrutura de tamanho da comunidade n o apresentou rela es significantes com a concentra o de clorofila-a (p > 0,05), mas ela foi associada com o aumento da densidade de peixes no período seco. O percentual de indivíduos com tamanhos intermediários (301-600 mm), tanto em biomassa quanto em densidade, foi positivamente relacionado c
Variability of δ13C and δ15N in three zooplankton species from the Upper Paraná River floodplain
Santana, Ana R. A.;Lansac-T?ha, Fabio Amodêo;Benedito, Evanilde;
Zoologia (Curitiba) , 2009, DOI: 10.1590/S1984-46702009000400017
Abstract: this study evaluated the isotopic composition of three zooplankton species - notodiaptomus amazonicus (wright, 1935), moina minuta hansen, 1899 and bosmina hagmanni stingelin, 1904 - from the upper paraná river floodplain. we predicted that there would be isotopic variability among species in the different sampled environments. samplings were conducted in three lakes from the baía subsystem and in two lakes from the paraná subsystem. at each location, some abiotic variables were measured, and zooplankton (3 to 4) and phytoplankton (3) samples were taken. the species sampled did not present significant differences between subsystems; however, they were different among the lakes, with variations of about 10.8‰ for δ13c and 5.8‰ for δ15n. the isotopic values found for phytoplankton also did not differ significantly among sampling stations, presenting variations of about 9.3‰ for δ13c and 7.4‰ for δ15n. these results indicate that the isotopic values of species varied among the lakes, and that they are dependent on isotopic signals from phytoplankton.
The Impact of Fish Predation and Cyanobacteria on Zooplankton Size Structure in 96 Subtropical Lakes  [PDF]
Jing Zhang, Ping Xie, Min Tao, Longgen Guo, Jun Chen, Li Li, XueZhen Zhang, Lu Zhang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076378
Abstract: Zooplankton are relatively small in size in the subtropical regions. This characteristic has been attributed to intense predation pressure, high nutrient loading and cyanobacterial biomass. To provide further information on the effect of predation and cyanobacteria on zooplankton size structure, we analyzed data from 96 shallow aquaculture lakes along the Yangtze River. Contrary to former studies, both principal components analysis and multiple regression analysis showed that the mean zooplankton size was positively related to fish yield. The studied lakes were grouped into three types, namely, natural fishing lakes with low nutrient loading (Type1), planktivorous fish-dominated lakes (Type 2), and eutrophic lakes with high cyanobacterial biomass (Type 3). A marked difference in zooplankton size structure was found among these groups. The greatest mean zooplankton size was observed in Type 2 lakes, but zooplankton density was the lowest. Zooplankton abundance was highest in Type 3 lakes and increased with increasing cyanobacterial biomass. Zooplankton mean size was negatively correlated with cyanobacterial biomass. No obvious trends were found in Type 1 lakes. These results were reflected by the normalized biomass size spectrum, which showed a unimodal shape with a peak at medium sizes in Type 2 lakes and a peak at small sizes in Type 3 lakes. These results indicated a relative increase in medium-sized and small-sized species in Types 2 and 3 lakes, respectively. Our results suggested that fish predation might have a negative effect on zooplankton abundance but a positive effect on zooplankton size structure. High cyanobacterial biomass most likely caused a decline in the zooplankton size and encouraged the proliferation of small zooplankton. We suggest that both planktivorous fish and cyanobacteria have substantial effects on the shaping of zooplankton community, particularly in the lakes in the eastern plain along the Yangtze River where aquaculture is widespread and nutrient loading is high.
Isotopic fractionation and trophic position of zooplankton species in the Upper Paraná River floodplain
Santana, ARA;Benedito, E;Ducatti, C;Lansac-T?ha, FA;
Brazilian Journal of Biology , 2011, DOI: 10.1590/S1519-69842011000100011
Abstract: this study aimed to evaluate the isotopic fractionation and trophic position of three zooplankton species (notodiaptomus amazonicus, moina minuta and bosmina hagmanni) in the upper paraná river floodplain. we predict that phytoplankton is the main food resource used by these species. three zooplankton samples and three phytoplankton samples were taken from each sampling site, with three to four samples collected for each species. the number of individuals for samples varied according to the body size: from 100 to 130 individuals for notodiaptomus amazonicus; 150 to 200 for moina minuta; and from 250 to 300 for bosmina hagmanni. the isotopic values for δ13c and δ15n were determined using mass spectrophotometer. the isotopic fractionation of 13c was performed according to the relationship δ = δ13czooplankton - δ13c phytoplankton. to determine the possible trophic position of these species, we used the expression tl = (δ15n zooplankton - δ15n phytoplankton)/δ+ 1. the species showed high variation in isotopic fractionation and in trophic position in the different environments. we verified that the species use other food resources in addition to phytoplankton. the elucidation and understanding of the trophic position of the organisms based on stable isotopic analysis offers complementary information to traditional techniques. this analysis helps explain the flow of matter and energy in the food chain of floodplain aquatic environments as well as trace the trophic relationships involved in the ecological roles and strategies of distinct species.
Use of Graph Model for the Resolution of Conflicts between Fishers of the Amazonian Floodplain Lakes  [cached]
Fabiola Nascimento,Carlos Edwar Freitas
Environment and Natural Resources Research (ENRR) , 2012, DOI: 10.5539/enrr.v3n1p16
Abstract: We evaluated the GMCR II (Model of the Graphs for Conflict Resolution) as a tool for the identification of fishing management strategies that could be possible solutions for fishing conflicts in the floodplain lakes of the Central Amazon. The procedures of this software are based on the Graph Theory, a mathematical approach derived from the Game Theory. In our modeling, the players were IBAMA (environmental agency in Brazil), commercial fishers and subsistence fishers. The GMCR II demonstrated that when IBAMA adopts the strategy of restriction of some fishing gear in floodplain lakes, the resolution of the conflict between fishers is more likely to happen. We also conclude that the use of a mathematical approach, by the employment of the GMCR II, would be an important tool for approaching conflict situations but that its use needs to be followed by other methodologies, mainly participative programs.
Potential heterogeneity in crustacean zooplankton assemblages in southern chilean saline lakes
De los Rios-Escalante, P;Gajardo, G.;
Brazilian Journal of Biology , 2010, DOI: 10.1590/S1519-69842010000500016
Abstract: the chilean saline lakes are distributed mainly in the atacama desert in northern chile and the southern patagonian plains. the scarce studies are restricted mainly to northern chilean saline lakes, and these revealed that the main component in these ecosystems are the halophylic copepod boeckella poopoensis marsh 1906, or the brine shrimp artemia franciscana (kellog, 1906), and both species do not coexist. the present study consisted of field observations in zooplankton assemblages in southern chilean saline lakes (51-53 os). these first observations revealed three different patterns, one saline lake only with a. persimilis (piccinelli and prosdocimi, 1968), a second lake only with b. poopensis, and a third lake with a. persimilis, b. poopoensis and unidentified harpacticoid copepod. these results are different in comparison with the observations in the literature that described the non-coexistence between b. poopoensis with brine shrimps. ecological and biogeographical topics were discussed.
Fish diversity of floodplain lakes on the lower stretch of the Solim?es River
Siqueira-Souza, F. K.;Freitas, C. E. C.;
Brazilian Journal of Biology , 2004, DOI: 10.1590/S1519-69842004000300013
Abstract: the fish community of the solim?es floodplain lakes was studied by bimonthly samples taken from may 2001 to april 2002. these were carried out at lakes maracá (03o51'33"s, 62o35'08,6"w), samaúma (03o50'42,1"s, 61o39'49,3"w), and sumaúma and sacambú (03o17'11,6"s and 60o04'31,4"w), located between the town of coari and the confluence of the solim?es and negro rivers. collections were done with 15 gillnets of standardized dimensions with several mesh sizes. we collected 1,313 animals distributed in 77 species, belonging to 55 genera of 20 families and 5 orders. characiformes was the most abundant order, with a larger number of representatives in the serrasalmidae and curimatidae. the most abundant species in the samplings were psectrogaster rutiloides (132 individuals), pigocentrus nattereri (115 individuals), and serrasalmus elongatus (109 individuals). lakes samaúma, sacambú, and sumaúma were adjusted to logarithmic and lognormal series. the diversity exhibited an inverse gradient to the river flow, showing the highest diversity at lake sumaúma, followed by samaúma, sacambú, and maracá. species richness estimated through the jackknife technique ranged from 78 to 107 species.
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