Claudia Bonecker | Universidade Estadual de Maringa (original) (raw)

Papers by Claudia Bonecker

Research paper thumbnail of Zooplankton in the Floodplains of a Tributary to the Paran� River in Mato Grosso Do Sul, Brazil

Studies on Neotropical Fauna and Environment, 1996

... et al 1982), the Caura river (Saunders III & Lewis Jr 1988) and the flood-pla... more ... et al 1982), the Caura river (Saunders III & Lewis Jr 1988) and the flood-plains of ... AF (1992) Seasonal variation of some limnological factors a várzea lake of the high rio Paraná, State of ... A longitudinal study of zoo-plankton along the lower Orinoco River and its delta (Venezuela ...

Research paper thumbnail of Community structure of rotifers in two environments of the upper River Paran� floodplain (MS) - Brazil

Hydrobiologia, 1996

... at each station, with a motor pump from open water (Stations Gl and B 1), and from Eichhornia... more ... at each station, with a motor pump from open water (Stations Gl and B 1), and from Eichhornia azurea (Station G2) using a plankton net of 70 µm mesh size The end of the 6-cm diameter tube of motorpumb was protected by plastic to avoid big debris Rotifers (ind m-3 ... Diversity ...

Research paper thumbnail of Acta Scientiarum 22(2):343-346, 2000. ISSN 1415-6814. Species composition of rotifers in different habitats of an artificial lake, Mato Grosso do Sul State, Brazil

ABSTRACT. Rotifers are small filter-feeders that are important in food chains and nutrient cyclin... more ABSTRACT. Rotifers are small filter-feeders that are important in food chains and nutrient cycling in aquatic environments. Little is known of the rotifer fauna in the State of Mato Grosso do Sul. We investigated the occurrence and distribution of rotifers in different habitats of an artificial lake near the city of Dourados, from May through November 1997. We recorded 36 taxa belonging to 15 families, mainly Brachionidae. In the different environments sampled, the presence of vegetation was an important factor determining the occurrence of the taxa. Key words: rotifers, composition, State of Mato Grosso do Sul, Brazil. RESUMO. Composição de rotíferos em diferentes habitats de um lago artificial, estado do Mato Grosso do Sul, Brasil. Os rotíferos são pequenos filtradores importantes para as cadeias tróficas dos ambientes aquáticos, bem como na ciclagem dos nutrientes. No Estado do Mato Grosso Sul pouco se conhece sobre a fauna desses invertebrados. Dessa forma, procurou-se, neste es...

Research paper thumbnail of tropical reservoirs (Paraná State, Brazil)

How to cite Complete issue More information about this article Journal's homepage in redalyc... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System

Research paper thumbnail of assemblages in different systems of the upper Paraná River floodplain (PR/MS-Brazil)

The present study evaluated the influence of water level fluctuations and the system type on the ... more The present study evaluated the influence of water level fluctuations and the system type on the structure of planktonic microcrustacean assemblage, in different lagoons on the Upper Paraná River floodplain. Sampling was performed in pelagic region from 15 lagoons associated with three rivers, during flood (February 1999) and dry (October 1999) periods. Forty nine cladoceran species and sixteen copepods species were identified. Null model ANOVA results did not show significant differences in microcrustacean densities among systems. Only B. hagmanni, B. deitersi and Calanoid nauplii densities were significantly different between periods. Differences between periods in each system and among systems in each hydrological period were not significant either. Thus, spatial differences were not superior in microcrustacean structuring. However, some temporal differences were observed for bosminids and Calanoid nauplii.

Research paper thumbnail of Zooplankton community resilience and aquatic environmental stability on aquaculture practices: a study using net cages

Brazilian Journal of Biology, 2012

Fish farming in net cages causes changes in environmental conditions. We evaluated the resilience... more Fish farming in net cages causes changes in environmental conditions. We evaluated the resilience of zooplankton concerning this activity in Rosana Reservoir (Paranapanema River, PR-SP). Samples were taken near the net cages installed at distances upstream and downstream, before and after net cage installation. The resilience was estimated by the decrease in the groups' abundance after installing the net cages. The zooplankton community was represented by 106 species. The most abundant species were Synchaeta pectinata, S. oblonga, Conochilus coenobasis, Polyarthra dolichoptera and C. unicornis (Rotifera), Ceriodaphnia cornuta, Moina minuta, Bosmina hagmanni and C. silvestrii (Cladocera) and Notodiaptomus amazonicus (Copepoda). The resilience of microcrustaceans was affected in the growing points as this activity left the production environment for longer, delaying the natural ability of community responses. Microcrustaceans groups, mainly calanoid and cyclopoid copepods, had a d...

Research paper thumbnail of Effects of nutrients increase on the copepod community of a reservoir using cages

Acta Limnologica Brasiliensia, 2015

Aim: This study investigated changes in copepod abundance and the influence of environmental vari... more Aim: This study investigated changes in copepod abundance and the influence of environmental variables in a reservoir with fish farming using cages, on temporal and spatial scales. We hypothesised that the copepod abundance will increase when influenced by changes in environmental variables due the increase of nutrients originating from fish farming. Methods A 120-day sampling of copepods and environmental variables was carried out in a subtropical reservoir of the Paraná River basin (Rosana reservoir), upstream and downstream of three sets of cages with different fish stocking densities. A Principal Component Analysis was conducted to characterise sampling periods and points through environmental variables. The differences between copepod abundance according to sampling periods and points were tested by ANOVA. Results We observed higher maximum values for most nutrient concentrations and dissolved oxygen in the final stage of the experiment and in the location of cages installation...

Research paper thumbnail of Ocorrência de tecamebas (Protozoa, Rhizopoda) em águas continentais brasileiras. I. Família Arcellidae

Acta Scientiarum Biological Sciences

The purpose of this paper is to increase the knowledge on testate amoebae in Brazilian inland wat... more The purpose of this paper is to increase the knowledge on testate amoebae in Brazilian inland waters, specifically the family Arcellidae (Protozoa, Amoebozoa, Rhizopoda). In this paper the current occurrence and geographical distribution of this family in Brazil is discussed. A total of 26 infra-generic taxa was recorded, among them 24 taxa belong to the genus Arcella and 2 to Pyxidicula. Arcella vulgaris Ehrenberg, A. gibbosa Pénard, A. megastoma Pénard, A. dentata Ehrenberg, A. discoides Ehrenberg, A. brasiliensis Cunha and A. crenulata Deflandre were the species with greater number of records. Some taxonomic information is also provided.

Research paper thumbnail of Ocorrência de tecamebas (Protozoa, Amoebozoa, Rhizopoda) em águas continentais brasileiras. II. Famílias Centropyxidae, Trigonopyxidae e Plagipyxidae

Acta Scientiarum Biological Sciences

The purpose of this study is to provide a checklist and a synthesis of the geographic distributio... more The purpose of this study is to provide a checklist and a synthesis of the geographic distribution of the species within Centropyxidae, Trigonopyxidae and Plagiopyxidae (Protozoa, Amoebozoa, Rhizopoda). A total of 24 infra-generic taxa were listed, of which 15 belong to the genus Centropyxis, 5 to Cyclopyxis, 2 to Bullinularia, 1 to Hoogenraadia and 1 to Trigonopyxis. Some taxonomic information is also provided. Centropyxis aculeata, C. constricta and C. marsupiformis presented widespread distribution in the freshwater environments in Brazil.

Research paper thumbnail of The likely effects of river impoundment on beta-diversity of a floodplain zooplankton metacommunity

Natureza & Conservação, 2015

Using a long-term dataset, we tested whether beta diversity of the zooplankton community in the U... more Using a long-term dataset, we tested whether beta diversity of the zooplankton community in the Upper Paraná River floodplain increases during periods of high environmental heterogeneity and productivity and decreases with increases in water level (when there is higher connectivity between sites). We detected temporal trends of increasing beta diversity. A temporal decrease in species occupancy was more frequent than a temporal increase. Our results do not support a generalized association between beta diversity and environmental heterogeneity or productivity. Water level variation was an important explanatory variable only for rotifers and in the opposite direction expected. Taken as whole, our results suggest that we are far from a comprehensive understanding of the processes underlying variation in beta diversity. We speculate that the large number of dams built upstream from the study area may account for the positive trend in beta diversity.

Research paper thumbnail of New record of planktonic cladoceran to the upper Paraná River, Brazil: Bosmina huaroensis Delachaux, 1918

Revista Brasileira de Biologia, 2000

In this paper we register the first occurrence of Bosmina huaroensis Delachaux, 1918 in the upper... more In this paper we register the first occurrence of Bosmina huaroensis Delachaux, 1918 in the upper Paraná River basin, which is probably the first record to Brazil. Illustrations and an updated description of the species are given.

Research paper thumbnail of Spatial and temporal density variation of microcrustacean assemblages in different systems of the assemblages in different systems of the upper Paraná River floodplain (PR/MS floodplain (PR/MS-Brazil)

The present study evaluated the influence of water level fluctuations and the system type on the ... more The present study evaluated the influence of water level fluctuations and the system type on the structure of planktonic microcrustacean assemblage, in different lagoons on the Upper Paraná River floodplain. Sampling was performed in pelagic region from 15 lagoons associated with three rivers, during flood (February 1999) and dry (October 1999) periods. Forty nine cladoceran species and sixteen copepods species were identified. Null model ANOVA results did not show significant differences in microcrustacean densities among systems. Only B. hagmanni, B. deitersi and Calanoid nauplii densities were significantly different between periods. Differences between periods in each system and among systems in each hydrological period were not significant either. Thus, spatial differences were not superior in microcrustacean structuring. However, some temporal differences were observed for bosminids and Calanoid nauplii.

Research paper thumbnail of Avaliação Da Biomassa De Microcrustáceos Em Ambientes Aquáticos Continentais Microcrustaceans Biomass Estimation in Continental Aquatic Environments Evaluación De La Biomasa De Microcrustáceos en Ambientes Acuáticos Continentales

Research paper thumbnail of Zooplankton body-size structure and biomass in tropical floodplain lakes: relationship with planktivorous fishes

Acta Limnologica Brasiliensia, 2011

AIM: This study evaluated whether the size structure of the zooplankton community, as analyzed fr... more 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), indicatin...

Research paper thumbnail of Dispersal Ability Determines the Role of Environmental, Spatial and Temporal Drivers of Metacommunity Structure

PLoS ONE, 2014

Recently, community ecologists are focusing on the relative importance of local environmental fac... more Recently, community ecologists are focusing on the relative importance of local environmental factors and proxies to dispersal limitation to explain spatial variation in community structure. Albeit less explored, temporal processes may also be important in explaining species composition variation in metacommunities occupying dynamic systems. We aimed to evaluate the relative role of environmental, spatial and temporal variables on the metacommunity structure of different organism groups in the Upper Paraná River floodplain (Brazil). We used data on macrophytes, fish, benthic macroinvertebrates, zooplankton, periphyton, and phytoplankton collected in up to 36 habitats during a total of eight sampling campaigns over two years. According to variation partitioning results, the importance of predictors varied among biological groups. Spatial predictors were particularly important for organisms with comparatively lower dispersal ability, such as aquatic macrophytes and fish. On the other hand, environmental predictors were particularly important for organisms with high dispersal ability, such as microalgae, indicating the importance of species sorting processes in shaping the community structure of these organisms. The importance of watercourse distances increased when spatial variables were the main predictors of metacommunity structure. The contribution of temporal predictors was low. Our results emphasize the strength of a trait-based analysis and of better defining spatial variables. More importantly, they supported the view that ''all-or-nothing'' interpretations on the mechanisms structuring metacommunities are rather the exception than the rule.

Research paper thumbnail of Zooplankton Community Metrics as Indicators of Eutrophication in Urban Lakes

Natureza & Conservação, 2011

Although the direct effects of eutrophication are well known, its indirect effects are poorly und... more Although the direct effects of eutrophication are well known, its indirect effects are poorly understood and the interaction with non-nutrient factors may alter some expected relationships. We analyzed the reliability of community-level metrics derived from three zooplankton groups as predictors of eutrophication in urban man-made lakes. Univariate and multivariate correlation analyses were used to test for relationships between environmental variables and community metrics derived from zooplankton data. Our results indicated that rotifer community metrics were the best eutrophication indicators. The main implication of our results is that arguments against the use of simple community-level metrics as indicators of eutrophication cannot be generalized. Our findings also suggest the need of complete sample analyses (i.e., identification and counting) to estimate reliable ecological indicators of eutrophication.

Research paper thumbnail of Length-weight regressions of the microcrustacean species from a tropical floodplain

Acta Limnologica Brasiliensia, 2012

AIM: This study presents length-weight regressions adjusted for the most representative microcrus... more AIM: This study presents length-weight regressions adjusted for the most representative microcrustacean species and young stages of copepods from tropical lakes, together with a comparison of these results with estimates from the literature for tropical and temperate regions; METHODS: Samples were taken from six isolated lakes, in summer and winter, using a motorized pump and plankton net. The dry weight of each size class (for cladocerans) or developmental stage (for copepods) was measured using an electronic microbalance; RESULTS: Adjusted regressions were significant. We observed a trend of under-estimating the weights of smaller species and overestimating those of larger species, when using regressions obtained from temperate regions; CONCLUSION: We must be cautious about using pooled regressions from the literature, preferring models of similar species, or weighing the organisms and building new models.

Research paper thumbnail of Net cages in fish farming: a scientometric analysis

Acta Limnologica Brasiliensia, 2012

AIM: This study presents a scientometric analysis of studies on net cages in order to determine w... more AIM: This study presents a scientometric analysis of studies on net cages in order to determine whether these studies are considering environmental issues or only seeking an increase in food production; METHODS: The survey of articles was accomplished using the Thomson Reuters Database (ISI Web of Knowledge), with "cage culture" and "net cage" as keywords. We selected 238 articles that were published between 1990 and 2009; RESULTS: There was a temporal increase in the number of articles published. These articles focused mainly on fish production and environmental impacts; CONCLUSION: The studies of net cages in fish farming mainly investigated fish production, although environmental issues relating to this recent human activity were also important. Policy makers should consider both sides of the coin (i.e., both the benefits and environmental impacts of fish production) in regulation of this activity.

Research paper thumbnail of Relationships Between Rotifers, Phytoplankton and Bacterioplankton in the Corumbá Reservoir, Goiás State, Brazil

Hydrobiologia, 2005

This study evaluates the relationships between rotifers and phytoplankton and rotifers and bacter... more This study evaluates the relationships between rotifers and phytoplankton and rotifers and bacterioplankton in a tropical reservoir. Fourteen stations in the reservoir were sampled, including in its arms and tributaries, in the dry and rainy seasons. The highest rotifer density was found in the dry season, mainly in the upper and intermediary stretches of the reservoir. Brachionus calyciflorus, Polyarthra vulgaris, Keratella tropica, K. cochlearis, K. americana and Pompholyx complanata were the most abundant species. Densities of B. calyciflorus and bacteria were significantly correlated. On the other hand, there was an inverse relationship between P. vulgaris and bacteria. Diatoms (Bacillariophyceae) were observed to be associated to K. americana. We suggest that the rotifer populations play a part in microbial and herbivory food webs.

Research paper thumbnail of Erratum to: Effects of fish farming on plankton structure in a Brazilian tropical reservoir

Research paper thumbnail of Zooplankton in the Floodplains of a Tributary to the Paran� River in Mato Grosso Do Sul, Brazil

Studies on Neotropical Fauna and Environment, 1996

... et al 1982), the Caura river (Saunders III &amp;amp;amp; Lewis Jr 1988) and the flood-pla... more ... et al 1982), the Caura river (Saunders III &amp;amp;amp; Lewis Jr 1988) and the flood-plains of ... AF (1992) Seasonal variation of some limnological factors a várzea lake of the high rio Paraná, State of ... A longitudinal study of zoo-plankton along the lower Orinoco River and its delta (Venezuela ...

Research paper thumbnail of Community structure of rotifers in two environments of the upper River Paran� floodplain (MS) - Brazil

Hydrobiologia, 1996

... at each station, with a motor pump from open water (Stations Gl and B 1), and from Eichhornia... more ... at each station, with a motor pump from open water (Stations Gl and B 1), and from Eichhornia azurea (Station G2) using a plankton net of 70 µm mesh size The end of the 6-cm diameter tube of motorpumb was protected by plastic to avoid big debris Rotifers (ind m-3 ... Diversity ...

Research paper thumbnail of Acta Scientiarum 22(2):343-346, 2000. ISSN 1415-6814. Species composition of rotifers in different habitats of an artificial lake, Mato Grosso do Sul State, Brazil

ABSTRACT. Rotifers are small filter-feeders that are important in food chains and nutrient cyclin... more ABSTRACT. Rotifers are small filter-feeders that are important in food chains and nutrient cycling in aquatic environments. Little is known of the rotifer fauna in the State of Mato Grosso do Sul. We investigated the occurrence and distribution of rotifers in different habitats of an artificial lake near the city of Dourados, from May through November 1997. We recorded 36 taxa belonging to 15 families, mainly Brachionidae. In the different environments sampled, the presence of vegetation was an important factor determining the occurrence of the taxa. Key words: rotifers, composition, State of Mato Grosso do Sul, Brazil. RESUMO. Composição de rotíferos em diferentes habitats de um lago artificial, estado do Mato Grosso do Sul, Brasil. Os rotíferos são pequenos filtradores importantes para as cadeias tróficas dos ambientes aquáticos, bem como na ciclagem dos nutrientes. No Estado do Mato Grosso Sul pouco se conhece sobre a fauna desses invertebrados. Dessa forma, procurou-se, neste es...

Research paper thumbnail of tropical reservoirs (Paraná State, Brazil)

How to cite Complete issue More information about this article Journal's homepage in redalyc... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System

Research paper thumbnail of assemblages in different systems of the upper Paraná River floodplain (PR/MS-Brazil)

The present study evaluated the influence of water level fluctuations and the system type on the ... more The present study evaluated the influence of water level fluctuations and the system type on the structure of planktonic microcrustacean assemblage, in different lagoons on the Upper Paraná River floodplain. Sampling was performed in pelagic region from 15 lagoons associated with three rivers, during flood (February 1999) and dry (October 1999) periods. Forty nine cladoceran species and sixteen copepods species were identified. Null model ANOVA results did not show significant differences in microcrustacean densities among systems. Only B. hagmanni, B. deitersi and Calanoid nauplii densities were significantly different between periods. Differences between periods in each system and among systems in each hydrological period were not significant either. Thus, spatial differences were not superior in microcrustacean structuring. However, some temporal differences were observed for bosminids and Calanoid nauplii.

Research paper thumbnail of Zooplankton community resilience and aquatic environmental stability on aquaculture practices: a study using net cages

Brazilian Journal of Biology, 2012

Fish farming in net cages causes changes in environmental conditions. We evaluated the resilience... more Fish farming in net cages causes changes in environmental conditions. We evaluated the resilience of zooplankton concerning this activity in Rosana Reservoir (Paranapanema River, PR-SP). Samples were taken near the net cages installed at distances upstream and downstream, before and after net cage installation. The resilience was estimated by the decrease in the groups' abundance after installing the net cages. The zooplankton community was represented by 106 species. The most abundant species were Synchaeta pectinata, S. oblonga, Conochilus coenobasis, Polyarthra dolichoptera and C. unicornis (Rotifera), Ceriodaphnia cornuta, Moina minuta, Bosmina hagmanni and C. silvestrii (Cladocera) and Notodiaptomus amazonicus (Copepoda). The resilience of microcrustaceans was affected in the growing points as this activity left the production environment for longer, delaying the natural ability of community responses. Microcrustaceans groups, mainly calanoid and cyclopoid copepods, had a d...

Research paper thumbnail of Effects of nutrients increase on the copepod community of a reservoir using cages

Acta Limnologica Brasiliensia, 2015

Aim: This study investigated changes in copepod abundance and the influence of environmental vari... more Aim: This study investigated changes in copepod abundance and the influence of environmental variables in a reservoir with fish farming using cages, on temporal and spatial scales. We hypothesised that the copepod abundance will increase when influenced by changes in environmental variables due the increase of nutrients originating from fish farming. Methods A 120-day sampling of copepods and environmental variables was carried out in a subtropical reservoir of the Paraná River basin (Rosana reservoir), upstream and downstream of three sets of cages with different fish stocking densities. A Principal Component Analysis was conducted to characterise sampling periods and points through environmental variables. The differences between copepod abundance according to sampling periods and points were tested by ANOVA. Results We observed higher maximum values for most nutrient concentrations and dissolved oxygen in the final stage of the experiment and in the location of cages installation...

Research paper thumbnail of Ocorrência de tecamebas (Protozoa, Rhizopoda) em águas continentais brasileiras. I. Família Arcellidae

Acta Scientiarum Biological Sciences

The purpose of this paper is to increase the knowledge on testate amoebae in Brazilian inland wat... more The purpose of this paper is to increase the knowledge on testate amoebae in Brazilian inland waters, specifically the family Arcellidae (Protozoa, Amoebozoa, Rhizopoda). In this paper the current occurrence and geographical distribution of this family in Brazil is discussed. A total of 26 infra-generic taxa was recorded, among them 24 taxa belong to the genus Arcella and 2 to Pyxidicula. Arcella vulgaris Ehrenberg, A. gibbosa Pénard, A. megastoma Pénard, A. dentata Ehrenberg, A. discoides Ehrenberg, A. brasiliensis Cunha and A. crenulata Deflandre were the species with greater number of records. Some taxonomic information is also provided.

Research paper thumbnail of Ocorrência de tecamebas (Protozoa, Amoebozoa, Rhizopoda) em águas continentais brasileiras. II. Famílias Centropyxidae, Trigonopyxidae e Plagipyxidae

Acta Scientiarum Biological Sciences

The purpose of this study is to provide a checklist and a synthesis of the geographic distributio... more The purpose of this study is to provide a checklist and a synthesis of the geographic distribution of the species within Centropyxidae, Trigonopyxidae and Plagiopyxidae (Protozoa, Amoebozoa, Rhizopoda). A total of 24 infra-generic taxa were listed, of which 15 belong to the genus Centropyxis, 5 to Cyclopyxis, 2 to Bullinularia, 1 to Hoogenraadia and 1 to Trigonopyxis. Some taxonomic information is also provided. Centropyxis aculeata, C. constricta and C. marsupiformis presented widespread distribution in the freshwater environments in Brazil.

Research paper thumbnail of The likely effects of river impoundment on beta-diversity of a floodplain zooplankton metacommunity

Natureza & Conservação, 2015

Using a long-term dataset, we tested whether beta diversity of the zooplankton community in the U... more Using a long-term dataset, we tested whether beta diversity of the zooplankton community in the Upper Paraná River floodplain increases during periods of high environmental heterogeneity and productivity and decreases with increases in water level (when there is higher connectivity between sites). We detected temporal trends of increasing beta diversity. A temporal decrease in species occupancy was more frequent than a temporal increase. Our results do not support a generalized association between beta diversity and environmental heterogeneity or productivity. Water level variation was an important explanatory variable only for rotifers and in the opposite direction expected. Taken as whole, our results suggest that we are far from a comprehensive understanding of the processes underlying variation in beta diversity. We speculate that the large number of dams built upstream from the study area may account for the positive trend in beta diversity.

Research paper thumbnail of New record of planktonic cladoceran to the upper Paraná River, Brazil: Bosmina huaroensis Delachaux, 1918

Revista Brasileira de Biologia, 2000

In this paper we register the first occurrence of Bosmina huaroensis Delachaux, 1918 in the upper... more In this paper we register the first occurrence of Bosmina huaroensis Delachaux, 1918 in the upper Paraná River basin, which is probably the first record to Brazil. Illustrations and an updated description of the species are given.

Research paper thumbnail of Spatial and temporal density variation of microcrustacean assemblages in different systems of the assemblages in different systems of the upper Paraná River floodplain (PR/MS floodplain (PR/MS-Brazil)

The present study evaluated the influence of water level fluctuations and the system type on the ... more The present study evaluated the influence of water level fluctuations and the system type on the structure of planktonic microcrustacean assemblage, in different lagoons on the Upper Paraná River floodplain. Sampling was performed in pelagic region from 15 lagoons associated with three rivers, during flood (February 1999) and dry (October 1999) periods. Forty nine cladoceran species and sixteen copepods species were identified. Null model ANOVA results did not show significant differences in microcrustacean densities among systems. Only B. hagmanni, B. deitersi and Calanoid nauplii densities were significantly different between periods. Differences between periods in each system and among systems in each hydrological period were not significant either. Thus, spatial differences were not superior in microcrustacean structuring. However, some temporal differences were observed for bosminids and Calanoid nauplii.

Research paper thumbnail of Avaliação Da Biomassa De Microcrustáceos Em Ambientes Aquáticos Continentais Microcrustaceans Biomass Estimation in Continental Aquatic Environments Evaluación De La Biomasa De Microcrustáceos en Ambientes Acuáticos Continentales

Research paper thumbnail of Zooplankton body-size structure and biomass in tropical floodplain lakes: relationship with planktivorous fishes

Acta Limnologica Brasiliensia, 2011

AIM: This study evaluated whether the size structure of the zooplankton community, as analyzed fr... more 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), indicatin...

Research paper thumbnail of Dispersal Ability Determines the Role of Environmental, Spatial and Temporal Drivers of Metacommunity Structure

PLoS ONE, 2014

Recently, community ecologists are focusing on the relative importance of local environmental fac... more Recently, community ecologists are focusing on the relative importance of local environmental factors and proxies to dispersal limitation to explain spatial variation in community structure. Albeit less explored, temporal processes may also be important in explaining species composition variation in metacommunities occupying dynamic systems. We aimed to evaluate the relative role of environmental, spatial and temporal variables on the metacommunity structure of different organism groups in the Upper Paraná River floodplain (Brazil). We used data on macrophytes, fish, benthic macroinvertebrates, zooplankton, periphyton, and phytoplankton collected in up to 36 habitats during a total of eight sampling campaigns over two years. According to variation partitioning results, the importance of predictors varied among biological groups. Spatial predictors were particularly important for organisms with comparatively lower dispersal ability, such as aquatic macrophytes and fish. On the other hand, environmental predictors were particularly important for organisms with high dispersal ability, such as microalgae, indicating the importance of species sorting processes in shaping the community structure of these organisms. The importance of watercourse distances increased when spatial variables were the main predictors of metacommunity structure. The contribution of temporal predictors was low. Our results emphasize the strength of a trait-based analysis and of better defining spatial variables. More importantly, they supported the view that ''all-or-nothing'' interpretations on the mechanisms structuring metacommunities are rather the exception than the rule.

Research paper thumbnail of Zooplankton Community Metrics as Indicators of Eutrophication in Urban Lakes

Natureza & Conservação, 2011

Although the direct effects of eutrophication are well known, its indirect effects are poorly und... more Although the direct effects of eutrophication are well known, its indirect effects are poorly understood and the interaction with non-nutrient factors may alter some expected relationships. We analyzed the reliability of community-level metrics derived from three zooplankton groups as predictors of eutrophication in urban man-made lakes. Univariate and multivariate correlation analyses were used to test for relationships between environmental variables and community metrics derived from zooplankton data. Our results indicated that rotifer community metrics were the best eutrophication indicators. The main implication of our results is that arguments against the use of simple community-level metrics as indicators of eutrophication cannot be generalized. Our findings also suggest the need of complete sample analyses (i.e., identification and counting) to estimate reliable ecological indicators of eutrophication.

Research paper thumbnail of Length-weight regressions of the microcrustacean species from a tropical floodplain

Acta Limnologica Brasiliensia, 2012

AIM: This study presents length-weight regressions adjusted for the most representative microcrus... more AIM: This study presents length-weight regressions adjusted for the most representative microcrustacean species and young stages of copepods from tropical lakes, together with a comparison of these results with estimates from the literature for tropical and temperate regions; METHODS: Samples were taken from six isolated lakes, in summer and winter, using a motorized pump and plankton net. The dry weight of each size class (for cladocerans) or developmental stage (for copepods) was measured using an electronic microbalance; RESULTS: Adjusted regressions were significant. We observed a trend of under-estimating the weights of smaller species and overestimating those of larger species, when using regressions obtained from temperate regions; CONCLUSION: We must be cautious about using pooled regressions from the literature, preferring models of similar species, or weighing the organisms and building new models.

Research paper thumbnail of Net cages in fish farming: a scientometric analysis

Acta Limnologica Brasiliensia, 2012

AIM: This study presents a scientometric analysis of studies on net cages in order to determine w... more AIM: This study presents a scientometric analysis of studies on net cages in order to determine whether these studies are considering environmental issues or only seeking an increase in food production; METHODS: The survey of articles was accomplished using the Thomson Reuters Database (ISI Web of Knowledge), with "cage culture" and "net cage" as keywords. We selected 238 articles that were published between 1990 and 2009; RESULTS: There was a temporal increase in the number of articles published. These articles focused mainly on fish production and environmental impacts; CONCLUSION: The studies of net cages in fish farming mainly investigated fish production, although environmental issues relating to this recent human activity were also important. Policy makers should consider both sides of the coin (i.e., both the benefits and environmental impacts of fish production) in regulation of this activity.

Research paper thumbnail of Relationships Between Rotifers, Phytoplankton and Bacterioplankton in the Corumbá Reservoir, Goiás State, Brazil

Hydrobiologia, 2005

This study evaluates the relationships between rotifers and phytoplankton and rotifers and bacter... more This study evaluates the relationships between rotifers and phytoplankton and rotifers and bacterioplankton in a tropical reservoir. Fourteen stations in the reservoir were sampled, including in its arms and tributaries, in the dry and rainy seasons. The highest rotifer density was found in the dry season, mainly in the upper and intermediary stretches of the reservoir. Brachionus calyciflorus, Polyarthra vulgaris, Keratella tropica, K. cochlearis, K. americana and Pompholyx complanata were the most abundant species. Densities of B. calyciflorus and bacteria were significantly correlated. On the other hand, there was an inverse relationship between P. vulgaris and bacteria. Diatoms (Bacillariophyceae) were observed to be associated to K. americana. We suggest that the rotifer populations play a part in microbial and herbivory food webs.

Research paper thumbnail of Erratum to: Effects of fish farming on plankton structure in a Brazilian tropical reservoir