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Bere T.,Instituto Internacional Of Ecologia | Bere T.,Federal University of São Carlos | Tundisi J.G.,Instituto Internacional Of Ecologia
Science of the Total Environment | Year: 2011

The objective of this study was to assess the interactive effects of Cd and Cr III on tropical phytoperiphyton community growth, metal sorption kinetics, as well as Cd and Cr mixtures toxicity to diatom assemblages in laboratory mesocosm experiments. A natural phytoperiphyton community sampled from the Monjolinho River (South of Brazil) was inoculated into seven experimental systems containing clean glass substrates for phytoperiphyton colonization. The communities were exposed to mixtures of dissolved Cd and Cr concentrations of 0.01 and 0.1mg.L -1 Cd and 0.05 and 0.2mg.L -1 Cr. Phytoperiphyton chlorophyll a, ash-free dry mass, growth rate, diatom cell density and diatom community composition were analyzed on samples collected after 1, 2 and 3weeks of colonization. High Cd concentration (0.1mg.L -1) affects phytoperiphyton growth while high concentration of Cr (0.2mg.L -1) decreased the toxic effects of Cd on phytoperiphyton growth demonstrating the importance of studying metal mixtures in field studies. Shifts in species composition (development of more resistant species like Achnanthidium minutissimum (Kützing) Czarnecki, and Nitzschia palea (Kützing) Smith and reduction of sensitive ones like Fragilaria capucina Desmazières, Navicula cryptocephala (Grunow) Cleve, Encyonema silesiacum (Bleisch) Mann, Eunotia bilunaris (Ehrenberg) Mills and Gomphonema parvulum (Kützing) Kützing), of phytoperiphyton communities with increasing Cd and Cr concentrations and exposure duration have been demonstrated in this study making phytoperiphyton communities appropriate monitors of metal mixtures in aquatic systems. Good Cd and Cr accumulation capacity by phytoperiphyton was demonstrated with total and intracellular metal content in phytoperiphyton reflecting the effects of dissolved concentrations of metal in the culture media and exposure duration. Increase in both Cd and Cr reduced sequestration of each other, with generally more Cd being sequestered compared to Cr. Field validation of the observed effects remains an interesting subject for further investigations. © 2011 Elsevier B.V.


Bere T.,Instituto Internacional Of Ecologia | Bere T.,Federal University of São Carlos | Chia M.A.,Federal University of São Carlos | Tundisi J.G.,Instituto Internacional Of Ecologia
Environmental Pollution | Year: 2012

Metal exposure pattern, timing, frequency, duration, recovery period, metal type and interactions, has obscured effects on periphyton communities in lotic systems. The objective of this study was to investigate the effects of intermittent exposures of Cr III and Pb on Cd toxicity and bioaccumulation in tropical periphyton communities. Natural periphyton communities were transferred to artificial stream chambers and exposed to metal mixtures at different pulse timing, duration, frequency and recovery periods. Chlorophyll a, dry mass and metal accumulation kinetics were recorded. Cr and Pb decrease the toxic effects of Cd on periphyton communities. Periphyton has high Cd, Cr and Pb accumulation capacity. Cr and Pb reduced the levels of Cd sequestrated by periphyton communities. The closer the frequency and duration of the pulse is to a continuous exposure, the greater the effects of the contaminant on periphyton growth and metal bioaccumulation. Light increased toxic and accumulative effects of metals on the periphyton community. © 2011 Elsevier Ltd. All rights reserved.


Bere T.,Instituto Internacional Of Ecologia | Bere T.,Federal University of São Carlos | Tundisi J.G.,Instituto Internacional Of Ecologia
Science of the Total Environment | Year: 2012

Understanding the cause and effect relationship between stressors and biota is crucial for the effective management, restoration and preservation of aquatic systems. The objective of the present study was to assess the effects of five Cd concentrations on tropical periphyton community growth, Cd accumulation kinetics, as well as the effects of Cd on diatom community structure and composition. Natural periphyton communities were transferred to artificial stream chambers and exposed to Cd concentrations of 0.005, 0.01, 0.03, 0.05 and 0.1mg.L-1. Metal accumulation (total and intracellular) in biofilms, dry weight and ash-free dry mass, growth rate, algal cell density and diatom community composition were analysed on samples collected after 1, 2 and 4weeks of colonization. Periphyton growth and development were significantly lowered by Cd concentrations>0.03mg.L-1. High Cd accumulation capacity by periphyton was demonstrated with total and intracellular Cd content in biofilms reflecting the effects of concentrations of Cd in the culture media and exposure duration. Total and intracellular Cd content generally increased in treatments in the order 0.005<0.01<0.03<0.05<0.1mg.L-1 at any sampling time with increasing level of accumulated Cd with duration of exposure in all the systems. Shifts in species composition (development of more resistant species like Achnanthidium minutissimum and reduction of sensitive ones like Diatoma vulgare, Navicula viridula and Navicula cryptocephala), decreases in species richness and diversity and morphological alterations (deformities) of diatom cells with increasing Cd concentration and exposure duration were observed. The results give valuable information on Cd impact of freshwater biofilms. © 2012 Elsevier B.V.


Chiba W.A.C.,Federal University of São Carlos | Passerini M.D.,Federal University of São Carlos | Tundisi J.G.,Instituto Internacional Of Ecologia
Brazilian Journal of Biology | Year: 2011

Benthic macroinvertebrates have many useful properties that make possible the use of these organisms as sentinel in biomonitoring programmes in freshwater. Combined with the characteristics of the water and sediment, benthic macroinvertebrates are potential indicators of environmental quality. Thus, the spatial occurrence of potentially toxic metals (Al, Zn, Cr, Co, Cu, Fe, Mn and Ni) in the water, sediment and benthic macroinvertebrates samples were investigated in a sub-basin in the southeast of Brazil in the city of São Carlos, São Paulo state, with the aim of verifying the metals and environment interaction with benthic communities regarding bioaccumulation. Hypothetically, there can be contamination by metals in the aquatic environment in the city due to lack of industrial effluent treatment. All samples were analysed by the USEPA adapted method and processed in an atomic absorption spectrophotometer. The sub-basin studied is contaminated by toxic metals in superficial water, sediment and benthic macroinvertebrates. The Bioaccumulation Factor showed a tendency for metal bioaccumulation by the benthic organisms for almost all the metal species. The results show a potential human and ecosystem health risk, contributing to metal contamination studies in aquatic environments in urban areas.


Bere T.,Instituto Internacional Of Ecologia | Bere T.,Federal University of São Carlos | Tundisi J.G.,Instituto Internacional Of Ecologia
Hydrobiologia | Year: 2011

Diatom-based indices are increasingly becoming important tools for the assessment of ecological conditions in lotic systems. The applicability of regional and foreign diatom-based water quality assessment indices to streams around São Carlos-SP, Brazil, is discussed. The relationship between measured water quality variables and diatom index scores was assessed. The indices, when compared to chemical analyses, proved useful in providing an indication of the quality of the investigated waters. Though all borrowed indices were applicable to the study area because many widely distributed diatom species have similar environmental tolerances to those recorded for these species elsewhere, ecological requirements of some diatom species from Brazil need to be clarified and incorporated in a diatom-based water quality assessment protocol unique to the region. © 2011 Springer Science+Business Media B.V.


Bere T.,Instituto Internacional Of Ecologia | Tundisi J.G.,Instituto Internacional Of Ecologia
Ecological Indicators | Year: 2012

The objective of the current study was to assess the applicability of the Pampean Diatom Index (the PDI) to natural communities other than epipelic diatom communities as well as those growing on artificial substrates in Monjolinho River and its tributaries, São Carlos-SP, Brazil. Benthic diatoms and water quality sampling was done at 10 sites during summer base flow period (2008 and 2009). The PDI scores were calculated based on epilithic, epiphytic, epipsammic and epipelic diatom communities as well as those growing on bricks and glass substrates. Pearson correlation was used to determine the relationship between the PDI scores from different substrates sampled and measured physical and chemical water quality data. Two-way ANOVA was used to compare these correlation values among substrates. The PDI scores based on all the substrates showed significant correlations with physical and chemical variables. Insignificant differences in the PDI scores based on different natural substrates were recorded, with all substrates classifying the sites into to roughly the same categories. In the light of these results, the PDI can be applied to communities other than epipelic, and is applicable to the study area. The choice of substrate sampled may not affect accuracy of the PDI-based water quality assessment. © 2011 Elsevier Ltd.


Tundisi J.G.,Instituto Internacional Of Ecologia | Tundisi T.M.,Instituto Internacional Of Ecologia
Biota Neotropica | Year: 2010

Mosaics of vegetation, riparian forests, and wetlands have an important quantitative and qualitative role on the hydrological cycle. Riparian forests protect the water quality of rivers, lakes and reservoirs. Wetlands control floods, sedimentation and regulate the water quality by enhancing processes such as denitrification, phosphorus and heavy metal retention. Both ecosystems of transition are fundamental. The removal of wetlands and forests (riparian and mosaics of vegetation) affects environmental services of these ecosystems, causing loss of economic assets of the capital natural and accelerating degradation of rivers, lakes, reservoirs and the watersheds. Protection of these ecosystems of transition is thus fundamental for the development of agriculture. The loss of services affects society, human health, increasing costs of recovery and deteriorating human-ecological relationships.


Bere T.,Instituto Internacional Of Ecologia | Tundisi J.G.,Instituto Internacional Of Ecologia
Hydrobiologia | Year: 2011

Benthic diatoms are important indicators of ecological conditions in lotic systems. The objective of this study was to elucidate the confounding effects of eutrophication, organic pollution and ionic strength and conductivity on benthic diatom communities. Benthic diatoms and water quality sampling was done at 10 sites during summer base flow period (2008 and 2009). Detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used to determine environmental gradients along which species vary with respect to ionic strength and conductivity and other environmental variables. Using variance partitioning, we assessed the individual importance of a set of environmental variables (eutrophication and organic pollution) versus ionic strength and conductivity on diatom community structure. The effects of ionic strength and conductivity and organic pollution, eutrophication and other environmental variables were integrated into overall resultant benthic diatom communities. Through partial CCA, we partitioned the variance in diatom data between two sets of exploratory variables, i.e. ionic strength and conductivity (26.9%); other variables, particularly eutrophication and organic pollution (23.0%); shared variance (11.3%) and unexplained variance (38.8%). Due to the interaction of the effects of ionic strength and conductivity and other variables in this study, laboratory experiments must be performed to confirm the observed effects of ionic strength and conductivity. © Springer Science+Business Media B.V. 2010.


Bere T.,Instituto Internacional Of Ecologia | Tundisi J.G.,Instituto Internacional Of Ecologia
Water SA | Year: 2011

The objective of this study was to determine the effects of land-use patterns on both diatom community composition and water quality in tropical streams during the dry season. Benthic diatom collections and water quality sampling were done 4 times at 10 sites. A suite of environmental variables that varied with human land-use pattern was assessed to find the combination of variables that best explained patterns of diatom community composition. Canonical Correspondence Analysis (CCA) was used to determine environmental gradients along which species were distributed. A clear relationship between both benthic diatom communities and water quality and land-use pattern was observed with species richness, diversity and evenness, decreasing significantly from the agricultural and forest area to the urban area. Upstream, forested, agricultural sites, with good water quality (BOD 5 = 0.9 to 2.6 mg·ℓ -1, DO = 6.8 to 8.2 mg·ℓ -1, phosphate = >2 to 4.7 μg·ℓ -1), were characterised by Thalassiosira weissflogii, Orthoseira dentroteres, Meridion anceps, Melosira varians, Diatoma spp, Diadesmis contenta, Eunotia papillo, E. bilunaris, E. intermedia, E. sudetica, Aulacoseira alpigena, A. ambigua, Cymbopleura naviculiformis and Stauroneis phoenicenteron. Urban sites, with medium to bad water quality (BOD 5 = ~7 mg·ℓ -1, DO = ~7 mg·ℓ -1, phosphate = 12.6 to 83.1 μg·ℓ -1), were characterised by Diadesmis dissimilis, Frustulia rhomboids, Nitzschia scalaris, Nitzschia linearis, Cyclotella pseudostelligera Neidium ampliatum, N. affine, Encyonema silesiacum, E. neomesianum, Aulacoseira granulata, Navicula cryptotenella, Pinnularia legumen, P. gibba, P. divergens, Surirella linearis, S. robusta, and Achnanthidium minutissimum. Downstream urban sites, with very bad water quality (BOD5 = 19.5 to 26.2 mg·ℓ -1, DO = 0.4 to 1.9 mg·ℓ -1, phosphate = 142.5 to 248.7 μg·ℓ -1), were characterised by Gomphonema parvulum, G. accuminatum, Nitzschia palea, Nupela praecipua, Sellaphora pupula, Planotidium lanceolata, Fallacia monoculata and Pinnularia subcapitata. Diatom communities demonstrated potential for acting as indicators of changes in water quality due to changes in catchment land-use patterns.


Bere T.,Instituto Internacional Of Ecologia | Tundisi J.G.,Instituto Internacional Of Ecologia
Water, Air, and Soil Pollution | Year: 2011

Diatoms are good indicators of water quality in lotic systems. Unlike in the temperate region, the effect of substrate on diatom-based water quality assessment in tropical streams is not fully understood. The purpose of this study was to assess the effect of substrate on diatom-based multivariate water quality assessment. Epilithic, epiphytic, epipsammic and epipelic diatom community and water quality sampling was done four times at 10 sites during the dry season (2008 and 2009). Artificial substrates (brick and glasses) were also placed at the sampling sites during this period and sampled after 1 month. Cluster analysis was performed to show the main differences and similarities in community composition amongst substrates sampled and amongst sampling sites. The IndVal method was used to identify indicator species characterising different substrates. Canonical correspondence analyses (CCAs) were performed to relate the structure of diatom communities from different substrates to predictor variables. A gradient of increasing metal and organic pollution, eutrophication and ionic strength was observed from the agricultural/forested area to the urban area. Diatom community structure closely reflected this gradient, with communities from polluted sites (8, 9 and 10) being different from other communities. Polluted sites were associated with such species as Nitzschia palea, Plantago lanceolata, Achnanthes exigua, Caloneis hyaline, Cyclotella meneghiniana, Gomphonema parvulum, Fallacia monoculata, Luticola goeppertiana, Pinnularia microstauron, Pinnularia subcapitata and Sellaphora pupula. Indicator species analysis showed that common diatom species were not restricted to a single substrate, though preference was generally high for natural (especially macrophytes) compared to artificial substrates. Six CCAs corresponding to six substrates performed to relate diatom community structure to simultaneous effects of predictor variables explained ∼50% of the diatom species variance in all cases and roughly separated highly polluted sites from the rest of the sites. This indicates that the results of diatom-based multivariate water quality assessment based on different substrates may be interchangeable. Only one substrate has to be collected at each site for water quality assessment surveys, thus avoiding unnecessary expensive and time-consuming oversampling. Given the limitations of artificial substrates, sampling of natural substrates is highly recommended. © 2010 Springer Science+Business Media B.V.

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