Comunidade fitoplanctônica como discriminador ambiental em açude eutrófico tropical semiárido (Barragem Armando Ribeiro Gonçalves, RN) e divulgação científica para reflexão social

The knowledge of the phytoplankton community, as an integral and dynamic processes of eutrophication, provides information essential for proper management and handling. A growing problem of cyanobacteria in reservoirs around the world as a result of artificial eutrophication processes, generating a particular concern, because some species produce cyanotoxins, which can cause adverse effects on human health. The present work aims to characterize the spatial and temporal dynamics of phytoplankton, assessing their potential as ecological indicator of water quality in reservoirs semiarid region. The samples of water were collected monthly between 2009 and 2011, at three points along the dam Armando Ribeiro Gonçalves / RN. In each sample were measured physico - chemical analysis of water and biological components. We conducted a scientific dissemination activity, with distribution and reading primer on eutrophication, informative talk about water quality, questionnaires and performing a play in a public school in the city of Itajá / RN. The reservoir was considered eutrophic in three points, taking into account the values of chlorophyll -a and phosphorus, adopted to characterize eutrophic environments of semi-arid areas. High density of cyanobacteria, with a maximum value of 2.227.862 cél.ml- 1 and minimum of 43.456 cél.ml- 1 was recorded in lentic and semilêntico points throughout the study, exceeding the levels of drinking water (20.000 cél.ml- 1) established in 2.914/2011 Ordinance of the Ministry of Health of Brazil. All samples contained microcystin, and 44 % had values superiores1μg L- 1. The thermal pattern of the water column showed micro stratifications with differences of less than 1 ° C from five feet deep. The distribution pattern was the type profile clinogrado with oxygen deficit in the bottom of the reservoir. Oxiclina from 10 meters depth was observed during the rainy season (May-June) in the two years of study. The phytoplankton community was represented by 10 functional groups: S1, M, H1, Lo, P, F, Sn, P, W2 and R. The assessment of the ecological status of the system by the index Q showed poor water quality. The results of the study show that the vertical variations were less pronounced than the seasonal variations of cyanobacteria and phytoplankton community in general in the reservoir. The presence of cyanotoxins confirms the need for the monitoring of water quality and measures to reduce eutrophication in water supply reservoirs semiarid RN and demonstrates the challenge for water managers and health authorities to ensure water quality and consequently minimize risks to human health. Compared to the lecture, the primer was considered more efficient in sensitizing the participants, featuring a dynamic practice, differentiated learning, create opportunities for students to rethink attitudes of respect and care for the environment, and shall have the opportunity to learn the subject content from your reality and living environment. The knowledge generated from the activity of scientific were seen as essential for raising awareness of some of the region`s environmental problems , such as eutrophication

Avaliação do potencial de toxicidade de florações de cianobactérias como subsídio para ações de gestão ambiental em açudes do semiárido potiguar

Blooms negatively compromise the aquatic environment, plants, animals and human health.Some species are toxin-producing, such as the neurotoxin saxitoxin and the hepatotoxin microcystin, which may contaminate water reservoirs, as those existing in the semiarid region of Rio Grande do Norte (Brazil) which are used to supply the population, fishing, aquiculture and recreational activities, thereby providing the risk of human exposure through water intake, dermal contact and respiratory tract. Thus, it is recommended a constant monitoring of the density of cyanobacteria with the quantification of cyanotoxins. One goal with this work was the monitoring of water in four reservoirs in semiarid of RN through the identification and enumeration of cyanobacteria and through the identification and quantification of cyanotoxins by ELISA. Furthermore, we intended to assess the environmental perception of farmers and artisanal fishers in reservoirs of semiarid of RN through semi-structured interviews with questions mostly related to water and eutrophication. Through these objectives the aim was the development of management strategies for aquaculture and prevention of risks to public health. The results showed that the highest values of microcystins were found in the rainy season. Standards for drinking water, according to the guidelines of Ministry of Health 2914/2011 and CONAMA 357/05, setting the maximum values for raw water density of cyanobacteria: 50,000 cel.mL-1; microcystin: 1 μg. L-1 and saxitoxin: 3 μg. L-1. The values found for microcystin ranged between 0.00227 μg. L-1 and 24.1954 μg. L-1. From 128 samples analyzed, 27% were above the limit. There was no clear seasonal pattern for saxitoxins and their values ranged between 0.003 μg. L-1 and 0.766 μg. L-1 with none of the values above the limit. Furthermore, 76% of the densities of cyanobacteria values were above the limit. About environmental perception, 52 interviews were conducted and the results show that the respondents recognize the main uses of water of the rervoirs, recognize the importance and have a positive view about the reservoirs. They also realize that the water has a poor quality and can cause health problems. The results provide data showing the persistence of cyanobacteria and cyanotoxins, many times over the limit, reinforcing the importance of constant monitoring. The assessment of environmental perception gives foundation for later proposed environmental education linked to public health management into the context of this particular population, making it more effective

Avaliação dos efeitos de um extrato bruto de cianobactérias contendo microcistinas sobre o desempenho reprodutivo e a embriofetotoxicidade de ratos

The presence of cyanobacterial blooms in reservoirs intended for supply to the population can create public health problems for many species could produce potentially toxic compounds and these are not eliminated in the conventional procedures used in water treatment plants. So even in amounts less than the maximum allowable limit imposed by MS, cyanotoxins can be present in drinking water distributed to the population, creating a chronic exposure. There is little information about the long-term effects of oral exposure to cyanotoxins. This work aimed to show the exposure orally (v.o) of animals to a crude extract of cyanobacteria containing cyanotoxins to evaluate the reproductive performance of pregnant rats and their offspring and fertility of male rats. The presence of microcystins (MCs) in samples collected during the flowering processes in freshwater reservoirs in the Rio Grande do Norte, was analyzed by enzyme immunoassay and its variants have been identified and quantified by chromatographic methods. It was observed that by administration v.o. cyanobacterial extract containing MCs (40, 100 or 250 ng of MCs / kg / day) did not cause systemic toxicity in adult rats or effect on reproductive performance of male and female rats treated. It was also not observed any changes in skeletal study in the offspring of pregnant rats treated with the extract above. Because the solutions used contained MCs in a concentration equal to or greater than the tolerable daily intake for MCs, the results suggest, therefore, that the development of this work contributed to better assess public health risk as the oral exposure to cyanotoxins, increasing thus the credibility of the maximum allowable limit (LMP) of MCs in drinking water distributed to the population of several countries that use the LMP established by WHO in its legislation

Biomonitoramento da qualidade da água e ações em educação ambiental em dois açudes da bacia hidrográfica Apodi-Mossoró, RN

Water scarcity is a reality for the inhabitants of the Brazilian semiarid region. The problem, in quantitative terms , is caused due to local climatic conditions due mostly to a water deficit. Qualitatively, results of multiple uses and resulting contamination by human activities. Eutrophication is presented as a threat to the sustainable use of water resources, in order to favor the predominance of dense populations of cyanobacteria, which can be potentially harmful to human health. The aim of this study is to understand the population dynamics of phytoplankton and cyanobacteria to assess water quality of reservoirs Santa Cruz do Apodi and Pau dos Ferros belonging to bacia Apodi Mossoró-RN . Water samples were collected monthly between October 2011 and May 2012 in reservoirs Santa Cruz do Apodi and Pau dos Ferros, in this latter , in Jan/12 we performed a diel profile . The abiotic variables obtained in the field and in the laboratory were: water temperature , dissolved oxygen , pH , turbidity , transparency , total nitrogen and total phosphorus . Phytoplankton samples were collected with a plankton net and bottle of Van dorn . Were performed : identification , quantification , calculation of biovolume , classification into functional groups and index calculation phytoplankton assembly ( Q ) , cyanotoxins were quantified by ELISA . Statistical analyzes supported the evaluation of the dynamics between biotic and abiotic factors. A questionnaire was conducted to examine the conceptions of the population, education professionals and students. The reservoir of Pau dos Ferros, shallow , turbid and eutrophic showed dominance of the functional group SN throughout the sample period . The phytoplankton biomass ranged from 20 to 70 mm ³ . L - 1, the lowest values coincided with the increase of the mixing zone and transparency, which contributed to the occurrence of a change in species composition phytoplankton . The application of the index Q proved relevant, the reservoir of Pau dos Ferros , depending on the species present , was classified ecologically as bad for almost the entire sample period . The reservoir Santa Cruz do Apodi showed low biomass ( 0.04 and 4.31 mm ³ . L - 1 ) and greater diversity in the phytoplankton composition . According to the index assembly (Q ), it showed moderate condition during most of the period influenced by different functional groups of typical meso- eutrophic environment (K S0, H1, C, F , J , E, D and N) . Associations of diatoms and green algae D and X1 succeeded populations of cyanobacteria in periods marked by greater instability in the system , caused by wind or rain. In summary , the occurrence of drought has a direct influence on the hydrological conditions of the reservoirs , in general, these events, reducing the reservoir level is directly related to decreased water quality and increased density of phytoplankton occurring predominance of cyanobacteria , the index Q reflected well to changes in phytoplankton composition , being a good indicator for biomonitoring of reservoirs in this study and survey of previous conceptions showed the need to work on environmental awareness for the preservation of water resources by conducting workshops for Environmental Education

Efeitos de florações de cianobactérias sobre os cladóceros ceriodaphnia dubia e daphnia gessneri

Cyanobacterial blooms are common in eutrophic reservoirs in Brazilian northeastern semi-arid. Given this reality, the present study aimed to analyze the effect of potentially toxic cyanobacterial blooms in Gargalheiras reservoir (semi-arid) on the cladocerans Ceriodaphnia dubia and Daphnia gessneri. In vitro chronic bioassays were performed with reservoir water dilutions from August/2011 to May/2012 and the following effects were evaluated on: intrinsic rate of population growth (r), reproductive parameters (age of first reproduction and fecundity per capita) and cladocerans movements. Phytoplankton was dominated by Cylindrospermopsis raciborskii and Planktothrix agardhii and saxitoxin and microcystin were detected in reservoir water. In most months C. dubia showed differences in r between control (absence of cyanobacteria) and treatments, and has shown negative effects on reproductive parameters. In all months paralysis of swimming movements was observed in C. dubia when both C. raciborskii and saxitoxin (cyanotoxin neurotoxic) were present in water. While C. dubia was sensitive to the reservoir water containing cyanobacteria, D. gessneri showed less intense negative effects in r and reproductive parameters. Furthermore, D. gessneri showed no paralysis of swimming movements. These results support the hypothesis in the literature that D. gessneri is resistant to the Cylindrospermopsis effects. The clone‟s life history may be a key to understand the results. The C. dubia clone, isolated from eutrophicated environment, is in the lab for ten years and it is an exotic species in Brazil. D. gessneri is a common species in the country and this clone was isolated from the Gargalheiras reservoir (where there are constant blooms of potentially toxic cyanobacteria) a year ago. Perhaps the recent contact with cyanobacteria explain the higher resistance presented by this D. gessneri clone. In conclusion, the cladocerans studied have different levels of sensitivity to cyanobacteria, characterizing species-specific responses

O efeito do regime hidrológico do semiárido na composição de espécies durante dominância de cianobactérias em um reservatório tropical

The potentially toxic cyanobacterial blooms in water bodies are spread across the globe, resulting in the loss of water quality and adverse effects on human health. In arid and semiarid regions, the hydrologic regime characterized by an annual cycle of drought and rain, change the volume and the retention time of the reservoir. Such changes affect the limnological characteristics and causing changes in composition and biomass community of cyanobacteria. The reservoir Cruzeta (Zmax = 8.7 m) is a eutrophic water supply source located in the semiarid tropical (Northeast Brazil). Raised the hypothesis that the hydrological regime of semi-arid tropical is a determining factor in the availability of resources in eutrophic water sources, which influences the composition of dominant species of cyanobacteria. The aim of this study was to analyze the changes in biomass and species composition of cyanobacteria for two annual hydrological cycles and evaluate factors drivers. The study was divided into five distinct periods (dry 2010, rain 2011, dry 2011, rain 2012, dry 2012). The dominant group found in all periods was Cyanobacteria (99% of total biomass), which contributed to the low diversity. The filamentous species Cylindrospermopsis raciborskii was present at both points in almost every study. The colonial species Microcystis panniformis and Sphaerocavum brasiliensis dominated only in periods with lower volumes of water. The diatoms contribute more to the biomass during the period of severe drought. The point near the dam (P1) had phytoplankton biomass larger than the point near the tributary (P2). The dominant species of colonial cyanobacteria lasted until the overflow in P1, and P2 this dominance was until the first rains. The redundancy analysis indicated that physical factors such as light availability and water level were the main factors driving the seasonal succession of phytoplankton. The composition of phytoplankton in spring was alternated by species of filamentous cyanobacteria in conditions of poor stability of the water column, such as Cylindrospermopsis raciborskii, and colonial species under conditions of high stability of the water column, such as Microcystis panniformis and Sphaerocavum brasiliensis. The extremes of torrential rains and severe droughts, governed by the hydrological regime of the semi-arid region led to the availability of resources in the watershed, directing the spatial and temporal dynamics of phytoplankton in the reservoir Cruzeta

Efeito da seca na dinâmica dos grupos funcionais fitoplanctônicos em reservatórios eutróficos do semiárido

Reservoirs are the main sources of surface water in Brazil´s semiarid region. The majority of these water supplies, however, are compromised by eutrophication. A severe drought in 2012 contributed to significant losses in water volume, influencing the availability of resources (nutrients and light) for phytoplankton. The aim of this study is to understand the dynamics of the functional groups of phytoplankton and the factors that affect them during a severe drought in the semiarid reservoirs of the northeast. We therefore studied the Dourado, Gargalheiras and Passagem das Traíras reservoirs in Rio Grande do Norte from January 2012 to January 2013. The effect of drought favoured homogeneity within the reservoir, in relation to biotic and abiotic variables, notably the absence of water supply given the lack of flow from its tributaries (intermittent river). The phytoplankton functional groups of bloomforming cyanobacteria (SN, S1 and M) dominated throughout the year 2012, in both the shallow and deep areas of the three reservoirs studied. The groups were related to high concentrations of volatile solids, total phosphorus and ammonia, and high turbidity. Cylindrospermopsis raciborskii (SN group) was the species with the greatest biomass in the three reservoirs. M group (Sphaerocavum brasiliense) performed better in shallow waters with more available phosphorus. Our data showed that high concentrations of nutrients and low availability of light, besides the stability of the water column due to lack of flow and the system´s high residence time, favoured the dominance of bloom-forming cyanobacteria groups, especially those tolerant to shadow

Influência da seca extrema na dinâmica fitoplanctônica de um reservatório da região tropical semiárida: uma abordagem morfofuncional

Droughts are climatic phenomena whose frequency has increased in the last decades and also compromised drinkable water supplies in semiarid regions. The lack of rain combined with high evaporation rates promotes a significant reduction of the volume of reservoirs in these regions. Shallower conditions favors nutrients concentration and phytoplankton overgrowth, including potentially toxic cyanobacteria blooming. Therefore, there is a tendency to the intensification of eutrophication in those reservoirs during drought periods. Phytoplankton can respond quickly to environmental conditions related to light and nutrient availability by changes in algal biomass and composition, therefore it is considered a good predictor of environmental variables. Two functional approaches - Reynolds’s Functional Groups (FG) and Kruk’s Morphologically Based Functional Groups (MBFG) - were used to assess which environmental variables were responsible for phytoplankton dynamics, in addition to compare which functional approach explains environmental changes better. This study highlights that the reduction of 90% in the volume of a tropical reservoir of Brazilian semi-arid region, as well as light limitation and nutrient increase, can promote phytoplankton overgrowth. Multivariate analyses using both functional approaches indicated a clear separation between high volumes and low volumes conditions, showing that light and nutrient availability were the main variables that better explained the combination of functional groups. The composition of phytoplankton assemblage changed from species of meso-eutrophic habitats (FG: F and J; MBFG: VI), to organisms of eutrophic and turbid environments (FG: SN and M; MBFG: VIII and VII) during shallower conditions. Both ecological approaches described properly the phytoplankton dynamics according to light and trophic state alterations related to the water volume reduction, therefore they can be considered as equivalent approaches for using in similar environments.

Adição de policloreto de alumínio e remoção de peixes bentívoros como técnicas de restauração de lagos rasos do semiárido brasileiro

Eutrophication is the most common cause of water quality degradation in the world. This process occurs by excessive nutrients inputs, nitrogen and phosphorus, to the aquatic systems resulting in algal and cyanobacterial blooms. In shallow lakes these effects are pronounced due to the higher interaction of the lake with watershed, air and sediment. There are innumerous restoration techniques of eutrophied lakes with a range of successful results but there is only one case of successful lake restoration in Brazil: Paranoá Lake in Brasília city. The Brazilian semiarid region has many artificial lakes, named açudes, which are mostly eutrophic and shallow lakes. The eutrophication in these lakes is reported and the phytoplankton community is dominated by potentially toxic cyanobacteria species, mainly Cylindrospermopsis raciborskii. The aim of this thesis is to test techniques for water quality management which can be easily applied in Brazilian semiarid lakes. Results from a laboratory experiment suggest that the addition of a phosphorus sorbent clay associated with an aluminium based coagulant is an effective technique in removing soluble reactive phosphorus and reducing C. raciborskii growth rate – cyanobacteria potentially toxic dominant in reservoirs of Brazilian semiarid – but this effect is dependent on the biomass in the application moment. Results from a field experiment in mesocosm in a eutrophied lake showed that the addition of aluminium based coagulant and removal of benthivorous fish is more efficient in removing total phosphorus and chlorophyll-a from water column than the isolated application of one of the techniques. Lastly, laboratory tests showed that aluminium based coagulant exhibited good performance in removing turbidity and total phosphorus from water of six reservoirs but the efficiency was reduced by algal biomass and pH. The results of this study showed that the improvement in water quality of eutrophied reservoirs in semiarid region is possible through internal loading control by phosphorus precipitation and inactivation in sediments or inhibition of phosphorus release by benthivorous fishes, and also that these results show are additives in water quality improvement.

Adição de policloreto de alumínio e remoção de peixes bentívoros como técnicas de restauração de lagos rasos do semiárido brasileiro

Eutrophication is the most common cause of water quality degradation in the world. This process occurs by excessive nutrients inputs, nitrogen and phosphorus, to the aquatic systems resulting in algal and cyanobacterial blooms. In shallow lakes these effects are pronounced due to the higher interaction of the lake with watershed, air and sediment. There are innumerous restoration techniques of eutrophied lakes with a range of successful results but there is only one case of successful lake restoration in Brazil: Paranoá Lake in Brasília city. The Brazilian semiarid region has many artificial lakes, named açudes, which are mostly eutrophic and shallow lakes. The eutrophication in these lakes is reported and the phytoplankton community is dominated by potentially toxic cyanobacteria species, mainly Cylindrospermopsis raciborskii. The aim of this thesis is to test techniques for water quality management which can be easily applied in Brazilian semiarid lakes. Results from a laboratory experiment suggest that the addition of a phosphorus sorbent clay associated with an aluminium based coagulant is an effective technique in removing soluble reactive phosphorus and reducing C. raciborskii growth rate – cyanobacteria potentially toxic dominant in reservoirs of Brazilian semiarid – but this effect is dependent on the biomass in the application moment. Results from a field experiment in mesocosm in a eutrophied lake showed that the addition of aluminium based coagulant and removal of benthivorous fish is more efficient in removing total phosphorus and chlorophyll-a from water column than the isolated application of one of the techniques. Lastly, laboratory tests showed that aluminium based coagulant exhibited good performance in removing turbidity and total phosphorus from water of six reservoirs but the efficiency was reduced by algal biomass and pH. The results of this study showed that the improvement in water quality of eutrophied reservoirs in semiarid region is possible through internal loading control by phosphorus precipitation and inactivation in sediments or inhibition of phosphorus release by benthivorous fishes, and also that these results show are additives in water quality improvement.

Estrutura e dinâmica do fitoplânctone bacterioplâncton em cultivos de camarão no Rio Grande do Norte-Brasil: impacto sobre o ambiente natural

This work aimed to study the structure and dynamic of Phytoplankton and Bacterioplankton in a complete cycle of shrimp cultivation (Litopenaeus vannamei) and determine the environmental factors responsible for the structural changes of these communities. The study was realized in a saltwater shrimp farm (Macaíba, RN), between September/2005 and February/2006, and in a freshwater shrimp farm (Ceará Mirim, RN), between May/2007 and September 2007. The samplings were collected weekly in saltwater farm and every fifteen days in freshwater farm. Total phosphorus, chlorophyll a and environmental parameters (pH, dissolved oxygen, salinity, temperature, depth and water transparency) were measured. Qualitative and quantitative analysis of the phytoplankton and bacterioplankton were carried out. The Shannon-Wiener ecologic indexes of diversity and the Pielou equitability indexes were calculated to the phytoplankton. Bacterial density was determined by epifluorescence microscopy. The data were statistically analyzed by Pearson correlation and t-Test. Chlorophycea were predominat in salt water and in the captation/drainage point (24 to 99%). Diatoms had higher wealth. The species Choricystis minor had the highest occurrence (100%) and dominance (90-100%), thus showing its adaptation to the high temperatures, salinity and low water transparency conditions. Filamentous Cyanobacteria like Oscillatoria sp., Pseudoanabaena sp. and Phormidium sp. had constant levels. The negative correlation between chlorophycea and water transparency, and the positive correlation between chlorophyll a and salinity, showed that the phytoplankton was well adapted to the low transparency and to the high salinity. The bacterioplankton was negatively correlated with the total phosphorus and salinity. In freshwater, Cyanobacteria were predominant (>80%), presenting some producers of toxins species like Microcystis sp., Aphanizomenon sp., Cylindrospermopsis raciborskii e Anabaena circinalis. Cyanobacterial density and total phosphorus and chlorophyll a concentrations exceeded the maximum value allowed by legislation. The means of total phosphorus varied from 264 to 627 Wg.L-1 and the means of chlorophyll a oscillated between 22 and 182 Wg.L-1. The phytoplankton species were selected by low availability of the light, high pH, temperature and high availability of total phosphorus. The bacterioplankton showed high densities (5,13 x 107 to 8,50 x107 Bac.mL-1). The studied environments (ponds and rivers) presented a high level of trophic state based on the high concentrations of chlorophyll a and total phosphorus and cyanobacteria dominance. The composition of species in the ponds and rivers was similar, as well as high concentrations of total phosphorus and chlorophyll a, highlighting the pollution caused by the discharges of the farms in natural environment

Efeitos de manipulações ascendentes e descendentes sobre a comunidade fitoplanctônica em um reservatório eutrófico no semi-árido brasileiro

Top-down (grazing) and bottom-up (nutrient, light) controls are important in freshwater ecosystems regulation. Relative importance of these factors could change in space and time, but in tropical lakes bottom-up regulation has to been appointed as more influent. Present study aimed to test the hypothesis that phytoplankton growths rate in Armando Ribeiro reservoir, a huge eutrophic reservoir in semi-arid region of Rio Grande do Norte state, is more limited by nutrient available then zooplankton grazing pressure. Bioassay was conduced monthly from September (2008) to August (2009) manipulating two levels of nutrients (with/without addition) and two level of grazers (with/without removal). Experimental design was factorial 2X2 with four treatments (X5), (i) control with water and zooplankton from natural spot ( C ), (ii) with nutrient addition ( +NP ), (iii) with zooplankton remove ( -Z ) and (iv) with zooplankton remove and nutrient addition ( -Z+NP ). For bioassay confection transparent plastic bottles (500ml) was incubate for 4 or 5 days in two different depths, Secchi`s depth (high luminosity) and 3 times Secchi`s depth (low luminosity). Water samples were collected from each bottle in begins and after incubates period for chlorophyll a concentration analysis and zoopalnktonic organisms density. Phytoplankton growths rates were calculated. Bifactorial ANOVA was performance to test if had a significant effect (p<0,005) of nutrient addition and grazers remove as well a significant interaction between factors on phytoplankton growths rates. Effect magnitude was calculated the relative importance of each process. Results show that phytoplankton growth was in generally stimulated by nutrient addition, as while zooplankton remove rarely stimulated phytoplankton growth. Some significant interactions happening between nutrient additions and grazers remove on phytoplankton growth. In conclusion this study suggests that in studied reservoir phytoplankton growth is more controlled by ascendent factors than descendent

Avaliação da toxicidade de florações naturais e de cultura de cianobactérias: efeitos sobre Ceriodaphnia silvestri (Crustacea, Cladocera)

The incidence of toxic cyanobacterial blooms is one of the important consequences of eutrophication in aquatic ecosystems. It is a very common phenomenon in reservoirs and shrimp ponds in the State of Rio Grande do Norte (RN), Brazil. Cyanobacterias produce toxins which can affect aquatic organisms and men trough the food chain. Aiming to contribute to the studies of cyanobacterias in RN, we propose: a) to evaluate the toxicity of isolated cyanobacterias in important fresh-water environments; and b) to verify the effects of both natural and cultured blooms occurred in reservoirs for human supply and in the cladoceran Ceriodaphnia silvestrii. This study was carried out using samples of natural blooms occurred between March and October of 2004 in Gargalheiras Dam (08º L e 39º W), in July of 2004 in Armando Ribeiro Gonçalves Dam (06o S e 37o W) and in commercial shrimp ponds (Litopenaeus vannamei) located in fresh-water environments. The samples were collected with plankton net (20µm.) for identification, isolation and obtaining of phytoplanktonic biomass for liophilization and later toxicity bioassays. The toxicity of cultured samples and natural blooms was investigated through bioassays in Swiss mice. Quantification of cyanobacteria in samples was conducted following the Ütermol method, with 300mL samples fixed with lugol. The toxicity test with Ceriodaphnia silvestrii followed ABNT, 2001 recommendations, and were accomplished with natural hepatotoxic bloom s samples and cultured samples of both non-toxic and neurotoxic C. raciborskii. In this test, five newborns, aged between 6 and 24 hours, were exposed to different concentrations (0 a 800 mg.L-1) of crude cyanobacterial extracts during 24 and 48 hours. Three replicates were used per treatment. The pH, temperature and dissolved oxygen at the beginning and after 24 and 48hours from the test were measured. We estimated the CL50 through the Trimmed Spearman-Karber method. The blooms were constituted by Microcystis panniformis, M. aeruginosa, Anabaena circinalis, Cylindrospermopsis raciborskii and Planktothrix agardhii, producers of mycrocistin-LR confirmed with HPLC analysis. Samples of hepatotoxic blooms registered toxinogenic potential for C. silvestrii, with CL50-24h value of 47.48 mg.L-1 and CL5048h of 38.15 mg.L-1 for GARG samples in march/2005; CL50-24h of 113,13 mg.L-1 and CL5048h of 88,24 mg.L-1 for ARG July/2004; CL50-24h of 300.39 mg.L-1 and CL50-48h of 149.89 mg.L-1 for GARG October/2005. For cultured samples, values of CL50-24h and CL50-48h for C. raciborskii toxic strains were 228.05 and 120.28 mg.L-1, respectively. There was no mortality of C. silvestrii during the tests with non-toxic C. raciborskii strain. The toxicity test with C. silvestrii presented good sensitivity degree to cyanotoxins. The toxicity of natural hepatotoxic blooms samples (microcystins) and cultured neurotoxic saxitoxins producer samples analyzed in this study give us strong indications of that toxin s influence on the zooplanktonic community structure in tropical aquatic environments. Eleven cyanobacteria strains were isolated, representing 6 species: Anabaenopsis sp., Cylindrospermopsis raciborskii, Chroococcus sp., Microcystis panniformis, Geitlerinema unigranulatum e Planktothrix agardhii. None presented toxicity in Swiss mice. The strains were catalogued and deposited in the Laboratório de Ecologia e Toxicologia de Organismos Aquáticos (LETMA), in UFRN, and will be utilized in ecotoxicológical and ecophysiological studies, aiming to clarify the causes and control of cyanobacterial blooms in aquatic environments in RN. This state s reservoirs must receive broader attention from the authorities, considering the constant blooms occurring in waters used for human consumption

Ecologia do fitoplâncton impactado por cultivo de tilápia do Nilo, oreochromis niloticus, em tanques-rede no açude Ministro João Alves, Parelhas, Rio Grande do Norte

The dams are limnic ecosystems of great importance for its multiple uses, among them, water supply for the public and to culture of artisanal fish are most relevant. The aim of the present study is to evaluate the physical-chemical characteristics and the phytoplankton community in two chosen sites (Point 1 littoral zone of point source; Point 2 pelagic zone of non-point source) of the Minister João Alves dam, which is also known as Boqueirão de Parelhas/RN. This represents the spatial distribution of the phytoplankton species in order to understand any possible alterations of the water quality and the phytoplankton composition in relation to the water quality originating from the impact of the tilapia, Oreochromis niloticus, culture. The study period also encompasses temporal variations exhibited in two seasons of an annual cycle, one during the dry season (Oct, Nov and Dec of 2008 and Jan of 2009), and the other rainy season (Mar, Apr, May and June of 2008) to extend the observation. The physicalchemical parameters, such as pH, temperature, electrical conductivity, concentration of dissolved oxygen were measured in situ and the values of the inorganic nutrients (nitrate, ammonium and orto-phosfato) and chlorophyll in the laboratory. The quali-quantitative analyses of the phytoplankton had been carried through sedimentation technique and the enumeration of the random of 400 cells, colonies and filaments counted using Sedgwick-Rafter counting chamber. The results of pH varied widely from the acidic to alkaline range with the minimum of 5.8 (± 0.8) and the maximum of 9.2 (± 0.7-0.8), at point 1 and 2. The dissolved oxygen content was higher in the rainy period than that in the dry period. The maximum electrical conductivity was of 1409 μScm-1 in point 1 and 431 minim of μScm-1, in point 2. There was a considerable alteration in the levels of inorganic nutrients such as nitrate-nitrogen, ammoniacal nitrogen and orthophosphate during the two cycles of study period. Phytoplankton assemblages presented a picture of alternate dominance among species Cyanobacteria, Bacillariophyceae and Chlorophyceae. The trophic state index diagnosed to the category of mesotrophic, which is based on the values of chlorophyll, total phosphorus and Secchi-disc measurements. The wind driven turbulence of the water column and the fresh inflow of water (flushing and dilution) during rainy season acted as constraint and did-not allow an exaggerated growth of the species of cyanobacteria. On the basis of the present we conclude that the culture of tilapias in cage-culture fails to produce pollution load that could compromise the quality of the water of the dam, probably be due to small dimension of the culture in relation to the size, volume of the water and the reservoir capacity support its own environment

Os dias são maus : o ensino religioso cristão em dias pós-modernos o desafio de fazer crer perante a cultura da incredulidade

This paper adopts the assumption that religion continues to be a major highlight in the dimension of the contemporary world - characterized by pluralism, the ideas of tolerance and freedom. But for certain streams of Christianity, the postmodern culture seems to be characterized as a highly damaging to their doctrines and principles, since this religious matrix carries a truth claim that would support all its significance, its definition values and their dissemination effort ( evangelism ). This is not to say that Christianity is the only religion that claims to the truth, which would be a gross mistake. Now, religion has been reputed as a phenomenon doomed to disappear, according to the " ideology " of Modernity, given the idea that scientific development would lead us inevitably to the statement that religion was merely a social institution based in the superstition, in fantasy, the imaginary and therefore had nothing "real " unless its existence as an institution capable of aggregating society (give it cohesion), provide values and meaning to different ontological anxieties and doubts of humankind. In the contemporary scenario - seeded by modernity - as Christian ideas, doctrines and principles are in harmony or conflict with postmodernity? These are our starting questions and issues that we intend to stop and reflect. From the assumption that the religious phenomenon has great force in the present day, this research aims to perform central analysis of how religious education, a Protestant denomination specific, harmonizes or clashes with the ideology or ideas more general and emphatic that we can observe in the western world is presented to us from the diagnoses made by the contemporary authors who debate about postmodernism and postmodernity, notably David Harvey, Jean - François Lyotard, Bauman Zygmunt and Fredric Jameson