Submitted by Ana Paula Lisboa Monteiro (monteiro@univates.br) on 2009-09-10T20:36:36Z No. of bitstreams: 1 KeliHepp.pdf: 5476892 bytes, checksum: 6565fed3806b061cc619999c887b6b1f (MD5) / Made available in DSpace on 2009-09-10T20:36:36Z (GMT). No. of bitstreams: 1 KeliHepp.pdf: 5476892 bytes, checksum: 6565fed3806b061cc619999c887b6b1f (MD5) / O desenvolvimento de florações de algas e cianobactérias vêm sendo cada vez mais frequente à medida que os ambientes aquáticos sofrem as interferências de ações antrópicas. Florações de cianobactérias são as principais responsáveis por problemas sanitários, devido ao potencial de produção de toxinas de certas espécies, além de conferir odor e coloração às águas. Tais fenômenos constituem sérios riscos à biota aquática e à comunidade associada, assim como à saúde pública. Em virtude da ocorrência de florações de cianobactérias no lago do Parque Professor Theobaldo Dick no município de Lajeado, Rio Grande do Sul, Brasil, possivelmente associada à mortandade de peixes documentada durante a floração, e por este se encontrar em uma área de preservação permanente, realizou-se uma avaliação da composição e da variação temporal e espacial de cianobactérias deste ecossistema. Foram analisadas 23 amostras durante os meses de fevereiro/2008 a janeiro/2009. As amostras de água foram obtidas mensalmente através da passagem de frasco na subsuperfície da água em dois pontos do lago. Foram analisadas as seguintes variáveis ambientais: temperatura do ar e da água (oC), pluviosidade (mm), transparência (m), pH, oxigênio dissolvido (mg.L-1), nitrogênio total (mg.L-1) e fósforo total (mg.L-1). A classe Cyanophyceae, objetivo deste estudo, esteve representada por 11 táxons, sendo Cylindrospermopsis raciborskii (Woloszynska) Seenayya & Subba Raju a espécie dominante durante o período estudado, com exceção do mês de janeiro/09 quando foi considerada abundante. A densidade (ind.mL-1) de cianobactérias representou 71,32% da densidade total verificada. A incidência destes organismos esteve relacionada às condições físico-químicas da água como consequência do lançamento de águas residuárias domésticas “in natura” no lago. Testes de toxicidade detectaram a presença de neurotoxinas, provavelmente associadas à morte de peixes registradas no lago.

The release of the neurotoxic alkaloid saxitoxin by cyanobacterial cells was previously thought to occur primarily after cell lysis, yet recent evidence also suggests active toxin export by membrane transporters. Transporter proteins associated with STX biosynthesis in Cylindrospermopsis raciborskii T3 (sxtF and sxtM) and Anabaena circinalis 131C (naDt) were predicted to be involved in the export of STX from cyanobacterial cells. The main aim of this project was to characterise the transporters associated with STX biosynthesis, by investigation of their genetic prevalence, functional substrates and specific regulation. An sxtM homologue was discovered in A. circinalis 131C, as part of an sxt cluster, and found to be uniquely associated with STX-producing strains. Bioinformatic and phylogenetic analysis showed that the translated sxt transporters clustered with the NorM prokaryotic MATE sub-family and membrane topology analysis predicted 12 membrane-spanning regions. To characterise the functional substrates of the putative STX-transporters, they were heterologously expressed in the antibiotic-sensitive E. coli strain KAM32. Expression of the sxt MATES complemented host sensitivity to the cationic fluroquinolone antibiotics, ciprofloxacin and ofloxacin. Disruption of gene homologues of naDt and the sxt MATE genes in Synechocystis sp. PCC6803 yielded mutant strains with increased sensitivity to the toxic organic cations, methyl viologen and acriflavine. Transcription of the putative STX transporters, and the putative STX biosynthesis gene sxtA, was studied in C. raciborskii T3 and A. circinalis 131C under alkali and Na+ stress. Alkali stress (pH 9) decreased total STX levels in A. circinalis 131C and was correlated with a down-regulation of the putative transport and biosynthetic genes. In C. raciborskii T3, alkali stress promoted higher extracellular but lower intracellular STX levels, which also correlated with large increases in transcription of the putative STX transport genes.

The release of the neurotoxic alkaloid saxitoxin by cyanobacterial cells was previously thought to occur primarily after cell lysis, yet recent evidence also suggests active toxin export by membrane transporters. Transporter proteins associated with STX biosynthesis in Cylindrospermopsis raciborskii T3 (sxtF and sxtM) and Anabaena circinalis 131C (naDt) were predicted to be involved in the export of STX from cyanobacterial cells. The main aim of this project was to characterise the transporters associated with STX biosynthesis, by investigation of their genetic prevalence, functional substrates and specific regulation. An sxtM homologue was discovered in A. circinalis 131C, as part of an sxt cluster, and found to be uniquely associated with STX-producing strains. Bioinformatic and phylogenetic analysis showed that the translated sxt transporters clustered with the NorM prokaryotic MATE sub-family and membrane topology analysis predicted 12 membrane-spanning regions. To characterise the functional substrates of the putative STX-transporters, they were heterologously expressed in the antibiotic-sensitive E. coli strain KAM32. Expression of the sxt MATES complemented host sensitivity to the cationic fluroquinolone antibiotics, ciprofloxacin and ofloxacin. Disruption of gene homologues of naDt and the sxt MATE genes in Synechocystis sp. PCC6803 yielded mutant strains with increased sensitivity to the toxic organic cations, methyl viologen and acriflavine. Transcription of the putative STX transporters, and the putative STX biosynthesis gene sxtA, was studied in C. raciborskii T3 and A. circinalis 131C under alkali and Na+ stress. Alkali stress (pH 9) decreased total STX levels in A. circinalis 131C and was correlated with a down-regulation of the putative transport and biosynthetic genes. In C. raciborskii T3, alkali stress promoted higher extracellular but lower intracellular STX levels, which also correlated with large increases in transcription of the putative STX transport genes.

Aquatic microalgae produce a variety of toxic secondary metabolites, which are a concern for public health and seafood industries, while also presenting a source of pharmacologically valuable compounds. The present study deals with the physiology and molecular genetics of saxitoxin (STX), a cyanobacterial neurotoxic alkaloid. Ecological and chemical parameters have been investigated for their effects on growth and STX production in the cyanobacterium Cylindrospermopsis raciborskii T3, in order to better understand the physiological responses of this cyanobacterium to the anthropogenic eutrophication of water bodies. The results indicated that phosphate, in particular, had an incremental effect on STX production, as well as promoting the up-regulation of transcription of the STX biosynthetic gene cluster (sxt). High temperature was found to negatively affect growth and STX production in this organism. The effects of the plant hormone, jasmonic acid, were also tested, since it has previously been shown to affect plant alkaloid production. The hypothesised similarity between cyanobacterial and plant secondary metabolism in response to this plant hormone was confirmed in the neurotoxic cyanobacterium, C. raciborskii T3, as well as the non-toxic Anabaena sp. PCC7120. Furthermore, investigation of the sxt gene cluster transcriptional map in C. raciborskii T3 was carried out, with identification of three main polycistronic and one monocistronic transcripts. Promoter regions putatively involved in the regulation of STX production in C. raciborskii T3 were also identified. Transcription factor consensus motifs, the pho boxes, were identified in the main promoter region. These conserved motifs are the binding regions for the transcriptional regulator, PhoB, to the pho regulon genes, involved in phosphate uptake during conditions of its depletion in the environment. Moreover, a genomic region adjacent to the sxt gene cluster in C. raciborskii T3 was identified and characterised, putatively encoding a regulatory two-component system. This system appears to be involved in the sensing of environmental signals, in particular depleted phosphate, while activating the transcription of genes involved in its uptake and transport. The results of this study lead to a greater understanding of the complex factors associated with the regulation of STX biosynthesis and bloom-formation, by the cyanobacterium C. raciborskii T3.

Aquatic microalgae produce a variety of toxic secondary metabolites, which are a concern for public health and seafood industries, while also presenting a source of pharmacologically valuable compounds. The present study deals with the physiology and molecular genetics of saxitoxin (STX), a cyanobacterial neurotoxic alkaloid. Ecological and chemical parameters have been investigated for their effects on growth and STX production in the cyanobacterium Cylindrospermopsis raciborskii T3, in order to better understand the physiological responses of this cyanobacterium to the anthropogenic eutrophication of water bodies. The results indicated that phosphate, in particular, had an incremental effect on STX production, as well as promoting the up-regulation of transcription of the STX biosynthetic gene cluster (sxt). High temperature was found to negatively affect growth and STX production in this organism. The effects of the plant hormone, jasmonic acid, were also tested, since it has previously been shown to affect plant alkaloid production. The hypothesised similarity between cyanobacterial and plant secondary metabolism in response to this plant hormone was confirmed in the neurotoxic cyanobacterium, C. raciborskii T3, as well as the non-toxic Anabaena sp. PCC7120. Furthermore, investigation of the sxt gene cluster transcriptional map in C. raciborskii T3 was carried out, with identification of three main polycistronic and one monocistronic transcripts. Promoter regions putatively involved in the regulation of STX production in C. raciborskii T3 were also identified. Transcription factor consensus motifs, the pho boxes, were identified in the main promoter region. These conserved motifs are the binding regions for the transcriptional regulator, PhoB, to the pho regulon genes, involved in phosphate uptake during conditions of its depletion in the environment. Moreover, a genomic region adjacent to the sxt gene cluster in C. raciborskii T3 was identified and characterised, putatively encoding a regulatory two-component system. This system appears to be involved in the sensing of environmental signals, in particular depleted phosphate, while activating the transcription of genes involved in its uptake and transport. The results of this study lead to a greater understanding of the complex factors associated with the regulation of STX biosynthesis and bloom-formation, by the cyanobacterium C. raciborskii T3.

Cianobactérias, conhecidas por sua habilidade de sintetizar metabólitos com ação tóxica, podem se tornar dominantes em águas com altas concentrações de nitrogênio e fósforo. Embora a toxicidade do glifosato, o herbicida mais usado no mundo, em alguns organismos aquáticos seja conhecida, poucos estudos abordam o efeito desse composto sobre a produção de metabólitos secundários por cianobactérias. O objetivo deste trabalho foi avaliar a influência de diferentes concentrações de glifosato (produto técnico) sobre o crescimento e produção de cianotoxinas e microgininas pelas cepas brasileiras Microcystis aeruginosa LTPNA 08 e Cylindrospermopsis raciborskii CENA 302. Na presença de 15 mg/L de glifosato, o crescimento e a produção de toxinas pela M. aeruginosa foram reduzidos e de microgininas significativamente aumentada. Já a C. raciborskii, quando exposta à 20 mg/L de glifosato teve seu crescimento e síntese de clorofila-a, carotenoides e saxitoxinas aumentados. Concentrações superiores a 20 e 30 mg/L impediram o crescimento celular das cepas LTPNA 08 e CENA 302, respectivamente. A análise de ácidos graxos mostrou perfis bastante distintos entre as cepas. Na cepa LTPNA 08, enquanto que na presença de 10 mg/L de glifosato ocorreu diminuição do teor do ácido linoleico, o ácido estearidônico foi aumentado. Nenhuma das concentrações testadas promoveu alteração sobre o perfil de ácidos graxos da cepa CENA 302. A toxicidade de 5 produtos formulados a base de glifosato foi comparada ao produto técnico em ambas as linhagens-teste. Observou-se uma resistência distinta entre as cepas e toxicidade também variável entre as formulações comerciais. Sendo assim, diante da elevada resistência das cianobactérias M. aeruginosa e C. raciborskii ao glifosato, e considerando-se a elevada interferência antrópica através das práticas agrícolas, pode-se inferir que o uso excessivo e frequente desse herbicida é capaz de estimular o crescimento e dominância desses organismos, podendo modificar a estrutura e funcionalidade de ecossistemas aquáticos / Cyanobacteria, known for their ability to synthesize toxic metabolites, can become dominant in water bodies with high concentrations of nitrogen and phosphorus. Although the toxicity of glyphosate, the most widely used herbicide in the world, in some aquatic organisms is well known, few studies address the effect of this compound on the production of secondary metabolites by cyanobacteria. The aim of this study was to evaluate the influence of different concentrations the herbicide glyphosate (technical grade) on growth and production of cyanotoxins and microginins by Brazilian strains of Microcystis aeruginosa LTPNA 08 and Cylindrospermopsis raciborskii CENA 302. In the presence of 15 mg/L of glyphosate, growth and toxin production by M. aeruginosa were reduced and microginins cell quota significantly increased. The C. raciborskii strain, when exposed to 20 mg/L of glyphosate, had the growth, and chlorophyll-a, carotenoids and saxitoxins production increased. Concentrations above 20 and 30 mg/L prevented cell growth of LTPNA 08 and CENA 302 strains, respectively. Fatty acid analysis showed distinct profiles among the strains. When exposed to 10 mg/L of glyphosate, a decrease in the linoleic acid and increase in stearidonic acid content were observed in M. aeruginosa LTPNA 08 strain. None of the tested concentrations of glyphosate promoted change on the fatty acid profile of CENA 302 strain. The toxicity of 5 glyphosate formulated products was compared to technical product to both strains. There was a distinct resistance among strains and also a variable toxicity among formulated products. Thus, given the high glyphosate resistance of M. aeruginosa and C. raciborskii cyanobacteria, and considering the high anthropogenic interference through agri cultural practices, it can be inferred that excessive and frequent use of this herbicide is able to stimulate growth and dominance of these organisms, which may modify the structure and function of aquatic ecosystems

Cianobactérias, conhecidas por sua habilidade de sintetizar metabólitos com ação tóxica, podem se tornar dominantes em águas com altas concentrações de nitrogênio e fósforo. Embora a toxicidade do glifosato, o herbicida mais usado no mundo, em alguns organismos aquáticos seja conhecida, poucos estudos abordam o efeito desse composto sobre a produção de metabólitos secundários por cianobactérias. O objetivo deste trabalho foi avaliar a influência de diferentes concentrações de glifosato (produto técnico) sobre o crescimento e produção de cianotoxinas e microgininas pelas cepas brasileiras Microcystis aeruginosa LTPNA 08 e Cylindrospermopsis raciborskii CENA 302. Na presença de 15 mg/L de glifosato, o crescimento e a produção de toxinas pela M. aeruginosa foram reduzidos e de microgininas significativamente aumentada. Já a C. raciborskii, quando exposta à 20 mg/L de glifosato teve seu crescimento e síntese de clorofila-a, carotenoides e saxitoxinas aumentados. Concentrações superiores a 20 e 30 mg/L impediram o crescimento celular das cepas LTPNA 08 e CENA 302, respectivamente. A análise de ácidos graxos mostrou perfis bastante distintos entre as cepas. Na cepa LTPNA 08, enquanto que na presença de 10 mg/L de glifosato ocorreu diminuição do teor do ácido linoleico, o ácido estearidônico foi aumentado. Nenhuma das concentrações testadas promoveu alteração sobre o perfil de ácidos graxos da cepa CENA 302. A toxicidade de 5 produtos formulados a base de glifosato foi comparada ao produto técnico em ambas as linhagens-teste. Observou-se uma resistência distinta entre as cepas e toxicidade também variável entre as formulações comerciais. Sendo assim, diante da elevada resistência das cianobactérias M. aeruginosa e C. raciborskii ao glifosato, e considerando-se a elevada interferência antrópica através das práticas agrícolas, pode-se inferir que o uso excessivo e frequente desse herbicida é capaz de estimular o crescimento e dominância desses organismos, podendo modificar a estrutura e funcionalidade de ecossistemas aquáticos / Cyanobacteria, known for their ability to synthesize toxic metabolites, can become dominant in water bodies with high concentrations of nitrogen and phosphorus. Although the toxicity of glyphosate, the most widely used herbicide in the world, in some aquatic organisms is well known, few studies address the effect of this compound on the production of secondary metabolites by cyanobacteria. The aim of this study was to evaluate the influence of different concentrations the herbicide glyphosate (technical grade) on growth and production of cyanotoxins and microginins by Brazilian strains of Microcystis aeruginosa LTPNA 08 and Cylindrospermopsis raciborskii CENA 302. In the presence of 15 mg/L of glyphosate, growth and toxin production by M. aeruginosa were reduced and microginins cell quota significantly increased. The C. raciborskii strain, when exposed to 20 mg/L of glyphosate, had the growth, and chlorophyll-a, carotenoids and saxitoxins production increased. Concentrations above 20 and 30 mg/L prevented cell growth of LTPNA 08 and CENA 302 strains, respectively. Fatty acid analysis showed distinct profiles among the strains. When exposed to 10 mg/L of glyphosate, a decrease in the linoleic acid and increase in stearidonic acid content were observed in M. aeruginosa LTPNA 08 strain. None of the tested concentrations of glyphosate promoted change on the fatty acid profile of CENA 302 strain. The toxicity of 5 glyphosate formulated products was compared to technical product to both strains. There was a distinct resistance among strains and also a variable toxicity among formulated products. Thus, given the high glyphosate resistance of M. aeruginosa and C. raciborskii cyanobacteria, and considering the high anthropogenic interference through agri cultural practices, it can be inferred that excessive and frequent use of this herbicide is able to stimulate growth and dominance of these organisms, which may modify the structure and function of aquatic ecosystems

Made available in DSpace on 2015-09-25T12:21:22Z (GMT). No. of bitstreams: 1 PDF - Hindria Renally Cavalcanti Guimaraes.pdf: 1729464 bytes, checksum: 04c8eb0a10288b9d2250aca9baa31e7e (MD5) Previous issue date: 2012-04-27 / The research aimed to evaluate the saxitoxin removal of the water supply in the conventional system followed by adsorption through granular activated carbon (GAC). The experiment was performed in three steps. In the first, coagulation diagrams were constructed for the aluminum sulfate. In the second stage, tests were conducted with aluminum sulfate and auxiliary coagulant (anionic and cationic polymers). In the third stage was carried conventional treatment (coagulation / flocculation /sedimentation / filtration) followed by adsorption on a column of granular activated carbon (GAC), in bench scale. The system was composed of a polypropylene plastic container for the storage of decanted water derived from the jar tests, with a capacity of 100 liters. The reservoir is connected via two peristaltic pumps with controlled flow for 1L/ h. Each pump is connected to two sand laboratory filters (SLF), which connected themselves to two columns of CAG, CC1 and CC2, with different coal granulometries. The system was monitored for 48 hours. The results of the coagulation tests showed good removal efficiency (>50%) for water of study (WS) at the natural pH of water (7.6), at a dosage of aluminum sulfate 25 mg/L, both in terms of turbidity and remaining true color. When evaluated the representability of the data, it was observed that the removal efficiency was not repeated. In the third stage, there was low saxitoxin removal by conventional treatment (7%), the removal was processed in the adsorption columns. CC1 and CC2 obtained removals ranging from 100 to 70%. However, for the maximum percentage removal CC2 removed greater amount of saxitoxin per unit time compared to CC1, nearly six hours of difference. The Langmuir and Freundlich isotherms showed better settings to the CC2 for the evaluated samples of activated carbon. / A pesquisa teve como objetivo principal avaliar a remoção de saxitoxina de água de abastecimento utilizando tratamento convencional seguido de adsorção por carvão ativado granular (CAG). O experimento foi realizado em três etapas. Na primeira, foram construídos diagramas de coagulação para o sulfato de alumínio. Na segunda etapa, foram realizados ensaios com sulfato de alumino e coagulantes auxiliares (polímeros aniônicos e catiônicos). Na terceira etapa foi realizado o tratamento convencional (coagulação/ floculação/ sedimentação/ filtração) seguido de adsorção em coluna de carvão ativado granular (CAG), em escala de bancada. O sistema esteve formado por um reservatório de plástico de polipropileno para o armazenamento de água decantada proveniente do jar tests, com capacidade para 100 litros. O reservatório foi interligado por intermédio de duas bombas peristálticas com vazão controlada para 1L/h. Cada bomba conectava-se a dois filtros de laboratório de areia (FLA), que se acoplavam a duas colunas de CAG, CC1 e CC2, com carvão de granulometrias distintas. O sistema foi monitorado durante 48h. Os resultados dos ensaios de coagulação mostraram boa eficiência de remoção (> 50 %) para água de estudo (AE) com pH natural da água (7,6), para uma dosagem de sulfato de alumínio de 25mg/L , tanto em termos de turbidez quanto de cor verdadeira remanescentes. Para os ensaios com polímeros sintéticos, o polímero catiônico, em geral, se destacou em relação ao polímero aniônico com percentuais médios de remoção de 57% para remoção de cor verdadeira. Quando avaliada a representabilidade dos dados, observou-se que as eficiências de remoções não se repetiram. Na terceira etapa, houve baixa remoção saxitoxina por parte tratamento convencional (7%), a remoção se processou nas colunas de adsorção. A CC1 e a CC2 obteram remoções entre 100 e 70%, entretanto, para percentuais máximos de remoção a CC2 removeu maior quantidade de saxitoxina por unidade de tempo em relação a CC1, praticamente seis horas de diferença. As isotermas de Freundlich e Langmuir para as amostras de carvão ativado avaliadas aprestaram melhores ajustes para a CC2.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / No semi-Ãrido brasileiro, devido Ãs caracterÃsticas climÃticas, ao regime irregular de chuvas e Ãs caracterÃsticas do solo, a principal fonte de Ãgua para abastecimento humano tem sido os reservatÃrios artificiais de superfÃcie, aÃudes. A ocupaÃÃo e exploraÃÃo desordenada dos recursos naturais nas bacias hidrogrÃficas, alÃm da alta evaporaÃÃo e da radiaÃÃo solar, interferem negativamente na qualidade da Ãgua armazenada. Como consequÃncia, esses reservatÃrios apresentam um processo de eutrofizaÃÃo acelerado, levando frequentemente a floraÃÃes de fitoplÃnctons, comunidade esta predominantemente dominada por CianobactÃrias. Devido grande parte desses organismos serem produtores de toxinas, podendo causar uma sÃrie de problemas à populaÃÃo, decidiu-se monitorar a comunidade fitoplanctÃnica do aÃude SÃtios Novos, reservatÃrio de usos mÃltiplos, localizado no municÃpio de Caucaia-CE, de janeiro de 2010 a junho de 2011 investigando a produÃÃo de toxinas pelos organismos dominantes. Identificou-se 41 tÃxons, 19 de cianobactÃrias e 22 de algas. Apesar da predominÃncia de nÃmero de tÃxons de algas, estas representaram menos de 10% dos organismos quantificados, com exceÃÃo de 1 amostragem. Jà as cianobactÃrias estiveram presentes em todas as amostragens, dominando quantitativamente o ambiente aquÃtico. Dentre o grupo de cianobactÃrias, destacaram-se Planktothrix agardhii (PA) e Cylindrospermosis raciborskii (CR). A abundÃncia de PA ao longo de todo o perÃodo de amostragem variou de 0 a 5.83x105 cel.mL-1, o que representou 94% da abundÃncia total do fitoplÃncton. A densidade mÃdia da PA foi 7.54.104 cel.mL-1. A abundÃncia CR no mesmo perÃodo variou de 0 a 3.32x104 cell.mL-1, representando 18,9% do total da comunidade fitoplanctÃnica. A abundÃncia mÃdia de CR foi 8.21.103 cel.mL-1. As espÃcies dominantes foram isoladas, e realizando-se bioensaios em camundongos, teste ELISA e mÃtodo de detecÃÃo por HPLC, observou-se a produÃÃo de STX e dc-STX pela CR e dc-GTX pela PA. Essa problemÃtica evidencia a necessidade da implementaÃÃo de aÃÃes integradas dos ÃrgÃos ambiental, de gestÃo dos recursos hÃdricos e companhia de sanamento estadual visando a prevenÃÃo e remediaÃÃo do processo de degradaÃÃo da qualidade da Ãgua, atuando na ampliaÃÃo do saneamento bÃsico, na educaÃÃo ambiental, na fiscalizaÃÃo dos usos e ocupaÃÃes do solo na bacia hidrogrÃfica mas, principalmente, no controle das atividades de piscicultura na bacia hidrÃulica, que ocorrem de maneira superintensiva. / In Brazilian semi-arid Northeast region due to irregular rainfall regime, climatic and soil characteristics, the main source of human water supply has been artificial surface reservoirs. Disorderly occupation and exploitation of natural resources on those hydrographic basins, alongside high evaporation and solar radiation, promote negative impact on stored water quality. As a consequence, the reservoirs present themselves in a process of accelerated eutrophication, often leading to phytoplankton blooms, predominantly dominated by Cyanobacteria. Due to many of these organisms are toxin-producing, which can cause a sort of problems to the population, it was decided to monitor the phytoplankton community of a multipurpose reservoir, located in the municipality of Caucaia-CE, from January 2010 to June 2011, as well as investigate the production of toxins by the dominant organisms. We identified 41 taxa, 19 of cyanobacteria and 22 of algae. Despite the predominance of algae over the identified taxa, they accounted for less than 10% of the quantified organisms, except for one sample. However cyanobacteria were present in all samples, quantitatively dominating the aquatic environment. Among the group of cyanobacteria, excelled Planktothrix agardhii (PA) and Cylindrospermosis raciborskii (CR). PA abundance along all sampling period ranged from 0 to 5.83x105 cells.mL-1 , which accounted for 94% of the total phytoplankton abundance. The average density of PA was 7.54.104 cells.mL-1 . The CR abundance in the same period ranged from 0 to 3.32x104 cells.mL-1 , accounting for 18,9% of total phytoplankton community. The average abundance of CR was 8.21.103 cells.mL-1. The dominant species were isolated and carrying out mice bioassay , ELISA and HPLC analysis, we observed the production of STX and dc-STX by CR and dc-GTX by PA. This issue highlights the need for the implementation of integrated actions from environmental agencies, water resources management and sanitation State companies towards the prevention and remediation of the degradation of water quality, acting in the expansion of sanitation, environmental education, oversighting of the use and occupation of the watershed lands, but mainly in the control of aquaculture activities in the hydraulic basin, which occur in a super intensive way.

The water quality from a reservoir is subject to all natural and anthropogenic factors acting in its watershed . The state of Cearà since the late 80s has adopted a policy of construction of water reservation to fulfill the so-called hydric emptiness. It has been observed that the waters of these new lakes, as well as the previously constructed , is experiencing a process of deterioration, mainly caused by eutrophication. The eutrophication causes a series of changes in the water system, the most relevant being the cyanobacteria blooms. Some of these organisms may be capable of producing toxins, termed cianotoxins , which are able of causing diseases and, in extreme cases, humans and animals death. This work was performed at the Acarape do Meio reservoir, located in the municipality of RedenÃÃo - CearÃ. Phytoplankton community data, with emphasis on cyanobacteria, was analyzed during the period of May 2012 to May 2013. 49 taxa distributed into 07 classes , Cyanobacteria representing 40 %, were identified. Despite the elevated number of taxa of algae, total quantity of these organisms ranged from 2.16 % (May/2012 ) to 0.34 % ( June/2012 ) while cyanobacteria were present in all samples, ranging between 97.84 % ( May/12 ) to 99.66% ( junho/12 ), quantitatively dominating the aquatic environment . The dominant species in all samples was the cyanobacterium Cylindrospermosis raciborskii, reaching an average density in April, 2012 of 1.121.328 cel.mL-1. As for the Trophic State Index, it pointed out that the reservoir was eutrophic . When the density of cyanobacteria was correlated with rainy periods and macronutrients , it showed a strong positive correlation with seasonality but a weak correlation with nitrogen and phosphorus, probably caused by the high quantities of these macronutrients present during the study period. / A qualidade da Ãgua de um reservatÃrio està condicionada a todos os fatores naturais e antrÃpicos que agem na sua bacia hidrogrÃfica. O estado do Cearà desde o final da dÃcada de 80 adotou uma polÃtica de construÃÃo de obras de reservaÃÃo hÃdrica, voltadas a preencher os chamados vazios hÃdricos. O que se tem observado, à que as Ãguas destes aÃudes, bem como os anteriormente construÃdos, vem sofrendo um processo de deterioraÃÃo de suas Ãguas, ocasionado principalmente pelo processo de eutrofizaÃÃo, onde as aÃÃes antrÃpicas sÃo as causas principais. A eutrofizaÃÃo ocasiona uma sÃrie de mudanÃas na massa de Ãgua de um sistema hÃdrico, sendo a mais relevante o surgimento de floraÃÃo de cianobactÃrias, podendo alguns destes organismos, serem capazes de produzir toxinas, denominadas de cianotoxinas, as quais sÃo capazes de ocasionar doenÃas e, em casos extremos, o Ãbito de seres humanos e animais. Este trabalho foi realizado no aÃude Acarape do Meio, localizado no municÃpio de RedenÃÃo-CE, com o objetivo de analisar durante o perÃodo de Maio de 2012 a Maio de 2013, a comunidade fitoplanctÃnica do citado reservatÃrio com Ãnfase em cianobactÃrias. Foram identificados 49 tÃxons distribuÃdos em 07 classes, dentre as CianobactÃrias representaram 40 %. Apesar da existÃncia do bom nÃmero de tÃxons de algas, estas variaram entre 2,16% (maio/2012) e 0,34% (junho/2012) dos organismos quantificados no reservatÃrio, enquanto as cianobactÃrias estiveram presentes em todas as amostragens, variando entre 97,84% (maio/12) a 99,66% (junho/12), dominando quantitativamente o ambiente aquÃtico. A espÃcie dominante em todas as amostragens foi a cianobactÃria Cylindrospermosis raciborskii, chegando a atingir uma densidade mÃdia no mÃs de abril de 1.121.328 cÃl. mL-Â. Quanto ao IET, este apontou que o manancial estava hipereutrÃfizado. Quando a densidade de cianobactÃrias foi correlacionada aos perÃodos chuvosos e secos e aos macronutrientes (nitrogÃnio e fÃsforo), havendo uma correlaÃÃo positiva com a sazonalidade, e uma fraca correlaÃÃo com o nitrogÃnio e o fÃsforo, provavelmente, ocasionada pela a alta taxa destes macronutrientes presentes durante o perÃodo de estudo.