1000 resultados para CNPQ::CIENCIAS BIOLOGICAS: DESENVOLVIMENTO E MEIO AMBIENTE
Resumo:
Neurodegenerative diseases are frequently studied due to the increasing number of cases associated with the populational ageing and to the impact on the conditions on the quality of life. Parkinson’s disease (DP) is the second most frequent neurodegenerative disease. Despite the fact that its etiology is not completely understood, it is known that DP is caused by environmental and genetic factors. Thus, the investigation of etiologic factors and mechanisms responsible for the changes that lead to DP may help early diagnostic and prevention. A possible association between DP and the common polymorphism of Brain Derived Neurotrophic Factor (BDNF) G196A (Val66Met) has been suggested by different studies with contrasting results. For this reason, the aim of this study is to investigate if the BDNF Val66Met polymorphism is related to susceptibility to DP in a cohort of Brazilian patients. Additionaly, we verify if the presence of the polymorphism implies in alterations in the BDNF whole blood concentrations, as well as variations in symptomatology. The sample comprised Brazilian patients accompanied by the neurology service of the Onofre Lopes University Hospital (HUOL) and healthy controls (CTRL). The motor aspects of DP were evaluated by Hoehn e Yahr Scale (HY), Unified Parkinson’s Disease Rating Scale (UPDRS) and Schwab & England Scale (SE). For the evaluation of non-motor symptoms were used the following instruments: Frontal Assessment Battery (BAF), Mini-Mental State Examination (MEEM), Beck Depression Inventory (IDB) and the Beck Anxiety Inventory (IAB). Blood samples were collected for BDNF Val66Met polymorphism genotyping and BDNF whole blood measurement. As expected, DP patients performed worse in motor, cognitive and emotional battery of questionnaires. Alleles distribution between DP and CTRL was not significantly different, but the A/G genotype was significantly associated with a protector factor for DP. In contrast, the G/G genotype was significantly associated with depression and anxiety development in DP patients. However, BDNF concentrations were not different between genotypes or groups. This is the first study of genetic association of this polymorphism with DP in Brazilian subjects and the first one that associate A/G genotype with protection against DP.
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Os estudos da territorialidade e de comportamentos associados a ela favorecem o entendimento da maneira como as interações ecológicas afetam a composição de espécies e a dinâmica de uma comunidade. No presente estudo tivemos como objetivo geral investigar o comportamento de Stegastes fuscus, um peixe-donzela territorialista, em ambiente natural e em cativeiro, com foco na capacidade de localização territorial, reconhecimento e defesa de uma área estabelecida. Para tanto subdividimos o trabalho em 3 capítulos. O primeiro teve como foco o estudo da espécie em ambiente natural objetivando estimar a área do território ocupado e os padrões comportamentais da por ela expressos. Sendo encontrado que a área média ocupada por S. fuscus foi de 274 cm2 e os comportamentos mais observados foram: vigilância, ingestão de alimento, tempo no abrigo/toca e displays agressivos. O segundo capítulo teve como alvo investigar a capacidade de localização espacial da espécie mediada por pistas visuais. Os resultados demonstraram que S. fuscus apresenta marcante aprendizagem condicionada e possibilidade de existência de orientação espacial na espécie. O terceiro capítulo teve como objetivo avaliar a influência da residência prévia estabelecida e do reconhecimento de coespecíficos nos resultados de confrontos agonísticos. Os resultados apontaram a residência como fator prioritário na dinâmica das disputas agonísticas e que aspectos relacionados à familiaridade como relevantes e destacam-se mais quando não existe um território previamente estabelecido. Diante disso nossos resultados podem favorecer o entendimento da dinâmica estrutural da comunidade na qual S. fuscus esta inserida, sendo isto significativo tendo em vista a importância ecológica da espécie para o ecossistema.
Resumo:
It is known that the catecholamine group is constituted by dopamine, noradrenaline and adrenaline, in which the synthesis is regulated by an enzyme named tyrosine hydroxylase. Thus, 3-hydroxytyramine/dopamine (DA) is a precursor of the noradrenaline and adrenaline synthesis and acts as a neurotransmitter in the central nervous system. The three main nuclei, named the retrorubral field (A8 group), the substantia nigra pars compacta (A9 group) and the ventral tegmental area (A10 group), are arranged in the die-mesencephalic portion and are involved in three complexes circuitries - the mesostriatal, mesolimbic and mesocortical pathways. These pathways are related to behavioral manifestations, motricity, learning, reward and pathologies such as Parkinson’s Disease and Schizophrenia. Thus, the aim of this study was to perform de morphological analysis of the A8, A9 and A10 nuclei of the common marmoset (Callithrix jacchus). The marmoset is a neotropical primate, whose morphological and functional characteristics supports the suitability of use of this animal in biomedical research. Coronal sections of the marmoset brain were submitted to cytoarchitectonic characterization and TH-immunohistochemistry. Based on the morphology of the neurons, it was possible to subdivide the A10 group in seven regions: interfascicular nucleus, raphe rostral linear nucleus and raphe caudal linear nucleus, in the middle line; paranigral and parainterfascicular nucleus, in the middle zone; rostral portion of the ventral tegmental area nucleus and parabrachial pigmented nucleus, located in the dorsolateral portion of the mesencephalic tegmentum. A9 group was divided into four regions: substantia nigra compacta dorsal and ventral tiers; substantia nigra compacta lateral and medial clusters. No subdivisions were founded into A8 group. These results revealed that A8, A9 and A10 are phylogenetically conserved between species, but it’s necessary to expand the studies about this compartmentalization, investigating its occurrence in other primate species or investigating its functional relevance.
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A epilepsia é uma patologia crônica do sistema nervoso central que afeta cerca de 65 milhões de indivíduos no mundo. Aproximadamente 30% desses indivíduos desenvolvem crises convulsivas que persistem apesar do tratamento monitorado com drogas antiepiléptica s. Assim, há uma evidente necessidade do desenvolvimento de novos fármacos antiepilépticos e as peçonhas podem ser uma excelente fonte de modelos. Nesse contexto, enquanto já vários estudos sobre peçonhas de serpentes, escorpiões e aranhas, pouco se sabe s obre as peçonhas de formigas. Estudos prévios do nosso laboratório demonstraram que a peçonha desnaturada da formiga Dinoponera quadríceps protegeu camundongos de crises convulsivas e morte induzidas por bicuculina (BIC). Nesse contexto, o objetivo desse t rabalho foi investigar o potencial anticonvulsivante de frações isoladas da peçonha de D. quadríceps em crises convulsivas induzidas pela BIC, bem como uma análise dos efeitos dessas frações no comportamento natural dos camundongos no campo aberto. Os anim ais foram divididos em grupos, os quais receberam injeções (1 mg/ml i.c.v.) de seis frações distintas e tiveram seu comportamento geral observado no campo aberto durante 3 0 min. No segundo experimento, o s animais receberam as mesmas frações 20 min antes da administração de bicuculina (10 mg/ml). Em seguida, foi analisado o comportamento motor convulsivo desses animais durante 30 minutos no campo aberto. No primeiro experimento, não foram observadas alterações comportamentais. Já no segundo experimento, a ad ministração prévia de DqTx1, DqTx3, DqTx4 e DqTx6 aumentou a latência para o desenvolvimento de crises tônico - clônicas. Além disso, todas as frações, exceto DqTx5, aumentaram a latência para a morte dos animais. Ainda, os melhores resultados foram obtidos com a fração DqTx6, que protegeu 62,5% dos animais testados contra o desenvolvimento de crises tônico - clônicas e 100% dos animais contra a morte.
Resumo:
The artifi cial eutrophication is one of the biggest t h reat for the quality of aquatic ecosystems in the whole world. The expectations for the future climatic scenarios in arid and semi - arid regions are intense and frequent droughts enhancing the risk of eutrophicati on and cyanobacterial blooms. Restoration techniques of eutrophic lakes were proposed to reduce nutrient loading and improve the water quality. A successful technique used in temperate regions is the biomanipulation by benthivorous fish removal . Our hypoth esis is that the benthivorous fish removal reduces phytoplankton total biomass and change the composition of phytoplankton functional groups, improving water quality. The aim of the study was evaluate the impact of biomanipulation on phytoplankton function al groups and in the water quality. We applied the technique of biomanipulation in the artificial lake ESEC, in a semi - arid region of Brazil and analyzed the physical and chemical variables and the dynamic of phytoplankton functional groups monthly during November 2012 to August 2013. With the removal of benthivorous fish we observed a significant increase of the euphotic depth, phytoplankton richness and the recruitment of green algae (groups F and J ), indicators of good water quality. However, we did not observe significant differences on total phosphorous concentration and on phytoplankton biomass and diversity. The drought effect in the region during the study was evident , promoting a drastic reduction on water level which influenced the availability of resource and affected phytoplankton community before the biomanipulation. To evaluate the effect of severe drought on the dynamic of phytoplankton functional groups and test if the drought periods are favorable to dominance of cyanobacterial groups, we stu died two artificial neighbors lakes (ESEC and Pocinhos) in a semi - arid tropical region during May 2012 to February 2013. We observed a temporal differentiation of biotic and abiotic variables caused by drought. Both lakes presented reduction of 2 meters of water level and increase on conductivity, turbidity, nutrients concentration and a reduction on water transparency, during the severe drought. The deeper lake (Pocinhos) increased phytoplankton total biomass and presented cyanobacterial functional group d ominance (group S N ) and the shallower lake (ESEC) reduced phytoplankton total biomass and presented dominance of mixotrophic and flagellate functional groups (groups W 1 e W 2 ). Summarizing, the knowledge of the effects of benthivorous fish removal in semi - a rid tropical lakes still unknown and this study had limitations caused by the impact of drought. Thus, it is necessary a long term monitoring to investigate the real effects of biomanipulation on the functioning of the studied ecosystems. Otherwise, period s of drought could have opposite effects (increase or reduction) on total biomass and composition of phytoplankton functional groups. Drought not always leads to dominance of cyanobacterial groups.
Resumo:
Estresses ambientais abióticos são fatores que causam respostas ao nível molecular, fisiológico e morfológico em plantas, dependendo também de sua intensidade e duração. É visto que algumas espécies apresentam tolerância a condições estressantes e ao mesmo tempo são fontes naturais de matéria prima para indústria. Nesse contexto encontra-se a mamona (Ricinus comunnis L.), principal fonte de óleo de rícino valorizado por suas aplicações farmacêuticas e principalmente industriais, vem sendo usada como cultura em regiões onde a disponibilidade de água é reduzida, usada como fonte de renda para agricultura da região nordeste brasileira. Visto que pouco se sabe sobre as respostas moleculares que levam essa planta a tolerar regiões secas e como as sementes, principais foco de interesse, respondem a essa escassez, nesse trabalho foram construídas duas bibliotecas de cDNAs, onde a partir de uma abordagem subtrativa, continham RNAs diferencialmente expressos em sementes de plantas mamona submetidas ao estresse hídrico durante 5 dias (biblioteca L7), e a outra RNAs diferencialmente expressos em sementes controle (biblioteca L5). A biblioteca L7 apresentou a maior variedade de transcritos com um total de 182. A maior parte das funções estabelecidas pelo sistema Gene Ontology - GO, foram direcionadas aos “Processos Metabólicos” (526), em segundo “Respostas a estímulos” (57), o terceiro termo mais abundante foram referentes a “Desenvolvimento”(26). Já na biblioteca L5, foram encontrados 91 transcritos, com maior parte de suas funções referentes a “Processos Metabólicos”(413), em segundo “Respostas a estímulos” (8) e em terceiro Regulação (6). Alguns dos transcritos da biblioteca L7 foram escolhidos para análise por repetirem-se mais de 3x e não aparecerem na biblioteca L5, o que indica uma possível regulação positiva sobre estresse. As análises sobre Metalotioneína (4x), mostraram que a sequência de proteica apresentava os domínios conservados que a caracterizava como tipo II, onde são encontrados dois domínios funcionais ricos em cisteína com posições altamente conservadas, desempenhando a função de ligar-se a metais pesados, correlacionadas assim como a atividade de eliminação EROs e defesa contra o estresse oxidativo, além de apresentar homologia com a sequência de Bruguiera gymnorhiza, uma planta de mangue adaptada a ambientes salinos. Analisamos também os transcritos da referente a proteína AUXIN-REPRESSED 12.5 KDA (3x), apontada como sendo reprimida pelo hormônio auxina e associada ao processo de dormência da semente, é descrito em uma família gênica onde vários membros pertencem as vias de resposta ao estresse. Por último, analisamos a proteína GLUTELIN TYPE-A 3 (5x), uma importante proteína de armazenamento com caráter hidrofílico, possivelmente direcionada para o vacúolo. Em nosso trabalho foi possível observar um aumento de transcritos em relação a subtração controle, possivelmente reflexo do aumento do metabolismo da semente, tanto para resposta defensiva ao estresse hídrico quanto para o amadurecimento rápido da semente onde foram observados transcritos referentes a resposta oxidativa, controle hormonal, proteínas de reserva e produção de óleo.
Resumo:
The goat and sheep industry shows up as an agricultural activity of great importance for the semiarid Northeast. However, the sheep and goats production is made with various difficulties. Among them, parasitic infections, particularly helminth infections of the gastrointestinal tract, the eimeriosis and toxoplasmosis; this one related to problems in reproduction. For this reason, the aim of this study is to to make a survey of the occurrence and some determinants of parasitic diseases that affect small ruminant flocks of the microregions Natal, Macaíba, Litoral Sul, Angicos, Vale do Açu and Borborema Potiguar. Thereunto, epidemiological tools were applied with producers, keepers or guardians of herds and also held collections of blood and feces of animals in eight properties located in seven municipalities of these microregions. The parasite load of the animals was determined through eggs and oocysts counting per gram of feces EPG and OPG, respectively. In addition, the recovery of infective larvae was made. Blood samples were used to measure the globular cell volume and the search for anti-Toxoplasma gondii IgG in sheep serum, by Enzyme Linked Immune Sorbent Assay (ELISA). For categorical variables, the statistical analysis was performed using Poisson regression, with significance level of 0.05. The analysis of the instruments showed that ivermectin is the anthelmintic used in 85,71% of properties. From the total of feces samples of the sheep (n = 179), 53,07% were positive for helminth eggs and 48,04% were positive for oocysts of Eimeria. From the samples of faeces of goats (n = 133), 72,18% were positive for helminth eggs and 96,99% for oocysts of Eimeria. The lowest EPG and OPG count was observed in the micro region of Angicos. Most of the EPG count was found in the micro region Litoral Sul and the OPG count in the micro-region Borborema Potiguar. Both cases the difference was statistically significant(p- value0,000)The most prevalent helminth genus found was Haemonchus, present in 49,87% of the sheep and 80,42% of goats. The average of hematocrit ranged from 22,91 to 33,25 in sheep and from 22,62 to 28,25 in goats. The prevalence of anti-Toxoplasma gondii IgG ranged from 63,33% to 100,00%. The goats showed to be more susceptible to infections by parasites of the gastrointestinal tract than the sheep. In all the properties was observed high prevalence of infection by T. gondii, with the lowest percentages recorded in the micro regions Angicos and Borborema Potiguar.
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With the development and improvement of techniques for molecular studies and their subsequent application to the systematic, significant changes occurred in the classification of gasteroid fungi. The genus Morganella belongs to the family Lycoperdaceae, and is characterized mainly by lignicolous habit and presence of paracapilicium. Recent data demonstrate the discovery of new species for the group and the existence of a wide variety of species occurring in tropical ecosystems. However, the phylogenetic relationships of the genus, as well as the taxonomic classification, still require revisions to be better understood, the literature studies that address this issue are still very scarce. Thus, the objective of this study was to conduct studies of molecular phylogeny with species of the genus Morganella, to enhance understanding of the phylogeny of the group by including tropical species data. For this, the specimens used both for DNA extractions as for morphological review were obtained from Brazilian and foreign herbaria. For morphological analysis were observed characters relevant to the group's taxonomy. For phylogenetic analysis the Maximum Parsimony and Bayesian Analyzes were used, using the internal transcribed spacer (ITS) of nuclear ribosomal DNA. In phylogenetic analyzes, representatives from Morganella form a monophyletic clade with good support value and based on these results the genus should not be included as subgenus of Lycoperdon. The analysis indicated that M. pyriformis was not grouped with other representatives of Morganella, and therefore should not be included in the group as representative of Apioperdon subgenus because it is a Lycoperdon representative. Moreover, M. fuliginea, M. nuda, M. albostipitata, M. velutina, M. subincarnata are grouped with high support values within the genus Morganella. Morganella arenicola based on morphological and molecular studies does not aggregate in Morganella. Morganella nuda was grouped with M. fuliginea giving indications that can be treated as an intraspecific variation. The results of the analyzes favor to a better understanding of the species of Morganella. However, additional studies using a greater number of species, as well as other molecular markers are needed for a better understanding of the phylogenetic of Morganella.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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A família Gobiidae é a mais diversificada no ambiente marinho, onde tamanha diversidade parece ter sido acompanhada por alterações cromossômicas significativas, a tornando um modelo biológico importante. Em geral apresentam ampla distribuição geográfica com características comportamentais e reprodutivas que as tornam propícias aos efeitos de barreiras biogeográficas. Comparados a outros representantes da ordem Perciformes apresenta características morfológicas reduzidas, com simplificações e perdas que dificultam estudos filogenéticos e tornam imprescindível a associação de novas metodologias para melhor entendimento dos processos ecológicos e evolutivos que garantiram tamanha diversificação. Dados citogenéticos para espécies presentes no litoral brasileiro são ínfimos. Os resultados aqui apresentados, abrangendo um maior espectro taxonômico e profundidade de análises, identificaram marcante diversidade cariotípica estrutural interespecífica para Coryphopterus glaucofraenum, Bathygobius mystacium, Bathygobius soporator, Bathygobius sp., Ctenogobius smaragdus, Ctenogobius boleosoma, Gobionellus oceanicus, Gobionellus stomatus, Microgobius meeki e Evorthodus lyricus. As espécies estudadas fazem parte de uma fauna críptica pouco percebida e estudada, frequentemente impactadas, mesmo por eventos locais estocásticos. Análises por morfometria geométrica indicaram variação significante na morfologia corporal de espécies do gênero Bathygobius e o reconhecimento de padrões de variação de forma corporal referentes ao sexo, com populações mais dimórficas em menores latitudes. Técnicas citogenéticas moleculares resolutivas aplicadas em estudos populacionais no litoral e em ilhas oceânicas identificaram diferenciações locais e reconheceram uma nova espécie para o gênero Bathygobius, residente no Atol das Rocas e Arquipélago de Fernando de Noronha. As análises ainda possibilitaram a descrição de cromossomos sexuais XY nas duas espécies do gênero Gobionellus e a participação de elementos repetitivos na diferenciação deste sistema. Os dados aqui apresentados dão suporte ao alto grau de diversificação evolutiva da família, ampliam o conhecimento citogenético para o grupo, permitem identificar estruturações populacionais e respostas evolutivas das espécies às variações geográficas. Como modelo biológico a família Gobiidae representa um útil contraponto evolutivo em relação aos padrões genéticos vigentes às espécies de grande vagilidade.
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The correlation between the type 1 diabetes mellitus and oxidative stress have been described in several studies, however its underlying mechanisms are not fully elucidated. The present work aimed to evaluate the effects of four weeks of streptozootocin-induced (STZ) diabetes in the redox homeostasis of rat hepatocytes. Thus, the liver of male Wistar rats from control and diabetic groups were collected and the activity and expression of antioxidant enzymes, as well the main markers of oxidative stress and content of H2O2 in these tissues were measured. The diabetes induced the activity of superoxide dismutase (SOD) and the gene expression of its mitochondrial isoform, SOD2. However, the expression of SOD1, the cytoplasmic isoform, was reduced by this disease. The activity and expression of catalase (CAT), as well the expression of glutathione peroxidase 1 (GPX1) and peroxiredoxin 4 (PRX4) were drastically reduced in the hepatocytes of diabetics rats. Even with this debility in the peroxidases mRNA expression, the content of H2O2 was reduced in the liver of diabetics rats when compared to the control group. The diabetes caused an increase of lipid peroxidation and a decrease of protein thiol content, showing that this disease causes distinct oxidative effects in different cell biomolecules. Our results indicate that four week of diabetes induced by STZ is already enough to compromise the enzymatic antioxidant systems of the hepatocytes.
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Glucans are polysaccharides with different pharmacological and biological activities described. However, there are some reports about the activities of the glucan type α (alpha). In this context, a group of α-D-glucans called dextrans extracted from Leuconostoc mesenteroides bacteria, with molecular weights of 10 (D10), 40 (D40) and 147 (D147) kDa and their phosphorylated derivatives P10, P40 and P147, were evaluated as for their antioxidant, anticoagulant and immunomodulatory potential for the first time, in order to elucidate compounds with potent activities and low toxicity. Infrared spectroscopy analysis, monosaccharide composition and chemical dosages showed that these dextrans are the same polysaccharide, but with different molecular weights, besides confirming the success of phosphorylation. None presented with anticoagulant features. The reducing power test showed that D147 was twice as potent as other dextrans. On the other hand, all six samples showed similar activity (50%) when it came to scavenging the OH radical. To the superoxide ion scavenging, only D10 had a pronounced activity (50%). D40 was the single native dextran that presented with immunomodulatory features since it double stimulated the proliferation of murine macrophages (RAW 264.7) and double the release of nitric oxide by the cells, both in the absence and presence of lipopolysaccharides (LPS). In addition, D40 showed a greater scavenging activity (50%) for the hydrogen peroxide, which caused it to also be the more potent dextran when it came to inhibiting lipid peroxidation (70%). On other hand, P147 showed the highest iron and copper ion chelation activity (~85%). P10 proved be the most effective compound to macrophage proliferation. The results point toward dextrans with a 40 kDa weight as being ideal for antioxidant and immunomodulatory use, could be supplemented with phosphorylated derivatives. However, future studies with the D40 and other similarly dextrans are to confirm this hypothesis.
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Nos períodos críticos de plasticidade neural ocorre uma maior permissividade do sistema nervoso ao ambiente, por isto, a ação do estresse sobre o individuo e suas repercussões sobre áreas responsáveis pelo controle dos sistemas de resposta ao estresse e por funções cognitivas complexas vem recebendo bastante atenção. A utilização de modelos experimentais translacionais tem sido imprescindível na elucidação destes mecanismos e das patologias associadas. Diante disto, este trabalho investigou os efeitos do estresse social sobre parâmetros fisiológicos, comportamentais, cognitivos e sobre a neurogênese no córtex pré-frontal (CPF) durante um período crítico de plasticidade cerebral, a fase juvenil, em machos de Callithrix jacchus. Durante cinco meses, 5 animais foram acompanhados em suas famílias (GF) e 5 animais foram isolados socialmente por 4 meses (GI), após um mês em observação em ambiente familiar (fase basal- FB). Ao final do 5º mês foram aplicados 2 testes de memória de trabalho (MT) nos animais GF e GI. Em seguida, 3 animais de cada grupo foram sacrificados para análise do fator de neurogênese BDNF ( Brain Derived Neurotrophic Factor) por imunofluorescência no CPF (sub-regiões orbitofrontal e lateral). Os animais do GF não variaram significativamente o cortisol ao longo do estudo, enquanto o GI elevou o cortisol e comportamentos indicadores de ansiedade (CA) na primeira semana do isolamento. Em seguida, o GI apresentou uma redução no cortisol, nos CA, no peso corporal e um aumento de comportamentos estereotipados e da anedonia, alterações tipicamente depressivas em primatas não-humanos. Ao final, o GI apresentaram níveis de cortisol menores que em FB. Ambos os grupos apresentaram dificuldades em realizar e aprender as tarefas cognitivas e a presença de BDNF no córtex pré-frontal foi independente do grupo (GF ou GI), porém correlacionou-se com os níveis de cortisol presentes na ultima semana do estudo, e os animais com presença de BDNF no CPF lateral e orbitofrontal apresentaram maiores níveis de cortisol. Estes resultados contribuem no processo de validação do sagui como um bom modelo psiquiátrico translacional e aponta para possibilidade de estudos sobre transtornos depressivos na juventude e suas repercussões posteriores. Além disto, os resultados observados para as tarefas cognitivas levou-nos a fazer uma releitura dos protocolos utilizados em estudos de memoria de trabalho com animais adultos desta espécie, com a finalidade de aprimora-los facilitando a aprendizagem em animais juvenis, naives e em situações de estresse. Ademais, evidenciou-se pela primeira vez a relação do estresse, cortisol e níveis de BDNF, em animais juvenis desta espécie, com a fim de contribuir com sua utilização como modelo animal neurocognitivo.
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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.
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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.