Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-03-12T14:44:41Z No. of bitstreams: 1 JessicaNayaraDeCarvalhoLeite_DISSERT.pdf: 1653844 bytes, checksum: a1fa3b230b445d2b44c344d47909c125 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-03-14T20:07:28Z (GMT) No. of bitstreams: 1 JessicaNayaraDeCarvalhoLeite_DISSERT.pdf: 1653844 bytes, checksum: a1fa3b230b445d2b44c344d47909c125 (MD5) / Made available in DSpace on 2018-03-14T20:07:28Z (GMT). No. of bitstreams: 1 JessicaNayaraDeCarvalhoLeite_DISSERT.pdf: 1653844 bytes, checksum: a1fa3b230b445d2b44c344d47909c125 (MD5) Previous issue date: 2017-11-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Em regi?es mais secas, muitos reservat?rios chegam a volumes t?o baixos que deixam de ser suficientes para abastecimento, sendo assim interrompida a tomada d??gua. No semi?rido brasileiro ? recorrente o esgotamento h?drico em alguns reservat?rios, os quais permanecem secos por meses ou at? anos, o que representa um problema para o abastecimento e causa preju?zos socioecon?micos. Ap?s um evento de esgotamento h?drico, em termos de impactos na qualidade da ?gua, espera-se que haja melhorias ap?s a renova??o com novas ?guas: Menor biomassa algal, maior transpar?ncia da ?gua, menor turbidez e baixa concentra??o de nutrientes. O objetivo deste estudo foi analisar a qualidade da ?gua de um reservat?rio do semi?rido tropical ap?s esgotamento h?drico durante um evento de seca prolongada. O reservat?rio estudado foi Dourado, localizado semi?rido brasileiro. O trabalho foi realizado com tr?s per?odos distintos, determinados de acordo com o volume h?drico. Os per?odos foram marcados por chuvas abaixo da m?dia hist?rica anual, estando assim inseridos em um per?odo de estiagem prolongada. Foram analisadas as vari?veis transpar?ncia da ?gua, turbidez, condutividade el?trica, pH, f?sforo total, f?sforo reativo dissolvido e clorofila-a. Ap?s a renova??o das ?guas, a expressiva redu??o na clorofila-a, indicativa de biomassa algal, indica melhora na qualidade da ?gua em termos de eutrofiza??o, devido ? mudan?a de estado de trofia de eutr?fico para mesotr?fico. As vari?veis pH, condutividade el?trica e turbidez tamb?m sofreram redu??o ap?s a renova??o das ?guas. N?o houve redu??o ap?s o aporte de ?gua para as vari?veis f?sforo total e f?sforo reativo dissolvido em compara??o aos per?odos anteriores. / In dry regions, many reservoirs reach volumes so low that they are no longer sufficient for supply, interrupting the water intake. In the Brazilian semi-arid region, occasional drying is recurrent in some reservoirs, which remains dry for months or even years, representing a problem for the supply and causing socioeconomic issues. After an event of drying, in terms of impacts on water quality, it is expected that there will be improvements after reflooding: Less algal biomass, increased water transparency, decreased turbidity and low concentration of nutrients. The aim of this study was to analyze the water quality of a tropical semi-arid reservoir after drying during an extended drought event. The studied reservoir was Dourado, located in the Brazilian semi-arid. This study consists of the comparison of three distinct periods accordingly to the water volume. Those periods were marked by rainfall below the annual historical average, therefore being inserted in an extended drought period. The variables water transparency, turbidity, electrical conductivity, pH, total phosphorus, soluble reactive phosphorus and chlorophyll-a were analyzed. After the water renewal, a significant reduction in chlorophyll-a, indicative of algal biomass, indicates an improvement in water quality in terms of eutrophication, due to the change of the trophic state from eutrophic to mesotrophic. pH, electrical conductivity and turbidity variables also reduced after the reflooding, indicating an improvement in water quality. There was no reduction in total phosphorus and soluble reactive phosphorus after the reflooding in comparison to the previous periods.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-04-15T23:04:38Z No. of bitstreams: 1 MarianaRodriguesAmaralDaCosta_DISSERT.pdf: 2488995 bytes, checksum: c1bb8bd3c6d969c70744bfd049bfdd73 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-04-20T21:52:13Z (GMT) No. of bitstreams: 1 MarianaRodriguesAmaralDaCosta_DISSERT.pdf: 2488995 bytes, checksum: c1bb8bd3c6d969c70744bfd049bfdd73 (MD5) / Made available in DSpace on 2016-04-20T21:52:13Z (GMT). No. of bitstreams: 1 MarianaRodriguesAmaralDaCosta_DISSERT.pdf: 2488995 bytes, checksum: c1bb8bd3c6d969c70744bfd049bfdd73 (MD5) Previous issue date: 2014-03-20 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A eutrofiza??o artificial ? uma das grandes amea?as ? qualidade ambiental de ecossistemas aqu?ticos em todo o mundo. As expectativas dos cen?rios clim?ticos futuros para regi?es ?ridas e semi?ridas s?o per?odos de secas mais intensas e frequentes, aumentando ainda mais o risco de eutrofiza??o e de flora??es de cianobact?rias. Muitas t?cnicas de restaura??o de lagos eutrofizados foram propostas para reduzir as cargas de nutrientes e melhorar a qualidade da ?gua. Uma t?cnica bastante utilizada ? a biomanipula??o por remo??o de peixes que v?m se mostrando eficiente em lagos eutr?ficos de regi?es temperadas. Trabalha mos a hip?tese de que a remo??o de peixes bent?v oros bioturbadores reduz a biomassa total do fitopl?ncton e altera a composi??o dos grupos funcionais fitoplanct?nicos , refletindo na melhora d a qualidade da ?gua . Assim , este estudo teve como objetivo avaliar o impacto da biomanipula??o na din?mica e estr utura d os grupos funcionais fitoplanct?nicos e n a qualidade da ?gua. Aplicamos a t?cnica da biomanipula??o no lago artificial ESEC, regi?o semi?rida do nordeste brasileiro e analisamos as vari?veis f?sicas e qu?micas da ?gua e a din?mica dos grupos funcion ais fitoplanct?nicos, mensalmente durante o per?odo de novembro de 2012 a agosto de 2013. Com a remo??o dos peixes bioturbadores, observamos um aumento significativo na zona euf?tica, na riqueza de esp?cies fitoplanct?nicas e o recrutamento de grupos funci onais fitoplanct?nicos de algas verdes (grupos F e J) indicadoras de boa qualidade ambiental. Por?m, n?o observamos diferen?as significativas na concentra??o de f?sforo total e na biomassa e diversidade fitoplanct?nica. O efeito da seca severa na regi?o du rante o estudo foi evidente , proporcionando uma redu??o dr?stica no n?vel de ?gua que influenciou na disponibilidade de recursos e afetou a comunidade fitoplanct?nica antes da biomanipula??o . Para avaliar o efeito de uma seca severa sobre a din?mica dos gr upos funcionais fitoplanct?nicos e testar se per?odos de seca s?o favor?veis ? domin?ncia de cianobact?rias, estudamos dois lagos artificiais vizinhos (ESEC e Pocinhos) no semi?rido tropical durante maio de 2012 a fevereiro de 2013. Observamos uma diferenc ia??o temporal das vari?veis abi?ticas e do fitopl?ncton causada pela seca severa. Ambos os lagos apresentaram redu??o de 2 metros do n?vel da ?gua e aumento nos valores de condutividade, turbidez, nas concentra??es de nutrientes e redu??o da transpar?ncia da ?gua, durante o per?odo da seca severa. Por?m, a comunidade fitoplanct?nica respondeu diferente ?s condi??es ambientais dependendo da profundidade de cada lago. O mais profundo (Pocinhos) aumentou a biomassa total do fitopl?ncton e apresentou domin?nci a do grupo funcional de cianobact?rias heterocitadas formadoras de flora??o (grupo S N ) e o lago menos profundo (ESEC) reduziu a biomassa total e apresentou domin?ncia de grupos funcionais de algas flageladas com metabolismo mixotr?fico (grupos W 1 e W 2 ) . Su marizando, o conhecimento sobre os efeitos da biomanipula??o por remo??o de peixes bent?voros bioturbadores em um lago raso no semi?rido tropical ainda ? incipiente e o estudo possui limita??es devido ao evento de seca prolongada durante o per?odo de estud o . Sendo assim, ? necess?rio um monitoramento em longo prazo para investigar os reais efeitos da biomanipula??o no funcionamento do ecossistema. Al?m disso, per?odos de seca podem ter efeitos antag?nicos (aumento ou redu??o) na biomassa total , bem como na composi??o dos grupos funcionais fitoplanct?nicos, que nem sempre levar? ? domin?ncia de cianobact?rias. / 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.