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Previous issue date: 2010-06-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The Cruzeta impoundment, situated in the city of Cruzeta, hinterland of the state of the
Rio Grande do Norte state has significant importance to the municipality as it represents the
only source of supplying water to the region. It was hypothesized that the regional
consequence of the global warming and the warming of surface water could substantially
contribute the significant growth of the aquatic macrophytes in the years 2008-2009. The
growth of these vegetation believed to be improved the degree of water transparency and as a
consequence of the improved growth of phytoplankton species and chlorophyll biomass. At
the same time the aquatic macrophyte could interact and compete potentially for the dissolved
inorganic nutrients resources and the phytoplankton community. This study presents a
comparison of years 2004-2005 when it did not have the expressive presence of the aquatic
macrophyte community or restricted to the littoral region. In contrast, the years 2008-2009
showed a significant growth of the aquatic macrophyte in the Cruzeta/RN impoundments. The
present study is an attempt to elucidate the significant presence of the aquatic macrophyte,
Eichhornia crassipes, Ceratophyllum submersum, Nymphea sp and Pistia sp, and its
interference on the ecology of phytoplankton. The samplings had been carried out from
September of 2008 to April of 2009 and consistently between 10:00 h and 12:00 h with the
aid of Van Dorn bottle and the plankton net of mesh size 20 Qm. The collections were made
in three depths ie., surface, mid-column and bottom. The Physical-Chemical parameters such
as pH, temperature, electrical conductivity and dissolved oxygen had been analyzed in situ.
The samples for analysis of nutrients and chlorophyll were kept under refrigeration for
posterior analysis in the laboratory. Phytoplankton samples were preserved in Lugol-iodine
and kept for sedimentation for quali-quantitative analysis of phytoplankton. Enumeration of
cells, colonies and filaments was done with the aid of Sedgwick-Rafter counting chamber and
expressed as numbers/ml. Chlorophyll a was analyzed as a functional component of
phytoplankton biomass and extracted with cold 90% acetone. The results indicate that the
chlorophyll concentration varied between 5,65-8,08 Qg.L-1 for the dry period and 5,09-6,23
Qg.L-1 for the rainy period and showed considerable reduction when compared to the values
to the 2004-2005 study period. The temperature was always presented higher in relation to the
2004-2005 study. Phytoplankton species showed a relative abundance of the Cyanophyceae
for both the period of dry and rainy. The predominance species are filamentous Leptolymbya
geophila Borzi (Planctolyngbya sp), Anabaena plankct?nica Brunnthaler, Oscillat?ria limosa
Ag. and Cylindrospermopsis raciborskii (Wolosz). The concentration of the nutrients such as
nitrate and orto-phosfato had always presented higher values during the rainy period and the
ammoniacal nitrogen retained moderate values in the dry period and a slight increase in rainy
season. The main conclusions are the reduction of the concentration of chlorophyll, diversity
of phytoplankton, and the increase in temperature and transparency of the water during the
period of the study / O a?ude Cruzeta, situado no munic?pio de Cruzeta do estado do Rio Grande do Norte,
tem import?ncia significativa, pois representa a ?nica fonte de abastecimento de ?gua para
este munic?pio. Nos anos de 2008-2009 como consequ?ncia regional do aquecimento global
houve crescimento significativo das macr?fitas aqu?ticas, estas por sua vez, importantes em
ecossistemas aqu?ticos rasos por estabilizar o grau da transpar?ncia da ?gua, aumentando
assim a penetra??o de luz e consequente crescimento fitoplanct?nico. Ao mesmo tempo as
macr?fitas aqu?ticas tamb?m competem potencialmente com a comunidade fitoplanct?nica
por recursos como os nutrientes inorg?nicos. Este estudo apresenta uma compara??o entre os
anos de 2004-2005 durante qual n?o houve a presen?a da comunidade de macr?f?tas aqu?ticas
ou foram apenas restringidas nas margens e nos anos 2008-2009 em que houve um
crescimento significativo das macr?fitas aqu?ticas no a?ude de Cruzeta, RN. O trabalho
elucida a presen?a significativa das macr?fitas aqu?ticas, Eichhornia crassipes,
Cerathophyllum submersum, Nymphea sp e Pistia sp, e sua interfer?ncia na estrutura do
fitopl?ncton. As coletas foram realizadas entre agosto de 2008 at? o julho de 2009 entre as
10:00 e 12:00 h da manh? com o auxilio de garrafa de Van Dorn e rede de pl?ncton de malha
de 20 Qm, em tr?s profundidades, superf?cie, meio e fundo. Os par?metros f?sico-qu?micos
foram analisados in situ. As amostras para an?lise de nutrientes e clorofila a foram mantidas
sob refrigera??o para an?lise. Para an?lise quali-quntitativa do fitoplancton foi ultilizada a
c?mara de Sedgwick-Rafter. Os resultados indicam que houve redu??o nos valores da
clorofila a em rela??o ao per?odo de 2004-2005, no qual as m?dias variaram entre 5,65-8,08
QgL-1 para o per?odo de estiagem e 5,09-6,23 para o per?odo chuvoso. Enquanto que no
per?odo de 2008-2009 foi verificado 3,98-5,65 QgL-1 da clorofila a para o per?odo de estiagem
e 3,56-4,36 QgL-1 para o per?odo chuvoso. A temperatura apresentou-se sempre mais elevada
em rela??o ao estudo de 2004-2005. No presente trabalho, a classe que apresentou maior
abund?ncia relativa para ambos os per?odos foi a Cyanophyceae, representadas com destaque
as esp?cies Leptolymbya geophila Borzy (= Planctonelymbia sp), Anabaena plankct?nica
Brunnthaler e Oscillat?ria limosa Ag. e Cylindrospermopsis raciborskii (Wolosz). Ocorreu
redu??o na concentra??o de clorofila a e diversidade do fitopl?ncton, aumento da
transpar?ncia e aumento da temperatura da ?gua, durante o per?odo em estudo, estes fatores
podem ter sido ocasionados pela elevada biomassa de macr?fitas aqu?ticas quando comparada
ao per?odo de 2004-2005 em que houve uma baixa biomassa de macr?fitas, neste ecossistema
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/13065 |
| Date | 26 June 2010 |
| Creators | Oliveira, Ranielly Karen de |
| Contributors | CPF:20016581415, http://lattes.cnpq.br/1365437036105422, Passavante, Jos? Zanon de Oliveira, CPF:00614874491, http://lattes.cnpq.br/7147339394595199, Canan, Bhaskara, CPF:15574172453, http://lattes.cnpq.br/6110001233943643, Chellappa, Sathyabama, Chellappa, Naithirithi Tiruvenkatachary |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Ci?ncias Biol?gicas, UFRN, BR, Biodiversidade; Biologia Estrutural e Funcional. |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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