2019-08-072019-08-072010-08SOUZA, Elton Carlos Furtado de. O fitoplâncton como ferramenta ecológica no estuário Guajarino, Belém (PA). Orientadora: Lucinice Ferreira Belúcio. 2010. 54 f. Trabalho de Curso (Bacharelado em Oceanografia) – Faculdade de Oceanografia, Instituto de Geociências, Universidade Federal do Pará, Belém, 2010. Disponível em: http://bdm.ufpa.br/jspui/handle/prefix/1599. Acesso em:.http://bdm.ufpa.br/jspui/handle/prefix/1599The Guajará Bay, a component of the Marajó Bay (located at the Amazon River mouth), is an important coastal ecosystem of Pará State (Brazil). It is formed by the confluence of Pará, Guamá and Acará rivers, and has slowly received human domestic, industrial and agro-industry effluents. That system, dominated by mesotides is dynamic and unique, due to the large volume of freshwater brought by the river. Microalgae include aquatic unicellular organisms, autotrophs that occur in the plankton or adhered to various substrates, which may be indicators of hydrological conditions and possible environmental modifications. This paper presents a characterization Guajará Bay, based on phytoplankton composition, corresponding to an annual cycle of sampling. To achieve this, we made a reasearch on composition, seasonal and spatial distribution, as well as their ecological tolerances to salinity. Samplings were taken at six fixed stations along the estuary from March to December 2005 (Project "Diagnosis of environmental quality in Guajará Bay, Belém-PA /CT-HIDRO/CNPq). The biological material collected with van Dorn bottle, was fixed with formaldehyde and analyzed by the Uthermöhl technique to determine floristic composition, richness and density. Climatic parameters (rainfall) and hydrological (turbidity, temperature, conductivity and pH) were also analyzed. It was observed that the temperature does not constitute a limiting factor for phytoplankton due to evident regional thermal stability. The low turbidity of the water may be cited as a reason for the low density of dinoflagellates. The pH proved to be acid to slightly acid, the lower values occurred in the innermost stations and in months of highest rainfall. The conductivity had a similar behavior. Both were determinants of phytoplankton species. 83 taxa were identified under Bacillariophyta, Chlorophyta, Cyanophyta and Dinophyta divisions. Diatoms were the dominant group. Aulacoseira granulata, Rhizosolenia setigera, Achtinoptychus splendens, Coscinodiscus oculus-iridis, Polymyxus coronalis e Triceratium favus were the most abundant and constant species. Both groups and species were good indicators of environmental conditions and changes occurring on the site. The occurrences of algae along the flows of fresh water as Maguari River and the association of cyanobacteria with the seasons enriched by nutrients or organic matter can be highlighted. The density was highest in periods of low rainfall (September to June). The number of species varied with the density. The planktonic species showed subtle dominance in relation to benthic, the last are favored by periods of turbulent flow of the bay. There was no clear spatial gradient in the species distribution in relation to salinity. We identified oligo-mesohalobian; mesohalobian; meso-euhalobians and euryhaline individuals. Thus, from the standpoint of phycology, this environment has estuarine characteristics and can be classified as mesohalobian. The precipitation and circulation patterns, and especially the entrance of the saline tide, which causes changes in physical and chemical properties of these waters and in the concentration of suspended particles, conferring specific characteristics to the system. The phytoplankton of Guajará Bay proved to be a good bioindicator of water quality and its trophic state, and the estuarine system.Acesso AbertoFitoplânctonBioindicadoresBaía do Guajará - PACNPQ::CIENCIAS EXATAS E DA TERRA::OCEANOGRAFIA::OCEANOGRAFIA BIOLOGICA::INTERACAO ENTRE OS ORGANISMOS MARINHOS E OS PARAMETROS AMBIENTAISTrabalho de Curso - Graduação - Monografia