RESUMO: Este trabalho foi realizado no Parque Estadual do Charapucu, sendo pioneiro para o arquipélago do Marajó e teve como objetivo conhecer a diversidade do fitoplâncton correlacionada com os fatores físico-químicos da água dos rios que margeiam e cortam este Parque. Para o estudo das variáveis físico-químicas, quali-quantitativo do fitoplâncton e para determinação da clorofila-a foram coletadas amostras nos meses de maio e outubro de 2013, representando os períodos de maior (mês chuvoso) e menor (mês seco) precipitação pluviométrica, respectivamente. Foram identificadas 164 espécies com o predomínio da classe Zygnematophyceae em riqueza. Os táxons Aulacoseira granulata, Aulacoseira spp., Coscinodiscus sp., Cryptomonas ovata, Eudorina elegans, Eunotia spp., Eunotia pectinalis, Mougeotia sp., Paralia sulcata, Pseudanabaena spp., Pseudanabaena mucicola, Surirella spp., Thalassionema nitzshioides e Ulotrix spp. se destacaram em termos de freqüência e abundância. A maioria das variáveis físico-químicas e biológicas apresentou variação ao longo do estudo sendo reguladas por flutuações de precipitação pluviométrica e pelas características típicas das águas brancas e pretas. A densidade foi mais elevada durante o período seco em águas brancas e a clorofila-a variou apenas sazonalmente, sendo os maiores valores registrados no mês seco. As correlações mostraram que a dinâmica da comunidade fitoplanctônica foi influenciada principalmente pelas variáveis temperatura, pH, condutividade elétrica, sólidos totais dissolvidos, potencial de oxi-redução, nitrato, fósforo total e clorofila-a. Palavras-chave: Diversidade,ABSTRACT: This work was conducted in the Charapucu State Park, a pioneer to the archipelago of Marajó and aimed to understand the diversity of phytoplankton correlated with physical-chemical factors of the water of the rivers that border and cut this park. To study the physical and chemical variables, qualitative and quantitative phytoplankton and determination of chlorophyll-a samples were collected in May and October 2013, representing the periods of highest (rainy month) and lower (dry month) rainfall. 164 species were identified, with the predominance of Zygnematophyceae class in ofrichness. The taxa Aulacoseira granulata, Aulacoseira spp., Coscinodiscus sp., Cryptomonas ovata, Eudorina elegans, Eunotia spp., Eunotia pectinalis, Mougeotia sp., Paralia sulcata, Pseudanabaena spp. Pseudanabaena mucicola, Surirella spp. Thalassionema nitzshioides and Ulotrix spp. were the most frequent and abundant. Most physical and biological variables showed variation throughout the study period being regulated by rainfall fluctuations and the typical characteristics of white and black waters. The density was significantly higher during the dry season and in white waters. The chlorophyll-a varied seasonally and the highest values were recorded in the dry months. The correlations showed that the phytoplankton community was mainly influenced by the variables temperature, pH, electrical conductivity, total dissolved solids, redo...

Composição, riqueza e índices ecológicos do fitoplâncton do lago Bolonha (Belém, Pará) Composition, richness and ecological index of phytoplankton of lake Bolonha (Belém, Pará

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The Bolonha reservoir (Belém, Pará) is eutrophicated and dominated by aquatic macrophytes that are often removed and deposited on the banks of the environment, suffering decomposition. Some microorganisms that live associated with macrophytes return to the environment through leaching, among them cyanobacteria. The objective of the study was to evaluate the growth of the species Anagnostidinema amphibium LBABL-2, in microcosm, by three experiments under different environmental conditions and nutritional stress simulating its growth during the cleaning process of the Bolonha reservoir. Growth was determined by optical density and chlorophyll-a. The species formed a slime mat composed of tangles of green, not capitate, not constricted, not attenuated, slightly curved trichomes 600 μm long, composed of cells that measured, on average, 4.1 μm -2.2 μm in length and width, respectively, and showed cyanophycin granules in the cell wall between two cells. The absence of nutrients was the main stressor of Anagnostidinema amphibium LBABL-2, which showed higher growth in the roots of macrophytes immersed in the reservoir, but low growth in the absence of nutrients. The study will support actions for the management of aquatic macrophytes in the reservoir with emphasis on stressors and growth promoters of cyanobacteria associated with their roots.

Cyanobacteria are photosynthetic prokaryotic organisms that in aquatic environments can compose the phytoplankton and phytobenthos, being important in the primary  production of these ecosystems. The objective of this work was to identify the main morphological variations of the cells, filaments and thallus of the cyanobacteria Nostoc sp. LBALBR-2 submitted to ultraviolet radiation (UV-C) in microcosm systems. The cyanobacteria Nostoc sp. was subjected to four treatments: 1- control treatment in nutrient medium; 2- treatment in nutrient medium with exposure to UV-C radiation; 3- control treatment in medium without nutrients and 4- treatment in medium without nutrients with exposure to UV-C radiation. Optical density and chlorophyll-a analyses were performed to determine the growth of Nostoc populations and microscopic analyses to characterize the morphological development of the species. Lack of nutrients generated short trichomes with terminal heterocytes, scattered solitary akinetes and appearance of hormogonia. On nutrient medium the trichomes of Nostoc sp. showed predominantly the vegetative serial form. Cultures exposed to UV-C produced anomalous cells, thick mucilage, fragmented trichomes and hormogonia. It is concluded that Nostoc sp. LBALBR-2 grew well under eutrophication conditions and although it showed cell deformation it was resistant to UV-C radiation.

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Elaborado por Maurício Amormino Júnior-CRB6/2422 O conteúdo dos artigos e seus dados em sua forma, correção e confiabilidade são de responsabilidade exclusiva dos autores. 2019 Permitido o download da obra e o compartilhamento desde que sejam atribuídos créditos aos autores, mas sem a possibilidade de alterá-la de nenhuma forma ou utilizá-la para fins comerciais.