Navegando por Assunto "Fitoplâncton"

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Acesso aberto (Open Access)
Composição do microfitoplâncton do Rio Arienga (Barcarena-Pará)
(Universidade Federal do Pará, 2012) SENA, Bethânia Alves; NAKAYAMA, Luiza; http://lattes.cnpq.br/3771896759209007; ROCHA, Rossineide Martins da; http://lattes.cnpq.br/4371300451793081
This work aims to describe the composition, relative abundance and frequency of occurrence of microphytoplankton in the Arienga River, determined from the analysis of ten samples collected in the rainy and dry seasons (May and September 2009 respectively), during five geo-referenced stations, using a conical plankton net with a mesh size of 20μm. In the period studied, the rainfall showed an atypical behavior, compared to the average of the last ten years for the region of Barcarena, as pH and temperature did not undergone great changes. A total of 128 species were identified, belonging to divisions: Dinophyta (0.78%), Chrysophyta (0.78%), Cyanobacterium (12.50%), Chlorophyta (26.56%), and Bacillariophyta (59.38%). Genres Microcystis Kützing ex Lemmermann, Staurastrum Meyen ex Ralfs, Ulothrix Kützing, Eudorina Ehrenberg ex Ralfs, Volvox Linnaeus, Hydrodictyon Roth, Pediastrum Meyen, Aulacoseira Thwaites, Coscinodiscus Kützing, Pinnularia Ehrenberg, Polymyxus Bailey, Rhizosolenia Brightwell, Actinoptychus Ehrenberg, Thalassiosira Ehrenberg, Tabellaria Ehrenberg ex Kützing, Fragilaria Lyngbye e Navicula Bory de St. Vincent had 100% of representativeness at in both fenods. It was possible to confirm two large groups, suggesting that the rainfall regime was the main controller factor of phytoplankton composition and spatial variation of species along the Arienga River. The phytoplankton diversity was considered characteristic of the Amazon region; therefore, it is considered that the human action did not affect the phytoplankton community of the Arienga River to date.
Acesso aberto (Open Access)
Comunidade fitoplanctônica de igarapés da volta grande do Xingu(Pará, Brasil)
(Universidade Federal do Pará, 2025-02-28) FERREIRA, Leydimara da Rocha Alves; NUNES, Daniela Santana; http://lattes.cnpq.br/6036935515134179; https://orcid.org/0000-0003-1268-4000; SILVA, Karina Dias da; http://lattes.cnpq.br/5039199140680191; https://orcid.org/0009-0000-7302-3957; PEREIRA, Tatiana da Silva; COSTA, Ully Mattilde Pozzobom; LOPES, Vanessa Guimarães; PETSCH, Danielle Katharine; http://lattes.cnpq.br/4005250095700054; http://lattes.cnpq.br/2126502797802986; http://lattes.cnpq.br/4940526473651633; https://orcid.org/0000-0002-8724-3464; https://orcid.org/0000-0001-7109-4911
The Amazon rainforest streams play a crucial role in the diversity of aquatic ecosystems, providing ecological balance to hydrographic microbasins. Phytoplankton, the base of the food web and an environmental bioindicator, responds to physicochemical factors and habitat structure. Considering this, this study aimed to conduct a checklist of the phytoplankton community and analyze the influence of environmental variables (water physicochemical parameters and the Habitat Integrity Index - HII) on the richness and biovolume of phytoplankton in streams of the Volta Grande do Xingu, Pará, Brazil. A total of 295 taxa were identified, with emphasis on Zygnematophyceae, Bacillariophyceae, and Cyanophyceae. Among the diatoms (Bacillariophyceae), we recorded the occurrence of Terpsinoë musica Ehrenberg, a species predominantly found in brackish waters, although also present in freshwater. The identification of the genera Microcystis Lemmermann and Dolichospermum P. Wacklin, cyanobacteria that produce cyanotoxins, reinforces the importance of environmental monitoring. Quantitative analysis revealed 79 taxa, with Bacillariophyceae being the richest and Zygnematophyceae contributing the most to biovolume. Depth, width, and pH significantly influenced the phytoplankton community. We observed that greater stream depths are associated with a larger phytoplankton biovolume, while stream width showed an inverse effect. Additionally, pH exerted a significant effect on the biovolume of the species, corroborating the hypothesis that this parameter is a determining factor for phytoplankton. The species Desmidium quadratum Nordstedt and Mougeotia sp. showed higher biovolume in streams with more acidic waters, while Hariotina reticulata P. A. Dangeard showed a preference for less acidic environments. Therefore, the monitoring of water physicochemical variables and habitat structure is essential to understand the dynamics of phytoplankton, providing information to help maintain the biodiversity and functionality of these aquatic ecosystems.
Acesso aberto (Open Access)
Dinâmica da comunidade microfitoplanctônica relacionada com os parâmetros físico-químicos do estuário do rio Guajará-Mirim (Vigia - PA)
(Universidade Federal do Pará, 2009-03-31) CARDOSO, Fábio Ferreira; PAIVA, Rosildo Santos; http://lattes.cnpq.br/0510818763187669
Estuaries are rich nutrients environments, favoring reproduction and development of several species. Phytoplankton represents a considerable portion of primary production in these environments and, together with other factors, regulates the biological productivity levels. This study aimed to know the microphytoplankton dynamics and its correlation with environmental factors in the Guajará-mirim river’s estuary in the city of Vigia-PA, an important fishery center of the Pará state. Every two months were made collections of the phytoplankton and take measurements of physicochemical parameters in four collection stations along the estuary, in ebb and flood tide periods. Were determined the specific composition and density of microphytoplankton (org.L-1) and analysis of frequency of occurrence, diversity and evenness, clustering and principal components. Seasonally, was noted, mainly during the ebb tide, a considerable physicochemical variation, strongly related with hydrological cycle in the region. Seventy-eight taxa were recorded belonging to the Bacillariophyta (65), Chlorophyta (6), Cyanophyta (3), Dinophyta (3) and Ochrophyta (1) divisions. Bacillariophyta was dominant in species number, frequency of occurrence and density (99.89%). The monthly average densities of the microphytoplankton ranged from 9.999 (July) to 535.411 org L-1 (January). In January happened a bloom of Skeletonema costatum (max = 1.996.613 org.L-1). The microphytoplankton community was characterized as the median diversity (annual general mean = 2.40). The seasonal variation of physicochemical parameters and species density was the predominant factor to the grouping of samples, and it formed two major groups, the first composed by samples of the rainy season and the second by samples of the drought period. The principal components analysis showed that, despite the physicochemical parameters have low spatial and seasonal variability, the variation in rate of rainfall, total dissolved solids content and salinity was decisive in the variation of density of most species and also promoted a slight increase in diversity in the drought period.
Acesso aberto (Open Access)
Microfitoplâncton de águas costeiras amazônicas: Ilha Canela (Bragança, PA, Brasil)
(Sociedade Botânica do Brasil, 2008-09) SOUSA, Eliane Brabo de; COSTA, Vanessa Bandeira da; PEREIRA, Luci Cajueiro Carneiro; COSTA, Rauquírio André Albuquerque Marinho da
Seasonal and nyctemeral variations of the microphytoplankton were studied at a fixed station (00º46'37.2''S-046º43'24.5''W) on Canela Island (North Brazil) in September and December/2004 (dry season) and in March and June/2005 (rainy season). Samples for qualitative phytoplankton studies were obtained by filtering 400 L of surface water in the surf zone of the island through plankton nets (65 μm mesh size). Field work was carried out during spring tides and samples were collected every 3 hours during a 24-hour period. The collected material was fixed in neutral formaldehyde at 4%. Simultaneously, salinity of the water surface was also measured. Salinity showed significant variation throughout the study period, ranging from 26.1 (June/2005) to 39.0 (December/2004), characterizing the environment as euhaline-polyhaline. A total of 130 taxa were identified, belonging to Cyanophyta (two taxa), Bacillariophyta (115 taxa) and Dinophyta (13 taxa). Diatoms were the dominant group of microphytoplankton at Canela Islan
Acesso aberto (Open Access)
Structure and temporal variation of the phytoplankton of a macrotidal beach from the Amazon coastal zone
(Universidade Federal do Pará, 2016-09) QUEIROZ, Jislene Brito Matos; OLIVEIRA, Suellen Mara Oliveira de; PEREIRA, Luci Cajueiro Carneiro; COSTA, Rauquírio André Albuquerque Marinho da
The present study aimed to analyze the structure and the temporal variation of the phytoplankton of Ajuruteua beach (Bragança, Pará) and to investigate the influence of environmental variables on the dynamics of this community to provide a basis about the trophic state of this environment. Biological, hydrological and hydrodynamic samplings were performed during a nyctemeral cycle in the months of November/08, March/09, June/09 and September/09. We identified 110 taxa, which were distributed among the diatoms (87.3%), dinoflagellates (11.8%) and cyanobacteria (0.9%), with the predominance of neritic species, followed by the tychoplankton species. Chlorophyll-a concentrations were the highest during the rainy period (24.5 mg m-3), whereas total phytoplankton density was higher in the dry period (1,255 x 103 cell L-1). However, phytoflagellates density was significantly higher during the rainy period. Cluster Analysis revealed the formation of four groups, which were influenced by the monthly differences in the environmental variables. The Principal Component Analysis indicated salinity and chlorophyll-a as the main variables that explained the components. Spearman correlation analysis supported the influence of these variables on the local phytoplankton community. Overall, the results obtained suggest that rainfall and strong local hydrodynamics play an important role in the dynamic of the phytoplankton of Ajuruteua beach, by influencing both environmental and biological variables.
Acesso aberto (Open Access)
Variação nictemeral do microfitoplâncton em um estuário do nordeste paraense, Brasil
(Universidade Federal do Pará, 2010-06-18) COSTA, Brenda Oliveira da; PAIVA, Rosildo Santos; http://lattes.cnpq.br/0510818763187669
This study’s object was to get to know micro phytoplankton’s diversity, as its nyctemeral variation related to environmental factors on Curuçá river (Curuçá, PA – Brazil). Twelve phytoplankton samples were collected in 3 collecting spots next to a Littopnaeus vannamei sea shrimp farm in a 24 hour time, during spring tides on the 14th and 15th of august 2004 and on the 24th and 25th of January 2005. It was determined its specific composition and phytoplankton density (org.L-1), analyzed its occurrence rate, diversity and evenness, grouping and main components. Physicochemical parameters did not show any significant variability between the collecting months, though it was observed an important rainfall influence on the salinity, filing the bottom values in jan/05 and the top ones in aug/04. There were 170 registered taxa that belong to the Baccilariophyta (149), Dinophyta (16), Chlorophyta (3) and Cyanobacteria (2) divisions. Bacillariophyta had the higher number of species shown, higher occurrence and density (97.59%). A few showed high abundance rates. During August the phytoplankton community is dominated by Bacteriastrum hyalinum, Bellerochea horologicalis, Chaetoceros curvisetus, Dimerograma dubium, Dytilium brigtwelli, Pseudo-nitzschia seriata and Skeletonema costatum. In January predominated Chaetoceros pseudocrinitus, Chaetoceros curvisetus and Skeletonema costatum. Neritic marine planktonic species, oceanic marine planktonic, neritic-oceanic marine planktonic predominated the samples. Specific diversity oscillated from 0.7591 bits.org-1 to 1.3314 bits. org-1 generally characterized by a low to very low diversity, showing a poorly diversified structure. Phisicochemical parameters and density among species was the main factor to determinate sample grouping in two big groups: the first one with august samples and the second one with January samples. Its component analysis showed that despite its low physicochemical variation amongst the collecting months, the rainfall and salinity variations were really important on the species density, causing an increase on phytoplankton density in January.