ABSTRACT. Spatial-temporal variation of Rotifera in an eutrophic reservoir in southern Brazil. We analyzed the spatial and temporal variation of rotifers in a small, shallow and eutrophic reservoir, with intense Cyanobacteria blooms, in seven sampling stations during 17 months (March/2002 to July/2003. Fifty-two taxa were identified, comprising 16 families. Brachionidae, Conochilidae, Synchaetidae, Lecanidae, Collothecidae, Trichocercidae, and Gastropodidae were the most commonly found. Collotheca sp. was abundant in the winter (dry period), while numbers of Conochilus coenobasis and Keratella cochlearis were low. The abundance of Brachionus mirus var. reductus, Filinia longiseta and Keratella lenzi peaked in the summer (rainy season), while for Kellicottia bostonensis, Ploesoma truncatum, Polyarthra remata, Polyarthra vulgaris and Ptygura sp., abundance was highest in the winter, mainly associated with atypical rainfall. Significant differences in the number of taxa and abundance of rotifers were observed during the sampling period. The canonical correspondence analysis explained 46% of the relationship between rotifer abundance and environmental variables, positively correlated with rainfall, nitrite, water temperature, organic nitrogen, nitrate and air temperature. Variations in rotifer abundance were observed a month after changes in the phytoplankton community. Taxa, such as Filinia longiseta, Keratella lenzi and Keratella cochlearis, showed a temporal variation similar to that of other eutrophic reservoirs, while the heterogeneous distribution pattern observed in most taxa could be due to the hydrodynamics of the recently built reservoir and the adverse climatic conditions. KEYWORDS.Water supply, eutrophication, Cyanobacteria. RESUMO.A variação espacial e temporal de rotíferos foi analisada em um reservatório pequeno, raso e eutrófico, com intensas florações de algas Cyanobacteria, em sete pontos de amostragem durante 17 meses (março/2002 a julho/2003). Foram identificados 52 táxons em 16 famílias, sendo Brachionidade, Conochilidae, Synchaetidae, Lecanidae, Collothecidae, Trichocercidae e Gastropodidae as mais frequentes. Collotheca sp. foi abundante no inverno (período seco), enquanto Conochilus coenobasis Skorikov, 1914 e Keratella cochlearis Gosse, 1851 apresentaram baixas abundâncias. Brachionus mirus var. reductus (Koste, 1972), Filinia longiseta (Ehrenberg, 1834) e Keratella lenzi (Hauer, 1953) apresentaram picos de abundância no verão (período chuvoso), e Kellicottia bostonensis (Rousselet, 1908), Ploesoma truncatum (Levander, 1894), Polyarthra remata (Skorikov, 1896), Polyarthra vulgaris Carlin, 1943 e Ptygura sp. no inverno, entretanto, relacionados a chuvas atípicas. Diferenças significativas do número de táxons e da abundância total dos rotíferos ocorreram entre os meses amostrados. A análise de correspondência canônica explicou 46% da relação da abundância dos rotíferos e variáveis ambientais, correlacionados com a pluviosidade, nitrito, temperatura da água, nitrogênio orgânico, nitrato e temp...
The aim of this study was to identify patterns of vertical distribution of planktonic cladocerean populations throughout the diel cycle, during the low and high water periods, and its ecological implications for a black water Amazonian lake. Tupé Lake is a black water lake located near the Brazilian city of Manaus. A channel links the lake with the Negro River and its flood pulse. This study was performed in a low-water period (November 2005) and in a high-water period (June 2006). Samples were taken on a 24-hour cycle, every 4 hours and at each meter of the water column, using a Schindler-Patalas trap equipped with a 55µm size mesh. A total of 16 species were registered during the low water period, wherein Bosminopsis deitersi, Moina minuta, and Ceriodaphnia cornuta were the most abundant species. B. deitersi migrated to the bottom during the afternoon, while M. minuta, Moina reticulata, and Holopedium amazonicum remained at the bottom for the entire diel cycle. During the high-water period, a total of 18 species were observed, and B. deitersi, C. cornuta, and Diaphanosoma polyspina were the most abundant species. During both sampling periods, no pattern was detected for C. cornuta. Generally, vertical patterns of distribution were less evident in the high water period, due to the mixing of the lake.
Nesse trabalho foram listadas e caracterizadas as espécies zooplanctônicas coletadas em cinco pontos no rio Itajaí-Acú, a jusante da cidade de Blumenau, Santa Catarina, no mês de julho de 2003. Foram identificadas 23 espécies de Rotifera, 22 de Cladocera e seis de Copepoda. Espacialmente, os pontos com fluxo mais lêntico e fundo arenoso-lodoso registraram maior número de espécies. Foram observadas maior riqueza e densidade de Rotifera, organismos esses considerados cosmopolitas e com um amplo espectro alimentar. Duas famílias de Cladocera, Bosminidae e Chydoridae apresentaram grande diversidade e densidade. A primeira, geralmente herbívora, foi registrada nos pontos com características mais lênticas, e a segunda é tipicamente bentônica, representada por várias espécies em todos os pontos. Copepoda registrou baixa densidade por ser um ambiente lótico, com o domínio das formas larvais (nauplio e copepodito) e maior número de espécies nos pontos mais lênticos. No presente estudo, o rio encontravase em intenso período de estiagem, podendo ser esse o fator da baixa diversidade em geral observada em todos os pontos. Todas as espécies registradas são comuns na região tropical.
ResumoO lago artificial do Parque Passeio Público tem sido submetido a grandes descargas de nutrientes, que associado à baixa profundidade e ao longo tempo de residência da água, contribuiu para a ocorrência de florações de fitoplâncton. O principal objetivo deste estudo foi analisar a variabilidade sazonal da estrutura das assembléias microfitoplanctônicas (composição e dominância) num lago urbano de Curitiba (PR). Os dados foram obtidos mensalmente, entre agosto/2002 a julho/2003, em quatro pontos de amostragem. O número total de táxons identificados foi vinte e nove. Houve predominância de Chlorococcaceae (17 taxa), seguido de Cyanophyceae (6 taxa) e Coscinodiscophyceae (4 taxa). As espécies com maior ocorrência, em ordem decrescente, foram: Scenedesmus quadricauda, Golenkinia radiata, Microcystis aeruginosa, Pediastrum duplex var. boryanum, Kirchneriella lunaris, Staurastrum paradoxum, Micractinium pusillum, Aulacoseira granulata, Lagerheimia ciliata e Sphaerocystis schroeteri. O estudo conclui que a comunidade fitoplanctônica responde às variações ambientais no lago, espacial e temporalmente. Palavras-chave: Microfitoplâncton; Lago urbano; Estado do Paraná. 4 4 AbstractThe artificial lake of "Passeio Público Park" has been submitted to a great discharge of nutrients. This fact associate with the low dept and the high time of water residence contributed for phytoplankton blooms. The main aim of this study was to analyze the seasonal variability of the structure of microphytoplankton assemblages (composition and dominance) in an urban lake of Curitiba (PR). The data were obtained monthly, among September/2002 to July/2003, in four sampling points. The total number of taxa identified was twenty nine. There was predominance of Chlorococcaceae (17 taxa), followed by Cyanophyceae (6 taxa) and Coscinodiscophyceae (4 taxa). The species with highest occurrence, in decreasing order, were: Scenedesmus quadricauda, Golenkinia radiata, Microcystis aeruginosa, Pediastrum duplex var. boryanum, Kirchneriella lunaris, Staurastrum paradoxum, Micractinium pusillum, Aulacoseira granulate, Lagerheimia ciliata and Sphaerocystis schroeteri. The study conclude that phytoplankton assemblages respond to the environmental changes in the lake, spatial and temporally.Assembléias microfitoplanctônicas num lago urbano da cidade de Curitiba (Estado do Paraná, Brasil)Estud. Biol.
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