Amor Island (Alter do Chão, Santarém, Pará, Brazil) is considered a region of great natural beauty and a national and international tourist attraction. The aim of this study was to determine the composition and density of the phytoplankton of the Amor Island, with emphasis on heterocytous cyanobacteria. Water samples for phytoplankton were collected and analyzed at seven points in October 2021. Filaments of heterocytous cyanobacteria were cultured and analyzed, measuring the cells of the first 30 trichomes. The abundance, diversity and evenness of phytoplankton species were calculated and balneability of beach in relation to algal blooms was evaluated. 106 generic and infrageneric taxa were identified, highlighting the Chlorophyta. Phytoplankton density was higher at Verde Lake (145.6 ± 22.0 org.L-1), diversity and evenness were higher at point 03 (Lake Verde) with 3.0 bits.cell-1 and 0.47, respectively. The most abundant species were: Aphanothece minutissima, Ankistrodesmus sp., Aphanothece sp., Aphanizomenon sp., Mougeotia sp., Merismopedia sp. and Quadrigula sp. The average density of cyanobacteria was higher in the Tapajós River (517.0 cell.mL-1). No algal and cyanobacterial blooms were identified, indicating water appropriate for bathing. Through morphological and morphometric description, the cultivated species were identified as Aphanizomenon gracile and Cylindrospermopsis/Raphidiopsis raciborskii, cited among the cyanobacteria with the highest occurrence of toxic blooms in the world. The region deserves phytoplankton monitoring studies, due to reports of cyanobacterial blooms, and greater knowledge of its planktonic biodiversity, since it is a threatened region.
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.
A polinização das flores e dispersão de frutos e sementes são fatores vitais para a manutenção de grande parte da população de espécies vegetais em florestas tropicais. A caracterização das síndromes de dispersão e polinização ocorrentes num fragmento de floresta tropical pode ser uma ferramenta de diagnóstico ambiental, demonstrando o grau de distúrbio que o ambiente possa estar sofrendo. Este trabalho teve como objetivo analisar e descrever as estratégias de polinização e dispersão dos diásporos de diferentes tipos vegetacionais no Parque Estadual do Utinga, unidade de conservação que compreende um gradiente florestal com áreas em diferentes estágios de preservação no município de Belém/PA. Foi utilizada a lista de espécies arbóreas levantadas no Plano de Manejo do Parque do Utinga, realizado em agosto de 2013. Utilizou-se a lista de espécies da flora por cada tipo vegetacional: Floresta Secundária, Floresta de Igapó e Floresta de Terra Firme. As espécies catalogadas no plano de manejo do parque foram caracterizadas quanto às suas síndromes de dispersão e polinização, baseando-se na análise de diferentes bibliografias especializadas, nas características morfológicas de seus diásporos e caracteres relacionados a polinização compartilhados em seus táxons. A síndrome de dispersão zoocórica foi a mais comum entre as espécies analisadas (72%) e entre os indivíduos (78,24%). Para as síndromes de polinização, mais de 90% das espécies e 76% dos indivíduos amostrados foram classificados dentro de alguma das síndromes de dispersão bióticas. Entre os tipos vegetacionais, houve diferença apenas quando analisadas as síndromes de polinização por número de indivíduos. As síndromes de dispersão e polinização bióticas são mais comuns em florestas tropicais com baixo nível de perturbação. Estes resultados indicariam um grau de distúrbio ambiental ainda moderado na unidade de conservação e em seus diferentes tipos vegetacionais. Levantamentos fitossociológicos, estudos de biologia floral e análises subsequentes são necessários para o acompanhamento da evolução deste quadro.
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.
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