This study evaluated the ecological potential of reservoirs in the Brazilian state of São Paulo, having phytoplankton as a biological quality element. Integrated water column sampling was carried out in the dam, and in the intermediate and fluvial zones of the Igaratá, Atibainha, Paiva Castro, Rio Grande, Itupararanga, Broa, Barra Bonita, Guarapiranga and Salto Grande reservoirs in July 2015. Physico-chemical and biological parameters were analyzed in all environments. The phytoplankton was analyzed under an inverted microscope, and measurements of density, diversity, equitability and dominance were determined. The data was ordered using PCA and CCA analysis. The ecological potential of the reservoirs was determined through the evenness index. The electrical conductivity, nitrate, nitrite and orthophosphate were higher in the more eutrophic reservoirs: Salto Grande, Barra Bonita, Guarapiranga and Rio Grande. A trophic gradient was observed among the sampling points, suggesting a conservation spectrum. There was dominance of cyanobacteria in the eutrophic reservoirs associated with low diversity and high dominance. The total density was correlated with TP, TN, and pH. A divergent relationship between the trophic state index and the evenness index was observed. The Atibainha, Itupararanga, Broa, Barra Bonita and Salto Grande reservoirs were classified as water bodies of very poor ecological quality (Bad). The evenness index seems to be a good alternative to the biomonitoring of the studied reservoirs.
Aim: The present study aims to evaluate the ecological status of the Broa reservoir through the application of the ecological index Evenness E2 on phytoplankton. Methods Phytoplankton samples from surface were obtained during the dry period (June/2015) in 9 points (P1 to P9), along a longitudinal transect in the reservoir. The qualitative analysis was performed using binocular optical microscope, and the quantitative analysis was performed using the sedimentation chamber method and inverted microscope analysis. The Uniformity Index was calculated on density and richness data. The reference values used in this study were set according to the literature covering 5 classifications (High, Good, Moderate, Low and Bad) for the water quality from Evenness E2 index for phytoplankton, being 1 the maximum value. Results The values observed ranged from 0.1142 in P1 to 0.1468 in P3, being both classified as “Bad”, since values were less than0.21. Conclusions The result reinforces the sanitary problem of the reservoir, the occurrence of consecutive algae blooms because the amount of nutrients in the region. A massive occurrence of Cyanobacteria was observed, with emphasis on the species Aphanizomenon gracile, which may be related to the adaptive advantages that this class presents on the community in eutrophic environments. Activities in the basin can contribute effectively to the eutrophication process of the reservoir, such as agriculture, sand mining and livestock. The water quality is compromised due to the dense presence of potentially toxic species, reflects of the eutrophication process, pointing commitments for the multiple uses of the reservoir, as well as human and ecosystem health. These processes could be corroborated by the application of the index and indication of poor water quality.
Muitos corpos hídricos têm sido degradados devido à interferência humana. A poluição causada pelas atividades antrópicas vem comprometendo a qualidade da água e promovendo eventos de eutrofização, afetando toda estrutura trófica do ambiente, podendo assim acarretar na proliferação de cianobactérias tóxicas. Nesse sentido, o conhecimento sobre esses organismos é de grande importância, principalmente em corpos hídricos com usos múltiplos. Esta pesquisa representa uma revisão de trabalhos publicados envolvendo qualidade ambiental e ecolotoxicologia aquática, tendo como foco estudos relacionados às cianobactérias e cianotoxinas. Para o trabalho foram analisados livros textos e artigos publicados entre 2010 e 2020 em periódicos nacionais e internacionais. Na literatura publicada nos últimos anos são apresentadas as principais metodologias envolvidas na detecção e remoção de cianotoxinas, além de bioensaios ecotoxicológicos. Fica evidente a importância do tratamento de efluentes e controle das fontes de poluição difusas e pontuais no ecossistema promovendo a melhoria da qualidade da água e controle de cianobactérias.ABSTRACTCyanobacteria play an important role among producers in aquatic ecosystems, however when associated with eutrophication they become an ecological and public health problem. The problem involving cyanobacteria is the blooming of potentially toxic strains. The present work aims to present and discuss the problems related to the proliferation of cyanobacteria in limnological environments, and its consequences for dynamics in the environment and effects on environmental health. In this sense, knowledge about these organisms is of great importance, especially in water bodies with multiple uses. This research represents a review of published works involving environmental quality and aquatic ecotoxicology, focusing on studies related to cyanobacteria and cyanotoxins. For the present work, textbooks and articles published between 2010 and 2020 in national and internationaljournals were analyzed. In the literature published in recent years, the main methodologies involved in the detection and removal of cyanotoxins are presented, in addition to ecotoxicological bioassays. The study of cyanobacteria and their metabolites comprises an area of interest that reaches a greater dimension when impacts on the quality of water supply are evident, thus the importance of treating effluents and controlling pollution sources in the ecosystem is evident, promoting improvement and maintenance the quality of the water bodies.
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