Levantamento da comunidade de cianobactérias em trechos do Rio Turvo Sujo, localizados nas proximidades da cidade de Viçosa, MG / Cyanobacteria community survey in areas of the Turvo Sujo River, located in the proximities of the city of Vicosa, MG

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Water quality found in several regions of the world have revealed the neglectance in which industrial, urban and agricultural discharges have been treated which leads, constantly, to the accelerated growth of cyanobacteria strains. The aim of this study was to assess the occurrence of cyanobacteria in the Turvo Sujo River, one of the responsible rivers for the water supply in the city of Vicosa- MG, as well as to characterize the physical, chemical and biological characteristics associated with the occurrence of these microorganisms in sites under anthropogenic influence. Water samples were collected from April to November of 2007, in five sampling points along the river. Physical and chemical parameters were analyzed: temperature, pH, electric conductivity, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrogen (total, ammonium and nitrate), phosphorus (total, orthophosphate, dissolved organic phosphate and particulated phosphorus), silica, water transparency and water flow. Biological characteristics included: chlorophyll-a, individual density, similarity analyses, frequency index and trophic state. The isolated species were kept in a growth room under photoautotrophic conditions. The values obtained through the physical and chemical analyzes were within established in the CONAMA Resolution 357/05, for class 2 water bodies, with the exception of the PT (for the month of July) and BOD (except the month of July), which presented concentrations above the established one; and the OD (for the month of November), which was below the established concentration according to the same resolution. During the studied period 12 taxa were identified, which were distributed in 4 orders. The order Nostocales was the most representative one with 8 genera: Cylindrospermum licheniforme, Anabaena ambigua, Nostoc cf. Muscorum, Nostoc cf. Carneum, Nostoc commune, Nostoc sp. (1), Nostoc sp. (2) and Calothrix sp.; Followed by the Oscillatoriales order, with 2 genera: Pseudoanabaena catenata and Phormidium sp., and Chroococcales (Synechococcus nidulans) and the Stigonematales (Scytonema sp.) order, with only 1 genera. Recorded cyanobacteria cell density throughout the monitoring time was shown to be below its requirement, under the legislation MS N 518/04. Based on the Index of Throphic State, a degree of oligothrophy was recorded on the Turvo Sujo River. There was no influence of physical and chemical parameters with the emergence of cyanobacteria in the studied sites. Monthly monitoring of rivers become important as a practice in the prevention and control of the cyanobacteria occurrence. The research conducted in the Turvo Sujo River showed the effectiveness of monthly monitoring of rivers and its importance as a practice of prevention in the conservation of the quality of waters and control of possible blooming.

ASSUNTO(S)

cianobactérias poluição antrópica botanica rio turvo sujo rio turvo sujo cyanobacteria pollution

ACESSO AO ARTIGO

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