RESUMO
The phylum Ciliophora is organized in 14 classes with ~8,000 described species ( Gao et al., 2016 ). Among unicellular microeukaryotes, ciliates are the most specialized, diversified and with the highest complexity in terms of cellular organization ( Puytorac, 1994 ). They typically occupy basal trophic levels and display a wide geographical distribution occurring in almost all environments such as marine, fresh and brackish waters, and also in edaphic systems like soils, mosses and lichens ( Lynn, 2008 ). Their diversity in lotic systems have been extensively studied in the northern hemisphere because of their potential use as water quality bioindicators ( Wiackowski, 1981 ; Primc, 1988 ; Groliére et al., 1990; Madoni, 2005 ). However, scarce information is available in literature about their diversity in aquatic ecosystems in Brazil, even though its privileged hydrological condition. The access to ciliate diversity and biogeography is a challenge tasks because they are diminute organisms, difficult to identify ( Finlay and Fenchel, 1999 ), there is a lack of experienced specialists ( Foissner, 2006 ) and a number of species stay encysted for most of their life cycles ( Foissner, 2004 ). In Brazil, significant works were performed with this emphasis such as conducted in Rio Grande do Sul (Safi et al., 2014), Paraná ( Pauleto et al., 2009 ; Buosi et al., 2011 ; Velho et al., 2005 , 2013 ), São Paulo ( Bagantini et al., 2013 ; Regali-Seleghim et al., 2011 ), Pará ( Castro et al., 2014 ), Minas Gerais ( Dias et al., 2008 , 2010 ) and Rio de Janeiro ( Paiva and Silva-Neto, 2004a , b ) states. Inventory studies constitute the first step for development of applied biotechnological usage of ciliates. Regali-Seleghim et al. (2011) highlight the importance of more works surveying the diversity of ciliates in less studied regions of Brazil given their ecological importance. Moreover, establishment of in vitrocultures will contribute with information to biomonitoring programs ( Madoni and Romeo, 2006 ; Shi et al., 2012 ) and for better evaluation of the biotechnological potential of these organisms ( Mansano et al., 2016 ). This present work aimed to survey the diversity of the species of ciliated protists in a neotropical lotic urban system located in Southern region of Minas Gerais state, Brazil.(AU)
RESUMO
The aim of this research was to study the ciliated protozoa community at three sampling stations that receive different levels of domestic sewage along the São Pedro Stream in the municipality of Juiz de Fora, Minas Gerais, Brazil, in order to determine the influence of organic pollution on this community and to assess the feasibility of using ciliates as water quality indicators. Four physical-chemical parameters of the water samples were evaluated: dissolved oxygen concentration, electrical conductivity, pH and temperature. The sediment was obtained manually, using dredges with capacity of 300 mL, at each collection point. Point 1 was located in a rural region that receives a low sewage load, while Points 2 and 3 were located in populated regions receiving high sewage loads. We found 22 ciliate species, of which 18 are included in the saprobic system and are considered bioindicators. These showed beta-mesosaprobic environments at Point 1 and alfa-mesosaprobic to polisaprobic environments at Points 2 and 3. The low levels of dissolved oxygen and the high electrical conductivity values at Points 2 and 3, together with the strong similarity between the ciliate taxocenoses of these points and the weak similarity between Point 1 and the other two, confirm the high sewage loads received at the latter two points. The combination of the biological indicators and physical-chemical analyses therefore proved itself to be an efficient method of evaluating water quality, and has excellent potential to support decisions on the conservation of headwaters and recuperation of degraded environments in lotic systems.
Assuntos
Cilióforos/classificação , Monitoramento Ambiental/métodos , Esgotos/parasitologia , Poluição da Água/análise , Animais , Cilióforos/crescimento & desenvolvimento , Condutividade Elétrica , Humanos , Concentração de Íons de Hidrogênio , Oxigênio/análise , Densidade Demográfica , Dinâmica Populacional , TemperaturaRESUMO
The aim of this research was to study the ciliated protozoa community at three sampling stations that receive different levels of domestic sewage along the São Pedro Stream in the municipality of Juiz de Fora, Minas Gerais, Brazil, in order to determine the influence of organic pollution on this community and to assess the feasibility of using ciliates as water quality indicators. Four physical-chemical parameters of the water samples were evaluated: dissolved oxygen concentration, electrical conductivity, pH and temperature. The sediment was obtained manually, using dredges with capacity of 300 mL, at each collection point. Point 1 was located in a rural region that receives a low sewage load, while Points 2 and 3 were located in populated regions receiving high sewage loads. We found 22 ciliate species, of which 18 are included in the saprobic system and are considered bioindicators. These showed beta-mesosaprobic environments at Point 1 and alfa-mesosaprobic to polisaprobic environments at Points 2 and 3. The low levels of dissolved oxygen and the high electrical conductivity values at Points 2 and 3, together with the strong similarity between the ciliate taxocenoses of these points and the weak similarity between Point 1 and the other two, confirm the high sewage loads received at the latter two points. The combination of the biological indicators and physical-chemical analyses therefore proved itself to be an efficient method of evaluating water quality, and has excellent potential to support decisions on the conservation of headwaters and recuperation of degraded environments in lotic systems.
O objetivo deste trabalho foi estudar a comunidade de protozoários ciliados em três estações amostrais, que recebem diferentes níveis de lançamento de esgoto doméstico, ao longo do córrego São Pedro, Juiz de Fora, MG, a fim de se determinar a influência da poluição orgânica sobre a composição e distribuição desta comunidade e avaliar a viabilidade da utilização dos ciliados como indicadores da qualidade da água. Foram mensurados quatro parâmetros físico-químicos da água amostrada: teor de oxigênio dissolvido, condutividade elétrica, pH e temperatura. Amostras do sedimento foram obtidas manualmente com o auxílio de dragas, com capacidade de 300 mL, em cada ponto de coleta. O ponto 1, localizado em uma região rural, recebe baixa carga de esgoto, enquanto os pontos 2 e 3, localizados em regiões com ampla ocupação humana, recebem altas cargas de esgoto. Foram registradas 22 espécies de ciliados, sendo que 18 estão incluídas no sistema sapróbio e são consideradas bioindicadoras de ambientes beta-mesossapróbio no ponto 1 e de alfa a polissapróbio nos pontos 2 e 3. Os baixos valores de oxigênio dissolvido e os altos valores de condutividade elétrica registrados nas estações 2 e 3, juntamente com a similaridade entre a taxocenose de ciliados destas estações e a baixa similaridade entre a estação 1 e as demais, confirmaram as altas cargas de esgoto recebidas nestas estações. A união do método biológico com a análise físico-química mostrou-se, portanto, um eficiente método na avaliação da qualidade da água, e apresenta grande potencial de utilização em tomadas de decisões relativas à conservação de nascentes e recuperação de ambientes degradados em sistemas lóticos.