Development of a Multimetric Index of Ecological Integrity for streams in the urban area of Campo Grande (Mato Grosso do Sul), based on benthic macroinvertebrates / Desenvolvimento de um Índice Multimétrico de Integridade Ecológica para córregos na área urbana de Campo Grande (Mato Grosso do Sul), baseado em macroinvertebrados bentônicos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Water pollution is a growing problem, especially in the water courses that flow through urban centres, receiving residential, commercial and even industrial effluents. The small amount of control that exists is often done by means of physical, chemical and bacteriological analyses. The lack of a biological alternative may be due to the paucity of research into the development of indices for pollution monitoring and control. In Brazil, such studies are still only beginning and in Mato Grosso do Sul are even rarer, especially in urban areas. For this reason, the present study proposed the development of an index of ecological integrity, based on the benthic macroinvertebrate communities of first order streams located within the urban perimeter of Campo Grande. To characterize the habitats at the sampling sites, an adaptation of the Protocol of Callisto et al. (2002) was developed. Sites 1, 2, 7 and 6 were classified, in decreasing order, as natural or semi-natural. The hydrological conditions of the streams were similar and mean velocity, depth and width explained 99.93% of the variation in the data. A Principal Components Analysis performed on the physical, chemical and bacteriological characteristics (namely, BOD, dissolved oxygen, volatile and fixed solids, turbidity, pH, total alkalinity, conductivity, calcium, orthophosphate, ammonia and total and fecal coliforms) of the sampling points explained 85.12% of the variance in the first two axes (56.72% in the first and 28.40% in the second). Only one water course characterized as natural was shown to be impacted according to the physical, chemical, bacteriological and macroinvertebrate communities (see below). In the analyses of taxonomic richness, Dominance of Simpson, and diversity and evenness of Shannon-Wiener of the macroinvertebrate communities, the least impacted sites could be distinguished. The natural sites one and two showed higher diversity and evenness, followed by site seven (diversity values of 2.3, 2.1 and 1.9, and evenness values of 0.5, 0.4 and 0.4, respectively). Only site six, identified as natural, showed low values, with diversity of 0.4 and evenness of 0.1 and the highest Dominance among all sites, 0,84. This demonstrates that the stream was suffering impacts, even though inside a Conservation Unit. In the analysis of the communities, using Hybrid Non-metric Multidimensional Scaling (stress = 0.08 and r2 = 0.94), the sites were separated in conformation with the habitat diversity protocol adopted. The family Chironomidae was most abundant at all the sites. Nevertheless, the natural and close to natural sites were separated with communities sensitive to impacts, and with medium to low tolerance, demonstrating greater ecosystem equilibrium. The impacted sites were dominated by communities tolerant to pollution. The developed index was multimetric. 40 metrics were tested, with 12 and 6 reflecting composition and tolerance, respectively, while 8 were indices. However, only three were found to be suitable to be used with confidence in the two studied basins, thus constituting an overall index of 15 points.

ASSUNTO(S)

ecologia multimetric index biomonitoramento biomonitoring limnologia limnology qualidade dágua Índice mutimétrico water quality macroinvertebrates macroinvertebrados

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