Effect of environmental quality and mesohabitat structure on a Biotic Integrity Index based on fish assemblages of cerrado streams from Rio Cuiabá basin, Brazil

Abstract

Over the last 30 years, the Cerrado has been experiencing various antropic impacts that have brought about alterations to species composition, structure and functioning of aquatic habitats. Therefore, studies on negative impacts are useful to prevent future damage and restore environmental quality. The objectives of our study were: i) to adapt an index of biotic integrity of streams in the Rio Cuiabá Basin and ii) to analyze if the Index of Biotic Integrity (IBI) correlated with the environmental quality measured by the Index of Environmental Quality (IEQ) and with the mesohabitat structure. We sampled 26 streams in sub-basins of the Cuiabá River. In each stream, we closed a stretch of 50 m with blockage nets and used electrofishing to capture fish. To obtain a measure of environmental quality in sampled units, we characterized the stream and its micro basin. For the analyses, we used the Spearman Correlation, Kruskal-Wallis test and Analysis of Multiple Regression. We collected 697 individuals distributed into 6 orders, 15 families and 49 species. The IBI followed changes on environmental quality measured by IEQ when we removed streams that present natural barriers from the analysis (r 2 = 0.4; r 2 = 0.58). Types of land use did not affect the biotic integrity (n = 26; df = 4; H = 4,860; p = 0.302), but natural and artificial barriers affected it (n = 26; df = 4; H = 11,027; p = 0.026). The IBI was not sensitive to variations in mesohabitat structure (F 2,23 = 0.373; r 2 = 0.031; Axe 1 p = 0.620; Axe 2 p = 0.490). The IBI is certainly a reasonable instrument for evaluating changes in the environment, but we cannot ignore the fact that we were able to obtain the same result with any combinations of metrics. This makes its analysis and interpretation difficult.Keywords: environmental quality, headwaters, ecosystems health, fish community, agriculture, land use, aquatic ecosystems.Efeito da qualidade ambiental e da estrutura do meso-habitat sobre um índice de integridade biótica baseado em assembleias de peixes de córregos de cerrado da bacia do rio Cuiabá, Brasil ResumoNos últimos 30 anos, o cerrado tem sofrido severos impactos antrópicos que provocam alterações na composição de espécies, na estrutura e no funcionamento de habitats aquáticos. Dessa forma, estudos sobre impactos negativos são úteis para prevenir futuras degradações e restaurar a qualidade ambiental. Os objetivos do nosso estudo foram: i) adaptar um índice de integridade biótica para os riachos da bacia do rio Cuiabá e ii) analisar se o índice de integridade biótica (IIB) é correlacionado com a qualidade ambiental medida pelo índice de qualidade ambiental (IQA) e com a estrutura do meso-habitat. Amostramos 26 riachos da sub-bacia do rio Cuiabá; em cada um deles, delimitados um segmento de 50 m, utilizando a pesca elétrica como método de coleta. Para obter a medida de qualidade ambiental nas unidades amostradas, caracterizamos os riachos e sua microbacia. Para as análises nós usamos a correlação de Sperman, o teste Kruskal-Wallis e a análise...

Fish from urban tributaries to the Vermelho River, upper Paraguay River Basin, Mato Grosso, Brazil

“…Other studies in the Cerrado region (Lemes and Garutti 2002;Verissimo et al 2005;Aquino et al 2009;Machado et al 2011;Casatti et al 2013) obtained the same results regarding the predominance of the orders Characiformes followed by Siluriformes. These authors emphasized that, in streams, the family Characidae stands out for having the greatest number of species, corroborating the results found in the urban streams of Rondonópolis.…”

Efeito Do Uso Do Solo Sobre Riachos De Cabeceira Na Bacia Do Rio Cuiabá, Mato Grosso

“…Então, a largura do canal dos riachos é relacionada ao tipo de uso do solo e a largura aumenta, em resposta ao aumento da descarga (Zimmerman et al, 1967). Estudos de associação entre índices de integridade bióticas e qualidade ambiental indicam que a degradação, perda de habitat, fragmentação e poluição são as principais causas de perda de integridade biótica e abiótica em riachos (Machado et al, 2011).…”

An influence of mesohabitat structures (pool, riffle, and run) and land-use pattern on the index of biological integrity in the Geum River watershed

“…The advantage of the IBI approach is low spatial and temporal variability due to high trophic position in the food chain of aquatic ecosystems and has a potential to integrate various aspects of the habitat on multiples scales (Karr et al 1986;Machado et al 2011). For this reason, applications of multi-metric models were successful in the managements and conservations of stream ecosystems.…”

“…The dams decreased river flow and, as a result, increased the accumulation of fine sediments (silt and clay) on the downstreams, which adsorb more organic matter (OM) and metals, due to their larger surface area (Shim et al 2015). The patterns of land uses within a watershed also influenced various intrinsic attributes of the Geum River system, including hydrological, geomorphological, chemical, and biological features such as fish assemblages (Lee, Hwang, et al 2011b;Machado et al 2011). Also, changes in the hydrological cycle and material inputs by differences of land-use patterns of the watershed may have negative consequences in fish assemblages or trophic structures (Machado et al 2011).…”

“…The patterns of land uses within a watershed also influenced various intrinsic attributes of the Geum River system, including hydrological, geomorphological, chemical, and biological features such as fish assemblages (Lee, Hwang, et al 2011b;Machado et al 2011). Also, changes in the hydrological cycle and material inputs by differences of land-use patterns of the watershed may have negative consequences in fish assemblages or trophic structures (Machado et al 2011). Removing native vegetation and building artificial barriers in the artificial weirs and dams decreased heterogeneous habitats and restrict fish movement, resulting in modifications of population viability and biotic integrity of the watershed (Pichon et al 2006;Machado et al 2011).…”