Effect of land use on the composition, diversity and abundance of insects drifting in neotropical streams

Abstract

Streams may exhibit differences in community structure of invertebrate drift, which may be a reflex of variation in environmental factors, able to change in conditions of anthropogenic interventions. The aim of this study was to analyze the composition, diversity and abundance of insects drifting in two neotropical streams under different land use and to identify the environmental factors involved in determining such patterns. 54 taxa of aquatic insects were identified in urban and rural streams. The results indicated significant differences in species composition due to the replacement of specialist species by generalist species in the urban stream. Higher diversity of taxa was recorded in the rural stream, with high levels of dissolved oxygen and high water flow, which favored the occurrence of sensitive groups to environmental disturbances, such as Ephemeroptera, Plecoptera, Trichoptera and Coleoptera taxa, that living mainly in clean and well oxygenated waters. On the other hand, a higher density of insects drifting, especially Chironomidae, was observed in the urban stream, where high values of pH, electrical conductivity and nitrogen were observed. These larvae are able to explore a wide range of environmental conditions, owing to their great capacity for physiological adaptation. Despite observing the expected patterns, there were no significant differences between streams for the diversity and abundance of species. Thus, the species composition can be considered as the best predictor of impacts on the drifting insect community.Keywords: aquatic invertebrates, urbanization, human impact, lotic environments.Efeito do uso do solo sobre a composição, diversidade e abundância de insetos à deriva em riachos neotropicais ResumoRiachos podem exibir diferenças na estrutura das comunidades de invertebrados à deriva, o que pode ser um reflexo da variação nos fatores ambientais, capazes de se alterar em condições de intervenções antrópicas. O objetivo deste trabalho foi analisar a composição, diversidade e abundância de insetos à deriva em dois riachos neotropicais sob diferentes usos do solo, além de identificar os fatores ambientais intervenientes na determinação de tais padrões. Foram registrados 54 táxons de insetos aquáticos nos riachos urbano e rural. Os resultados evidenciaram diferenças significativas na composição de espécies, devido à substituição de espécies especialistas por espécies generalistas no riacho urbano. Maior diversidade de táxons foi registrada no riacho rural, com altos níveis de oxigênio dissolvido e elevado fluxo hídrico, que favoreceram a ocorrência de grupos sensíveis a perturbações ambientais, como táxons das ordens Ephemeroptera, Plecoptera, Trichoptera e Coleoptera, que vivem principalmente em águas limpas e bem oxigenadas. Por outro lado, maior densidade de insetos a deriva, especialmente Chironomidae, foi observada no riacho urbano, onde foram registrados elevados valores de pH, condutividade elétrica e nitrogênio. Estas larvas são capazes de explorar uma vasta gama de condi...

Urbanisation affects the diet and feeding selectivity of the invasive guppy Poecilia reticulata

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Evaluation of land use impact on river water quality using macroinvertebrates as bioindicator in Lahumoko Watershed, Buton Island, Indonesia

“…Water temperature in the upstream of the watershed was low due to the closure of the water body by the forest compared to the middle and downstream part which was already opened, especially at the edge of the river (Rezende et al 2016). Water temperature greatly influences organisms in the river and is inversely proportional to DO and Conductivity (Brooks et al 2013;Gimenez et al 2015;Patrick et al 2015). This is shown in this study that TDS and Conductivity increased towards the downstream, accompanied by a decrease in DO (Shafie et al 2017;Pina et al 2016;Sharifinia et al 2016).…”

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The effect of urbanization on freshwater macroinvertebrates – Knowledge gaps and future research directions

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