Influence of agricultural land-use and pesticides on benthic macroinvertebrate assemblages in an agricultural river basin in southeast Brazil

Abstract

Land-use alterations and pesticide run-offs are among the main causes for impairment in agricultural areas. We evaluated the influence of different land-uses (forest, pasture and intensive agriculture) on the water quality and on benthic macroinvertebrate assemblages on three occasions: in the dry season, wet season and at the end of the wet season. Macroinvertebrates responded to this gradient of impairment: agricultural sites had significantly lower richness numbers than forested and pasture sites, and all major invertebrate groups were significantly affected. Most taxa found in forested sites were found in pasture sites, but often with lower densities. In this case, the loss of habitats due to sedimentation and the lower complexity of substrates seem to be the disruptive force for the macroinvertebrate fauna.Keywords: stream ecosystems, water quality, macroinvertebrates, biomonitoring, agricultural river basins.Influência de pesticidas e uso da terra sobre as assembléias de macroinvertebrados bentônicos em uma bacia hidrográfica no Sudeste do Brasil ResumoO desmatamento e o uso de pesticidas representam impactos importantes que ameaçam a integridade ambiental das áreas agrícolas. Neste estudo, foi avaliada a influência de diferentes usos do solo associados com atividades agrícolas (floresta, pastagem e agricultura intensiva) na qualidade da água e em comunidades de macroinvertebrados bentônicos em três ocasiões: estação seca, estação chuvosa e fim da estação chuvosa. A comunidade de macroinvertebrados bentônicos respondeu a esse gradiente de impacto: as áreas intensamente ocupadas por cultivos apresentaram uma riqueza significativamente menor do que as áreas florestadas e ocupadas por pastagens, com todos os grupos de macroinvertebrados sendo significativamente afetados. A maior parte dos táxons encontrados nas áreas de floresta foi registrada nas áreas de pastagem, mas sempre em menores densidades. Nesse caso, a redução de habitat em função da sedimentação e da menor heterogeneidade de substratos parece ser o principal impacto que ameaça a comunidade.Palavras-chave: ecossistemas de rios, qualidade da água, macroinvertebrados aquáticos, biomonitoramento, áreas agrícolas.

Landscape composition as a determinant of diversity and functional feeding groups of aquatic macroinvertebrates in southern rivers of the Araucania, Chile

“…Similar trends were found in other studies (Miserendino & Masi, 2010;Egler et al, 2012) which indicate that macroinvertebrate fauna can be altered by land use practices (e.g., agriculture, forest plantations). Macroinvertebrates showed significant differences between stations and seasons responding to this gradient; sites with strong anthropogenic pressures had lower abundances than low impacted sites.…”

Metabolism, bioaccumulation, and toxicity of pesticides in aquatic insect larvae

“…11) As compared with the Brazilian river neighboring forest and meadow, less abundance of macroinvertebrates with poor taxon richness was reported for the river flowing through the agricultural site applied with many insecticides, and some EPT species disappeared altogether. 12) By comparing species abundance with the concentrations of imidacloprid at various freshwater sites in the Netherlands, an extensive statistical analysis showed a significant negative relationship between them, with high correlations for the most abundant Glyptotendipes pallens (midge), Caenis horaria (mayfly), and Oecetis lacustris (caddisfly). 13) The toxicity of a pesticide should basically be interpreted from the standpoint of its body burden and mode of action (MOA) in aquatic insects.…”

Aquatic macroinvertebrates assemblages related to diverse land uses in the Apatlaco and Chalma-Tembembe rivers (Balsas basin), Mexico

“…El ACP revela que los sitios influenciados por suelos agrícolas tienen una mayor carga de materia orgánica, al presentar los valores más altos de DBO 5 , color y coliformes, y la mayor concentración de nitratos, nitritos, nitrógeno amoniacal, nitrógeno total, ortofosfatos y fósforo total. Las zonas agrícolas suelen permitir una mayor erosión de suelos, lo que puede favorecer el ingreso de materia orgánica de la cuenca de captación y, como consecuencia, incrementar la DBO 5 y los nutrientes en el curso de los ríos, como lo han detectado Egler et al, (2012) y Ribeiro et al (2014); además, en este estudio, debido a que se incorporó a las zonas pecuarias dentro de la zonas agrícolas, el aumento de coliformes en éstas puede atribuirse a la actividad pecuaria. Por otra parte, los sitios con influencia urbana presentaron mayor conductividad, alcalinidad, dureza y concentración de cloruros.…”