Benthic macroinvertebrates in rivers of agricultural lands in Argentina: the functional diversity response to environmental stress

Abstract

Context. The rapid intensification of human impacts on rivers is a major threat for the provision of key ecosystem services for societies. In this context, many of these services rely on the ecological functions performed by macroinvertebrates. Therefore, understanding the relationship between human impacts and the functional diversity of macroinvertebrates is urgent. Aims. We aimed at analysing the relationship between human impact and the functional diversity of macroinvertebrates in rivers of agricultural lands of Argentina. Methods. We sampled seven rivers of central Argentina during three seasons (spring, autumn and winter). In each site, we measured pesticides, metals, chlorophyll-a, nutrients and the taxonomic and functional diversity of macroinvertebrates. We summarised the environmental information using principal-component analysis and assessed the relationship between the assemblage metrics with the first three principal components. Key results. We found that functional metrics presented a negative relationship with the humanimpact gradient in the three seasons. However, taxonomic metrics showed less sensitivity. Conclusion. The functional diversity of macroinvertebrates, but not the taxonomic diversity, decreases with increasing human impacts on rivers. Implications. Our result implies that functional metrics should be included in environmental monitoring in agricultural lands of Argentina.