Assessing the effects of hydrological and chemical stressors on macroinvertebrate community in an Alpine river: The Adige River as a case study

Abstract

In this study, the combined effects of hydrological and chemical stressors on benthic macroinvertebrates were evaluated in order to explore the response of the biological community to multiple stressors. The Adige River, located in the south‐eastern Alps, was selected as a case study because representative of the situation of a large river in which the variety of stressors present in the Alpine region act simultaneously. As expected, streamflow showed a seasonal pattern, with high flows in the spring–summer period; however, locally, the natural hydrological regime was altered by the presence of hydropower systems, which chiefly affected low flows. Multivariate analysis showed seasonal and spatial patterns in both chemical and hydrological parameters with a clear gradient in the concentration of nitrate, personal care, and pharmaceutical products moving from headwaters to the main stem of the river. The macroinvertebrate community composition was significantly different in summer and winter and between up and downstream sites. Streamflow alteration chiefly due to water use by hydropower affected community composition but not richness or diversity. Gammarus sp., Hirudinea, and Psychomyia sp., were positively correlated with flow variability, increasing their densities in the sites with higher streamflow variability because of hydropeaking. The results obtained in this study show that the composition of the macroinvertebrate community responded to seasonality and to changes in the main stressors along the river and highlights the importance of the spatial and temporal variability of stressors in this Alpine river. Taking into account, this variability will help the decision‐making process for improving basin management.

Chemical surveillance in freshwaters: small sample sizes underestimate true pollutant loads and fail to detect environmental quality standard exceedances

“…The findings of this study are relevant for all studies investigating the effects of environmental variables on abundance data and species composition of biocenoses by using mean annual concentrations. However, there are only very few studies that investigate the relationship between micropollutants and biological data [5,[55][56][57][58]. For one thing, this may be due to the fact that micropollutants have only been the focus of research for a few years or, for another, it may be due to the fact that, so far, too few data have been available for large-scale evaluation.…”

“…For this reason, it is hypothesized that in the case of environmental concentrations with high temporal variability, individually measured values or mean values determined from small sample sizes diminish the model performance of multivariate analyses. Since monitoring data is often scarce, especially for large-scale studies, many studies have to work with small sample sizes [55][56][57][58]. In such studies, scientists should bear in mind that the explanatory power of the relationships between environmental parameters with high temporal variability and freshwater biocenoses is likely to be reduced due to the small sample size.…”

Temporal changes in headwater streams macroinvertebrate assemblages during the snowmelt season in northeast china

“…The upstream surrounding environment of glacier-fed streams is covered with ice and snow all year round, and there is very little vegetation on both sides (Martyniuk et al, 2019), while nonglacier-fed streams are mostly located in mid-to high-latitude and alpine areas with riparian forest (Jacobsen et al, 2020). The low plants (mainly herbs) on the slopes during the melting period of ice and snow have not yet turned green, and they have less resistance to the water flow formed by the ice and snow melt (Giulivo et al, 2019). Water flow mixed with a large amount of litter quickly enters the stream, providing a large amount of organic matter and nutrients to headwater streams (Wang et al, 2019).…”

Structural and Functional Variations of the Macrobenthic Community of the Adige Basin along the River Continuum

“…The first ecological studies [22,23] found that macrobenthic fauna accumulated pollutants from surrounding industries and other human activities. More recently, Giulivo et al [24] analyzed the structural response of the macrobenthic community of Adige river to seasonality and environmental stressors. They found that human stressors, such as streamflow alteration and pollutants, affect the community composition but not the diversity.…”