Abstract
Simple SummaryMacroinvertebrates are very important to aquatic ecosystems. They are food for vertebrates and their biodiversity serves as a testament of the quality of their habitats. The majority of research on macroinvertebrates simply describes the composition and population density of species living in large rivers and lakes. The aim of our study was to compare the biodiversity of macrozoobenthos assemblages and to determine the effect of physicochemical and hydrological conditions on their abundance and density in 10 small rivers in agricultural areas. Overall, 105 taxa were identified as species living in changing conditions. Oxygenation of water and nitrogen content were important factors determining the existence of macroinvertebrates in these rivers. Some groups of organisms showed sensitivity to changes in water temperature as well as to the flow and depth in rivers.Most publications on the influence of environmental factors on macroinvertebrate communities focus on large rivers, whereas relatively few examine small watercourses in agricultural areas, which, due to their size and pressure from intensive agricultural production, are much more susceptible to the effects of unfavourable environmental conditions or anthropopressure. The aim of our study was to compare the biodiversity of macrozoobenthos assemblages and to determine the effects of physicochemical and hydrological conditions on their abundance and density in 10 small rivers in agricultural areas located in northwest (53°23′ N 15°14′ E) and central (52°11′ N 20°48′ E) Poland. In total, 105 taxa were recorded, with the majority being euryoecious. Among the assessed physicochemical parameters, oxygenation was found to affect the density and number of taxa; another important factor was the content of nitrate nitrogen. Sensitivity to changes in water temperature was observed in some macrozoobenthos taxa (especially Decapoda). Of the examined hydrological parameters, the greatest effects were exerted by speed, flow, and depth.
Highlights
Lotic habitats are of extremely high ecological value and have great significance for biodiversity protection [1]; they are the most often exploited ecosystems on our planet [2]
Our results indicate that eutrophicated watercourses under strong anthropopressure in agricultural areas are characterised by low macrozoobenthos species richness and diversity, and that physicochemical and hydrological conditions have a great effect on the density of these organisms
The small watercourses we studied had a reduced oxygen content and a high level of nitrogen and phosphorus compounds, which was related to their location in agricultural areas
Summary
Lotic habitats are of extremely high ecological value and have great significance for biodiversity protection [1]; they are the most often exploited ecosystems on our planet [2]. Macroinvertebrates are among the sensitive groups that react to both natural and anthropogenic changes in the river environment [10,11]. Due to their sensitivity to oxygen concentration and changes in chemical properties of the water [12], food availability [13], and changes in the habitat structure [14], they are most often used in ecological assessment as an indicator of the quality of various aquatic environments [15,16]. Changes in zoobenthos structure reflect long-term changes in water quality [18] due to the association between physicochemical changes in the aquatic environment and the sensitivity of particular taxa [1,19,20]. In the aquatic environment, benthic organisms constitute an important link between primary producers and secondary consumers, play an important part in the trophic cycle, and promote the decomposition of organic matter through the consumption and breakdown of plant and animal tissues [24,25]
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