Abstract
AbstractReliable methods for assessing the ecological status of degraded rivers are essential for evaluating restoration efforts in lotic habitats. Several methods are based on biological indicators, such as benthic macroinvertebrates. The Hester–Dendy multi‐plate sampler is a commonly used tool for sampling macroinvertebrates, but its performance under different environmental conditions is not well understood. In a laboratory experiment, we assessed if fluctuating and increasing water velocity influences the performance of Hester–Dendy samplers, by studying colonization of the samplers in relation to a pre‐determined composition of benthic macroinvertebrates. Biodiversity (Shannon‐Wiener index) of colonizing macroinvertebrates was higher in a constant than in a fluctuating flow treatment, but there was no effect on the number of colonizing individuals. The results suggest a potential bias in the interpretation of biodiversity data from sites with sub‐daily flow changes, for example, downstream of hydropeaking power plants.
Highlights
Degradation of aquatic environments due to human overexploitation and pollution of rivers and streams have created a need for reliable methods to assess the ecological status of lotic ecosystems
There was no difference in the number of colonizing benthic macroinvertebrates between the constant and the fluctuating flow treatment (1.8 ± 0.4) (GLM: flow χ2 = 1.35, df = 1, p = .25, aquarium χ2 = 13.41, df = 5, p = .02, trial round χ2 = 3.29, df = 3, p = .35)
When analyzing the diversity of all living benthic macroinvertebrates found in the aquaria, there was no difference between the constant (1.59 ± 0.06) and fluctuating flow treatment (1.60 ± 0.06) (LM: flowF1,6 = 0.05, p = .84, aquarium F5,6 = 0.86, p = .54, trial round F3,6 = 1.44, p = .28)
Summary
Degradation of aquatic environments due to human overexploitation and pollution of rivers and streams have created a need for reliable methods to assess the ecological status of lotic ecosystems. This need has resulted in the development of many bioassessment programs, protocols, and methods (Birk et al, 2012). Benthic macroinvertebrates are relatively easy and cost-effective to sample, and are, the most widely used biotic indicator group in bioassessments of aquatic ecosystems (Barbour et al, 1999; Birk et al, 2012; Moog et al, 2018)
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