The suitability of Hester-Dendy macroinvertebrate samplers in fluctuating flows

摘要

Reliable 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.