Abstract
AbstractA primary goal of river restoration is to reestablish lost ecological functions. Yet the impact of restoration on diatom assemblages and algal biomass in a stream is rarely addressed in the scientific literature reporting the outcomes of restoration projects aimed at improving riverine habitat. To investigate the potential for using benthic diatoms as indicators of the benefits to habitat associated with river restoration, we conducted a pilot diatom study in Whychus Creek, a headwater tributary of the Deschutes River in Oregon, USA. As part of a work study project for college students, we collected periphyton samples in a restored reach, a restored transition reach and an unrestored reach (control) and compared diatom assemblages and algae biomass of these reaches. Diatom assemblages and traits differed substantially between the control and restored reaches and the median percentage of chlorophyll a in the periphyton biomass increased from 9% in the control reach to 12% in the restored reach. The results of this pilot study suggest that benthic diatom assemblage may be useful indicators of river restoration success, particularly for approaches that aim to reconfigure channels and increase floodplain connectivity and habitat complexity.
Highlights
River restoration seeks to reinstate impaired stream functions, forms and habitats (Geist & Hawkins, 2016; Johnson et al, 2019) often with the aim of aiding the recovery of a particular riverine species that has been driven close to extinction by alteration of the river environment
Despite their potential as an indicator in stream bioassessment, few studies have investigated the use of diatoms to monitor the benefits of river restoration efforts aimed at increasing habitat diversity
Benthic diatoms are well suited for evaluating river restoration because they rapidly colonize surfaces that are exposed following a disturbance to the stream bed; they represent the main source of primary production and are known to reflect important stream processes such as groundwater flow, sediment transport and nutrient cycling (Stevenson, Pan & van Dam, 2010)
Summary
River restoration seeks to reinstate impaired stream functions, forms and habitats (Geist & Hawkins, 2016; Johnson et al, 2019) often with the aim of aiding the recovery of a particular riverine species that has been driven close to extinction by alteration of the river environment. Benthic diatoms are well suited for evaluating river restoration because they rapidly colonize surfaces that are exposed following a disturbance to the stream bed; they represent the main source of primary production and are known to reflect important stream processes such as groundwater flow, sediment transport and nutrient cycling (Stevenson, Pan & van Dam, 2010). Given their potential as indicators of habitat change, it is our hypothesis that diatoms may be useful for monitoring change in ecological function of a river due to restoration. We present and interpret the results of this pilot study, comment on their significance for evaluating river restoration and outline plans for further investigations
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