Coupled benthic–hyporheic responses of macroinvertebrates to surface water pollution in a gravel-bed river

Estimates of resource transfer via winged adult insects from the hyporheic zone in a gravel‐bed river

“…The study extends on previous studies on aquatic larvae of insects and the identification of amphibitic insect taxa in the study river. Negishi, Hibino, et al (2019) found one species of Plecoptera belonging to the family Chloroperlidae (Alloperla ishikariana) mostly in the hyporheic zone (see also Alam et al, 2020), and this species dominated hyporheic insect biomass comprising >70% (unpublished data, JN Negishi). Species of Chloroperlidae are widely adapted to habitat in the hyporheic zone (e.g., McElravy & Resh, 1991;Ray et al, 2010;Silveri et al, 2009), and thus, we focused on A. ishikariana as a model organism to estimate resource transfer associated with insects found in hyporheic zone (i.e., hyporheic insects, HIs).…”

“…Although Diptera (D) can be a significant contributor of resource transfers to riparian zone (Carlson et al, 2016;Jonsson & Stenroth, 2016), preliminary sample observations suggested that this was not the case in our study and thus D was not included as major targeted taxa in this study. To check the validity of this assumption, we also reported estimates only in the lateral dimension including D, by also considering that a part of D comprises HIs (Negishi, Hibino, et al, 2019). We hypothesized that HIs would be an important contributor to total aquatic resources to the riparian zone.…”

“…Spur dikes to control flood and riverbed erosion existed within the segment (Yamaguchi et al, 2013), and there was a multi-purpose dam to generate hydroelectricity and control floods approximately 25 km upstream from the studied segment (Takahashi & Nakamura, 2011) the study segment. More details of the study area were provided in Negishi, Hibino, et al (2019) and Negishi, Terui, et al (2019).…”

“…Non-hyporheic Plecoptera (non-hyporheic P) referred to Plecoptera without A. ishikariana, unless otherwise noted. Among Diptera, we only sorted out Chironomidae and Tipulidae because they were dominating Diptera in the hyporheic zone of the study area according to Negishi, Hibino, et al (2019).…”

“…To check how the exclusion of D would affect the estimation, supplementary estimates were recalculated by including D as HIs. To specify D that might have originated from the hyporheic zone (hyporheic D) and benthic zone (non-hyporheic D), we divided the fluxes of Chironomidae and Tipulidae by considering 50% and 10% of them were from the hyporheic zone according to the information provided in Negishi, Hibino, et al (2019). Then, we summed the family-level data to obtain the benthic and hyporheic zones originating Diptera mediated fluxes.…”