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

Mirza A T M Tanvir Rahman; Junjiro N Negishi; Takumi Akasaka; Futoshi Nakamura

doi:10.1002/ece3.7366

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

Ecol Evol. 2021 Mar 11;11(9):4656-4669. doi: 10.1002/ece3.7366. eCollection 2021 May.

Authors

Mirza A T M Tanvir Rahman^{1

2}, Junjiro N Negishi³, Takumi Akasaka⁴, Futoshi Nakamura⁵

Affiliations

¹ Laboratory of Watershed Conservation and Management, Graduate School of Environmental Science Hokkaido University Sapporo Japan.
² Department of Environmental Sciences Jahangirnagar University Dhaka Bangladesh.
³ Laboratory of Watershed Conservation and Management, Faculty of Environmental Earth Science Hokkaido University Sapporo Japan.
⁴ Laboratory of Conservation Ecology, Department of Agriculture and Animal Science Obihiro University of Agriculture and Veterinary Medicine Obihiro Japan.
⁵ Laboratory of Ecosystem Management, Research Faculty of Agriculture Hokkaido University Sapporo Japan.

Abstract

Hyporheic zone (HZ) locates below the riverbed providing habitat for macroinvertebrates from where the winged adult insects (i.e., hyporheic insects, HIs) emerge and bring out aquatic resources to the riparian zone. This study estimated mean daily flux as dry biomass (BM), carbon (C), and nitrogen (N) deriving from the dominant HI species Alloperla ishikariana (Plecoptera, Chloroperlidae) for a 4th-order gravel-bed river during the early-summer to summer periods. We hypothesized that HIs were an important contributor in total aquatic resources to the riparian zone. In 2017 and 2018, we set parallelly (May to August) and perpendicularly (June to October) oriented Malaise traps to catch the lateral and longitudinal directional dispersing winged adults of A. ishikariana, and other Ephemeroptera, Plecoptera, Trichoptera, and Diptera from the river and estimated the directional fluxes of them. We further split the directional fluxes as moving away or back to the channel (for lateral) and from down- to upstream or up- to downstream (for longitudinal). Alloperla ishikariana was similar to other Plecoptera species and differed clearly from Ephemeroptera and Trichoptera in directional characteristics of resources flux, suggesting that the extent and directions of HZ-derived resource transfer depend on taxon-specific flight behaviors of HIs. Contributions of A. ishikariana to the riparian zone in total aquatic C and N transfer seasonally varied and were lower in May (5%-6%) and August (2%-4%) and the highest in July (52%-70%). These conservative estimates largely increased (9% in May) after the supplementary inclusion of Diptera (Chironomidae and Tipulidae), part of which were considered HIs. We demonstrated that HZ could seasonally contribute a significant portion of aquatic resources to the riparian zone and highlighted the potential importance of HZ in nutrient balance in the river-riparian ecosystem.

Keywords: Plecoptera; dispersal; resource transfer; riparian zone; subsurface interface.

Associated data

Dryad/10.5061/dryad.wstqjq2kg