Quantifying the habitat and zoogeomorphic capabilities of spawning European barbelBarbus barbus, a lithophilous cyprinid

Catherine Gutmann Roberts,J Robert Britton,Stephen Rice,Tea Bašić,Andrew G Pledger

doi:10.1002/rra.3573

Abstract

AbstractSuitable gravel availability is critical for the spawning success of lithophilous fishes, including redd builders. Redd construction during spawning can alter substrate characteristics, thereby influencing hydraulic conditions and sediment transport, highlighting the importance of spawning as a zoogeomorphic activity. Here, interactions between redd‐building fish and their spawning environment were investigated for European barbelBarbus barbuswith a comparative approach across three English rivers: Teme (western), Great Ouse (eastern) and Idle (central). Sediment characteristics of spawning habitats were similar across the rivers, including subsurface fine sediment (<2 mm) content (≈20% dry weight), but elevated subsurface silt content and coarser surface sediments were found in the river Teme. Water velocities were similar at spawning sites despite differences in channel width and depth. Redds were characterized by a pit and tailspill, with no differences in surface grain‐size characteristics between these and the surrounding riverbed, but with topographic alteration (dimensions and tailspill amplitude) in line with those of salmonids. Estimates of the fraction of the bed that spawning barbel were capable of moving exceeded 97% in all rivers. Estimated reproductive potential varied significantly between the rivers Idle and Teme (3,098 to 9,715 eggs/m2), which was largely due to differences in barbel lengths affecting fecundity. Larger barbel, capable of producing and depositing more eggs, but in more spatially extensive redds, meaning fewer redds per given surface area of riverbed. Predictions of barbel egg mortality based on sand content were low across both rivers. The effects of silt on barbel egg and larvae development are unknown, but the levels detected here would significantly impact salmon egg mortality. Similarities in fish length to redd area and the size of moveable grains by spawning barbel and salmon suggest they have similar geomorphic effects on sediments, although fine sediment tolerance is highly divergent.

Highlights

Geological, morphological and hydrological processes in rivers have important implications for sustaining biological communities (Bravard et al, 1997; Elosegi, Díez, & Mutz, 2010)
Lithophilous fishes are especially dependent on the physical environment for their spawning success, as construction of redds for egg deposition and incubation means egg survival and larval emergence rates can be impacted by suboptimal spawning substratum (Goode, Luce, & Buffington, 2012; Greig, Sear, & Carling, 2007; Lapointe, Bergeron, Berube, Pouliot, & Johnston, 2004)
There were no significant differences between the surface grain-size characteristics of the pit and tailspill areas compared with their surrounding riffle for D5, D50, D95, mean, sorting, skewness, kurtotsis and percentage of fine sediment (Table 5)

Summary

Introduction

Geological, morphological and hydrological processes in rivers have important implications for sustaining biological communities (Bravard et al, 1997; Elosegi, Díez, & Mutz, 2010). Lithophilous fishes are especially dependent on the physical environment for their spawning success, as construction of redds for egg deposition and incubation means egg survival and larval emergence rates can be impacted by suboptimal spawning substratum (Goode, Luce, & Buffington, 2012; Greig, Sear, & Carling, 2007; Lapointe, Bergeron, Berube, Pouliot, & Johnston, 2004). Large quantities of fine sediment (

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