Thermal Characteristics of a Beaver Dam Analogues Equipped Spring-Fed Creek in the Canadian Rockies

Tariq Munir,Cherie Westbrook

doi:10.3390/w13070990

Abstract

Beaver dam analogues (BDAs) are becoming an increasingly popular stream restoration technique. One ecological function BDAs might help restore is suitable habitat conditions for fish in streams where loss of beaver dams and channel incision has led to their decline. A critical physical characteristic for fish is stream temperature. We examined the thermal regime of a spring-fed Canadian Rocky Mountain stream in relation to different numbers of BDAs installed in series over three study periods (April–October; 2017–2019). While all BDA configurations significantly influenced stream and pond temperatures, single- and double-configuration BDAs incrementally increased stream temperatures. Single and double configuration BDAs warmed the downstream waters of mean maxima of 9.9, 9.3 °C by respective mean maxima of 0.9 and 1.0 °C. Higher pond and stream temperatures occurred when ponding and discharge decreased, and vice versa. In 2019, variation in stream temperature below double-configuration BDAs was lower than the single-configuration BDA. The triple-configuration BDA, in contrast, cooled the stream, although the mean maximum stream temperature was the highest below these structures. Ponding upstream of BDAs increased discharge and resulted in cooling of the stream. Rainfall events sharply and transiently reduced stream temperatures, leading to a three-way interaction between BDA configuration, rainfall and stream discharge as factors co-influencing the stream temperature regime. Our results have implications for optimal growth of regionally important and threatened bull and cutthroat trout fish species.

Highlights

When streams have degraded to the point that they are inhospitable for beavers, beaver dam analogues (BDAs) are used as a low-cost, low-tech restoration solutions [9,10,11,12]
Stream discharge was the strongest control over variations in downstream temperatures followed by BDA configuration and pond depth in that order
Results of a linear mixed-effects models (LMEM) for stream temperature were validated by a linear regres

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Beavers (Caster canadensis and C. fiber) are ubiquitously considered as aquatic ecosystem engineers in recognition of the ecosystem functions provided by their dams [1,2,3,4]. Changes in the streamflow regime can lead to channel aggradation [5,6]. In streams from which beavers have been lost via removal or relocation, channels incise and riparian areas ecologically degrade [7,8]. When streams have degraded to the point that they are inhospitable for beavers, beaver dam analogues (BDAs) are used as a low-cost, low-tech restoration solutions [9,10,11,12]. BDAs can be installed in a variety of configurations, ranging from individual structures to multiple structures in sequence [13,14], the goal of which is ensuring some BDAs persist following larger flow events [4]

Objectives

Methods

Results

Conclusion