Short-Term Impacts of Remeandering Restoration Efforts on Fish Community Structure in a Fourth-Order Stream

Jennifer Clark,Justin Montemarano

doi:10.3390/w9070546

Abstract

Channel reconfiguration is a common but debated method used to restore streams, often causing disturbance and producing subsequent negative impacts on biota. Here, we report results from short-term assessment (i.e., one and three years’ post-restoration) of habitat variables (e.g., reach depth, substrate, and canopy cover) and fish community composition and structure (using electrofishing surveys; e.g., proportion of juveniles and tolerant fishes) from a 675 m section of Eagle Creek (Portage County, OH, USA) restored using channel remeandering in August 2013. Mesohabitat analysis was not conducted as part of this study. Sites upstream and downstream of restoration efforts were also monitored. Surveys were completed in 10 separate 50 m stretches: one upstream control site, three new channel sites, two old channel sites, and three downstream sites. Following restoration, fish communities in downstream sites became more similar to new channel sites and diverged from the upstream control site over time, as reflected in increased proportions of juvenile and tolerant fishes. Shifts in fish communities were not explained by habitat variables. Diversity was significantly lower in new channel sites post-restoration than in the upstream control, while downstream sites remained similarly high in diversity compared to the upstream control site over time. Overall, in the short-term, new channel colonizing communities were unable to recover to reflect upstream community composition and structure, and fish communities downstream of restoration were negatively impacted.

Highlights

To improve stream health and function due to anthropogenic degradation, restoration efforts are common across the U.S with more than US $1 billion spent on projects each year [1,2].The majority of stream restoration projects have one or more goals targeted towards increasing biodiversity, stabilizing the channel, improving riparian habitat, improving water quality, and creating in-stream habitat for biota, and most efforts utilize in-stream hydromorphic changes and channel hydromorphic alteration/reconfiguration along with riparian restoration with riparian plantings to accomplish project goals [3]
Higher in the upstream control site than that in both the downstream sites and new channel sites, whereas water depth was greater in the downstream control sites compared to that in both the upstream control site and new channel sites
Substrate size was statistically similar between the upstream control site and downstream sites (Tukey’s honest significant difference (HSD) > 0.05), and no differences were detected in canopy cover, depth, or substrate size across years (p > 0.08)

Summary

Introduction

To improve stream health and function due to anthropogenic degradation, restoration efforts are common across the U.S with more than US $1 billion spent on projects each year [1,2].The majority of stream restoration projects have one or more goals targeted towards increasing biodiversity, stabilizing the channel, improving riparian habitat, improving water quality, and creating in-stream habitat for biota, and most efforts utilize in-stream hydromorphic changes (e.g., addition of boulders, other sediments, and log jams) and channel hydromorphic alteration/reconfiguration (e.g., raising or lowering the bed to reconnect to the floodplain, creating new meanders, and lateral movement of the channel) along with riparian restoration with riparian plantings to accomplish project goals [3]. The practice of stream restoration is widespread, both short-and long-term monitoring to evaluate restoration goals are generally lacking [1,3,4,5]. Short-term monitoring efforts have increased in recent years [6] and are largely due to implementation by the U.S Army Corps of Engineers and U.S Environmental Protection Agency of the 2008 Compensatory Mitigation for. As part of this legislation, projects under the Clean Water Act section. 404 and Department of the Army permits are required to monitor compensatory mitigation efforts (e.g., stream restoration projects) for no less than five years to assess whether or not the performance objectives are met [7]. When monitoring occurs, a standard set of criteria are not used, baseline data prior to restoration is limited, and few make comparisons to nearby streams with similar degradation prior to restoration

Objectives

Results

Conclusion