Ecological consequences of shoreline armoring on littoral fish and benthic macroinvertebrate communities in an Eastern O
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Aquatic Sciences
RESEARCH ARTICLE
Ecological consequences of shoreline armoring on littoral fish and benthic macroinvertebrate communities in an Eastern Ontario lake Auston D. Chhor1 · Daniel M. Glassman1 · John P. Smol2 · Jesse C. Vermaire3,4 · Steven J. Cooke1,3,4 Received: 11 September 2019 / Accepted: 10 July 2020 © Springer Nature Switzerland AG 2020
Abstract Shoreline erosion in lakes is a pressing issue for many landowners, yet common erosion mitigation practices that involve armoring can alter littoral habitat and potentially diminish near-shore biodiversity. We studied the effects of two armoring methods (i.e., riprap, retaining walls) on habitat, taxonomic richness, relative abundance, and total abundance of fishes and benthic macroinvertebrates at shorelines on Big Rideau Lake in eastern Ontario, Canada. Snorkel surveys were conducted to assess aquatic habitat characteristics and fish diversity, and benthic infauna were sampled using kick-nets. Submergent and emergent macrophytes were more abundant at natural rocky shorelines compared to shorelines modified with riprap or retaining walls. Coarse woody debris was also more abundant at natural shorelines compared to riprap and retaining wall shorelines. Relative abundances of some fish species varied between shoreline types, but overall species richness and total abundance did not. Largemouth Bass (Micropterus salmoides) were more abundant at natural sites than armored sites. Conversely, Rock Bass (Ambloplites rupestris), Pumpkinseed (Lepomis gibbosus), Bluegill (Lepomis macrochirus), Yellow Perch (Perca flavescens), and baitfish from the family Cyprinidae were more abundant at both types of armored sites compared to natural sites. Taxonomic richness of benthic macroinvertebrates did not vary among shoreline types, however abundance of Amphipoda, Isopoda, Ephemeroptera, and Cladocera was greater at armored shorelines. These results suggest that human modification of shorelines is altering littoral ecosystems and potentially leading to shifts in the community structure of littoral nekton. More study is needed to fully understand the community level effects of shoreline erosion mitigation involving armoring in freshwater lakes and determine the effectiveness of alternative mitigation strategies that preserve natural habitat features. Keywords Aquatic habitat · Erosion mitigation · Riprap · Retaining walls · Shoreline
Introduction
* Auston D. Chhor [email protected] 1
Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, ON, Canada
2
Department of Biology, Queen’s University, Kingston, ON, Canada
3
Institute of Environmental and Interdisciplinary Sciences, Carleton University, Ottawa, ON, Canada
4
Department of Geography and Environmental Studies, Carleton University, Ottawa, ON, Canada
Anthropogenic alteration of natural ecosystems is arguably the greatest challenge facing biodiversity today (Vitousek et al. 1997). Historically, shorelines have been popular sites for human set
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