The scale-dependent role of submerged macrophytes as drift-feeding lotic fish habitat

Canadian Journal of Fisheries and Aquatic Sciences
By: , and 

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Abstract

Although submerged macrophyte (hereafter, “macrophyte”) communities are globally prevalent in low-gradient rivers, the net reach-scale effect of macrophytes on drift-feeding fish microhabitat preference is poorly understood. We used snorkeling and bioenergetics to study fish habitat selection for rainbow trout (Oncorhynchus mykiss) in the Henrys Fork, ID, USA, investigating microhabitat preference across a reach-scale gradient of macrophyte growth. Fish preferred microhabitats with deep water, low velocity, and low macrophyte coverage. Preferences for microhabitats with higher net rate of energy intake (NREI) were modulated by reach-scale macrophyte coverage, higher coverage increasing preferences for higher NREI. Macrophyte coverage was a weak positive predictor for depth and NREI, and a weak negative predictor for water velocity and median substrate. Our results suggest trade-offs between fish predation risk and bioenergetic food intake, with macrophytes modulating these trade-offs across scales by affecting reach-scale geomorphology, bioenergetics, and predation risk. As such, this study highlights the important and dynamic role that macrophytes can play in fish population dynamics in rivers, with important implications for management decisions.

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Publication type Article
Publication Subtype Journal Article
Title The scale-dependent role of submerged macrophytes as drift-feeding lotic fish habitat
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/cjfas-2022-0182
Volume 80
Issue 9
Year Published 2023
Language English
Publisher Canadian Science Publishing
Contributing office(s) Coop Res Unit Seattle
Description 14 p.
Country United States
State Idaho
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