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Does resolution of flow field observation influence apparent habitat use and energy expenditure in juvenile coho salmon?

August 1, 2016

This study investigated how the resolution of observation influences interpretation of how fish, juvenile Coho Salmon (Oncorhynchus kisutch), exploit the hydraulic environment in streams. Our objectives were to evaluate how spatial resolution of the flow field observation influenced: (1) the velocities considered to be representative of habitat units; (2) patterns of use of the hydraulic environment by fish; and (3) estimates of energy expenditure. We addressed these objectives using observations within a 1:1 scale physical model of a full-channel log jam in an outdoor experimental stream. Velocities were measured with Acoustic Doppler Velocimetry at a 10 cm grid spacing, whereas fish locations and tailbeat frequencies were documented over time using underwater videogrammetry. Results highlighted that resolution of observation did impact perceived habitat use and energy expenditure, as did the location of measurement within habitat units and the use of averaging to summarize velocities within a habitat unit. In this experiment, the range of velocities and energy expenditure estimates increased with coarsening resolution (grid spacing from 10 to 100 cm), reducing the likelihood of measuring the velocities locally experienced by fish. In addition, the coarser resolutions contributed to fish appearing to select velocities that were higher than what was measured at finer resolutions. These findings indicate the need for careful attention to and communication of resolution of observation in investigating the hydraulic environment and in determining the habitat needs and bioenergetics of aquatic biota.

Citation Information

Publication Year 2016
Title Does resolution of flow field observation influence apparent habitat use and energy expenditure in juvenile coho salmon?
DOI 10.1002/2015WR018501
Authors Desiree D. Tullos, Cara Walter, Jason B. Dunham
Publication Type Article
Publication Subtype Journal Article
Series Title Water Resources Research
Series Number
Index ID 70185053
Record Source USGS Publications Warehouse
USGS Organization Forest and Rangeland Ecosystem Science Center