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Saturday May 16, 2020
AUTHORS:
Andrew Wymore, Travis Landon, and Lydia Brown
FACULTY: Dr. Chris Walser
DEPARTMENT: Biology
Dry Creek, an intermittent headwater stream in Southwest Idaho, supports a genetically pure population of Columbia River redband trout, subspecies of the Rainbow trout. The stream, drying from the bottom up during the peak of summer, poses several unique challenges to these trout during this stressful time; high temperatures, low dissolved oxygen (DO), and decreased resource availability. While common, these inttermittent streams are not well studied. This study aims to enhance our understanding on the effects of stream drying on the stream, and how this in turn affects the biota it supports. We measured several indicators of stream health, macroinvertebrate density, and redband trout condition at 10 sites from June to September of 2019. Findings include decreased stream velocity over time, leading to increased temperature and decreased DO levels. Indeed, redband trout were able to persist in pools with less than 6 mg/l, and were generally found in greater abundance at upstream sites with more ideal conditions. The average trout was in significantly better condition at the beginning of the study than at the end, which we attribute in part to decreased DO, as well as significantly decreased macroinvertebrate drift, which constitutes a notable portion of food available to trout.
The College of Idaho 2112 Cleveland Blvd Caldwell, ID 8360 USA 208-459-5011 800-2C-IDAHO
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