2023 Early Hearing Detection & Intervention Conference
March 5-7, 2023 • Cincinnati, OH
5/24/2021 | 2:00 PM - 3:30 PM | EFFECTS OF DECREASING FLOWS ON STREAM PHYSICOCHEMISTRY, MACROINVERTEBRATE ABUNDANCE, AND REDBAND TROUT (ONCORHYNCHUS MYKISS) CONDITION IN AN EPHEMERAL SYSTEM | Virtual Platform
EFFECTS OF DECREASING FLOWS ON STREAM PHYSICOCHEMISTRY, MACROINVERTEBRATE ABUNDANCE, AND REDBAND TROUT (ONCORHYNCHUS MYKISS) CONDITION IN AN EPHEMERAL SYSTEM
Intermittent rivers and ephemeral streams are one of the most common, yet least studied types of aquatic ecosystems. Dry Creek, an ephemeral stream in southwestern Idaho, supports a genetically pure population of redband trout (Oncorhynchus mykiss). Our objective was to evaluate trout response to changing physicochemical conditions as stream flows decline. From June to September 2019, we used loggers to monitor stream temperatures and dissolved oxygen concentrations at 30-min intervals across 10 study reaches. We measured current velocity weekly, drifting macroinvertebrates were collected biweekly, while trout were sampled monthly at all reaches. Fish Condition Factor (K) was calculated to estimate fish health. We found current velocity decreased at all reaches. Mean daily water temperatures (6.4-22.3°C) were within an acceptable range for trout, but in late summer dissolved oxygen fell below the critical limit for trout (6.0mg/L). Across all reaches, rate of delivery of macroinvertebrates (number/15 min.) was significantly lower in August than June and July (p<0.05). Mean K for trout was significantly higher in July (1.25) than September (0.99) (p<0.05). We attribute this decline in trout condition to decreases in dissolved oxygen and macroinvertebrates brought upon by reduced stream flow.
- Climate change
- Flow
- Stream
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Presenters/Authors
Chris Walser
(), The College of Idaho, cwalser@collegeofidaho.edu;
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Andrew Wymore
(), The College of Idaho, andrew.wymore@yotes.collegeofidaho.edu;
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