2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/21/2019 | 12:15 PM - 12:30 PM | EXTREME DROUGHT LIMITS SURVIVAL OF ENDANGERED COHO SALMON IN INTERMITTENT STREAMS | 151 G

EXTREME DROUGHT LIMITS SURVIVAL OF ENDANGERED COHO SALMON IN INTERMITTENT STREAMS

Droughts are becoming more frequent and severe throughout the world. Despite evidence that droughts can extirpate populations of freshwater biota, there is also growing recognition of the importance of habitat refugia in buffering drought impacts. In this study, we explored the role of intermittent stream pools in sustaining populations of endangered coho salmon (Oncorhynchus kisutch). We used mark-recapture techniques to quantify over-summer survival of juvenile coho in stream pools across eight study reaches during California’s record-breaking drought. We explored spatial variability in salmon survival within and among reaches and quantified the effects of abiotic environmental variables and intraspecific salmon density on cumulative survival estimates. Our results show that some stream reaches acted as refugia and maintained survival similar to non-drought years. Within reaches, we also found that some pools sustained fish throughout the summer, whereas others dried completely. Duration of pool disconnection was the most influential variable in predicting over-summer survival. Few, if any, salmon survived when pools were disconnected for longer than 40 days. Our results underscore the importance of intermittent streams as habitat refugia, but also highlight their vulnerability to extreme droughts.

Disturbance
Fish
Intermittency

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Presenters/Authors

Ross Vander Vorste (), Rivers Study Center and Department of Biology - University of Wisconsin La Crosse , vandervorste.ross@gmail.com;