Assessing predation risks for small fish in a large river ecosystem between contrasting habitats and turbidity conditions

American Midland Naturalist
By: , and 

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Abstract

This study examined predation risk for juvenile native fish between two riverine shoreline habitats, backwater and debris fan, across three discrete turbidity levels (low, intermediate, high) to understand environmental risks associated with habitat use in a section of the Colorado River in Grand Canyon, AZ. Inferences are particularly important to juvenile native fish, including the federally endangered humpback chub Gila cypha. This species uses a variety of habitats including backwaters which are often considered important rearing areas. Densities of two likely predators, adult rainbow trout Oncorhynchus mykiss and adult humpback chub, were estimated between habitats using binomial mixture models to examine whether higher predator density was associated with patterns of predation risk. Tethering experiments were used to quantify relative predation risk between habitats and turbidity conditions. Under low and intermediate turbidity conditions, debris fan habitat showed higher relative predation risk compared to backwaters. In both habitats the highest predation risk was observed during intermediate turbidity conditions. Density of likely predators did not significantly differ between these habitats. This information can help managers in Grand Canyon weigh flow policy options designed to increase backwater availability or extant turbidity conditions.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Assessing predation risks for small fish in a large river ecosystem between contrasting habitats and turbidity conditions
Series title American Midland Naturalist
DOI 10.1674/0003-0031-175.2.206
Volume 175
Issue 2
Year Published 2016
Language English
Publisher University of Notre Dame
Publisher location Notre Dame, IN
Contributing office(s) Southwest Biological Science Center
Description 16 p.
First page 206
Last page 221
Country United States
State Arizona
Other Geospatial Grand Canyon
Online Only (Y/N) N
Additional Online Files (Y/N) N