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Date Permissions Signed

6-29-2022

Date of Award

Summer 2022

Document Type

Masters Thesis

Department or Program Affiliation

College of the Environment

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Love, Brooke

Second Advisor

Murray, Christopher S.

Third Advisor

Sobocinski, Kathryn L.

Fourth Advisor

Cooper, W. James, 1969-

Abstract

Anthropogenic climate change, including the interactive effects of ocean acidification and temperature rise, is projected to affect marine ecosystems by challenging the environmental tolerance limits of individual species. Such impacts have been documented in a handful of marine fishes, including major physiological effects experienced in early-life stages of Pacific herring, an important forage and commercial fish species widely distributed in coastal systems across the North Pacific. In this study, we investigated the effects of temperatures between 10- 16°C and two pCO2 levels (ambient and high pCO2) on hatching and survival of Pacific herring. Survival after acute temperature exposure was assessed and compared between incubation treatments, as may be experienced by herring egg deposits during low tide on warm days. We compared early and late spawning populations to determine if their responses differed when exposed to chronic temperature and pCO2 conditions and to short term temperature stress. A subset of embryos from the 10°C and 16°C treatments were exposed to critical thermal maximum (CTmax) trials that simulated the acute temperature fluctuations associated with marine heat waves and tidal processes in shallow nearshore habitats. Hatching success was primarily influenced by temperature in both winter and spring embryos. CTmax results indicate that embryos were able to withstand acute exposure to 20°C regardless of spawning population or incubation treatments, but survival was greatly reduced after 2-3 hours at 25°C. Post-exposure heart contraction measurements revealed a greater rate of increase in heart rate in the combined treatment of 10°C and CTmax duration hours compared to 16°C, suggesting respiratory acclimation at higher incubation temperatures. Oxygen consumption rates (MO2 ) measured at stable incubation conditions resulted in higher MO2 values at elevated temperatures and pCO2 v levels. Overall, this study reinforces that Pacific herring are resilient to moderate pCO2 and temperature stress but are vulnerable to acute temperature increases that may accompany marine heatwave events and late season low tide temperatures, and in some cases the combination of elevated pCO2 and temperature can introduce additional challenges for these important forage fish.

Type

Text

Keywords

forage fish, climate change, ocean acidification, Pacific herring, temperature tolerance, temperature rise, Salish Sea, herring, marine science, oxygen consumption, heart rate

Publisher

Western Washington University

OCLC Number

1341408508

Subject – LCSH

Pacific herring--Effect of temperature on--Northwest, Pacific; Ocean acidification--Environmental aspects--Northwest, Pacific; Ocean temperature--Northwest, Pacific

Geographic Coverage

Northwest, Pacific

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

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