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Date of Award

Fall 2024

Document Type

Masters Thesis

Department or Program Affiliation

Biology

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Olson, M. Brady (Michael Brady)

Second Advisor

Cooper, W. James, 1969-

Third Advisor

Lemkau, Karin

Abstract

Polyunsaturated aldehydes (PUAs) are secondary oxylipins produced by some diatoms. PUAs are produced at a greater rate when diatom cells are damaged, suggesting that they may act as chemical grazing deterrents. Past studies showed the deleterious effects of particulate PUAs on diatom consumers like copepods and marine invertebrates. However, to date, very few studies have explored the potential for diatom-derived PUAs to affect marine vertebrates, such as forage fishes. Forage fishes are a foundational functional group in marine ecosystems whose early life history stages are often sympatric with diatoms due to their nearshore spawning behavior and planktivorous diet. In this study, I addressed the question of whether PUAs detrimentally affect a common Salish Sea forage fish, the surf smelt (Hypomesus pretiosus; Girard 1854). The project focused on determining whether PUAs affect the development and physiology of surf smelt embryos and larvae. This was done by measuring survival and hatch success rates, embryonic heart rates, usage of endogenous energy reserves, and morphological features at hatch. Higher concentrations of PUAs resulted in higher mortality and lower hatch success rates of embryonic surf smelt. Embryonic heart rates were equivalent among treatments when embryos were exposed to PUAs soon after fertilization, suggesting that surf smelt embryos can acclimate to PUAs if exposed during early development. However, higher concentrations of PUAs significantly lowered the heart rates of embryos that were exposed to PUAs days after fertilization. Exposure to PUAs diminished the consumption rate of endogenous energy reserves, and the overall size of surf smelt at hatch was reduced. Our results indicate that exposure to dissolved PUAs could impair the fitness of ecologically foundational forage fish early life history stages. Negative effects that manifest into low adult population sizes will have cascading effects on marine ecosystems.

Type

Text

Keywords

Polyunsaturated aldehydes, diatoms, forage fish, larvae, food web

Publisher

Western Washington University

OCLC Number

1479455058

Subject – LCSH

Polyenes; Allelopathic agents; Diatoms; Forage fishes--Larvae; Food chains (Ecology)

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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