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Date Permissions Signed

11-23-2022

Date of Award

Fall 2022

Document Type

Masters Thesis

Department or Program Affiliation

Huxley School of the Environment

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Sofield, Ruth M.

Second Advisor

Bodensteiner, Leo R., 1957-

Third Advisor

Hayes, Marc P.

Abstract

Amphibian populations have been declining globally since at least the 1970s. In the western United States, disappearances have resulted in significant range contractions due to habitat loss, climate change, predation by non-native species, pesticide use, and disease, most recently by the fungal pathogen, Batrachochytrium dendrobatidis. Several recent studies have addressed amphibian population declines due to climate change, yet few studies have examined the interacting effects of climate change and metal contaminants as they relate to amphibians. Risks may be especially pronounced in amphibians that reside in high-alpine aquatic ecosystems, such as the Cascades frog (Rana cascadae), which may be affected by metal contamination and climate change acting as multiple stressors.

To explore the relationship between Cascades frog (Rana cascadae) survival, metals, and climate, a two-phase study was conducted to evaluate metals and temperature as multiple factors, and how they may affect in aquatic environments with breeding populations of Cascades frog. In Phase I, the goal was to identify and select aqueous metals present in mountain ponds during the Cascades frog breeding season to understand potential exposure levels. During this Phase, surface water grab samples were collected, and stabilized liquid membrane devices (SLMDs) deployed. The metals found in the surface water samples and the SLMDs were used to inform and select metals to test in Phase II, where laboratory toxicity testing of copper (Cu), nickel (Ni), and zinc (Zn) was conducted at 20.0°C and 22.5°C. Toxicological endpoints included: time to hatch, time to mortality, length, percent malformed, and percent survival. The test organism was the locally abundant species, the Northern red-legged frog (Rana aurora), which was used as a surrogate for Cascades frog.

Phase I of this study revealed several metals including aluminum (Al), chromium (Cr), Ni, Cu, Zn, arsenic (As), cadmium (Cd), and lead (Pb) in breeding ponds that exceeded USEPA Criterion Continuous Concentration (CCC) and the Criterion Maximum Concentration (CMC) Water Quality Criteria (WQC) for Aquatic Life. In addition, the Phase II laboratory toxicity testing found that exposure to Cu and Ni, as single-metal toxicants and in combination at two environmentally relevant temperatures, have the potential to impact Cascades frog even at small concentrations. Mixed metal toxicity tests also revealed that Ni may have an ameliorating effect on Cu toxicity. Moreover, the higher of the two environmentally relevant temperatures did not appear to significantly affect the surrogate species but the temperature data reveals ambiguities that merit further investigation.

Type

Text

Keywords

Cascades frog, montane amphibians, metal toxicity, temperature, copper, nickel, climate change

Publisher

Western Washington University

OCLC Number

1352073537

Subject – LCSH

Cascades frog--Abnormalities; Cascades frog--Effect of metals on; Cascades frog--Reproduction--Effect of temperature on ; Metals--Toxicology; Water temperature--Physiological effect

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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