Dulse seaweed Devaleraea mollis mitigates effects of ocean acidification on larval Pacific oysters Magallana gigas
department or school: Land and Food Systems, Faculty of
data provider: DSpace
degree campus: UBCV
creator: Wessler, Leah
issued: 2025-10-16T17:54:24Z
issued: 2025
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Ocean acidification (OA), driven by upwelling and climate change, can negatively impact the ecological and economic contribution of marine calcifiers along coasts worldwide. OA interferes with calcification, particularly in early life stages, causing mortality, reduced growth, and morphological abnormalities in shellfish such as the Pacific oyster (Magallana gigas). This issue is gaining traction as climate change intensifies, placing shellfish in wild populations and farms alike at risk. Macroalgal photosynthesis by seaweed such as Pacific dulse (Devaleraea mollis) has been proposed to provide small-scale OA refuges, but few controlled experiments quantify this effect, and none have focused on larval shellfish. This study examines the potential for Pacific dulse to mitigate OA and its effects on Pacific oyster larvae. Under continuous light for 23 days, the presence of dulse resulted in a consistent increase in seawater aragonite saturation state by 0.1-0.9, and pH by 0.1-0.5 units, depending on OA condition. Newly fertilized oysters were reared for 48 hours in the absence or presence of dulse under treatments corresponding to ambient (pH 7.8, 450 μatm COâ), future OA (pH 7.6, 800 μatm COâ), and future OA + upwelling (pH 7.4, 1200 μatm COâ) seawater conditions. Dulse fully mitigated OA effects on larval size that ranged from decreases of 5% to 10%. Under the future OA + upwelling treatment, dulse presence reduced the odds of underdeveloped oyster larvae at 14 hours post fertilization (hpf), and larvae with hinge abnormalities at 24 hpf, by over 50%. Dulse induced minor changes to immune response gene expression at 48 hpf. These findings highlight the benefits of seaweed when adjacent to organisms sensitive to OA. These findings will be particularly useful for shellfish farms, habitat restoration efforts, and ocean stewardship practices as a potential mitigation strategy under the changing climate.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/92635
note: DULSE SEAWEED Devaleraea mollis MITIGATES EFFECTS OF OCEAN ACIDIFICATION ON LARVAL PACIFIC OYSTERS Magallana gigas by Leah Wessler B.A., Colorado College, 2017 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Applied Animal Biology) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) October 2025 © Leah Wessler, 2025 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the thesis entitled: DULSE SEAWEED Devaleraea mollis MITIGATES EFFECTS OF OCEAN ACIDIFICATION ON LARVAL PACIFIC OYSTERS Magallana gigas submitted by Leah Wessler in partial fulfilment of the requirements for the degree of Master of Science in Applied Animal Biology Examining Committee: Dr. Andrea Y. Frommel, Assistant Professor, Faculty of Land and Food Systems, UBC Supervisor Dr. Christopher D.G. Harley, Professor, Zoology, UBC Supervisory Committee Member Dr. Colin J. Brauner, Professor, Zoology, UBC Additional Examiner Additional Supervisory Committee Members: Dr. Marina A.G. von Keyserlingk, Professor, Faculty of Land and Food Systems, UBC Supervisory Committee Member iii Abstract Ocean acidification (OA), driven by upwelling and climate change, can negatively impact the ecological and economic contribution of marine calcifiers along coasts worldwide. OA interferes with calcification, particularly in early life stages, causing mortality, reduced growth, and morphological abnormalities in shellfish such as the Pacific oyster (Magallana gigas). This issue is gaining traction as climate change intensifies, placing shellfish in wild populations and farms alike at risk. Macroalgal photosynthesis by seaweed such as Pacific dulse (Devaleraea mollis) has been proposed to provide small-scale OA refuges, but few controlled experiments quantify this effect, and none have focused on larval shellfish. This study examines the pot…
has type: Thesis/Dissertation
date issued: 2025-11
is shown at: 10.14288/1.0450465
language: eng
degree discipline: Applied Animal Biology
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Frommel, Andrea Y.
type: Text
identifier URI: http://hdl.handle.net/2429/92635