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Dissertation/Thesis Abstract

Effects of Ocean Acidification on the Growth and Survival in Early-Stage Red Abalone (Haliotis rufescens): Adaptive Strategies for Conservation and Production Aquaculture
by Boles, Sara Elizabeth, Ph.D., University of California, Davis, 2020, 122; 28150568
Abstract (Summary)

The shellfish aquaculture industry has been identified as a sustainable source of protein to feed a growing global population. Absorption of carbon dioxide (CO2) by the world’s oceans is leading to a decline in ocean pH, resulting in process termed ocean acidification (OA), and is occurring at an unprecedented rate. The result of OA has reduced global surface oceans by 0.1 pH units and is projected to decrease by 0.3 to 0.4 pH units by the year 2100. The negative consequences of OA have been shown to reduce calcification, growth, and survival during sensitive larval and post-settlement life-history stages in both ecologically and economically important species of shellfish. The consequences of OA are threatening the viability of these economically and ecologically important resources; however, few adaptive aquaculture strategies exist to mitigate the negative effects of OA. Red abalone (H. rufescens) are a culturally, ecologically, and economically important species of shellfish, yet few studies have investigated the effects of OA across sensitive life-history stages and adaptive culture strategies for this species are absent. To address these gaps in knowledge during sensitive larval and post-settlement stages with the following objectives we examined: (1) the mitigative effect of post-settlement diet in wild-caught (VD: Van Damme, CA) and captive (SB: Santa Barbara, CA) populations of red abalone exposed to OA conditions; and (2) the capacity of seawater chemistry manipulations and the tailoring post-settlement and grow-out temperatures during sensitive stages to buffer the negative carry-over effects of OA into later life-history stages.

To test the OA-buffering effect of natural (CCA: crustose coralline algae) and commercially grown (NV: Navicula sp. Diatoms) post-settlement diets on the survival of wild-caught and captive populations of red abalone, embryos were cultured from 6 hours post-fertilization to 97 days post-fertilization (dpf) under either control-pH or OA treatment conditions. We found that CCA enhanced post-settlement survival in both populations under both control-pH and OA treatment conditions compared to abalone settled on NV diatoms; however, this effect remained significant only in the SB population at later post-settlement stages. Variation in response to pH treatment conditions was observed between the two populations with SB abalone displaying a considerable decline in post-settlement survival when cultured under OA conditions, whereas, survival of VD-sourced abalone was not affected by OA. We also observed a significant effect of settlement diet on the relationship between total larval lipids stores and post-settlement survival, a relationship that was more pronounced in VD compared to SB abalone.

To assess the mitigative capacity of pH manipulations to buffer the negative consequence of OA, we cultured red abalone from embryos (6 hours post-fertilization) to 7 dpf under control-pH or OA conditions and were settled under a factorial combination of these treatments. Post-settlement and grow-out temperatures were tailored to enhance the growth of abalone cultured under the various pH treatment conditions. Slight warming during post-settlement and grow-out stages enhanced the growth of red abalone; however, this effect was dependent on pH treatment exposure history. Results from this dissertation reveal the effects of OA across larval and post-settlement stages in red abalone are complex; however, they highlight the potential for adaptive culture techniques to sustain and advance red abalone conservation and production aquaculture in the face of ocean change.

Indexing (document details)
Advisor: Whitehead, Andrew
Commitee: Sanford, Eric, Miller, Michael
School: University of California, Davis
Department: Pharmacology and Toxicology
School Location: United States -- California
Source: DAI-B 82/8(E), Dissertation Abstracts International
Subjects: Climate Change, Aquatic sciences, Physiology
Keywords: Aquaculture, Climate resilience, Global environmental change, Lipid regulation, Ocean Acidification, Haliotis rufescens, Red Abalone
Publication Number: 28150568
ISBN: 9798582531517
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