Evolutionary underpinnings of stress response in Pacific oysters
Investigators
University of Alaska Fairbanks
University of Alaska Fairbanks
University of Alaska Fairbanks
Overview
The issue
Pacific oyster mariculture in Alaska represents an important and growing source of marine revenue for coastal communities and the state overall. At the farm level, reduced oyster growth and survival poses an important barrier to profitability for farmers and hatchery operators. Identifying factors contributing to variability in growth and survival is therefore a major research gap in the Alaskan oyster industry. This work is highly appropriate for Alaska Sea Grant support given that it addresses several near-term research aims of the Alaska Mariculture Development Plan, including addressing questions around oyster larvae growth, meat yields, as well as toxin accumulation and clearance in Pacific oysters. Additionally, use of Solid Phase Absorption Toxin Tracking (SPATT) devices will aid not only as a tool in environmental monitoring of toxin levels within water, contrast of SPATT results with oyster tissue concentrations will provide data regarding a low-cost toxin monitoring approach. Through study of thermal and toxicological environmental stressors, this work will provide necessary data regarding the sub-lethal impact of temperature and algal toxins on Pacific oyster growth and survival.
Objectives
The goals of this work are directed towards understanding the influence of ecologically relevant thermal drivers (temperature) and toxic algal organisms upon the growth and survival of Pacific oysters in Alaskan mariculture. To safeguard producer incomes and develop strategies for impact reduction, we aim to understand the influence of environmental stressors on the growth and physiology of cultured Pacific oysters. Through partnering with resource managers, marine resource agencies, and communities, we propose to conduct controlled challenge trials as well as monitor maricultured populations to examine the impacts of thermal and toxicological stressors. At present, it is unclear how well different strains tolerate environmental temperature fluctuations at Alaskan mariculture sites. Similarly, data is lacking regarding the chronic impacts and toxin clearance times of oysters exposed to harmful dinoflagellate Alexandrium in Alaska. Directly from this work, results will provide solid data regarding the impact of heat stress and algal toxins on oyster growth, metabolism, and tissue integrity. Long-term, data might be used by producers to select oyster strains, make management decisions during stressor events such as heat waves or algal blooms, as well as aid producer understanding of the influence of these environmental stressors in instances of ‘no grow’ stock or mortality events.
How will researchers conduct their study?
Through assessment of oyster shells and tissue, we propose to examine visual, genetic and microscopic cellular indicators of response to thermal stress and algal toxin exposure in two oyster strains: Miyagi and Midori. Analysis of gene expression using RNA sequencing technology will allow us to characterize the genomic response in early developing oysters of each strain to environmental stressors as part of a controlled challenge trial. Through observation and sample collection from mariculture sites, the uncontrolled influence of these environmental factors on sub-adults will also be monitored. In both experiments, gene expression will provide insight into the heat stress response, growth and metabolic consequences of stressors. Through sample collection from maricultured populations and environmental measures we will also not only determine ecologically meaningful levels of thermal and toxin exposures in Alaskan waters, but measure their sub-lethal impacts on oyster stocks. Temperature measures and use of SPATT devices will allow for measurement of environmental stressors. Mortality data, tissue weight, shell length, and histopathology of viscera will allow for measurement of morphometric impacts of these stressors on growth and survival of oysters. Combined with routine pathogen surveillance and toxin quantification within oyster tissue, chronic impacts of these environmental stressors and the rate of resolution will also be tracked. Overall, these methods will aid in understanding the chronic or sub-lethal consequences of environmental algal toxins and temperature fluctuations on sub-adult populations.
