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Research Project: Examining Inheritance and Breeding for Resistance to Effects of Ocean Acidification in Pacific Oysters

Location: Forage Seed and Cereal Research

Project Number: 2072-31000-005-02-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 28, 2015
End Date: Sep 27, 2018

The objective of this cooperative research is to identify genetic factors associated with the expression and regulation of economically important traits in cultured Pacific oysters (Crassostrea gigas) and to use this information to develop marker assisted selection techniques that enhances broodstock development with improved characteristics. Specific project objectives are to: 1) Analyze data generated from two on-going projects designed to determine heritability of Pacific oyster larval and adult traits (growth, survival, meat content, shell shape) of several mixed family populations subjected to acidified (high pCO2) seawater treatment and 2) Use quantitative and molecular data from these on-going projects, the Oregon State University shellfish breeding program (MBP) at the Hatfield Marine Science Center (HMSC), and other data sources, to design and implement breeding strategies to improve traits of Pacific oysters of high value to industry.

The levels of genetic (co) variation available in existing and potential shellfish germplasm resources for economically important phenotypic characters as well as the number of loci contributing to these traits and the nature of their effects (genetic architecture) will be examined through quantitative and molecular genetic approaches. A new marine environmental regime characterized by strong upwelling events that bring deep, hypoxic, acidified (high pCO2) seawater into near-shore bays and estuaries on the US West Coast has been shown to adversely affect oyster larvae by increasing shell dissolution rates, hampering shell formation, and potentially affecting metamorphosis and growth. On-going breeding programs for oysters have not addressed larval survival, growth and setting success as traits for selection because larval production was previously not considered to be a major limiting step in oyster production. Two on-going projects are designed to research the effects of ocean acidification (OA) on Pacific oysters and determine whether sufficient genetic variation exists within Pacific oyster lines to enable adaptation to changing rearing conditions. Researchers will use the data collected on the pedigrees of selected individual oysters from mixed family population experiments and information on gene expression to quantify and determine trait heritability and design new breeding experiments. Collaborate in quantitative analysis of data from an on-going project designed to determine heritabilities of larval and adult traits of a mixed family breeding experiment conducted using broodstock from Pipestem Inlet, BC. Parentage analyses using ARS-determined microsatellite data have been completed for surviving larvae and spat as well as resulting seed planted at three field sites in summer 2014. Conduct quantitative analyses to determine family effects and trait heritability and assist collaborators in completing a second experiment replicating pair-mated cross for these Pipestem families and examining intergenerational effects following early exposure to high pCO2. Collaborate using microsatellite and other genetic markers to determine heritabilities and markers for larval and adult traits of three mixed family populations subjected to high or low OA seawater. Families of known pedigree will be crossed using a mating scheme to allow determination of heritability values for larval traits of interest and examine the performance (hatching success, survival, larval growth, settlement and early juvenile growth and survival). Develop analytical approaches to use quantitative and molecular data from these projects, the MBP program and other data sources including years that span the onset of OA conditions on the west coast, to investigate regions of the genome that underwent disproportionate change during these years: candidates for gene regions conferring resiliency to OA in this species. Use these candidate regions to provide a framework for investigating adaptation to OA as well as identify a set of markers to explore in breeding designs to improve traits of Pacific oysters of high value to the shellfish aquaculture industry.