Date of Award
Summer 8-2023
Degree Type
Masters Thesis
Degree Name
Master of Science (MS)
School
Ocean Science and Engineering
Committee Chair
Dr. Eric Saillant
Committee Chair School
Ocean Science and Engineering
Committee Member 2
Dr. Eric Powell
Committee Member 2 School
Ocean Science and Engineering
Committee Member 3
Dr. Bill Walton
Abstract
Summer mortalities in Gulf of Mexico eastern oysters have been linked to excessively high temperatures, and chronic exposure to low salinity. In this study, the feasibility of improving tolerance to these two stresses by selection was evaluated in common garden experiments employing a pool of 160 families. Heat stress tolerance was evaluated in seed (3.5 months) and adults (14 months) by applying a sustained temperature of 38-39 °C until all oysters expired. Low salinity challenges on juveniles (9 months) and adults (15 months) applied a salinity of 2.5 psu. Survival duration of individual oysters during challenges was recorded and tissue samples were taken for genotyping and parentage assignment. The condition index was recorded at the end of the juvenile salinity challenge.
Parentage was recovered using a 192 SNP array and the heritability (h2) of tolerance traits and genetic correlations were estimated using linear mixed models. Heritability of heat stress tolerance in seed was low and did not differ significantly from zero (0.216±0.199). Heat stress tolerance in adults and condition index in juveniles were both heritable (h2 estimates 0.749±0.086 and 0.275±0.096 respectively). The estimate of heritability of salinity stress tolerance in adults was intermediate (0.326±0.274) but did not differ significantly from zero. Significant genetic correlations were estimated between seed and adult heat stress tolerance (0.672±0.205), and between adult salinity and adult heat stress tolerances (0.418±0.165). Additional studies are needed to understand the mechanisms of tolerance to heat and salinity stress and develop reliable early predictors of breeding values for these traits.
Recommended Citation
McDonald, Paul, "GENETIC PARAMETERS FOR HEAT AND SALINITY STRESS TOLERANCE IN NORTHERN GULF OF MEXICO EASTERN OYSTER, CRASSOSTREA VIRGINICA" (2023). Master's Theses. 991.
https://aquila.usm.edu/masters_theses/991