Meeting Abstract
The Olympia oyster, Ostrea lurida, is the only oyster native to the west coast of N. America and a foundation species in estuarine habitats. Once abundant, O. lurida is now considered functionally extinct. Human-assisted reintroduction of O. lurida is one potential strategy to restore O. lurida numbers in the wild. Therefore, the ability of oysters to tolerate climate change will be a major factor in the long-term success of this restoration strategy. Ideally, restoration would use genotypes capable of surviving future conditions, however, which O. lurida populations will be most tolerant of climate change is unknown. In San Francisco Bay, oysters that can withstand exposure to low salinity water are predicted to be suitable candidates for reintroduction because climate change is projected to increase the frequency of heavy rainfall and freshwater flooding events that can cause mass mortality in oyster beds. Salinity tolerance was examined in three O. lurida populations in and around San Francisco Bay to identify genotypes tolerant of low salinity. Oysters from Loch Lomond had significantly higher survival rates during freshwater challenge than Oyster Point or Tomales Bay populations. My research uses RNA-Seq to explore the physiological and evolutionary mechanisms of differential salinity tolerance among these populations. Shifts in gene expression following exposure to reduced salinity are being compared among the populations to determine physiological changes that underlie enhanced freshwater tolerance. Changes in allele frequency between oysters surviving freshwater challenge and those held at ambient conditions are being identified to understand the evolutionary basis of salinity tolerance.
