Microbiome response differs among selected lines of Sydney rock oysters to ocean warming and acidification

Oyster microbiomes are integral to healthy function and can be altered by climate change conditions. Genetic variation among oysters is known to influence the response of oysters to climate change and may ameliorate any adverse effects on oyster microbiome; however, this remains unstudied. Nine full-sibling selected breeding lines of the Sydney rock oyster (Saccostrea glomerata) were exposed to predicted warming (ambient = 24 degrees C, elevated = 28 degrees C) and ocean acidification (ambient pCO(2) = 400, elevated pCO(2) = 1000 mu atm) for 4 weeks. The haemolymph bacterial microbiome was characterized using 16S rRNA (V3-V4) gene sequencing and varied among oyster lines in the control (ambient pCO(2), 24 degrees C) treatment. Microbiomes were also altered by climate change dependent on oyster lines. Bacterial alpha-diversity increased in response to elevated pCO(2) in two selected lines, while bacterial beta-diversity was significantly altered by combinations of elevated pCO(2) and temperature in four selected lines. Climate change treatments caused shifts in the abundance of multiple amplicon sequence variants driving change in the microbiome of some selected lines. We show that oyster genetic background may influence the Sydney rock oyster haemolymph microbiome under climate change and that future assisted evolution breeding programs to enhance resilience should consider the oyster microbiome.