The Prokaryotic and Eukaryotic Microbiome of Pacific Oyster Spat is Shaped by Ocean Warming but not Acidification

Abstract

AbstractPacific oysters (Magallana gigas,also known asCrassostrea gigas), the most widely farmed oysters, are under threat from climate change and emerging pathogens. In part, their resilience may be affected by their microbiome, which, in turn, may be influenced by ocean warming and acidification. Consequently, for three weeks, we exposed early-development Pacific oyster spat to different temperatures (18 and 24 °C) andpCO2levels (800, 1600 and 2800µatm) in a fully crossed design. Under all conditions, the microbiome developed over time, with potentially pathogenic ciliates (Uronema marinum) greatly reduced in all treatments, suggesting that the spat’s microbiome undergoes adaptive shifts as the oysters age. The microbiome composition also differed significantly with temperature, but not acidification, indicating thatM. gigasspat microbiomes can be altered by ocean warming but resilient to ocean acidification in our experiments. These findings highlight the spat microbiome’s flexibility to environmental changes as well as its “protective” capability against potentially pathogenic microbes.