Pacific oyster (Crassostrea gigas) hemolymph microbiota in response to temperature, stress and infection: an experiment

In order to experimentally examine temperature and condition dependent interactions between hosts, microbiota and external pathogens, Pacific oysters acclimated to 8°C or 22°C were either temperature stressed or infected with a Vibrio sp. strain, or both. Their health and survival were monitored for a week-long period and hemolmyph samples were taken before and three times during the experiment, from dead and alive animals. The composition and dynamics of hemolmyph microbiota were highly influenced by temperature and temperature stress, but they remained stable. They were also robust against infection, as long as the oysters did not develop disease. Dying and dead oysters had microbiomes with low diversity, characterized by proliferation of opportunistic pathogens.