Host- microbiome interactions in a changing sea: the gill microbiome of
an invasive oyster under drastic changes in temperature
Abstract
The gill tissue of bivalve mollusks hosts rich symbiotic microbial
communities that may contribute to the host wellbeing. Spondylus
spinosus is a Lessepsian invasive oyster to the eastern Mediterranean
Sea that has become highly abundant, while constantly expending its
range northwestward. Using 16S rRNA gene amplicon sequencing we examined
how temperature affects the gill microbiota of S. spinosus, and the
oysters themselves, in a series of experiments: exposing the oysters to
the current annual seawater temperature range; to the colder temperature
of the western Mediterranean Sea; and to elevated temperature as
predicted under global warming scenarios. The bacterial genus
Endozoicomonas dominated the communities of the S. spinosus, mainly upon
exposure to winter-like temperatures. Exposure to elevated seawater
temperature resulted in a significant change in the bacterial
communities, while the oysters maintained normal functioning, suggesting
that the oyster may survive a seawater warming scenario. Exposure to
colder winter temperature typical to the western Mediterranean Sea
resulted in health deterioration of the oysters, emergence of
opportunistic pathogens, and a decline in the relative abundance of
Endozoicomonas, suggesting that S. spinosus might not survive in the
cold western Mediterranean Sea. The findings indicate that gill bacteria
are greatly affected by temperature, which could consequently restrict
the range expansion of this and other invasive oysters.