Much in the same way that we rely on our gut flora to help digest our food, seagrasses also rely in part on microorganisms living in, on or near their roots (the rhizosphere) to regenerate their nutrients. However, the interaction among seagrass roots, the sediments and the microorganisms they contain remains, quite literally, in the dark. Additionally, as seagrasses are often faced with deteriorating light conditions, it is also necessary to determine how resilient these microbial communities may be to a reduction in light availability provided to the host plant.
Here we present preliminary findings on the community structure of the root microbiome of three seagrass species; Halophila ovalis, Halodule uninervis and Cymodoceae serrulata. These three species co-occur along the north coast of Australia and are often challenged with reduction in light availability from natural and anthropogenic disturbances. To capture the short-term response of the root microbiome to light availability, seagrasses were grown in mesocosms under reduced light for two weeks. 16S rRNA amplicon sequencing revealed distinct microbiomes associated with the roots of each seagrass species. However, these microbial communities were unaffected by light reduction. Taken together, these results suggest 1) seagrasses operate in much the same way as many terrestrial plants in that they are capable of exerting selective pressures that lead to the development of unique microbial communities, and 2) root microbiomes of seagrasses appear to be resilient to short term reduction in light availability. Future work aims to identify potential plant drivers in the development of these communities and to unravel their potential functional importance in seagrass ecosystems.