Short-term indicators of seagrass transplant stress in response to rhizosphere and bacterial community disruption

Bacterial communities in sediments engage in activities that determine the pathways and rates of organic matter remineralization. Changes in bacterial community composition might result in greater restoration success if interactions among seagrasses, sediment, and bacterial communities were elucidated. A manipulative experiment that disrupted the sediment bacterial community examined the response of Thalassia testudinum transplants. Planting units were transported to a suitable location and replanted with either autoclaved, transplant, or donor site sediments. Sediments from the rhizosphere were sub-sampled for analysis of the 16S rDNA gene. The autoclave treatment group had significantly lower bacterial diversity than the other treatments, as measured with terminal restriction fragment length polymorphism. Significantly higher mortality of the transplants was observed in the autoclave treatment group, while mortality in the donor and transplant treatment groups was low relative to the control group. Rhizosphere disruption through the removal of surrounding sediments did not increase mortality, while manipulating the composition of the bacterial community increased mortality in transplants. A native bacterial community was a critical component for minimizing short-term stress associated with a seagrass transplant, which suggests a tighter coupling between seagrasses and sediment bacterial communities than previously thought.