The effects of root zone manipulation of microcosm Turtlegrass (Thalassia testudinum) transplants

The objective of this research was to determine whether the survival and growth rate of transplanted seagrasses is hindered by sediment sulfide addition and bacterial community disruption. A microcosm experiment was designed to control for temperature, salinity, and light availability. Bare root transplanted seagrass shoots were exposed to one of four treatments; plus sulfide, plus autoclave; minus sulfide, plus autoclave; plus sulfide, unmanipulated (not autoclaved); and minus sulfide, unmanipulated. Bare root transplants had less than half the rate of growth of the control that was transplanted as a plug with sediments, demonstrating the sensitivity of root disturbance in Thalassia testudinum. Bare root transplants in autoclaved sediments grew slower than in unmanipulated sediments regardless of sulfide treatments. The greatest amount of extractable DNA was measured in bare root transplanted treatments that had not been autoclaved. Standard diversity indices along with a Bray-Curtis similarity index of Terminal Restriction Fragment Length Polymorphism in a MDS were used to assess community composition. The MDS showed no significant differences, while comparisons of diversity indices indicated differences between transplants and control. The results support the conclusion that an intact sediment bacterial community increases transplant success, but the nature of the interaction (e.g., functional, structural) remains unclear.