Comparing productivity and biogeochemistry of native and transplanted Thalassia testudinum and Halodule beaudettei in Big Lagoon, Florida, USA

Seagrasses provide ecosystem services such as nursery habitats, refuge, and biogeochemical cycling. However, because seagrass communities are in decline, restoration efforts have increased. The seagrass restoration and monitoring programs at the Florida Department of Environmental Protection (FDEP) transplanted plugs of salvaged seagrasses from dock and marine construction sites. In this study, we used a 2-yr-old FDEP transplant site at Big Lagoon, Pensacola, FL, to compare primary production, respiration, and nutrient fluxes in mixed seagrass beds of Thalassia testudinum (turtle grass) and Halodule beaudettei (shoal grass) with intact, native beds of these seagrasses. We placed light and dark incubation chambers in native and transplanted seagrass beds on 10 different days during the growing season between May and Oct. to measure fluxes of oxygen, nitrate (NO₃), dissolved inorganic phosphate (DIP), and ammonium (NH₄⁺). This study found no significant differences in the fluxes of any of the nutrients measured or in the production or respiration rates of native vs transplanted seagrass beds. The most significant environmental factor influencing net community production was light level. Nutrient fluxes were very low and variable, although there were consistent ammonium uptake and nitrate release early in the growing season. This rapid convergence in seagrass function by the transplanted beds to rates similar to those of native beds was likely the result of several factors, including use of plugs for restoration and planting adjacent to existing, healthy beds.Journal ArticleFinal article publishe