(418f) In Situ Biochar-Driven Restoration of Seagrass in the Indian River Lagoon

Due to declining dissolved oxygen (DO) levels, seagrass populations in the Indian River Lagoon (IRL) are overcome with anoxic and anaerobic bacteria, leading to detrimental economic and ecological effects. Current transplantation stabilization efforts do not properly address the long-term health issues of seagrass. In-situ stabilization of seagrass and surrounding sediment is essential to long-term seagrass restoration. Supplying oxygen to microbial communities in sediment via modified biochar to enhance bacterial diversity and nutrient cycling has shown merit in previous studies. This study considers pine-derived biochar mixed with shoal grass, an endangered, fast-growing species of seagrass, in an aquatic growth chamber. Biochar-seagrass systems at concentrations of 0, 1, 3 and 5% were submerged in seawater, and a 30-day study was conducted to identify the optimal biochar-seagrass ratio in terms of seagrass growth and health with periodic chemical characterizations of the biomass and seawater. The optimal biochar concentration of 5% was supported by the highest percentage of biomass growth and DO increase. Additionally, the NH₄⁺-N, PO₄^3--P, and SO₂^4—S concentrations decreased over the 30-day period. Furthermore, biomass characterization revealed periodic changes in the surface morphology and oxygen content.