The Potential Use of Wild & Aquaculture-raised Seaweed for Human Consumption & Environmental Bioindicators: Putting Blue Carbon to Work

Charleston Harbor has a diverse and under-studied flora of seaweed, or macroalgae. Native macroalgae have great economic potential as sources of food, novel industrial or agricultural products, biomedical compounds, and as tools for water quality bioindication and wastewater treatment. The native macroalgae Sea Lettuce (Ulva spp.) and Graceful Red Weed (Gracilaria tikvahiae) are abundant in the Charleston area and have been used extensively in aquaculture. Thus, we propose to use wild harvested and aquaculture-raised Ulva spp. and G. tikvahiae as target species to assess their potential for local human consumption and water quality bioindicators. Analyses to evaluate their safety and health benefits will include tissue concentrations of heavy metals (i.e., arsenic, cadmium, lead, mercury), nutrients, and bacterial assays for fecal coliforms and Vibrio parahaemolyticus. If bacterial contamination is present, then we propose to develop rinsing methods to test the efficacy of reducing bacterial contamination. We also propose to conduct stable isotope analyses (δ15N) to determine the nitrogen sources absorbed by macroalgae at local sites. The ratio of δ 15N in macroalgae is a useful ecological indicator for nutrients that originate from a highly derived source (i.e., sewage) or less derived source (i.e., inorganic fertilizer). Macroalgae provide a more accurate representation of nutrient dynamics than discrete water sampling and hold potential as an additional water quality bioindicator. The harvesting and aquaculture of macroalgae may provide innovative and sustainable products for South Carolina that contribute to economic and environmental betterment and provide an agricultural yield resilient to climate change impacts.