Impacts of long-line aquaculture of Pacific oysters (Crassostrea gigas) on sulfate reduction and diffusive nutrient flux in the coastal sediments of Jinhae-Tongyeong, Korea

We investigated the environmental impacts of long-line aquaculture of Pacific oysters (Crassostrea gigas) on sediment geochemistry and carbon oxidation by sulfate reduction and diffusive benthic nutrient flux in a coastal ecosystem in Korea. Inventories of the NH4+ and HPO42- at the farm site were 7.7-11.5 and 1.8-8.0 times higher, respectively, than those at a reference site. Sulfate reduction rates (SRRs) at the oyster farm were 2.4-5.2 times higher than SRRs at the reference site. The SRRs at the farm site were responsible for 48-99% (average 70%) of the total C oxidation in the sediment. The diffusive benthic fluxes of NH4+ and HPO42- at the oyster farm were comparable to 30-164% and 19-58%, respectively, of the N and P demands for primary production, and were responsible for the enhanced benthic microalgal biomass on the surface sediment.