Meeting Abstract

P2-95   -   Hydrogen sulfide formation in anoxic sediment and its impact on Zostera marina restoration through seeding Price, Z*; Wyllie-Echeverria, S; Ogston, A; Takesue, R; Emory University; University of Washington; University of Washington; Pacific Coastal and Marine Sciences Center, United States Geological Survey zoe.price@emory.edu

Decline of the marine flowering plant Zostera marina, eelgrass, is evident at several sites in the San Juan Archipelago region of Washington State. With these plants being important to nearshore food webs by providing spawning sites and shelter for finfish and invertebrates, as well as food for several species, there is cause for concern. Efforts are underway to develop an efficient technique to restore eelgrass populations. The use of eelgrass seeds is a common restoration technique in other regions and a pilot program to explore seed-based restoration techniques is underway at the Friday Harbor Laboratories. Excessive sediment hydrogen sulfide (H2S), can threaten seedling survival in coastal sediments. It is therefore important to vet a restoration site to determine if hydrogen sulfide concentration will impede seedling restoration success. In this study, we chose ten locations that surrounded the test area and encompassed different depths and extracted sediment cores from each. We determined H2S levels from the porewater and sediment grain size and organic matter from the different stratigraphic layers that relevant to seedling growth. Specifically on the surface of the core just below the oxygenated (oxic) layer and the rhizosphere where roots would be present. Porewater was extracted using Rhizon filters and analyzed with a CHEMets sulfide testing kit to determine concentrations of hydrogen sulfide in each layer. Sediment samples were dried, weighed and processed in a Ro-Tap to obtain grainsize. Surface sediments were dried and placed in a muffle furnace to determine Organic Matter content. We found that hydrogen sulfide levels were not a limiting factor for seedling survival and organic matter levels were normal for the type of sediment found there. We recommend that our methods be used to determine sediment suitability for restoration using eelgrass seeds because it provides comprehensive, timely, and cost-efficient results.