Microbial diversity influenced by sediment organic enrichment and hydrogen sulfide concentrations

Adriana Sepulveda & Sylvia Yang

Shannon Point Marine Center, Western Washington University


Organic matter found in marine habitats include phytoplankton resulting of eutrophication-originated algal blooms (Graco, et al. 2001) and wood (sawdust, wood chips, bark) waste resulting of saw mill residue accumulation at saw mill sites over the years. (Breems and Goodman. 2009). In marine sediments, organic matter pollution promotes growth of bacterial populations (Elliott, et al. 2006). Microbial mats that develop on these sediments are commonly constituted by sulfurous bacteria and these proliferate in presence of organic carbon sources. Sulfate is reduced as free oxygen is depleted through bacterial respiration, resulting in increased hydrogen sulfide (H2S) levels. (Mascaró et al. 2008). Diversity of microbial mats results to be higher than previously thought and this may have an effect on H2S levels (Elliott 200). Sediments in which these H2S levels develop are key ecological mediums in a marine system.

Multiple organisms depend on healthy sediments for their survival. A prime example of their importance is clear in eelgrass, a plant essential in thriving estuaries. Short (1987) suggested that the biogeochemical state of seagrass sediments may control the plant's growth. This study's objective is to increase understanding of microbial mats that develop on carbon-rich sediments, their dynamics, and how this might be related to sulfide concentrations. An increased knowledge on how microbial dynamics in carbon-enriched sediments may be related to sulfide concentrations can improve remediation plans of polluted sites and their restoration.

In this study we investigated whether organic matter source and carbon level affected microbial mat development and sulfide concentrations in marine sediments.

Literature cited

  • Short, FT. (1987) Effects of sediment nutrients on seagrasses: Literature review and mesocosm Experiment. Aquatic Botany, Volume 27, Issue 1, January 1987: 41-57.

  • Graco, M., Farias, L, Molina, V, Gutierrez, D, Nielsen, LP. (2001) Massive developments of microbial mats following phytoplankton blooms in a naturally eutrophic bay: Implications for nitrogen cycling. Limnology and Oceanography, 46(4): 821-832.

  • Breems, J and T Goodman. (2009) Wood waste assessment and remediation in Puget Sound. Prepared for the Estuary and Salmon Restoration Program, by Washington Department of Natural Resources, Sediment Quality Unit, Olympia, WA. 14 pp.

  • Elliott, JK, Spear E, Wyllie-Echeverria, S. (2006) Mats of Beggiatoa bacteria reveal that organic pollution from lumber mills inhibits growth of Zostera marina. Marine Ecology 27: 372-380

  • Mascaró, O, Valdemarsen, T, Holmer, M, Pérez, M, Romero, J. (2008) Experimental manipulation of sediment organic content and water column aeration reduces Zostera marina (eelgrass)growth and survival. Journal of Experimental Marine Biology and Ecology 373: 26-34

  • Millero, JM, Plese, T, Fernandez, M. (1988) The dissociation of hydrogen sulfide in seawater. American Society of Limnology and Oceanography 33(2) 269-274.

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