12/19/2018

Coastal Erosion: Priming Microbial Changes

Study shows dissolved organic matter can encourage changes in microbial community composition and gene abundance in marine environments.

The Science

Coastline erosion can send ancient sediments tumbling into the sea to decompose. When this land organic material encounters organic matter derived from algae, decomposition speeds up, a process called priming. But what does priming do to the marine microbial community? Scientists studied changes in how the community functions when exposed to this sedimentary material. They discovered that, when the algal and sedimentary material are both present, the dominant micro-organisms shift, and certain genes increase in abundance.

The Impact

The Atlantic Coast faces both rising sea levels and more frequent extreme storms. These changes cause erosion, especially from wetlands like salt marshes. This erosion frees ancient sediments, and the carbon contained in them, to flow into the sea. Determining how this previously stable sedimentary carbon reacts once exposed to the diverse organic materials and microbial communities in seawater is of critical importance to understanding the full impact of coastal erosion on ecosystems.

Summary

In laboratory experiments, scientists from the University of Florida, Pacific Northwest National Laboratory’s (PNNL’s) Marine Sciences Laboratory, University of Washington, Texas A&M University, and EMSL examined how marine microbial communities responded to the presence of dissolved organic matter. The scientific team compared effects of two kinds of dissolved organic matter: wetland peat and dissolved organic matter from aquatic algae. Using EMSL’s powerful Fourier-transform ion cyclotron resonance mass spectrometer and liquid chromatography-mass spectrometer, they looked at how microbial communities reacted to these two types of matter, separately and in combination. The scientists found that the algal dissolved organic matter stimulated carbon dioxide production in microbial communities. The addition of the wetland peat further enhanced this production. Under the Facilities Integrating Collaborations for User Science (FICUS) program, the scientists then worked with the Joint Genome Institute to study DNA from the microbial communities. They discovered that the community composition and functional gene abundance also changed with each organic matter treatment. For example, scientists observed 23 genes associated with pathways to break down peat organic matter uniquely present when peat and algal material were combined. These results provide the first glimpse at the genomic mechanisms underlying aquatic priming effects and will help determine the influence of coastal erosion on global changes in carbon.

Principal Investigator(s)

Nicholas Ward
Pacific Northwest National Laboratory
nicholas.ward@pnnl.gov

Funding

This work was supported by the U.S. Department of Energy’s Office of Science (Office of Biological and Environmental Research), including support of the Environmental Molecular Sciences Laboratory (EMSL) and the Joint Genome Institute, both DOE Office of Science User Facilities. A portion of this research was performed under the Facilities Integrating Collaborations for User Science (FICUS) initiative and PNNL laboratory-directed research and development funding.

References

Ward, N.D., E.S. Morrison, Y. Liu, A. Rivas-Ubach, T.Z. Osborne, A.V. Ogram, and T.S. Bianchi. “Marine microbial community responses related to wetland carbon mobilization in the coastal zone.” Limnology and Oceanography: Letters 4(1), 25-33 (2018). DOI:10.1002/lol2.10101