The oceans cover 70% of the planet’s surface, and with an average depth of around 4 km, the marine environment is the largest biome on earth. Marine bacteria and archaea, which maintain abundances of 105- 107 cells ml-1 surface seawater (roughly 80% of all C biomass), play crucial roles in global elemental cycles, consuming around half of all primary production, and causing net remineralization of organic into inorganic compounds. As the most abundant biological entities on earth (maintaining densitiesof 106-108 particles ml-1 seawater) marine viruses have significant impacts on their bacterial and archaeal hosts, causing significant mortality, controlling host assemblage structure, and conferring genomic capabilities via lysogenic conversion and gene transfer. Despite their global-scale importance, we are only starting to get a foothold on the diversity, distribution, and activities of microorganisms in the marine environment.
Research in the Hewson laboratory combines biological oceanography and microbial ecology (known as microbial oceanography) and focuses upon understanding the structure and function of the marine microbial loop and how it relates to biogeochemical function on local and global scales. Questions addressed in the lab include: How do marine viruses influence elemental cycling in the ocean? What controls the composition and activities of microbial assemblages in seawater and sediments? Work in the field onboard ocean-going research vessels, at marine field stations, and in the marine microbiology laboratory at Cornell employs approaches from traditional oceanographic and microbiological techniques through to assemblage fingerprinting and high-throughput sequencing of metagenomes and assemblage gene transcripts.
Ian Hewson earned a B.Sc (Hons) in Botany at the
Selected Recent Publications:
Hewson, I. Poretsky, R.S., Beinart, R.A., White, A.E., Shi, T., Bench, S.R., Moisander, P.H., Paerl, R.W., Tripp. H.J., Montoya, J.P., Moran, M.A., Zehr, J.P. (in press) "In situ transcriptomic analysis of the globally important keystone N2-fixing taxon Crocophaera watsonii" ISME Journal
Poretsky, R.S., Hewson, I., Sun, S., Allen, A., Moran, M.A., Zehr, J.A. (in press) "Diel metatranscriptomic analysis of microbial communities in the North Pacific Subtropical Gyre" Environmental Microbiology
Zehr, J.P., Bench, S.R., Carter, B.J., Hewson, I., Niazi, F., Shi, T., Tripp, H.J., Affourtit, J.P. (2008) "Globally distributed uncultivated oceanic N2-Fixing cyanobacteria lack oxygenic photosystem II" Science 322:1110-1112
Fuhrman, J.A., Steele, J.A., Hewson, I., Schwalbach, M.S., Brown, M.V., Green, J.L., Brown, J.H. (2008) "A latitudinal diversity gradient in planktonic marine bacteria" Proceedings of the National Academy of Sciences USA 105:7774-7778
Hewson, I., Moisander, P.H., Achilles, K.M., Carlson, C.A., Jenkins, B.D., Mondragon, E.A., Morrison, A.E. and Zehr, J.P. (2007) "Characteristics of diazotrophs in surface to abyssopelagic waters of the Sargasso Sea" Aquatic Microbial Ecology 46:15-30
Hewson, I., Jacobson/Meyer, M.E., Fuhrman, J.A. (2007) "Sediment bacterial assemblage diversity and enzyme activity across the San Pedro Basin, Southern California Borderlands" Environmental Microbiology 9:923-933
Hewson, I., Fuhrman, J.A. (2007) "Characterization of lysogens in bacterioplankton assemblages of the Southern California Borderland" Microbial Ecology 53:631-638
Fuhrman, J.A., Hewson, I., Schwalbach, M.S., Steele, J.A., Brown, M.V., Naeem, S. (2006) "Annually reoccurring bacterial communities are predictable from ocean conditions" Proceeding of the National Academy of Sciences 103:13104-13109
Hewson, I., Fuhrman, J.A. (2006) "Viral impacts upon marine bacterioplankton assemblage structure" Journal of the Marine Biological Association of the UK 86:577-589
Hewson, I., Capone, D.G., Steele, J.A., Fuhrman, J.A. (2006) "Influence of Amazon and Orinoco offshore surface water plumes on oligotrophic bacterioplankton diversity in the West Tropical Atlantic" Aquatic Microbial Ecology 43:11-22
Hewson, I., Steele, J.A., Capone, D.G., Fuhrman, J.A. (2006) "Remarkable heterogeneity in meso- and bathypelagic bacterioplankton assemblage structure" Limnology and Oceanography 51:1274-1283
Hewson, I., Steele, J.A., Capone, D.G., Fuhrman, J.A. (2006) "Temporal and spatial scales of oligotrophic surface water bacterioplankton assemblage variation" Marine Ecology Progress Series 311:67-77