Bloomer DOM addition experiment

To better define the processes and population dynamics associated with marine microbial DOM cycling in ocean surface waters, we performed controlled experiments using seawater microcosms amended with freshly prepared, naturally occurring DOM. High molecular weight DOM (HMWDOM), was prepared by ultrafiltration using a 1 nm membrane filter, followed by a second filtration step to remove viruses. Whole, unfiltered seawater was distributed into replicate microcosms (20L each), that were incubated at in situ temperatures and light intensities. The ambient concentration of dissolved organic carbon (DOC) in the unamended microcosms was 82 *M DOC, while the HMWDOM-amended microcosms contained 328 *M DOC, representing a 4-fold increase in over ambient DOC concentrations. Control (no addition) and experimental (DOM amended) microcosms were sampled at 0 hr, 2 hr, 12 hr and 27 hr time points and extracted for DNA and RNA, and the resulting DNA and cDNA produced was pyrosequenced.