The interface between the world's atmosphere and hydrosphere is the sea surface microlayer (upper 0-1000 µm). This microlayer controls the exchange of natural and artificial substances between the air and sea, and previous studies have shown it to be a region of high metabolic activity. In comparison to bulk water, the sea surface microlayer is far more concentrated in substances such as hydrocarbons, fatty acids, polysaccharides and protein, and thus hosts numerous biological and photo-chemical processes. In a 1997 study, González and Moran, discovered that a-Proteobacteria account for 28% (±2%) of the eubacteria identified in clonal libraries through measurement of 16S rDNA. Because a-Proteobacteria dominate bacterioplankton communities, their presence in the microlayer, bulk water and aerosols may convey information about the relative activity and potential, that each contributes to its surrounding environment.

All water samples were collected from Main Channel in Stony Brook Harbor, NY. Sea-surface microlayer samples were collected using the polyester-mesh Garrett screen, which gives a 200 µm thick microlayer sample. Sampling of bulk water was accomplished by submerging a polyethylene container below surface. Artificial aerosols were generated by a lab set-up that mimicked real aerosol production using a carbon filtered aquarium bubbling stone. Aerosols that were ejected more than 2 cm in the air were collected on concave glass impaction plate and subsequently collected in a small beaker. All water samples were preserved with buffered formalin with a final concentration of 2.5 % and sterile-sea water in the case of aerosols. An In-situ hybridization technique was used to determine the relative enrichment of the various water samples, especially for the microlayer and aerosols. Cells were hybridized with oligonucleotides probes, including EU338 for Eu-bacteria, DAPI for total bacterial count and ALF1b for a-Proteobacteria. A propidium iodide stain was used to identify cells with compromised cell membranes and therefore presumably limited activity. Slides were examined with an epiflourescent microscope under UV light (360-370 nanometers) and red light (530-560 nanometers) for their a-Proteobacteria enrichment. Data is being analyzed for conclusions. This research was supported by the Simons Foundation and National Science Foundation grants to Josephine Aller.