Theses and Dissertations

Defense Date

11-9-2012

Document Type

Thesis

Degree Name

M.S. Marine Biology

Second Degree Name

M.S. Coastal Zone Management

Department

Oceanographic Center

First Advisor

Alexander Soloviev

Second Advisor

Silvia Matt

Third Advisor

Mahmood Shivji

Fourth Advisor

Aurelien Tartar

Abstract

The sea surface microlayer is a millimeter-scale interfacial layer between the atmosphere and the ocean. A number of studies have suggested that there is a unique ecosystem for marine bacteria in the sea surface microlayer, but little information exists on the microbial community composition of this ecosystem due to sampling complexities. In this work, we present an improved method to sample and compare the bacterial diversity of the sea surface microlayer with that of subsurface water at the same site. Bacterial samples were collected from the sea surface microlayer with a sampling method, which minimized sample contamination from the research platform and the subsurface water. Sampling was conducted using a polycarbonate membrane filter to obtain the bacterial community structure at open water and coastal water sites in the Straits of Florida. The microlayer sampling was planned to coincide with synthetic aperture radar satellite overpasses (COSMO SkyMed), which capture a range of fine-scale features on the sea surface. The presence of surfactants affect the synthetic aperture radar imaging process because surfactants in the sea surface microlayer suppress short gravity-capillary ocean surface waves, thereby decreasing the backscatter and allowing the radar to detect surfactant-covered areas. Although sources of surfactants vary, certain marine bacteria are known to produce and transform surfactants, which suggest that these surfactant-related marine bacteria have an important biological influence on fine-scale synthetic aperture radar satellite imagery. Therefore, the comparison between synthetic aperture radar satellite images and in situ field samples may be used for interpreting and studying fine-scale features on the sea surface. The surfactant-associated bacterial composition of the sampling sites was determined using high-throughput, 454 pyrosequencing methods. A total of 61,663 sequences were analyzed and the results indicated the presence of surfactant-associated bacteria such as Moraxellaceae, Halomonadaceae, Enterobacteriaceae, Bacillaceae, and Nocardiaceae. By establishing these bacterial groups that influence the presence of surfactants, remote sensing techniques which involve monitoring the microlayer are expected to be enhanced and may provide additional information on the state of the upper ocean ecosystem.

Comments

Supported as part of the NSUOC project “Hydrodynamics and Remote Sensing of Far Wakes of Ships” and the ONR project “Characterization of Impact of Oceanographic Features on the Electromagnetic Fields in Coastal Waters”. Supported from the Kevin Kohler Memorial Scholarship Research Fund at NSUOC and the GoMRI project “Consortium for Advanced Research on Transport of Hydrocarbons in the Environment” via a subcontract to UM RSMAS.

  Link to NovaCat

Share

COinS