Date of Award

Winter 12-2022

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)


Ocean Science and Engineering

Committee Chair

Kristina Mojica

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Xiaodong Zhang

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Christopher Hayes

Committee Member 3 School

Ocean Science and Engineering


Marine viruses are the smallest and most abundant biological entities in the ocean. Marine viruses play a significant role in carbon and nutrient cycles through the liberation of dissolved organic matter (DOM) through the lysis of their numerically dominant hosts (i.e. bacteria and phytoplankton). Despite their importance, little is known about how viruses contribute to seawaters inherent optical properties (IOP) of seawater, specifically backscatter. All particles produce backscatter, with their contribution dependent on particle size, concentration, and composition. Living particles contribute 10-20% of the total backscatter with the remaining 80% of unclassified backscatter, “missing backscatter”, contributed by submicron particles (

Seawater samples were collected on the STRATIPHYT-21 cruise over a latitudinal transect from 15°N to 35°N at 26°W from the euphotic zone and in three areas of the Gulf of Mexico (Petit Bois, Horn Island, Cat Island). Samples were subjected to two size fractionations (0.2 µm, and 30 kDa) where marine viruses are assumed present in thefor 0.2 µm – 30 kDa) of seawater. When examining the contribution of virus scattering to the dissolved fraction of seawater, virus scattering contributes, on average, 50% of the dissolved fraction backscatter. This study demonstrates the potential of viruses to contribute to the backscatter of the dissolved fraction and begins to fill in the gap in our understanding of the “missing backscatter”.