Modeling the effect of marine snow fragmentation by Euphausia pacifica on carbon flux

Thesis (M.S.)--Humboldt State University, Environmental Systems: Mathematical Modeling, 2008Marine snow aggregates are important components in the ocean carbon cycle because their sinking transports carbon from the surface layer of the ocean to the deep ocean where carbon can be sequestered for hundreds to thousands of years. The sedimentation rate of marine snow out of the mixed layer can be influenced by swimming euphausiids, Euphausia pacifica, because euphausiids are able to fragment a single aggregate into multiple smaller particles and potentially reduce carbon flux out of the ocean surface layer also known as the mixed layer. The interaction between rapidly sinking large particles and animal behavior has been recently discovered and there are not many studies on this process. We used a system of ordinary differential equations to develop a mathematical model that examines the change in the concentration and the total volume of aggregates with and without fragmentation by euphausiids and investigated how these changes influence marine snow sedimentation. Our results shows that through swimming behavior alone euphausiids are able to reduce carbon transport out of the ocean surface layer by approximately 30%. Fragmentation by euphausiids is an important process affecting marine snow sedimentation and the transport of carbon out of the mixed layer, and thus it has an impact on the global carbon cycle