Numerical Simulation of Diel Vertical Migrations of Zooplankton in Oil Emulsions and Freshwater Lenses

Event Name/Location

2016 Gulf of Mexico Oil Spill and Ecosystem Science Conference, Tampa, Florida, February 1-4, 2016

Document Type


Publication Date



Modeling, Physical processes, Plankton


Diel vertical migration (DVM) of zooplankton may have an impact on ocean mixing, though details are not completely clear. Zooplankton that undergo DVM can have an impact on oil transport through the water column and oil can have a negative effect on the ability to vertically migrate due to the highly viscous nature of oil emulsions. DVM patterns may also be altered by freshwater inflow, due to convective rains or river runoff, which produces strong anomalies of stratification associated with lenses of freshened water in the near surface layer of the ocean. A computational fluid dynamics model was used to simulate the turbulence signature of DVM in the upper ocean in the presence of oil emulsions and freshwater lenses. The model was initialized with typical vertical density and velocity profiles in the De Soto Canyon (CARTHE GLAD experimental range) located in the northeastern Gulf of Mexico. The effect of oil emulsions on DVM was included by altering the molecular viscosity of water in the upper layer of the ocean. The freshwater lenses were simulated as localized (in space) salinity and temperature anomalies, propagating as gravity currents, eventually mixing with the environment and increasing the vertical stratification. The model results suggest that propulsion speed of some organisms may somewhat change because of buoyancy effects due to varying salinity stratification in the upper layer of the ocean; the presence of oil emulsions, however, can have a more dramatic effect on the DVM of zooplankton (with dire consequences for the marine ecosystem).

Conference Proceeding Title

Part of Poster Session 18: Fusion of Bio-physical Data and Predictive Modeling to Understand Gulf of Mexico Marine Species Resilience to Environmental Stresses and Disasters