Changes in water stratification due to methane plumes on the Washington Margin

Abstract

The changing climate is causing more methane releases from the seafloor making it important to understand how methane plumes can impact the ocean. Methane plumes can have impacts on stratification and circulation which can influence primary productivity and possibly atmospheric greenhouse gas levels if the methane from the plume gets exchanged with the atmosphere. Along the Washington margin there has been over 1772 individual bubble plumes located and identified in depths ranging from 40m to 1988m. Using a compilation of CTD (Conductivity, Temperature, Depth) casts off the Washington Margin from various cruises, temperature, salinity, density, buoyancy frequency and flux of sites with and without methane were compared. When comparing the sites with and without the presence of methane plumes, there were no significant differences among the temperature, salinity, density, or calculated buoyancy flux and frequency. Additional data and further analysis on the methane plume sites on the Washington Margin are needed to fully understand the potential impact of the methane plume on the stratification of the water column.