Practicum Project | 2010

Contribution of Diatoms to Carbon Export in Coastal Oceans

Student: Sarah E. A. Diringer

Independent Project

Advisor: Dr. Rebecca Shipe

Single celled marine primary producers provide a sink for excess CO2 in the atmosphere caused by burning fossil fuels and changes in land use. However, it is unclear how effectively they can sequester carbon to depth, especially in coastal regions. Diatom (class Bacilliariophyceae) blooms represent an increase in ocean surface biomass during upwelling and increased nutrient events, and are the dominant primary producers in coastal upwelling regions such as the western US coastline. However, the ability of diatoms to sequester carbon by settling out of the water column or by contributing to biomass in higher trophic levels is highly debated. Many suggest that bacterial decomposition of diatoms accounts for a large amount of carbon release before settling, significantly reducing carbon sequestration (Boyd et al. 2004). This study examines the portion of coastal biomass, as indicated by biogenic silica, which sinks below 250 meters, and evaluates three major hypotheses regarding export of organic material by diatoms to the deep ocean. Contribution of Diatoms to Carbon Export in Coastal Oceans.