Aggregation in Phosphate Limited Versus Replete Cultures of Marine Synechococcus

Kimberly MohabirMentor: Susanne NeuerSchool of Life SciencesArizona State UniversityAggregation in Phosphate Limited Versus Replete Cultures of Marine Synechococcus

The Biological Carbon Pump

BackgroundProterozoic OceanNo eukaryotes present, only prokaryotic primary producersProkaryotic primary producers thought to be the ancestors of todays cyanobacteriaUse of Synechococcus as a model organism

ObjectiveTo determine the difference in aggregation and settling rates between nutrient replete and phosphate limited cultures of SynechococcusMethodsPhosphate limited culture vs. replete culture3 treatments from each culture 0, 8, and 24 hours of rollingSettling for 8 hoursSinking rates, aggregate abundance, and equivalence spherical diameter (ESD) determined

Results: Aggregate Abundance During RollingResults: Settling ExperimentsReplete CulturePhosphate Limited Culture

ConclusionsLarge aggregates sink fasterPlay important role in biological carbon pumpRelatively low settling rates small early carbon export in Proterozoic OceanNo difference in aggregation between nutrient limited and replete cultures

8AcknowledgementsWei Deng and Dr. Susanne NeuerThe Neuer labNASA Space Grant at ASU