Kimberly Halsey, Ph.D.
Oregon State University
The "Z-scheme" of primary productivity.
Wednesday — October 12, 2011
Pacific Forum — 3:00 p.m.
Phytoplankton are the source of organic carbon in aquatic environments. Net primary production (NPP) is the rate at which new phytoplankton biomass accumulates and thus becomes available for consumption by higher trophic levels. The broadly recurring annual patterns of phytoplankton distributions in the oceans reflect nutrient availability as well as growth strategies evolved for optimizing NPP. Despite the rapidly expanding availability of data derived from genomes and molecular microbial ecology, physiological information that might explain the environmental distributions of different phytoplankton groups is surprisingly sparse. Our studies of phytoplankton show that the energy derived from gross photosynthesis is allocated into metabolic sinks that vary between phytoplankton groups and with environmental conditions. In contrast, relationships between gross photosynthesis, gross carbon production, and NPP appear to be remarkably conserved across phytoplankton groups, suggesting that models based on underlying principles of cellular energy economy may emerge. From this physiological view we are developing a cellular model to describe how photosynthesis and cellular processes integrate under changing nutrient conditions of the aquatic environment. Such metabolic strategies are important for understanding and accurately modeling photosynthetic production across broad scales.
Next: October 13 — MTS Presents: OceanGate Foundation