Genomes to Life Contractor-Grantee Workshop III
February 6-9, 2005, Washington, D.C.
Genomics:GTL Program Projects
Sandia National Laboratories
23
Connecting Temperature and Metabolic Rate to Population Growth Rates in Marine Picophytoplankton
Andrea Belgrano* (ab@ncgr.org) and Damian Gessler
National Center for Genome Resources, Santa Fe, NM
Photosynthetic picophytoplankton bacteria such as Synechococcus can contribute up to more then 50% of the total water column primary production, thus playing an important role in controlling the net flux of CO2 between the atmosphere and the ocean, by the sequestration of carbon from the atmosphere via photosynthesis, and to global carbon cycling in marine systems.
We present how the rate of photosynthesis is regulated by changes in CO2 concentration, irradiance and temperature, including allometric scaling theory and Rubisco activity as the primary catalyst, for the fixation of carbon by picophytoplankton.
To integrate physiological, biogeochemical, and environmental data in a single model, we integrate ¾-power scaling laws, along with irradiance, temperature, and nutrient uptake functions. Body mass scaling provides the theoretical and empirical model for constraints on the supply and use of energetic resources for picophytoplankton. We use a Boltzamann factor approach to capture the temperature-dependence of metabolism, and additionally introduce a Michaelis-Menten approach for nutrient uptake that includes cell quotas in a single growth model for Synechococcus.
We present evidence that a rise in oceanic temperature may reduce the relative contribution that picophytoplankton plays in the ocean as a carbon pathway. This highlights the importance of understanding shifts in the size composition of phytoplankton assemblages in relation to oceanic primary production of biomass, cell density, and nutrient status in the northwestern North Atlantic Ocean.
* Presenting author
