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1999 Projects: Upper ocean biogeochemistryInorganic carbon in coastal upwelling ecosystemsProject lead/manager: Gernot Friederich The primary purpose of this project is to observe and analyze the distribution and variability of inorganic carbon in Central California coastal upwelling system as a result of the 1997-98 El Niņo event. Results from mooring and shipboard measurements will be combined with previous results to obtain a refined understanding of carbon cycling in this upwelling system. Methods and instruments recently designed and implemented by the project team have addressed many sampling problems that were previously encountered. Instruments installed on MBARI moorings currently make continuous sea-surface measurements of the partial pressure of carbon dioxide. Automated systems that require only modest personnel effort gather data for mapping the distribution of inorganic carbon and nutrients on MBARI-sponsored expeditions and on ships of opportunity. The data generated by these analytical systems have begun to enhance our understanding of coastal upwelling. While much past effort focused on instrument development, the emphasis of this project team will now shift to interpretation of the data being generated. However, we also will take advantage of new partnerships formed with industry and externally funded proposals to continue some instrumentation development efforts. While coastal upwelling systems have been studied extensively during recent decades, relatively little attention has been given to their inorganic carbon budgets. This is partly because inorganic carbon usually cannot be considered as limiting to primary productivity and, also, because the time and length scales of variability complicates sampling in coastal environments. This project will address some of these sampling problems and utilize the absence of a carbon-limitation factor to link the observed variability of inorganic carbon distributions to estimates of community productivity. Although coastal upwelling regions comprise only a small part of the world’s oceans, the total biological carbon flux in coastal upwelling systems is similar in magnitude to that of any other major oceanic ecosystem. The current state of knowledge cannot definitively assign the direction of the net exchange of carbon between the atmosphere and the ocean in these coastal upwelling systems. Some of our past observations indicate that ratios of carbon-to-nitrogen uptake in coastal waters may frequently exceed the oceanic norm, especially during phytoplankton bloom conditions. These ratios indicate that the amount of carbon transferred to ocean depths via the "biological pump" may be greater than expected. The temporal and spatial information on sea-surface inorganic carbon and nutrients provided by this study will be combined with satellite data on temperature and chlorophyll to estimate carbon consumption and air-sea exchange under a variety of upwelling conditions along the Central California coast. Information from specific ecosystems is required to improve future models of carbon transfer between atmosphere, land, and the oceans. Last updated: 07 October 2004 |
