9529804 Delong The primary objective of this research is to investigate the physiological properties, metabolic activities and ecological significance of a newly discovered abundant component of marine picoplankton: planktonic marine archaebacteria. Recently results have demonstrated that planktonic marine archaebacteria are widely distributed and can be relatively abundant in marine prokaryote assemblages. Available data suggest that these microorganisms may significantly influence carbon and energy flux in marine picoplankton. In addition, since all other known archaebacteria have unique metabolic and physiological properties, it is quite possible that planktonic marine archaebacteria have unique characteristics which influence their ecological function, and qualitatively distinguish them from other prokaryotic picoplankters. This study will investigate the qualitative properties of planktonic archaebacteria, and their quantitative contributions to picoplanktom biomass and production in the Santa Barbara Channel. Methods that selectively detect planktonic archaebacterial presence, metabolites, and activities will be used to assess their ecological significance. Measurements of archaebacteria relative abundance and distribution will be used to estimate their contribution to picoplankton biomass. Techniques that estimate incorporation of radiolabel into specific archaebacterial cellular metabolites (rRNA, lipids) will be used to determine the relative flux of nutrients into planktonic archaebacterial metabolic pools. This study will provide new information on a ubiquitous but, little understood component of marine picoplankton. The ultimate goal of this research is to relate the unique properties, biomass, and metabolic activities of planktonic marine archaebacteria to the biological interactions and biogeochemical processes through which they influence flows of energy and matter in the sea. ***
