Microplanktonic ATP-biomass and GTP-productivity associated with upwelling off Pt. Sur, California

Abstract

Microplanktonic ATP-biomass and GTP-productivity were studied in upwelling features off Pt. Sur, California. Biomass, determined by adenosine triphosphate (ATP) and chlorophyll- a, was found to have a definite preferential location in the strong gradients of temperature and nutrients on the equatorward edge of the feature. Productivity, as sampled using the new method of guanosine triphosphate (GTP) sampling was found to be high throughout the thermo-nutrient gradient associated with an upwelling feature in an early stage of development. The measurement of productivity and "growth potential" using GTP and GTP/ATP ratios was found to be a valuable tool in examining rapidly changing upwelling features. Preliminary results obtained using the GTP technique suggest a relationship between the flux of nutrients across ocean fronts and planktonic productivity associated with frontogenic coastal upwelling systems.