ABR: New Production in the Eastern Equatorial Pacific and its Relation to Flux of Nitrogen and Carbon

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This project represents an accomplishment based renewal for continuing studies of upwelling new production processes. The major goals are to test hypotheses developed from coastal and equatorial measurements and to modify current models of upwelling system new production accordingly. The region selected for the study is Monterey Bay where nitrogen uptake has been measured at 2 weeks intervals for 2 years. The seasonal cycle shows an alternation between open ocean and upwelling conditions allowing a comparison of the 2 regimes, one expected to show open ocean, oligotrophic characteristics and the other eutrophic coastal upwelling parameters. The project seeks to understand the factors which trigger the transition from the one ecosystem to the other. The basic hypothesis is that the process of nitrate incorporation into the primary producers is the key factor in determining the trophic status of a marine ecosystem. Further, previous results indicate that the critical factors in development of new production of bloom proportions are nitrate concentration and ambient irradiance. These 2 factors set boundaries for the acceleration process between low new production conditions and high new production. The results of this project will contribute to global models of new production and its impact on carbon cycling. The results should be especially helpful in understanding the role of upwelling ecosystems in global new production and carbon cycling.