Physiological responses of phytoplankton to turbulent and stable environments in an upwelling region

The assimilation of ¹⁴C into photosynthetic products was monitoredin two phytoplankton blooms growing in turbulent environmentsduring February and March, 1981. The March community appearedto store a large proportion of carbon in sugars, polysaccharidesand lipids in the upper euphoric zone, but as the cells weremixed to deeper depths the flow of carbon was directed intoorganic acids, amino acids and protein near the bottom of theeuphotic zone. In February, the winds that induced initial deepmixing moderated during the second half of the study allowingthe water mass to stabilize. Total assimilation by the communitywas greater under mixing conditions than in the stable water,implying faster growth in a turbulent environment. When thecommunity was growing in the stable water a greater percentageof carbon was incorporated into protein, however. Since algalgrowth is linked to protein synthesis it is suggested that growthin the stable environment was faster than in the turbulent environment.