The release and uptake of dissolved free amino acids(DFAA), determined byHPLC method, in culture at 25±1℃ of diatom Chaetoceros minutissimus Maker etPr-Lavr were studied from Nov. l986 to Feb. l987' The results suggested thatphytoplankon is not only a major produeer of DFAA in seawater but also a consumer. Phytoplankon takes up DFAA as its nitrogen sourees even though nitrate issuffient in seawater. During the first stage of Chaetoceros minutissimus bloom, theconcefitrations of DFAA and DCHO declined, and...