Surveys of the California Current System in 1993 revealed high concentrations of photosynthetic pigment biomass at -200-m depth, well below the euphotic zone. The deep fluorescence feature contained an estimated 2.2 X 10J metric tons of carbon and contained -2.5 times the amount of chloroph,yll observed in surface waters directly above it. Deep phytoplankton assemblages may be a signature of wa...