This provides a source of nutrients which leads to vigorous phytoplankton growth near the surface. Figure 1 shows typical surface phytoplankton pigment distribution patterns in a cold upwelling plume. Much of this organic material remains ungrazed and sinks. As the turnover of basin waters is slow, the decomposition of the sinking material leads to permanent anoxia below about 275 m depth. Varved sediments that accumulate within the bottom anoxic waters then provide a detailed record of annual to decadal scale change over several dozen millenia.
Water is collected with bottles that are closed automatically at any depth via computer control.
Data are read out continuously on a computer screen on board the ship as we lower the device to approximately 1,380 m, the bottom of the Cariaco Basin. Water samples are analyzed for various parameters including phytoplankton biomass, dissolved and particulate nutrient and carbon concentration, and primary productivity rates. We also measure total bacterial production. These funnel-shaped traps are synchronized to collect samples over 2 week periods into a series of jars. Afterward, surface temperatures rose and the isotherms deepened.