This CTD (conductivity, temperature, depth) Rosette samples water at different depths and the water can be analyzed for a variety of environmental parameters such as nutrient concentrations, particulate organic matter, dissolved organic matter and chlorphyll concentrations as well as many other properties. For this cruise we are using water from the rosette to determine chorophyll a concentrations from which we estimate phytoplankton abundance. Image courtesy of Sanctuary Quest 2002, NOAA/OER.