The major integrated science objective for the 2015 expeditions are to investigate biological variability over diel timescales in a coherent body of water. More specifically we will be measuring production and loss processes over the day-night cycle related to productivity/respiration, growth/grazing, and more. These rate measurements will be related to community composition, microorganism physiology, and also microbe-microbe interaction via production and exchange of metabolites. The shipboard work will be in the stable, low-variable oligotrophic open ocean at Stn ALOHA to connect this expedition with the long-term times-series monitoring program. The sampling strategy will pursue a Lagrangian approach whereby the research vessel will deploy and track a drifter during the period of diel-orientated measurements.