Several techniques are available to measure metabolite concentrations in the environment, including nuclear magnetic resonance spectroscopy and mass spectrometry (Viant & Sommer 2013). For example,Durham et al.(2015) quantified a C3-sulfonate,2,3-dihydroxypropane-1-sulfonate (DHPS),produced by phytoplankton and consumed by bacteria in the intracellular and extracellular phases in the eastern North Pacific.In another example,Kaiser & Benner (2012) measured the concentrations of several metabolites in the North Pacific near Hawaii and found an increase in glycine (as a percentage of total dissolved amino acids) with depth.