The relative lability, elemental stoichiometry, and remineralization rates of various particulate organic matter (POM) substrates by natural heterotrophic marine microorganisms was investigated. POM was harvested from laboratory cultures of a marine diazotroph (Trichodesmium IMS101), a cosmopolitan diatom (Thalassiosira weissflogii), a common marine cyanobacteria (Prochlorococcus MED4), and from surface waters off...