Particulate organic matter (POM) in seawater contains a wide range of chemical compounds, many of which come directly from phytoplankton. Phytoplankton may alter their biochemical characteristics in response to stress, which in turn alters the relative abundance of carbon (C) and phosphorus (P) compounds in the POM. The objective of this research was to examine changes in the P and C forms of algae cultured under light intensity, temperature and P nutrition stress, using 13C CPMAS and 31P NMR spectroscopy. Of the C forms, lipids and protein were significantly related to light intensity, while lipids were significantly increased at high temperatures. Low-P nutrition significantly altered 13C NMR spectra, but did not alter modeled C forms. There were few changes in P forms with light and temperature stress. Low- and high-P nutrition altered C:P and N:P ratios. Low-P nutrition did not alter P forms. High-P nutrition increased pyrophosphate, indicating luxury P consumption. Polyphosphates did not appear to be related to light and temperature stress, because no significant changes in polyphosphates were observed in cultured algae under light and temperature stress.