The carbon and chlorophyll content of phytoplankton from various nutrient regimes

We have measured the relationship between chlorophyll and carbon in phytoplankton cultures and natural populations of phytoplankton using simple standard extraction procedures without correction for degradation products. During exponential growth of four cultures of unicellular and colonial green algae and one diatom, chlorophyll varied from 1.22 to 6.08% of the phytoplankton carbon content ( x¯ =3.03%). The chlorophyll content of the cultures was lower during nitrogen and phosphorus deficiency. Results from natural populations of phytoplankton from eutrophic lakes and from a coastal marine station gave values mostly ranging from 1.5 to 3.7% chlorophyll, corresponding to carbon/chlorophyll ratios of 27–67. If only a rough estimate of the phytoplankton carbon biomass is required, a simple, efficient extraction procedure can be used without any corrections for degradation products.