S. Burkhardt et U. Riebesell, CO2 AVAILABILITY AFFECTS ELEMENTAL COMPOSITION (C-N-P) OF THE MARINE DIATOM SKELETONEMA-COSTATUM, Marine ecology. Progress series, 155, 1997, pp. 67-76
The effect of variable CO2 concentrations on the elemental composition
(C:N:P) of marine diatoms was investigated in 2 strains of Skeletonem
a costatum (Grev.) Cleve. Five or 6 concentrations of dissolved molecu
lar carbon dioxide [CO2 (aq)], ranging from 0.5 to 39 mu mol l(-1), we
re applied in dilute batch cultures. In both strains, elemental ratios
were clearly dependent on [CO2 (aq)]. With decreasing CO2 concentrati
ons, a decline in C:P and N:P and an increase in C:N was observed. The
close correlation between C:P or N:P and [CO2 (aq)] corresponded to a
ca 45 to 65% decrease in elemental ratios from highest (greater than
or equal to 30 mu mol l(-1)) to lowest (ca 1 mu mol l(-1)) CO2 concent
rations. C:N at low [CO2 (aq)] was up to 24% higher than at high [CO2
(aq)]. To date, the elemental composition of marine phytoplankton has
been considered to be independent of CO2 availability. If dependency o
f the C:N:P ratio on [CO2 (aq)] proves to be a general phenomenon in m
arine phytoplankton, changes in the elemental composition may be expec
ted in response to the currently observed increase in partial pressure
of atmospheric CO2.