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HIGH PHOTOSYNTHETIC RATES UNDER A COLIMITATION FOR INORGANIC PHOSPHORUS AND CARBON DIOXIDE 1
Author(s) -
Spijkerman Elly
Publication year - 2010
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.2010.00859.x
Subject(s) - photosynthesis , biology , rubisco , phosphorus , botany , mixotroph , phytoplankton , total inorganic carbon , photosynthetic efficiency , zoology , carbon dioxide , nutrient , heterotroph , ecology , bacteria , chemistry , genetics , organic chemistry
Inorganic phosphorus (P i ) and carbon (here, CO 2 ) potentially limit the photosynthesis of phytoplankton simultaneously (colimitation). A single P i limitation generally reduces photosynthesis, but the effect of a colimitation is not known. Therefore, photosynthesis was measured under P i ‐limited conditions and high and low CO 2 , and osmo‐mixotrophic (i.e., growth in the presence of glucose) conditions that result in colimiting conditions in some cases. The green alga Chlamydomonas acidophila Negoro was used as a model organism because low P i and CO 2 concentrations likely influence its photosynthetic rates in its natural environment. Results showed a decreasing maximum photosynthetic rate ( P max ) and maximum quantum yield (Φ II ) with increasing P i limitation. In addition, a P i limitation enhanced the relative contribution of dark respiration to P max ( R d : P max ) but did not influence the compensation light intensity. P max positively correlated with the cellular RUBISCO content. Osmo‐mixotrophic conditions resulted in similar P max , Φ II , and RUBISCO content as in high‐CO 2 cultures. The low‐CO 2 cultures were colimited by P i and CO 2 and had the highest P max , Φ II , and RUBISCO content. Colimiting conditions for P i and CO 2 in C. acidophila resulted in an enhanced mismatch between photosynthesis and growth rates compared to the effect of a single P i limitation. Primary productivity of colimited phytoplankton could thus be misinterpreted.