Phosphorus kinetics in phytoplankton species of very acidic mining lakes, Lusatia, Germany
Zusammenfassung der Projektergebnisse
In the acidic mining lake 111 (pH 2.65) Chlamydomonas acidophila is a dominant phytoplankton species and an important primary producer. Previous studies revealed that primary productivity in very acidic lakes is often lower than in neutral counterparts. Therefore, the effects of some possible Stressors on the photosynthesis of C. acidophila were explored. The low external pH does not lower the growth and photo synthetic rates of C. acidophila, but results in an increased presence of stress-induced proteins. More specifically, the presence of small stress-induced proteins indicates a role of these proteins for the survival of the acidophilic alga. Although the concentrations of inorganic phosphorus (Pi) in Lake 111 are not as low as to suggest a Pi limitation in neutral lakes, a Pi limitation in the growth of C. acidophila in the epilimnion of Lake 111, as well as in other acidic lakes seems likely. Under Pi-limited conditions, photosynthetic rates in C. acidophila are lower and this reduction is magnified by high concentrations of CO2 or dissolved organic carbon (glucose). Therefore, Pi potentially determines primary production of C. acidophila in acidic lakes. Furthermore, ajudgement of a potential Pi-limitation of primary productivity in acidic conditions cannot be uncoupled from carbon availability. Despite the complex chemical composition of the mining water that induces a stress response and increase metal binding, no increased costs in C. acidophila were found in growth, photosynthesis or cellular phosphorus quota. Although the photosynthesis of C. acidophila is not limited by the low CO2 concentrations present in the lake water, increased growth rates can be realized under increased CO2 conditions. This enhanced growth rate is likely the result of the loss of a carbon concentrating mechanism and a lower cellular Rubisco content.
Projektbezogene Publikationen (Auswahl)
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Dr. Elly Spijkerman Final report SP69S/2 Spijkerman, E., D. Barua, A. Gerloff-Elias, J. Kern, U. Gaedke & S.A. Heckathorn, 2007b. Stress responses and metal tolerance of Chlamydomonas acidophila in metalenriched lake water and artificial medium. ExtremophiJes 11:551-562,
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Gerloff-Elias, A,, D. Barua, A. Mölich & E. Spijkerman, 2006. Temperature and pHdependent accumulation of heat shock proteins in the acidophilic green alga Chlamydomonas acidophila. FEMS Microbial Ecology 56 (3): 345-354.
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Gerloff-Elias, A. 2006 Ökophysiologische Untersuchung an Chlamydomonas acidohila Negoro, eine einzellige Grünalge aus Tagebaurestseen der Lausitz. Ph.D. thesis. University of Rostock. 6 January.
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Spiikerman, E., V. Bissinger, A. Meister & U. Gaedke, 2007. Low potassium and inorganic carbon concentrations influence a possible phosphorus limitation in Chlamydomonas acidophila (CMorophyceae). European Journal of Phycology 42: 327-339.
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Spijkerman, E. 2007. Phosphorus acquisition by Chlamydomonas acidophila under autrophic and osmo-mixotrophic growth conditions. Journal of Experimental Botany 58:4195-4202.
