@article{SpijkermanBissingerGaedke2007, author = {Spijkerman, Elly and Bissinger, Vera and Gaedke, Ursula}, title = {Low potassium and inorganic carbon concentrations influence a possible phosphorus limitation in Chlamydomonas acidophila}, doi = {10.1080/09670260701529596}, year = {2007}, abstract = {Chlamydomonas acidophila, a dominant phytoplankton species in the very acidic Lake 111 (pH 2.7) situated in Germany, faces low concentrations of inorganic phosphorus (P-i), inorganic carbon (C-i) and potassium (K+) in its environment, which may lead to a complex colimitation by these nutrients. We performed laboratory and field investigations to test for P-i limitation and its dependence on C-i and K+ concentrations. The minimum cell quota for phosphorus (Q(0)) and phosphatase enzyme activity were similar to those for neutrophilic algae, despite the low pH and high concentrations of iron and aluminium, indicating no extra metabolic costs or inhibition of enzymes by the extreme environment. The threshold concentration of soluble reactive phosphorus for growth (SRPt), the algal C:P ratio and the alkaline phosphatase enzyme activity all suggested a moderate P-i limitation of C. acidophila in Lake 111. SRPt and Q(0) were higher at low CO2 and K+ concentrations in culture, showing a relationship between C-i and P-i acquisition. Furthermore, SRPt and Q(0) were higher under K+/P-i-colimiting conditions than under P-i-limiting conditions alone, suggesting that K+ concentrations influence P-i limitation in C. acidophila as well. Our results show that a limitation by one macronutrient requires consideration of the availability of the others as their uptake mechanisms depend on each other. Notwithstanding these interactions, C-i or K+ concentrations had no clear influence on the P-i limitation of C. acidophila in Lake 111.}, language = {en} } @phdthesis{Spijkerman2008, author = {Spijkerman, Elly}, title = {Ecophysiological studies on planktonic desmids and an acidophilic Chlamydomonas species}, address = {Potsdam}, pages = {l.o.}, year = {2008}, language = {en} } @article{Spijkerman2009, author = {Spijkerman, Elly}, title = {Physiological characteristics of co-limiting conditions for P and C in Chlamydomonas}, issn = {0031-8884}, doi = {10.2216/0031-8884-48.sp4.1}, year = {2009}, language = {en} } @article{Spijkerman2010, author = {Spijkerman, Elly}, title = {High Photosynthetic Rates under a Colimitation for Inorganic Phosphorus and Carbon Dioxide1}, issn = {0022-3646}, doi = {10.1111/j.1529-8817.2010.00859.x}, year = {2010}, abstract = {Inorganic phosphorus (P-i) and carbon (here, CO2) 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 CO2, 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 CO2 concentrations likely influence its photosynthetic rates in its natural environment. Results showed a decreasing maximum photosynthetic rate (P-max) and maximum quantum yield (Theta(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, Theta(II), and RUBISCO content as in high-CO2 cultures. The low-CO2 cultures were colimited by P-i and CO2 and had the highest P-max, Theta(II), and RUBISCO content. Colimiting conditions for P-i and CO2 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.}, language = {en} } @article{SpijkermandeCastroGaedke2011, author = {Spijkerman, Elly and de Castro, Francisco and Gaedke, Ursula}, title = {Independent Colimitation for Carbon Dioxide and Inorganic Phosphorus}, series = {PLoS one}, volume = {6}, journal = {PLoS one}, number = {12}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0028219}, pages = {12}, year = {2011}, abstract = {Simultaneous limitation of plant growth by two or more nutrients is increasingly acknowledged as a common phenomenon in nature, but its cellular mechanisms are far from understood. We investigated the uptake kinetics of CO(2) and phosphorus of the algae Chlamydomonas acidophila in response to growth at limiting conditions of CO(2) and phosphorus. In addition, we fitted the data to four different Monod-type models: one assuming Liebigs Law of the minimum, one assuming that the affinity for the uptake of one nutrient is not influenced by the supply of the other (independent colimitation) and two where the uptake affinity for one nutrient depends on the supply of the other (dependent colimitation). In addition we asked whether the physiological response under colimitation differs from that under single nutrient limitation. We found no negative correlation between the affinities for uptake of the two nutrients, thereby rejecting a dependent colimitation. Kinetic data were supported by a better model fit assuming independent uptake of colimiting nutrients than when assuming Liebigs Law of the minimum or a dependent colimitation. Results show that cell nutrient homeostasis regulated nutrient acquisition which resulted in a trade-off in the maximum uptake rates of CO(2) and phosphorus, possibly driven by space limitation on the cell membrane for porters for the different nutrients. Hence, the response to colimitation deviated from that to a single nutrient limitation. In conclusion, responses to single nutrient limitation cannot be extrapolated to situations where multiple nutrients are limiting, which calls for colimitation experiments and models to properly predict growth responses to a changing natural environment. These deviations from single nutrient limitation response under colimiting conditions and independent colimitation may also hold for other nutrients in algae and in higher plants.}, language = {en} } @article{Spijkerman2011, author = {Spijkerman, Elly}, title = {The expression of a carbon concentrating mechanism in Chlamydomonas acidophila under variable phosphorus, iron, and CO2 concentrations}, series = {Photosynthesis research}, volume = {109}, journal = {Photosynthesis research}, number = {1-3}, publisher = {Springer}, address = {Dordrecht}, issn = {0166-8595}, doi = {10.1007/s11120-010-9607-z}, pages = {179 -- 189}, year = {2011}, abstract = {The CO2 acquisition was analyzed in Chlamydomonas acidophila at pH 2.4 in a range of medium P and Fe concentrations and at high and low CO2 condition. The inorganic carbon concentrating factor (CCF) was related to cellular P quota (Q(p)), maximum CO2-uptake rate by photosynthesis (V-max; O-2), half saturation constant for CO2 uptake (K-0.5), and medium Fe concentration. There was no effect of the medium Fe concentration on the CCF. The CCF increased with increasing Q(p) in both high and low CO2 grown algae, but maximum Q(p) was 6-fold higher in the low CO2 cells. In high CO2 conditions, the CCF was low, ranging between 0.8 and 3.5. High CCF values up to 9.1 were only observed in CO2-limited cells, but P- and CO2-colimited cells had a low CCF. High CCF did not relate with a low K-0.5 as all CO2-limited cells had a low K-0.5 (<4 mu M CO2). High Ci-pools in cells with high Qp suggested the presence of an active CO2-uptake mechanism. The CCF also increased with increasing V-max; O-2 which reflect an adaptation to the nutrient in highest demand (CO2) under balanced growth conditions. It is proposed that the size of the CCF in C. acidophila is more strongly related to porter density for CO2 uptake (reflected in V-max; O-2) and less- to high-affinity CO2 uptake (low K-0.5) at balanced growth. In addition, high CCF can only be realized with high Q(p).}, language = {en} } @article{SpijkermanWacker2011, author = {Spijkerman, Elly and Wacker, Alexander}, title = {Interactions between P-limitation and different C conditions on the fatty acid composition of an extremophile microalga}, series = {Extremophiles : life under extreme conditions}, volume = {15}, journal = {Extremophiles : life under extreme conditions}, number = {5}, publisher = {Springer}, address = {Tokyo}, issn = {1431-0651}, doi = {10.1007/s00792-011-0390-3}, pages = {597 -- 609}, year = {2011}, abstract = {The extremophilic microalga Chlamydomonas acidophila inhabits very acidic waters (pH 2-3.5), where its growth is often limited by phosphorus (P) or colimited by P and inorganic carbon (CO(2)). Because this alga is a major food source for predators in acidic habitats, we studied its fatty acid content, which reflects their quality as food, grown under a combination of P-limited and different carbon conditions (either mixotrophically with light + glucose or at high or low CO(2), both without glucose). The fatty acid composition largely depended on the cellular P content: stringent P-limited cells had a higher total fatty acid concentration and had a lower percentage of polyunsaturated fatty acids. An additional limitation for CO(2) inhibited this decrease, especially reflected in enhanced concentrations of 18:3(9,12,15) and 16:4(3,7,10,13), resulting in cells relatively rich in polyunsaturated fatty acids under colimiting growth conditions. The percentage of polyunsaturated to total fatty acid content was positively related with maximum photosynthesis under all conditions applied. The two factors, P and CO(2), thus interact in their effect on the fatty acid composition in C. acidophila, and colimited cells P-limited algae can be considered a superior food source for herbivores because of the high total fatty acid content and relative richness in polyunsaturated fatty acids.}, language = {en} } @article{CleggGaedkeBoehreretal.2012, author = {Clegg, Mark R. and Gaedke, Ursula and B{\"o}hrer, Bertram and Spijkerman, Elly}, title = {Complementary ecophysiological strategies combine to facilitate survival in the hostile conditions of a deep chlorophyll maximum}, series = {Oecologia}, volume = {169}, journal = {Oecologia}, number = {3}, publisher = {Springer}, address = {New York}, issn = {0029-8549}, doi = {10.1007/s00442-011-2225-4}, pages = {609 -- 622}, year = {2012}, abstract = {In the deep, cooler layers of clear, nutrient-poor, stratified water bodies, phytoplankton often accumulate to form a thin band or "deep chlorophyll maximum" (DCM) of ecological importance. Under such conditions, these photosynthetic microorganisms may be close to their physiological compensation points and to the boundaries of their ecological tolerance. To grow and survive any resulting energy limitation, DCM species are thought to exhibit highly specialised or flexible acclimation strategies. In this study, we investigated several of the adaptable ecophysiological strategies potentially employed by one such species, Chlamydomonas acidophila: a motile, unicellular, phytoplanktonic flagellate that often dominates the DCM in stratified, acidic lakes. Physiological and behavioural responses were measured in laboratory experiments and were subsequently related to field observations. Results showed moderate light compensation points for photosynthesis and growth at 22A degrees C, relatively low maintenance costs, a behavioural preference for low to moderate light, and a decreased compensation point for photosynthesis at 8A degrees C. Even though this flagellated alga exhibited a physiologically mediated diel vertical migration in the field, migrating upwards slightly during the day, the ambient light reaching the DCM was below compensation points, and so calculations of daily net photosynthetic gain showed that survival by purely autotrophic means was not possible. Results suggested that strategies such as low-light acclimation, small-scale directed movements towards light, a capacity for mixotrophic growth, acclimation to low temperature, in situ exposure to low O-2, high CO2 and high P concentrations, and an avoidance of predation, could combine to help overcome this energetic dilemma and explain the occurrence of the DCM. Therefore, corroborating the deceptive ecophysiological complexity of this and similar organisms, only a suite of complementary strategies can facilitate the survival of C. acidophila in this DCM.}, language = {en} } @article{SpijkermanWackerWeithoffetal.2012, author = {Spijkerman, Elly and Wacker, Alexander and Weithoff, Guntram and Leya, Thomas}, title = {Elemental and fatty acid composition of snow algae in Arctic habitats}, series = {Frontiers in microbiology}, volume = {3}, journal = {Frontiers in microbiology}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-302X}, doi = {10.3389/fmicb.2012.00380}, pages = {15}, year = {2012}, abstract = {Red, orange or green snow is the macroscopic phenomenon comprising different eukaryotic algae. Little is known about the ecology and nutrient regimes in these algal communities. Therefore, eight snow algal communities from five intensively tinted snow fields in western Spitsbergen were analysed for nutrient concentrations and fatty acid (FA) composition. To evaluate the importance of a shift from green to red forms on the FA-variability of the field samples, four snow algal strains were grown under nitrogen replete and moderate light (+N+ML) or N-limited and high light (-N+HL) conditions. All eight field algal communities were dominated by red and orange cysts. Dissolved nutrient concentration of the snow revealed a broad range of NH4+ (<0.005-1.2 mg NI-1) and only low PO43- (< 18 mu g P I-1) levels. The external nutrient concentration did not reflect cellular nutrient ratios as C:N and C:P ratios of the communities were highest at locations containing relatively high concentrations of NH4- and PO43-. Molar N:P ratios ranged from 11 to 21 and did not suggest clear limitation of a single nutrient. On a per carbon basis, we found a 6-fold difference in total FA content between the eight snow algal communities, ranging from 50 to 300 mg FA g C-1. In multivariate analyses total FA content opposed the cellular N:C quota and a large part of the FA variability among field locations originated from the abundant FAs C181n-9, C18 2n-6, and C183n-3. Both field samples and snow algal strains grown under -N+HL conditions had high concentrations of C181n-9. FAs possibly accumulated due to the cessation of growth. Differences in color and nutritional composition between patches of snow algal communities within one snow field were not directly related to nutrient conditions. We propose that the highly patchy distribution of snow algae within and between snow fields may also result from differences in topographical and geological parameters such as slope, melting water rivulets, and rock formation.}, language = {en} } @inproceedings{SpijkermanBehrendFachetal.2013, author = {Spijkerman, Elly and Behrend, Hella and Fach, Bettina and Gaedke, Ursula}, title = {INDIRECT EFFECT ON ECOSYSTEM FUNCTIONING : DECREASED PHOSPHORUS INCORPORATION NOT IRON TOXICITY DECREASES PHOTOSYNTHESIS AND GROWTH IN A GREEN MICROALGA}, series = {Phycologia}, volume = {52}, booktitle = {Phycologia}, number = {4}, publisher = {International Phycological Society}, address = {Lawrence}, issn = {0031-8884}, pages = {104 -- 105}, year = {2013}, language = {en} }