TY  - JOUR
A1  - Chorus, Ingrid
A1  - Spijkerman, Elly
T1  - What Colin Reynolds could tell us about nutrient limitation, N:P ratios and eutrophication control
JF  - Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica
N2  - Colin Reynolds exquisitely consolidated our understanding of driving forces shaping phytoplankton communities and those setting the upper limit to biomass yield, with limitation typically shifting from light in winter to phosphorus in spring. Nonetheless, co-limitation is frequently postulated from enhanced growth responses to enrichments with both N and P or from N:P ranging around the Redfield ratio, concluding a need to reduce both N and P in order to mitigate eutrophication. Here, we review the current understanding of limitation through N and P and of co-limitation. We conclude that Reynolds is still correct: (i) Liebig's law of the minimum holds and reducing P is sufficient, provided concentrations achieved are low enough; (ii) analyses of nutrient limitation need to exclude evidently non-limiting situations, i.e. where soluble P exceeds 3-10 mu g/l, dissolved N exceeds 100-130 mu g/l and total P and N support high biomass levels with self-shading causing light limitation; (iii) additionally decreasing N to limiting concentrations may be useful in specific situations (e.g. shallow waterbodies with high internal P and pronounced denitrification); (iv) management decisions require local, situation-specific assessments. The value of research on stoichiometry and co-limitation lies in promoting our understanding of phytoplankton ecophysiology and community ecology.
KW  - phytoplankton
KW  - nitrogen limitation
KW  - redfield ratio
KW  - co-limitation
KW  - enrichment experiments
Y1  - 2020
U6  - https://doi.org/10.1007/s10750-020-04377-w
SN  - 0018-8158
SN  - 1573-5117
VL  - 848
IS  - 1
SP  - 95
EP  - 111
PB  - Springer Nature
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Spijkerman, Elly
T1  - The expression of a carbon concentrating mechanism in Chlamydomonas acidophila under variable phosphorus, iron, and CO2 concentrations
JF  - Photosynthesis research
N2  - 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).
KW  - C3 photosynthesis
KW  - Micro-algae
KW  - Carbon concentrating mechanism
KW  - Phosphorus limitation
KW  - Iron toxicity
Y1  - 2011
U6  - https://doi.org/10.1007/s11120-010-9607-z
SN  - 0166-8595
VL  - 109
IS  - 1-3
SP  - 179
EP  - 189
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Gerloff-Elias, Antje
A1  - Barua, Deepak
A1  - Mölich, Andreas
A1  - Spijkerman, Elly
T1  - Temperature- and pH-dependent accumulation of heat-shock proteins in the acidophilic green alga Chlamydomonas acidophila
N2  - Chlamydomonas acidophila, a unicellular green alga, is a dominant phytoplankton species in acidic water bodies, facing severe environmental conditions such as low pH and high heavy metal concentrations. We examined the pH-, and temperature-dependent accumulation of heat-shock proteins in this alga to determine whether heat-shock proteins play a role in adaptation to their environment. Our results show increased heat-shock proteins accumulation at suboptimal pHs, which were not connected with any change in intracellular pH. In comparison to the mesophilic Chlamydomonas reinhardtii, the acidophilic species exhibited significantly higher accumulations of heat-shock proteins under control conditions, indicating an environmental adaptation of increased basal levels of heat-shock proteins. The results suggest that heat- shock proteins might play a role in the adaptation of C. acidophila, and possibly other acidophilic algae, to their extreme environment
Y1  - 2006
UR  - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0168-6496
U6  - https://doi.org/10.1111/j.1574-6941.2006.00078.x
SN  - 0168-6496
ER  - 
TY  - JOUR
A1  - Spijkerman, Elly
A1  - Barua, Deepak
A1  - Gerloff-Elias, Antje
A1  - Gaedke, Ursula
A1  - Heckathorn, S. A.
T1  - Stress responses and metal tolerance of Chlamydomonas acidophila in metal-enriched lake water and artificial medium
N2  - Chlamydomonas acidophila faces high heavy-metal concentrations in acidic mining lakes, where it is a dominant phytoplankton species. To investigate the importance of metals to C. acidophila in these lakes, we examined the response of growth, photosynthesis, cell structure, heat-shock protein (Hsp) accumulation, and metal adsorption after incubation in metal-rich lake water and artificial growth medium enriched with metals (Fe, Zn). Incubation in both metal-rich lake water and medium caused large decreases in photosystem II function (though no differences among lakes), but no decrease in growth rate (except for medium + Fe). Concentrations of small Hsps were higher in algae incubated in metal-rich lake- water than in metal-enriched medium, whereas Hsp60 and Hsp70A were either less or equally expressed. Cellular Zn and Fe contents were lower, and metals adsorbed to the cell surface were higher, in lake-water-incubated algae than in medium- grown cells. The results indicate that high Zn or Fe levels are likely not the main or only contributor to the low primary production in mining lakes, and multiple adaptations of C. acidophila (e.g., high Hsp levels, decreased metal accumulation) increase its tolerance to metals and permit survival under such adverse environmental conditions. Supposedly, the main stress factor present in the lake water is an interaction between low P and high Fe concentrations.
Y1  - 2007
UR  - http://www.springerlink.com/content/p7273234p8255263/
U6  - https://doi.org/10.1007/s00792-007-0067-0
ER  - 
TY  - JOUR
A1  - Lachmann, Sabrina C.
A1  - Maberly, Stephen C.
A1  - Spijkerman, Elly
T1  - Species-specific influence of P-i-status on inorganic carbon acquisition in microalgae (Chlorophyceae)
JF  - Botany
N2  - Inorganic phosphorus (P-i) is often the primary limiting nutrient in freshwater ecosystems. Since P(i-)limitation affects energy transduction, and inorganic carbon (C-i) acquisition can be energy demanding, C(i-)acquisition strategies were compared in four species of green algae grown under P-i-replete and P-i-limited conditions predominantly at low and partly at high CO2. Although P-i-limitation was evident by the 10-fold higher cellular C:P ratio and enhanced phosphatase activity, it only decreased C-i-acquisition to a small extent. Nonetheless, the effects of Pi-limitation on both CO2 and HCO3- acquisition were demonstrated. Decreased CO2 acquisition under conditions of Pi limitation was mainly visible in the maximum uptake rate (V-max) and, for the neutrophile Scenedesmus vacuolatus, in the affinity for CO2 acquisition. Discrimination against C-13 was higher under P-i-limited, high CO2 conditions, compared with P-i-replete, highCO(2) conditions, in Chlamydomonas acidophila and S. vacuolatus. In the pH-drift experiments, HCO3- acquisition was reduced in P-i-limited C. reinhardtii. In general, energy demanding bicarbonate uptake was indicated by the less strong discrimination against (13)Cunder lowCO(2) conditions in the neutrophiles (HCO3- users), separating them from the acidophilic or acidotolerant species (CO2 users). The high variability of the influence of Pi supply among different green algal species is linked to their species-specific C(i-)acquisition strategies.
KW  - CCM
KW  - Chlamydomonas
KW  - inorganic carbon uptake kinetics
KW  - inorganic phosphorus limitation
KW  - stable carbon isotope discrimination
Y1  - 2017
U6  - https://doi.org/10.1139/cjb-2017-0082
SN  - 1916-2790
SN  - 1916-2804
VL  - 95
SP  - 943
EP  - 952
PB  - NRC Research Press
CY  - Ottawa
ER  - 
TY  - JOUR
A1  - Marzetz, Vanessa
A1  - Spijkerman, Elly
A1  - Striebel, Maren
A1  - Wacker, Alexander
T1  - Phytoplankton community responses to interactions between light intensity, light variations, and phosphorus supply
JF  - Frontiers in Environmental Science
N2  - In a changing world, phytoplankton communities face a large variety of challenges including altered light regimes. These alterations are caused by more pronounced stratification due to rising temperatures, enhanced eutrophication, and browning of lakes. Community responses toward these effects can emerge as alterations in physiology, biomass, biochemical composition, or diversity. In this study, we addressed the combined effects of changes in light and nutrient conditions on community responses. In particular, we investigated how light intensity and variability under two nutrient conditions influence (1) fast responses such as adjustments in photosynthesis, (2) intermediate responses such as pigment adaptation and (3) slow responses such as changes in community biomass and species composition. Therefore, we exposed communities consisting of five phytoplankton species belonging to different taxonomic groups to two constant and two variable light intensity treatments combined with two levels of phosphorus supply. The tested phytoplankton communities exhibited increased fast reactions of photosynthetic processes to light variability and light intensity. The adjustment of their light harvesting mechanisms via community pigment composition was not affected by light intensity, variability, or nutrient supply. However, pigment specific effects of light intensity, light variability, and nutrient supply on the proportion of the respective pigments were detected. Biomass was positively affected by higher light intensity and nutrient concentrations while the direction of the effect of variability was modulated by light intensity. Light variability had a negative impact on biomass at low, but a positive impact at high light intensity. The effects on community composition were species specific. Generally, the proportion of green algae was higher under high light intensity, whereas the cyanobacterium performed better under low light conditions. In addition to that, the diatom and the cryptophyte performed better with high nutrient supply while the green algae as well as the cyanobacterium performed better at low nutrient conditions. This shows that light intensity, light variability, and nutrient supply interactively affect communities. Furthermore, the responses are highly species and pigment specific, thus to clarify the effects of climate change a deeper understanding of the effects of light variability and species interactions within communities is important.
KW  - phytoplankton communities
KW  - light variability
KW  - photosynthetic rate
KW  - climate change
KW  - resource competition
KW  - light intensity (irradiance)
KW  - pigment composition
KW  - nutrient supply
Y1  - 2020
U6  - https://doi.org/10.3389/fenvs.2020.539733
SN  - 2296-665X
VL  - 8
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Marzetz, Vanessa
A1  - Spijkerman, Elly
A1  - Striebel, Maren
A1  - Wacker, Alexander
T1  - Phytoplankton Community Responses to Interactions Between Light Intensity, Light Variations, and Phosphorus Supply
JF  - Frontiers in Environmental Science
N2  - In a changing world, phytoplankton communities face a large variety of challenges including altered light regimes. These alterations are caused by more pronounced stratification due to rising temperatures, enhanced eutrophication, and browning of lakes. Community responses toward these effects can emerge as alterations in physiology, biomass, biochemical composition, or diversity. In this study, we addressed the combined effects of changes in light and nutrient conditions on community responses. In particular, we investigated how light intensity and variability under two nutrient conditions influence (1) fast responses such as adjustments in photosynthesis, (2) intermediate responses such as pigment adaptation and (3) slow responses such as changes in community biomass and species composition. Therefore, we exposed communities consisting of five phytoplankton species belonging to different taxonomic groups to two constant and two variable light intensity treatments combined with two levels of phosphorus supply. The tested phytoplankton communities exhibited increased fast reactions of photosynthetic processes to light variability and light intensity. The adjustment of their light harvesting mechanisms via community pigment composition was not affected by light intensity, variability, or nutrient supply. However, pigment specific effects of light intensity, light variability, and nutrient supply on the proportion of the respective pigments were detected. Biomass was positively affected by higher light intensity and nutrient concentrations while the direction of the effect of variability was modulated by light intensity. Light variability had a negative impact on biomass at low, but a positive impact at high light intensity. The effects on community composition were species specific. Generally, the proportion of green algae was higher under high light intensity, whereas the cyanobacterium performed better under low light conditions. In addition to that, the diatom and the cryptophyte performed better with high nutrient supply while the green algae as well as the cyanobacterium performed better at low nutrient conditions. This shows that light intensity, light variability, and nutrient supply interactively affect communities. Furthermore, the responses are highly species and pigment specific, thus to clarify the effects of climate change a deeper understanding of the effects of light variability and species interactions within communities is important.
KW  - phytoplankton communities
KW  - light variability
KW  - photosynthetic rate
KW  - climate change
KW  - resource competition
KW  - light intensity (irradiance)
KW  - pigment composition
KW  - nutrient supply
Y1  - 2020
U6  - https://doi.org/10.3389/fenvs.2020.539733
SN  - 2296-665X
VL  - 8
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Spijkerman, Elly
T1  - Physiological characteristics of co-limiting conditions for P and C in Chlamydomonas
Y1  - 2009
UR  - http://www.phycologia.org/perlserv/?request=get-archive
U6  - https://doi.org/10.2216/0031-8884-48.sp4.1
SN  - 0031-8884
ER  - 
TY  - JOUR
A1  - Grzesiuk, Malgorzata
A1  - Wacker, Alexander
A1  - Spijkerman, Elly
T1  - Photosynthetic sensitivity of phytoplankton to commonly used pharmaceuticals and its dependence on cellular phosphorus status
JF  - Ecotoxicology
N2  - Recently pharmaceuticals have become significant environmental pollutants in aquatic ecosystems, that could affect primary producers such as microalgae. Here we analyzed the effect of pharmaceuticals on the photosynthesis of microalgae commonly found in freshwater-two species of Chlorophyceae and a member of the Eustigmatophyceae, via PAM fluorometry. As pharmaceuticals, three medicines often consumed in households were chosen: (i) fluoxetine, an antidepressant, (ii) propranolol, a beta-blocker and (iii) ibuprofen, an anti-inflammatory and analgesic medicine. The EC50 for the quantum yield of photosystem II in phytoplankton acclimated to inorganic phosphorus (P-i)-replete and P-i-limited conditions was estimated. Acute toxicity experiments over a 5 h exposure revealed that Nannochloropsis limnetica was the least sensitive to pharmaceuticals in its photosynthetic yield out of all species tested. Although the estimation of sub-lethal effects can be vital in contrast to that of LC(50)s, the EC50 values in all species and for all medicines were orders of magnitude higher than concentrations found in polluted surface water. Chlamydomonas reinhardtii was the most sensitive to fluoxetine (EC50 of 1.6 mg L-1), and propranolol (EC50 of 3 mg L-1). Acutodesmus obliquus was most sensitive to ibuprofen (EC50 of 288 mg L-1). Additionally, the sensitivity to the pharmaceuticals changed under a P-i-limitation; the green algae became less sensitive to fluoxetine and propranolol. In contrast, P-i-limited algal species were more sensitive to ibuprofen. Our results suggest that the sensitivity of algae to pharmaceuticals is (i) highly compound- and species-specific and (ii) dependent on the cellular P status.
KW  - Freshwater algae
KW  - Medicine
KW  - EC50
KW  - PAM fluorometry
KW  - Tolerance
Y1  - 2016
U6  - https://doi.org/10.1007/s10646-016-1628-8
SN  - 0963-9292
SN  - 1573-3017
VL  - 25
SP  - 697
EP  - 707
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Wacker, Alexander
A1  - Piepho, Maike
A1  - Spijkerman, Elly
T1  - Photosynthetic and fatty acid acclimation of four phytoplankton species in response to light intensity and phosphorus availability
JF  - European journal of phycology
N2  - Photosynthetic acclimation of phytoplankton to lower irradiation can be met by several strategies such as increasing the affinity for light or increasing antenna size and stacking of the thylakoids. The latter is reflected by a higher proportion of polyunsaturated fatty acids (PUFAs). Additionally, photosynthetic capacity (P-max), respiratory losses, and proton leakage can be reduced under low light. Here we consider the effect of light intensity and phosphorus availability simultaneously on the photosynthetic acclimation and fatty acid composition of four phytoplankters. We studied representatives of the Chlorophyceae, Cryptophyceae and Mediophyceae, all of which are important components of plankton communities in temperate lakes. In our analysis, excluding fatty acid composition, we found different acclimation strategies in the chlorophytes Scenedesmus quadricauda, Chlamydomonas globosa, cryptophyte Cryptomonas ovata and ochrophyte Cyclotella meneghiniana. We observed interactive effects of light and phosphorus conditions on photosynthetic capacity in S. quadricauda and Cry. ovata. Cry. ovata can be characterized as a low light-acclimated species, whereas S. quadricauda and Cyc. meneghiniana can cope best with a combination of high light intensities and low phosphorus supply. Principal component analyses (PCA), including fatty acid composition, showed further species-specific patterns in their regulation of P-max with PUFAs and light. In S. quadricauda and Cyc. meneghiniana, PUFAs negatively affected the relationship between P-max and light. In Chl. globosa, lower light coincided with higher PUFAs and lower P-max, but PCA also indicated that PUFAs had no direct influence on P-max. PUFAs and P-max were unaffected by light in Cry. ovata. We did not observe a general trend in the four species tested and concluded that, in particular, the interactive effects highlight the importance of taking into account more than one environmental factor when assessing photosynthetic acclimation to lower irradiation.
KW  - chlorophyll content
KW  - dark respiration
KW  - FAME
KW  - light acclimation
KW  - oxygen evolution
KW  - photosynthesis
KW  - phytoplankton
KW  - polyunsaturated fatty acids
Y1  - 2015
U6  - https://doi.org/10.1080/09670262.2015.1050068
SN  - 0967-0262
SN  - 1469-4433
VL  - 50
IS  - 3
SP  - 288
EP  - 300
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Spijkerman, Elly
T1  - Phosphorus acquisition by Chlamydomonas acidophila under autotrophic and osmo-mixotrophic growth conditions
Y1  - 2007
ER  - 
TY  - JOUR
A1  - Clegg, Mark R.
A1  - Wacker, Alexander
A1  - Spijkerman, Elly
T1  - Phenotypic Diversity and Plasticity of Photoresponse Across an Environmentally Contrasting Family of Phytoflagellates
JF  - Frontiers in plant science : FPLS
N2  - Organisms often employ ecophysiological strategies to exploit environmental conditions and ensure bio-energetic success. However, the many complexities involved in the differential expression and flexibility of these strategies are rarely fully understood. Therefore, for the first time, using a three-part cross-disciplinary laboratory experimental analysis, we investigated the diversity and plasticity of photoresponsive traits employed by one family of environmentally contrasting, ecologically important phytoflagellates. The results demonstrated an extensive inter-species phenotypic diversity of behavioural, physiological, and compositional photoresponse across the Chlamydomonadaceae, and a multifaceted intra-species phenotypic plasticity, involving a broad range of beneficial photoacclimation strategies, often attributable to environmental predisposition and phylogenetic differentiation. Deceptively diverse and sophisticated strong (population and individual cell) behavioural photoresponses were observed, with divergence from a general preference for low light (and flexibility) dictated by intra-familial differences in typical habitat (salinity and trophy) and phylogeny. Notably, contrasting lower, narrow, and flexible compared with higher, broad, and stable preferences were observed in freshwater vs. brackish and marine species. Complex diversity and plasticity in physiological and compositional photoresponses were also discovered. Metabolic characteristics (such as growth rates, respiratory costs and photosynthetic capacity, efficiency, compensation and saturation points) varied elaborately with species, typical habitat (often varying more in eutrophic species, such as Chlamydomonas reinhardtii), and culture irradiance (adjusting to optimise energy acquisition and suggesting some propensity for low light). Considerable variations in intracellular pigment and biochemical composition were also recorded. Photosynthetic and accessory pigments (such as chlorophyll a, xanthophyll-cycle components, chlorophyll a:b and chlorophyll a:carotenoid ratios, fatty acid content and saturation ratios) varied with phylogeny and typical habitat (to attune photosystem ratios in different trophic conditions and to optimise shade adaptation, photoprotection, and thylakoid architecture, particularly in freshwater environments), and changed with irradiance (as reaction and harvesting centres adjusted to modulate absorption and quantum yield). The complex, concomitant nature of the results also advocated an integrative approach in future investigations. Overall, these nuanced, diverse, and flexible photoresponsive traits will greatly contribute to the functional ecology of these organisms, addressing environmental heterogeneity and potentially shaping individual fitness, spatial and temporal distribution, prevalence, and ecosystem dynamics.
KW  - photoresponse
KW  - behaviour
KW  - physiology
KW  - composition
KW  - photosynthesis
KW  - acclimation
KW  - Chlamydomonas
KW  - ecophysiology
Y1  - 2021
U6  - https://doi.org/10.3389/fpls.2021.707541
SN  - 1664-462X
IS  - 12
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Spijkerman, Elly
A1  - Stojkovic, Slobodanka
A1  - Holland, Daryl
A1  - Lachmann, Sabrina C.
A1  - Beardall, John
T1  - Nutrient induced fluorescence transients (NIFTs) provide a rapid measure of P and C (co-)limitation in a green alga
JF  - European journal of phycology
N2  - Nutrient Induced Fluorescence Transients (NIFTs) have been shown to be a possible way of testing for the limiting nutrient in algal populations. In this study we tested the hypothesis that NIFTs can be used to detect a (co-)limitation for inorganic phosphorus (Pi) and CO2 in the green alga Chlamydomonas acidophila and that the magnitude of the NIFTs can be related to cellular P:C ratios. We show a co-limitation response for Pi and CO2 via traditional nutrient enrichment experiments in natural phytoplankton populations dominated by C. acidophila. We measured NIFT responses after a Pi- or a CO2-spike in C. acidophila batch cultures at various stages of Pi and inorganic C limitation. Significant NIFTs were observed in response to spikes in both nutrients. The NIFT response to a Pi-spike showed a strong negative correlation with cellular P:C ratio that was pronounced below 3 mmol P: mol C (equivalent to 0.2 pg P cell(-1)). Both cellular P and C content influenced the extent of the Pi-NIFT response. The NIFT response to a CO2-spike correlated to low CO2 culturing conditions and also had a negative correlation with cellular P content. A secondary response within the Pi-NIFT response was related to the CO2 concentration and potentially reflected co-limitation. In conclusion, NIFTs provided a quick and reliable method to detect the growth-limiting nutrient in an extremophile green alga, under Pi-, CO2- and Pi/CO2 (co-)limited growth conditions.
KW  - acidophile
KW  - Chlamydomonas
KW  - CO2 concentrating mechanism
KW  - CO2 limitation
KW  - extremophile
KW  - nutrient limitation
KW  - photosynthesis response
KW  - phytoplankton
KW  - stoichiometry
Y1  - 2016
U6  - https://doi.org/10.1080/09670262.2015.1095355
SN  - 0967-0262
SN  - 1469-4433
VL  - 51
SP  - 47
EP  - 58
PB  - Hindawi
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Lachmann, Sabrina C.
A1  - Mettler-Altmann, Tabea
A1  - Wacker, Alexander
A1  - Spijkerman, Elly
T1  - Nitrate or ammonium
BT  - Influences of nitrogen source on the physiology of a green alga
JF  - Ecology and evolution
N2  - In freshwaters, algal species are exposed to different inorganic nitrogen (Ni) sources whose incorporation varies in biochemical energy demand. We hypothesized that due to the lesser energy requirement of ammonium (NH4+)-use, in contrast to nitrate (NO3-)-use, more energy remains for other metabolic processes, especially under CO2-and phosphorus (Pi) limiting conditions. Therefore, we tested differences in cell characteristics of the green alga Chlamydomonas acidophila grown on NH4+ or NO3- under covariation of CO2 and Pi-supply in order to determine limitations, in a full-factorial design. As expected, results revealed higher carbon fixation rates for NH4+ grown cells compared to growth with NO3- under low CO2 conditions. NO3- -grown cells accumulated more of the nine analyzed amino acids, especially under Pi-limited conditions, compared to cells provided with NH4+. This is probably due to a slower protein synthesis in cells provided with NO3-. In contrast to our expectations, compared to NH4+ -grown cells NO3- -grown cells had higher photosynthetic efficiency under Pi-limitation. In conclusion, growth on the Ni-source NH4+ did not result in a clearly enhanced Ci-assimilation, as it was highly dependent on Pi and CO2 conditions (replete or limited). Results are potentially connected to the fact that C. acidophila is able to use only CO2 as its inorganic carbon (Ci) source.
KW  - amino acids
KW  - carbon uptake kinetics
KW  - CO2 conditions
KW  - nitrogen
KW  - phosphorus limitation
Y1  - 2019
U6  - https://doi.org/10.1002/ece3.4790
SN  - 2045-7758
VL  - 9
IS  - 3
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Spijkerman, Elly
A1  - Garcia-Mendoza, E.
A1  - Matthijs, H. C. P.
A1  - Van Hunnik, E.
A1  - Coesel, P. F. M.
T1  - Negative effects of P-buffering and pH on photosynthetic activity of planktonic desmid species
N2  - The photosynthetic activities of three planktonic desmid species (Staurastrum brachiatum, Staurodesmus cuspidatus var. curvatus, and Staurastrum chaetoceras) were compared after adaptation to medium enriched with either a 20 mM Na+- phosphate (P) or HEPES buffer. Incubations up to 2 d were carried out at pH 6 or 8 under normal air or air enriched with 5 % CO2. Gross maximum photosynthetic rate (Pmax) and growth rate were decreased in both S. brachiatum and Std. cuspidatus at higher pH when using the HEPES buffer and this effect was independent of CO2 concentration, indicating that pH had an inhibitory effect on photosynthesis and growth in these species. The P-buffer at pH 8 caused a large decrease in Pmax and quantum yield for charge separation in photosystem 2 (PS2), compared to HEPES-buffered algae. This effect was very large in both S. brachiatum and Std. cuspidatus, two species characteristic of soft water lakes, but also significant in S. chaetoceras, a species dominant in eutrophic, hard water lakes. The decreased Pmax in P- buffer could not be related to a significant increase in cellular P content known to be responsible for inhibition in isolated chloroplasts. Experiments at pH 6 and 8 showed that two conditions, high pH and high Na+ concentration, both contributed to the decreased Pmax and quantum yield in the desmids. Effects of a P-buffer were less pronounced by using K+-P buffer. The use of P-buffer at pH 8 possibly resulted in high irradiance stress in all species, indicated by damage in the PS2 core complex. In the soft water species pH 8 resulted in increased non-photochemical quenching together with a high de-epoxidation state of the xanthophyll cycle pigments.
Y1  - 2004
UR  - http://www.springerlink.com/app/home/ contribution.asp?wasp=d7fd2f5af00d494191eaadb905f68db3&referrer=parent&backto=searcharticlesresults,3,7;
ER  - 
TY  - JOUR
A1  - Spijkerman, Elly
A1  - Bissinger, Vera
A1  - Gaedke, Ursula
T1  - Low potassium and inorganic carbon concentrations influence a possible phosphorus limitation in Chlamydomonas acidophila
N2  - 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.
Y1  - 2007
UR  - http://www.tandfonline.com/doi/full/10.1080/09670260701529596
U6  - https://doi.org/10.1080/09670260701529596
ER  - 
TY  - JOUR
A1  - Gerloff-Elias, Antje
A1  - Spijkerman, Elly
A1  - Schubert, H.
T1  - Light acclimation of Chlamydomonas acidophila accumulating in the hypolimnion of an acidic lake (pH 2.6)
N2  - 1. The unicellular green alga Chlamydomonas acidophila accumulates in a thin phytoplankton layer in the hypolimnion (deep chlorophyll maximum, DCM) of an extremely acidic lake (Lake 111, pH 2.6, Lusatia, Germany), in which the underwater light spectrum is distorted and red-shifted. 2. Chlamydomonas acidophila exhibited a significantly higher absorption efficiency and a higher cellular chlorophyll b content when incubated in the red shifted underwater light of Lake 111 than in a typical, blue-green dominated, light spectrum. 3. Chlamydomonas acidophila has excellent low light acclimation properties (increased chlorophyll b content, increased oxygen yield and a low light saturation point for photosynthesis) that support survival of the species in the low light climate of the DCM. 4. In situ acclimation to the DCM under low light and temperature decreased maximum photosynthetic rate in autotrophic C. acidophila cultures, whereas the presence of glucose under these conditions enhanced photosynthetic efficiency and capacity. 5. The adaptive abilities of C. acidophila to light and temperature shown in this study, in combination with the absence of potent competitors because of low lake pH, most probably enable the unusual dominance of the green alga in the DCM of Lake 111
Y1  - 2005
SN  - 0046-5070
ER  - 
TY  - JOUR
A1  - Spijkerman, Elly
T1  - Is there really insufficient support for Tilman's R* concept? A comment on Miller et al
Y1  - 2007
ER  - 
TY  - JOUR
A1  - Wacker, Alexander
A1  - Marzetz, Vanessa
A1  - Spijkerman, Elly
T1  - Interspecific competition in phytoplankton drives the availability of essential mineral and biochemical nutrients
JF  - Ecology : a publication of the Ecological Society of America
N2  - The underlying mechanisms and consequences of competition and diversity are central themes in ecology. A higher diversity of primary producers often results in higher resource use efficiency in aquatic and terrestrial ecosystems. This may result in more food for consumers on one hand, while, on the other hand, it can also result in a decreased food quality for consumers; higher biomass combined with the same availability of the limiting compound directly reduces the dietary proportion of the limiting compound. Here we tested whether and how interspecific competition in phytoplankton communities leads to changes in resource use efficiency and cellular concentrations of nutrients and fatty acids. The measured particulate carbon : phosphorus ratios (C:P) and fatty acid concentrations in the communities were compared to the theoretically expected ratios and concentrations of measurements on simultaneously running monocultures. With interspecific competition, phytoplankton communities had higher concentrations of the monounsaturated fatty acid oleic acid and also much higher concentrations of the ecologically and physiologically relevant long-chain polyunsaturated fatty acid eicosapentaenoic acid than expected concentrations based on monocultures. Such higher availability of essential fatty acids may contribute to the positive relationship between phytoplankton diversity and zooplankton growth, and may compensate limitations by mineral nutrients in higher trophic levels.
KW  - biodiversity
KW  - C:P ratio
KW  - competition
KW  - eicosapentaenoic acid
KW  - elemental composition
KW  - EPA
KW  - food quality
KW  - minerals
KW  - phosphorus
KW  - polyunsaturated fatty acids
KW  - PUFA
KW  - resource use efficiency
Y1  - 2015
U6  - https://doi.org/10.1890/14-1915.1
SN  - 0012-9658
SN  - 1939-9170
VL  - 96
IS  - 9
SP  - 2467
EP  - 2477
PB  - Wiley
CY  - Washington
ER  - 
TY  - JOUR
A1  - Spijkerman, Elly
A1  - Wacker, Alexander
T1  - Interactions between P-limitation and different C conditions on the fatty acid composition of an extremophile microalga
JF  - Extremophiles : life under extreme conditions
N2  - 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.
KW  - Acidophilic algae
KW  - Cellular P quota
KW  - Chlamydomonas acidophila
KW  - Chlorophyceae
KW  - Colimitation
KW  - CO(2)
KW  - Fatty acid composition
KW  - Food quality
KW  - Glucose
KW  - Mixotrophy
KW  - Photosynthesis
KW  - Phytoplankton
KW  - Phosphorus limitation
Y1  - 2011
U6  - https://doi.org/10.1007/s00792-011-0390-3
SN  - 1431-0651
VL  - 15
IS  - 5
SP  - 597
EP  - 609
PB  - Springer
CY  - Tokyo
ER  -