TY  - JOUR
A1  - Piepho, Maike
A1  - Arts, Michael T.
A1  - Wacker, Alexander
T1  - Species-specific variation in fatty acid concentrations of four phytoplankton species does phosphorus supply influence the effect of light intensity of temperature?
JF  - Journal of phycology
N2  - We tested, in the laboratory, the influence of light intensity, temperature, and phosphorus (P) supply on fatty acid (FA) concentrations of four freshwater algae: the green algae Scenedesmus quadricauda (Turpin) Breb. and Chlamydomonas globosa J. Snow, the cryptophyte Cryptomonas ovata Ehrenb., and the diatom Cyclotella meneghiniana Kutz. We investigated the main and interactive effects of two variables on algal FA concentrations (i.e., light intensity and P supply or temperature and P supply). Interactive effects of light intensity and P supply were most pronounced in C. meneghiniana, but were also found in S. quadricauda and C. ovata. Changes in several saturated and unsaturated FA concentrations with light were more distinct in the low-P treatments than in the high-P treatments. Interactive effects of temperature and P supply on various FA concentrations were observed in all four species, but there was no consistent pattern. In lake ecosystems, P limitation often coincides with high light intensities and temperatures in summer. Therefore, it is important to examine how combinations of these environmental conditions affect FA concentrations of primary producers that are important sources of FAs for higher trophic levels.
KW  - Chlamydomonas
KW  - Cryptomonas
KW  - Cyclotella
KW  - fatty acids
KW  - light
KW  - lipids
KW  - phosphate
KW  - PUFA
KW  - Scenedesmus
KW  - temperature
Y1  - 2012
U6  - https://doi.org/10.1111/j.1529-8817.2011.01103.x
SN  - 0022-3646
VL  - 48
IS  - 1
SP  - 64
EP  - 73
PB  - Wiley-Blackwell
CY  - Malden
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  -