Effects of Nutritional Conditions on the Stable Carbon and Nitrogen Isotope of Microalgae

Abstract

Carbon and nitrogen stable isotopes were studied among different groups and species of marine phytoplankton on the aspect of growth phase and nutrient conditions. Three investigated algal species which represent the Chlorophyceae, Dinophyceae and Desmokontae classes were grown in batch monocultures and analysed for δ13C and δ15N in both exponential and stationary phase. For all the cultured species, δ13C signatures range from 24.77 (A.carterae) to 17.10 (P. micans) as well as δ15N range from-15.66(P. helgolandica) to 14.40(P. helgolandica).These three species (Platymonas helgolandicavar. tsingtaoensis,Amphidinium carteraeHulburt andProrocentrum micans) were also grown under nutrient sufficient and nitrogen or phosphorus deficient conditions. Nitrogen limitation resulted in a more negative δ13C signature, whereas no effect could be observed during phosphorus limitation compared to nutrient sufficient conditions. But nitrogen and phosphorus limitation resulted in a more positive δ15N signature. The results show that the carbon and nitrogen isotopic signature of phytoplankton may be differ among different phytoplankton species, between exponential and stationary phase, as well as between nutrient treatments.