Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 14, 2815-2829, 2017
https://doi.org/10.5194/bg-14-2815-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
09 Jun 2017
Increased temperature causes different carbon and nitrogen processing patterns in two common intertidal foraminifera (Ammonia tepida and Haynesina germanica)
Julia Wukovits1, Annekatrin Julie Enge1, Wolfgang Wanek2, Margarete Watzka2, and Petra Heinz1 1University of Vienna, Department of Palaeontology, Vienna, Austria
2University of Vienna, Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, Vienna, Austria
Abstract. Benthic foraminifera are highly abundant heterotrophic protists in marine sediments, but future environmental changes will challenge the tolerance limits of intertidal species. Metabolic rates and physiological processes in foraminifera are strongly dependent on environmental temperatures. Temperature-related stress could therefore impact foraminiferal food source processing efficiency and might result in altered nutrient fluxes through the intertidal food web. In this study, we performed a laboratory feeding experiment on Ammonia tepida and Haynesina germanica, two dominant foraminiferal species of the German Wadden Sea/Friedrichskoog, to test the effect of temperature on phytodetritus retention. The specimens were fed with 13C and 15N labelled freeze-dried Dunaliella tertiolecta (green algae) at the start of the experiment and were incubated at 20, 25 and 30 °C respectively. Dual labelling was applied to observe potential temperature effects on the relation of phytodetrital carbon and nitrogen retention. Samples were taken over a period of 2 weeks. Foraminiferal cytoplasm was isotopically analysed to investigate differences in carbon and nitrogen uptake derived from the food source. Both species showed a positive response to the provided food source, but carbon uptake rates of A. tepida were 10-fold higher compared to those of H. germanica. Increased temperatures had a far stronger impact on the carbon uptake of H. germanica than on A. tepida. A distinct increase in the levels of phytodetrital-derived nitrogen (compared to more steady carbon levels) could be observed over the course of the experiment in both species. The results suggest that higher temperatures have a significant negative effect on the carbon exploitation of H. germanica. For A. tepida, higher carbon uptake rates and the enhanced tolerance range for higher temperatures could outline an advantage in warmer periods if the main food source consists of chlorophyte phytodetritus. These conditions are likely to impact nutrient fluxes in A. tepida/H. germanica associations.

Citation: Wukovits, J., Enge, A. J., Wanek, W., Watzka, M., and Heinz, P.: Increased temperature causes different carbon and nitrogen processing patterns in two common intertidal foraminifera (Ammonia tepida and Haynesina germanica), Biogeosciences, 14, 2815-2829, https://doi.org/10.5194/bg-14-2815-2017, 2017.
Publications Copernicus
Download
Short summary
This study reports the response of two intertidal foraminifera to increased temperatures on the level of carbon and nitrogen uptake. Interspecific variations in the ability to cope with shifting environmental variables within the two commonly associated species show that temperature and food source might be critical factors that control their abundances. This should support the interpretation of sediment samples and increase knowledge about nutrient fluxes through foraminiferal communities.
This study reports the response of two intertidal foraminifera to increased temperatures on the...
Share