Theme 2
Program 3040

Sensing Seasonality
Program coordinator(s): Dr. G. M. Ganssen
Theme(s): 2
Funding date: 11-dec-09

Understanding sensitivity of Earth's climate system to perturbations is one of the most important challenges mankind is facing. Records of past climate have shown that the Earth's history is punctuated by many short-term (i.e. millenial-scale) switches in climate states and associated changes in seawater temperature and chemistry. These switches have been suggested to comprise a major seasonal component. Whereas numerical modeling studies of such past climate change address the full annual cycle, geological constraints are still limited to yearly averages. Here we propose to calibrate, validate and apply planktonic foraminiferal proxies to constrain the full seasonal cycle using ecological, geochemical and paleoceanographic approaches. Within project 1 the baseline calibration for trace metal incorporation and stable isotope fractionation (Mg/Ca ratios, as well as δ18O and δ13C) of individual foraminifera will be determined using physiological experiments. Project 2 consists of a field calibration and validation using plankton tows, sediment traps and surface sediments. Project 3 applies the proxyrelationships for detailed reconstructions of evolution and variability in terms of seasonality during time intervals of rapid climate change of the past 50.000 years in the most seasonal climate of the world, the monsoonal system of the Arabian Sea.

This program contains the following projects:
3041: The biological imprint of calcification in foraminifera
3042: Validation of seasonal proxies using planktic foraminifera
3043: Seasonal extremes during rapid (sub-)millennial climate changes in the northern Arabian Sea

Raitzsch M, Duenas-Bohorquez A, Reichart GJ, De Nooijer LJ, Bickert T (2010). Incorporation of Mg and Sr in calcite of cultured benthic foraminifera: impact of calcium concentration and associated calcite saturation state. BIOGEOSCIENCES7: 869-881.
Darwin Center authors: de Nooijer L.J., Reichart G. J.

Langer G, De Nooijer LJ, Oetjen K (2010). On the role of the cytoskeleton in coccolith morphogenesis: The effect of cytoskeleton inhibitors. PHYCOLOGY46: 1252-1256.
Darwin Center authors: Langer G., de Nooijer L.J.

Duenas-Bohorquez A, da Rocha RE, Kuroyanagi A, De Nooijer LJ, Bijma J, Reichart GJ (2011). Interindividual variability and ontogenetic effects on Mg and Sr incorporation in the planktonic foraminifer Globigerinoides sacculifer. GEOCHIMICA ET COSMOCHIMICA ACTA75: 520-532.
Darwin Center authors: Bijma J., de Nooijer L.J., Reichart G. J.

Jonkers L, De Nooijer LJ, Reichart GJ, Zahn R, Brummer G-JA (2012). Encrustration and trace element composition of Neogloboquadrina dutertrei assessed from single chamber analysis: Implications for paleotemperature estimates. Biogeosciences9: 4851-4860.
Darwin Center authors: de Nooijer L.J., Reichart G. J.

Hoppe, C. J. M. , Langer, G. , Rokitta, S. D. , Wolf-Gladrow, D. A. and Rost, B. (2012). Implications of observed inconsistencies in carbonate chemistry measurements for ocean acidification studies. Biogeosciences9: 2401-2405.
Darwin Center authors: Langer G.

Stoll, H. , Langer, G. , Shimizu, N. and Kanamaru, K. (2012). B/Ca in coccoliths and relationship to calcification vesicle pH and dissolved inorganic carbon concentrations. Geochimica et Cosmochimica Acta80: 143-157.
Darwin Center authors: Langer G.

Langer, G. , Oetjen, K. and Brenneis, T. (2012). Calcification of Calcidiscus leptoporus under nitrogen and phosphorus limitation. Journal of Experimental Marine Biology and Ecology413: 131-137.
Darwin Center authors: Langer G.

Ziveri, P. , Thoms, S. , Probert, I. , Geisen, M. and Langer, G. (2012). A universal carbonate ion effect on stable oxygen isotope ratios in unicellular planktonic calcifying organisms. Biogeosciences9: 1025-1032.
Darwin Center authors: Langer G.

Glas, M. , Langer, G. and Keul, N. (2012). Calcification acidifies the microenvironment of a benthic foraminifer (Ammonia sp.). Journal of Experimental Marine Biology and Ecology424: 53-58.
Darwin Center authors: Keul N., Langer G.

Langer, G., Oetjen, K., Brenneis, T. (2012). On culture artefacts in coccolith morphology. Helgoland Marine Research
Darwin Center authors: Langer G.