In laboratory experiments, Dr. Alderkamp determines the responses of P. antarctica and three Antarctic diatoms to a dynamic light regime similar to that induced by vertical mixing in the water column. In addition, the influence of Fe limitation on acclimation to a dynamic light regime will be determined. Results from the experiments will be used to parameterize the dynamic light component of the Coupled Ice And Ocean (CIAO) model, a RossSea ecosystem model developed by Prof. Kevin R. Arrigo, et al. (Stanford University, California, USA). The CIAO model will be used to determine if the differences in the acclimation to variable light conditions regulate taxonomic composition of phytoplankton blooms in the Ross Sea. C ombining laboratory and modeling activities can strongly advance the understanding of the controls of phytoplankton taxonomic distributions in the Ross Sea. The proposed project will then also contribute to our understanding how possible scenarios caused by global warming will affect phytoplankton community composition and hence carbon sequestration in the Ross Sea.