Microenvironments and single-cell variability in Trichodesmium colonies
N2-fixation by the colony-forming cyanobacteriumTrichodesmium is an important source of new nitrogen in the subtropical and tropical oligotrophic oceans. For understanding the ecology and physiology of this keystone species in a changing climate, we need to consider the implications of colony formation for chemical microenvironments and biotic interactions. The seminar will focus on a field study targeting gradients of O2 and pH as well as single-cell fluxes of carbon and nitrogen inTrichodesmium colonies under different pCO2 levels. Microsensor measurements and single-cell analysis by nanoSIMS indicated that cells within colonies experienced large fluctuations in O2, pH and CO2 concentrations, and showed high variability in carbon and nitrogen assimilation on a single-cell level. I will discuss the implications of our findings for responses of colony-forming phytoplankton to both short- and long-term variability in their environment.
Host: Hans-Peter Grossart