A temperature & irradiance controlled growth chamber for phytoplankton physiological research

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Marine phytoplankton, unicellular algae, have a major impact on the global carbon cycle-and hence climate-by fixing atmospheric carbon dioxide to organic carbon. A significant fraction of this organic C is transported to the deep ocean via the so-called 'biological pump'. The ocean's capacity to sequester atmospheric carbon dioxide today is lower than during the last ice-ages, as phytoplankton growth is limited by inadequate Fe supply in 30% of the ocean. Despite chronic Fe limitation in vast oceanic regions, some phytoplankton species are abundant in these waters, while others maintain low 'seed' populations which can respond vigorously to sporadic Fe inputs. It is thus clear that different phytoplankton have distinct strategies to acquire and store Fe, and may have the ability to substitute Fe for a more abundant trace element. These different physiological adaptations have important ecological implications during periods of extensive Fe starvation or sporadic Fe inputs. To improve our understanding of the carbon cycle, it is imperative to investigate the role of trace metals and pCO2 in controlling marine productivity and ecology. Our research groups, through laboratory and field studies, investigate the physiological adaptations of marine phytoplankton to light-mediated oxidative stress, variable carbon dioxide concentrations, and limiting trace metals concentrations by determining the rates of various metabolic processes, and examining the expression of genes and proteins involved in photosynthesis, C acquisition/fixation and trace metal acquisition/metabolism/storage. Our research approach consists of a) elucidating phytoplankton physiological responses under tightly controlled laboratory culture conditions and b) examining whether these responses operate at sea. Our research depends critically on environmental growth chambers for culturing phytoplankton under well controlled temperature and light regimes. This proposal requests funds for a new, state of the art, culturing chamber to support our laboratory research program.