Ecophysiology of Phototrophic Carbon Allocation and Partitioning in Marine Microbial Mats

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9415985 Paerl Previous research on carbon (C) dynamics of microbial mat communities has involved the quantification of C in and out of the mats. While these studies have increased the knowledge of the collective C fluxes of marine microbial mats, they have failed to take into account that mats are composed of physiologically and evolutionary distinct constituents including bacteria, cyanobacteria and eukaryotic microallgae. This research will pursue the next logical step which is to discern the contributions to the C budget of microbial mats by the individual components of the mat community. The distinguishing feature of this research is the use of a mechanistic/functional approach for identifying the principal organisms and ecophysiological factors controlling the key processes in benthic microbial mats. Principal research objectives include: 1) elucidating the ecophysiological processes responsible for mat community structure and function, 2) revealing mechanisms controlling microbial mat consortial interactions, and 3) identifying species and functional group succession. Specifically the research will document seasonal changes in the identity (taxonomic groups) and abundance (standing stock) of mat phototrophs and diazotrophs using microscopy and HPLC methods. C fixation and allocation will be evaluated using 14C, O2 microelectrodes, microautoradiography and in situ growth rates, The primary ecophysiological factors (light, nutrients, sub aerial exposure, etc.) that regulate C fixation, allocation and community succession will be assessed in a series of controlled mat manipulation experiments.