9415688 Proctor Many important microbial processes in the marine environment are anaerobic. Nitrogen fixation, sulfate reduction, methanogenesis and the availability of many trace elements are but a few of the processes which are mediated by either anaerobic bacteria or enzymes which are active only under anaerobic conditions. There is paradoxical evidence that anaerobic processes occur in the water column with chemical signatures of anaerobic microbial activity such as methane peaks present in marine waters. Where are these anaerobic microbial assemblages? How can anaerobes or anaerobic processes occur in a well-oxygenated water column. Microbial assemblages associated with the digestive systems of marine zooplankton may be important microenvironments for anaerobic processes in the water column. From a microbiological point of view, the gut represents a high nutrient, low oxygen environment within the high oxygen but low nutrient environment of the water column. Nitrogen fixation and methanogenesis are two of the metabolically- demanding processes which require large sources of carbon and energy that could be supplied in the digestive tracts of marine zooplankton. The primary goal of this ROW planning award is to select a model organism for a physiological and ecological study of anaerobes and anaerobic processes in the gut microflora of marine zooplankton. One of the immediate objectives is to survey the gut contents of marine zooplankton in order to estimate the abundance and variability of bacteria found within the gut of a variety of zooplankton and select a suitable candidate species for further study. The key to success in this study of gut anaerobes and anaerobic processes will be the use of strict anaerobic technique, a procedure which has not been routinely used in other studies of marine anaerobes. ***
