Microbial productivity and organic carbon in plumes

In situ microbial production is potentially the most important source of organic C to buoyant and especially neutrally buoyant plumes (Lilley etal., 1995 Winn etal., 1995 Cowen etal., 2001). However, plume productivity is poorly constrained only limited simultaneous measurements of substrate oxidation rates and C02 incorporation rates have been made in hydrothermal plumes for key substrates. For example, rates of dark C02 assimilation and methane oxidation in plumes from the Manus and Lau basins were found to be relatively high (1200-2500ngC-1 day-1 and 1300ngC 1day 1, respectively), but dropped considerably with increasing distance from the vents (Lein etal., 1997). 

the mid-ocean ridge corridor could be a 55000km long source of labile organic carbon that is independent of seasonal upper ocean production 

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