Contribution of aerobic photoheterotrophic bacteria to the carbon cycle inthe ocean

The vertical distribution of bacteriochlorophyll a, the numbers of infrared fluorescent cells, and the variable fluorescence signal at 880 nanometers wavelength, all indicate that photosynthetically competent anoxygenic photo trophic bacteria are abundant in the upper open ocean and comprise at Least 11% of the total microbial community. These organisms are facultative phot oheterotrophs, metabolizing organic carbon when available, but are capable of photosynthetic Light utilization when organic carbon is scarce. They are globally distributed in the euphotic zone and represent a hitherto unrecog nized component of the marine microbial community that appears to be critic al to the cycling of; both organic and inorganic carbon in the ocean.