Bacterial carbon dynamics on marine snow

Abstract

We studied the biomass and production of heterotrophic bacteria on several types of marine snow including those composed predominantly of diatoms, fecal pellets, larvacean house mucus, or miscellaneous detrital components at 8 stations in the Pacific Ocean off California. We concurrently measured photoautotrophic biomass and production, and particulate organic carbon (POC) on marine snow to examine the quantitative significance of bacterial processes in carbon flow pathways in different types of marine snow. Although a typical marine marine snow floc contained about 10 super(6) bacteria, the bacterial carbon (BOC) and phytoplankton carbon (PhytoC) were each < 13% of total POC. Most of the floc carbon therefore consisted of detritus, unlike whole seawater samples (in other studies) where BOC + PhytoC generally comprises about 50% of the POC. PhytoC on marine snow and in the surrounding water was generally similar to BOC (except at one station). Floc POC turnover time based on bacterial carbon demand, assuming a 30% carbon assimilation efficiency, was 20 to 100 d.