How bacterioplankton is affected by the shifts in biogenic carbon flow from particulate primary production to dissolved forms

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainPhotosynthesis by phytoplankton in sunlit surface waters transforms inorganic carbon and nutrients into particulate and dissolved organic matter (POC and DOC). POC can be efficiently transported downwards by the biological carbon pump whereas DOC is mostly recycled by bacteria back into dissolved inorganic forms and is the trophic link between photoautotrophs and bacteria heterotrophs. DOC production is an important part of the global primary production. There are, scarce studies that quantify its contribution in a large scale and probably does not include data from different oceans using a consistent methodology. Malaspina 2010 offers an excellent opportunity to cover the lack of knowledge regarding DOC primary production large scale variability and the degree of coupling with bacterioplankton. Simultaneously measuring DOC-14, POC14 and H-3 leucine bacterial production (within, the euphotic layer of the low-latitude Atlantic, Indian and Pacific Ocean) gave consistent results on planktonic community functioning. POC and DOC production rates tended to follow a similar vertical pattern with percent extracellular release (PER) values (42 % ± 2) not significantly different between depths. DOC and POC production rates were positively and significantly correlated with a slope significantly different than 1. On average, most of the bacterial production was sustained by DOC primary production within the euphotic layer all over the oceans. The vertical variability of DOC primary production and its degree of coupling with bacterioplankton metabolism in these largely unexplored systems will help us better understand the global oceanic carbon cyclePeer Reviewe