Dissolved and particulate primary production and bacterial production in offshore Antarctic waters during austral summer: coupled or uncoupled?

Abstract

3H-leucine incorporation, was accounted for by dissolved primary production. BHP bore no relationship with other phytoplankton-related variables. Assuming a conservative bacterial growth efficiency of 14%, as reported by recent work in Antarctic waters, our experiments indicate that phytoplanktonically produced DOC would suffice to meet bacterial carbon demand. These results suggest a strong coupling between phytoplankton and bacterioplankton through DOC release and uptake under non-bloom conditions in the Southern Ocean.

The percentage of living bacterial cells related to organic carbon release from senescent oceanic phytoplankton

“…Previous attempts at testing the response of the bacterial community (metabolism and/or physiological status) to DOCp release were conducted among systems but remained elusive and variable. For instance, in open-ocean sites, bacterial production and dissolved primary production (DPP) are often tightly linked (Morán et al, 2001; Antarctic off shore waters), while in coastal (Morán et al, 2002a; NE Atlantic coastal system, Morán et al, 2002b) or eutrophic sites (Baines and Pace, 1991;Morán et al, 2002b, Antarctic coastal) persists a lack of linkage. Our study provides, to the best of our knowledge, the first demonstration of a direct relationship between recently released labile photosynthate, the preferred carbon source for heterotrophic bacteria (Norrman et al, 1995), and the bacterial health status expressed as the percentage of living bacterial cells.…”

“…The error of the measurements of TPP and PPP represented 14 and 9 %, respectively, in our study. The DOCp was calculated as the difference between total and particulate primary production (Morán et al, 2001) and the percentage of phytoplankton extracellular carbon release (PER = 100 DOCp/TPP) was calculated.…”

Heterotrophic bacterial production in the eastern South Pacific: longitudinal trends and coupling with primary production

“…In the South Pacific Gyre primary production was strongly limited by nitrogen (Bonnet et al, 2007). We attempted to estimate DOC excretion by using empirical equations on DOC production and particulate primary production obtained in field studies (Baines and Pace, 1991;Moran et al, 2001;Teira et al, 2001;Moran et al, 2002). This approach is, however, limited because the rates of primary production analyzed are higher than those encountered in the South Pacific Ocean.…”

Multiscale control of bacterial production by phytoplankton dynamics and sea ice along the western Antarctic Peninsula: A regional and decadal investigation

“…Morán and colleagues investigated phytoplankton-bacteria coupling experimentally in the 18 same region (Morán and Estrada, 2002;Morán et al, 2001). They identified the flow of recently-19 synthesized DOC from active phytoplankton (14% of total particulate plus dissolved PP) and its 20 immediate (within hours) incorporation into bacteria as the mechanism of coupling.…”