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Fe and C co-limitation of heterotrophic bacteria in the naturally fertilized region off the Kerguelen Islands


Obernosterer, I and Fourquez, M and Blain, S, Fe and C co-limitation of heterotrophic bacteria in the naturally fertilized region off the Kerguelen Islands, Biogeosciences, 12 pp. 1983-1992. ISSN 1726-4170 (2015) [Refereed Article]


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Copyright 2015 The authors Licensed under Creative Commons Attribution 3.0 Unported

DOI: doi:10.5194/bg-12-1983-2015


It has been univocally shown that iron (Fe) is the primary limiting nutrient for phytoplankton metabolism in high-nutrient, low-chlorophyll (HNLC) waters, yet the question of how this trace metal affects heterotrophic microbial activity is far less understood. We investigated the role of Fe for bacterial heterotrophic production and growth at three contrasting sites in the naturally Fe-fertilized region east of the Kerguelen Islands and at one site in HNLC waters during the KEOPS2 (Kerguelen Ocean and Plateau Compared Study 2) cruise in spring 2011. We performed dark incubations of natural microbial communities amended either with iron (Fe, as FeCl3) or carbon (C, as trace-metal clean glucose), or a combination of both, and followed bacterial abundance and heterotrophic production for up to 7 days. Our results show that single and combined additions of Fe and C stimulated bulk and cell-specific bacterial production at the Fe-fertilized sites, while in HNLC waters only combined additions resulted in significant increases in these parameters. Bacterial abundance was enhanced in two out of the three experiments performed in Fe-fertilized waters but did not respond to Fe or C additions in HNLC waters. Our results provide evidence that both Fe and C are present at limiting concentrations for bacterial heterotrophic activity in the naturally fertilized region off the Kerguelen Islands in spring, while bacteria were co-limited by these elements in HNLC waters. These results shed new light on the role of Fe in bacterial heterotrophic metabolism in regions of the Southern Ocean that receive variable Fe inputs.

Item Details

Item Type:Refereed Article
Keywords:Southern Ocean, heterotrophic bacteria, iron, carbon
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological oceanography
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean oceanic processes
UTAS Author:Fourquez, M (Dr Marion Fourquez)
ID Code:108982
Year Published:2015
Web of Science® Times Cited:19
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2016-05-16
Last Modified:2016-08-04
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