Conway, TM and Hoffmann, LJ and Breitbarth, E and Strzepek, RF and Wolff, EW, The growth response of two diatom species to atmospheric dust from the Last Glacial Maximum, PLoS ONE, 11, (7) Article e0158553. ISSN 1932-6203 (2016) [Refereed Article]
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Copyright: © 2016 Conway et al. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License, ((https://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Relief of iron (Fe) limitation in the surface Southern Ocean has been suggested as one driver of the regular glacial-interglacial cycles in atmospheric carbon dioxide (CO2). The proposed cause is enhanced deposition of Fe-bearing atmospheric dust to the oceans during glacial intervals, with consequent effects on export production and the carbon cycle. However, understanding the role of enhanced atmospheric Fe supply in biogeochemical cycles is limited by knowledge of the fluxes and ‘bioavailability’ of atmospheric Fe during glacial intervals. Here, we assess the effect of Fe fertilization by dust, dry-extracted from the Last Glacial Maximum portion of the EPICA Dome C Antarctic ice core, on the Antarctic diatom species Eucampia antarctica and Proboscia inermis. Both species showed strong but differing reactions to dust addition. E. antarctica increased cell number (3880 vs. 786 cells mL-1), chlorophyll a (51 vs. 3.9 μg mL-1) and particulate organic carbon (POC; 1.68 vs. 0.28 μg mL-1) production in response to dust compared to controls. P. inermis did not increase cell number in response to dust, but chlorophyll a and POC per cell both strongly increased compared to controls (39 vs. 15 and 2.13 vs. 0.95 ng cell-1 respectively). The net result of both responses was a greater production of POC and chlorophyll a, as well as decreased Si:C and Si:N incorporation ratios within cells. However, E, antarctica decreased silicate uptake for the same nitrate and carbon uptake, while P. inermis increased carbon and nitrate uptake for the same silicate uptake. This suggests that nutrient utilization changes in response to Fe addition could be driven by different underlying mechanisms between different diatom species. Enhanced supply of atmospheric dust to the surface ocean during glacial intervals could therefore have driven nutrient-utilization changes which could permit greater carbon fixation for lower silica utilization. Additionally, both species responded more strongly to lower amounts of direct Fe chloride addition than they did to dust, suggesting that not all the Fe released from dust was in a bioavailable form available for uptake by diatoms.
|Item Type:||Refereed Article|
|Keywords:||iron, diatom, atmospheric dust, Southern Ocean, Antarctic|
|Research Division:||Earth Sciences|
|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:||Strzepek, RF (Dr Robert Strzepek)|
|Web of Science® Times Cited:||3|
|Deposited By:||Australian Antarctic Program Partnership|
|Downloads:||3 View Download Statistics|
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