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Optical imaging of mesopelagic particles indicates deep carbon flux beneath a natural iron-fertilized bloom in the Southern Ocean


Jouandet, M and Trull, Tw and Guidi, L and Picheral, M and Ebersbach, F and Stemmann, L and Blain, S, Optical imaging of mesopelagic particles indicates deep carbon flux beneath a natural iron-fertilized bloom in the Southern Ocean, Limnology and Oceanography, 56, (3) pp. 1130-1140. ISSN 0024-3590 (2011) [Refereed Article]

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Copyright 2011 American Society of Limnology and Oceanography, Inc.

DOI: doi:10.4319/lo.2011.56.3.1130


We recorded vertical profiles of size distributions of particles (ranging from 0.052 to several mm in equivalent spherical diameter) in the natural iron-fertilized bloom southeast of Kerguelen Island (Southern Ocean) and in surrounding high-nutrient, low-chlorophyll (HNLC) waters with an Under Water Video Profiler during the Kerguelen Ocean and Plateau Compared Study cruise (Jan–Feb 2005). Total particle numerical abundance and total particle volume (TPV) in the 0–200-m layer were respectively 3-fold and 20-fold higher in the bloom, and integrated TPV was correlated to integrated chlorophyll concentration. The difference persisted well into the ocean interior with a 10-fold higher TPV at 400-m depth beneath the natural iron-fertilized bloom. Below 400 m, increases in TPV values at the bloom stations reflect the suspension of bottom sediments. Bloom waters had a greater proportion of large particles from the surface to 400 m and also exhibited an increase of this proportion with depth compared to HNLC waters. Multiple visits to the bloom reference Sta. A3, suggest preferential removal of large particles as the bloom declined. Comparing our particle abundance size spectra with those observed previously in polyacrylamide gel-filled sediment traps allows us to estimate mesopelagic particle sinking rates. These results suggest that particles sink faster in the HNLC waters than beneath the bloom. The fact that sinking speeds were not a simple monotonic function of particle size and varied spatially highlights the need to go beyond parameterizations of sinking rate as a function of size alone.

Item Details

Item Type:Refereed Article
Keywords:mesopelagic particles, carbon flux, iron fertilisation, Southern Ocean
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical oceanography
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean oceanic processes
UTAS Author:Jouandet, M (Dr Marie-Paule Jouandet)
UTAS Author:Trull, Tw (Professor Thomas Trull)
ID Code:76927
Year Published:2011
Web of Science® Times Cited:27
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2012-03-15
Last Modified:2017-10-31

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