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δ56Fe in seabird guano reveals extensive recycling of iron in the Southern Ocean ecosystem


Wing, SR and Gault-Ringold, M and Stirling, CH and Wing, LC and Shatova, OA and Frew, RD, δ56Fe in seabird guano reveals extensive recycling of iron in the Southern Ocean ecosystem, Limnology and Oceanography, 62, (4) pp. 1671-1681. ISSN 0024-3590 (2017) [Refereed Article]

Copyright Statement

Copyright 2017 Association for the Sciences of Limnology and Oceanography

DOI: doi:10.1002/lno.10524


Availability of iron limits productivity in the Southern Ocean where vast regions of high‐nitrogen low‐chlorophyll conditions are punctuated by hotspots of production surrounding the subAntarctic islands. Here, we compare patterns in accumulation of iron, as indicated by [Fe] and Fe:C (from Wing et al. 2014), with proxies for uptake of iron within food webs, as indicated by Fe:Al and δ56Fe within the subAntarctic Auckland Island ecosystem. We compare these proxies for dynamics of iron within egested material collected from six seabird species, representing three distinct foraging guilds. Fractions of biogenic iron, estimated from Fe:Al, were lowest in the coastal foraging guild (0.83  0.01), and higher in the oceanic and predator guilds (0.94  0.01 and 0.95  0.01), consistent with high rates of biological recycling. The isotopic ratio of iron 56Fe/54Fe, reported as δ56Fe, is depleted in the heavy isotope 56Fe by recycling in the microbial loop, and is likely further depleted in 56Fe when taken up by animals within the food web. δ56Fe was most negative for the oceanic foraging group indicating intensive recycling (−1.16  0.16), most positive in the coastal group where direct lithogenic sources of iron are more available (−0.14  0.15), and intermediate

Item Details

Item Type:Refereed Article
Keywords:iron isotopes, seabirds, guano, sub-Antarctic
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Geochemistry not elsewhere classified
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Biodiversity in Antarctic and Southern Ocean environments
UTAS Author:Gault-Ringold, M (Dr Melanie East)
ID Code:125208
Year Published:2017
Web of Science® Times Cited:5
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2018-04-06
Last Modified:2018-05-07

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