Dataset Information

Climatically sensitive transfer of iron to maritime Antarctic ecosystems by surface runoff.

ABSTRACT: Iron supplied by glacial weathering results in pronounced hotspots of biological production in an otherwise iron-limited Southern Ocean Ecosystem. However, glacial iron inputs are thought to be dominated by icebergs. Here we show that surface runoff from three island groups of the maritime Antarctic exports more filterable (<0.45??m) iron (6-81?kg?km-2?a-1) than icebergs (0.0-1.2?kg?km-2?a-1). Glacier-fed streams also export more acid-soluble iron (27.0-18,500?kg?km-2?a-1) associated with suspended sediment than icebergs (0-241?kg?km-2?a-1). Significant fluxes of filterable and sediment-derived iron (1-10?Gg?a-1 and 100-1,000?Gg?a-1, respectively) are therefore likely to be delivered by runoff from the Antarctic continent. Although estuarine removal processes will greatly reduce their availability to coastal ecosystems, our results clearly indicate that riverine iron fluxes need to be accounted for as the volume of Antarctic melt increases in response to 21st century climate change.

SUBMITTER: Hodson A

PROVIDER: S-EPMC5316877 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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Climatically sensitive transfer of iron to maritime Antarctic ecosystems by surface runoff.

Hodson Andy A Nowak Aga A Sabacka Marie M Jungblut Anne A Navarro Francisco F Pearce David D Ávila-Jiménez María Luisa ML Convey Peter P Vieira Gonçalo G

Nature communications 20170215

Iron supplied by glacial weathering results in pronounced hotspots of biological production in an otherwise iron-limited Southern Ocean Ecosystem. However, glacial iron inputs are thought to be dominated by icebergs. Here we show that surface runoff from three island groups of the maritime Antarctic exports more filterable (<0.45 μm) iron (6-81 kg km-2 a-1) than icebergs (0.0-1.2 kg km-2 a-1). Glacier-fed streams also export more acid-soluble iron (27. ...[more]

PMID: 28198359

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Project description:Understanding underwater optics in natural waters is essential in evaluating aquatic primary production and risk of UV exposure in aquatic habitats. Changing environmental conditions related with global climate change, which imply potential contrasting changes in underwater light climate further emphasize the need to gain insights into patterns related with underwater optics for more accurate future predictions. The present study evaluated penetration of solar radiation in six sub-Antarctic estuaries and fjords in Chilean North Patagonian region (39-44°S) and in an Antarctic bay (62°S). Based on vertical diffuse attenuation coefficients (Kd), derived from measurements with a submersible multichannel radiometer, average summer UV penetration depth (z1%) in these water bodies ranged 2-11 m for UV-B (313 nm), 4-27 m for UV-A (395 nm), and 7-30 m for PAR (euphotic zone). UV attenuation was strongest in the shallow Quempillén estuary, while Fildes Bay (Antarctica) exhibited the highest transparency. Optically non-homogeneous water layers and seasonal variation in transparency (lower in winter) characterized Comau Fjord and Puyuhuapi Channel. In general, multivariate analysis based on Kd values of UV and PAR wavelengths discriminated strongly Quempillén estuary and Puyuhuapi Channel from other study sites. Spatial (horizontal) variation within the estuary of Valdivia river reflected stronger attenuation in zones receiving river impact, while within Fildes Bay a lower spatial variation in water transparency could in general be related to closeness of glaciers, likely due to increased turbidity through ice-driven processes. Higher transparency and deeper UV-B penetration in proportion to UV-A/visible wavelengths observed in Fildes Bay suggests a higher risk for Antarctic ecosystems reflected by e.g. altered UV-B damage vs. photorepair under UV-A/PAR. Considering that damage repair processes often slow down under cool temperatures, adverse UV impact could be further exacerbated by cold temperatures in this location, together with episodes of ozone depletion. Overall, the results emphasize the marked spatial (horizontal and vertical) and temporal heterogeneity of optical characteristics, and challenges that these imply for estimations of underwater optics.

Dataset Information

Climatically sensitive transfer of iron to maritime Antarctic ecosystems by surface runoff.

Publications

Climatically sensitive transfer of iron to maritime Antarctic ecosystems by surface runoff.

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