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Subantarctic zone oceanography - SAZ Project 1997-1998 - Iron Related Data

Entry ID: ASAC_2256_Iron

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Summary

Abstract: Oceanographic processes in the subantarctic region contribute crucially to the physical and biogeochemical aspects of the global climate system. To explore and quantify these contributions, the Antarctic Cooperative Research Centre (CRC) organised the SAZ Project, a multidisciplinary, multiship investigation carried out south of Australia in the austral summer of 1997-1998.

Taken from the ... abstracts of the referenced papers:

In March 1998 we measured iron in the upper water column and conducted iron- and nutrient-enrichment bottle-incubation experiments in the open-ocean Subantarctic region southwest of Tasmania, Australia. In the Subtropical Convergence Zone (~42 degrees S, 142 degrees E), silicic acid concentrations were low (less than 1.5 micro-M) in the upper water column, whereas pronounced vertical gradients in dissolved iron concentration (0.12-0.84 nM) were observed, presumably reflecting the interleaving of Subtropical and Subantarctic waters, and mineral aerosol input. Results of a bottle-incubation experiment performed at this location indicate that phytoplankton growth rates were limited by iron deficiency within the iron-poor layer of the euphotic zone. In the Subantarctic water mass (-46.8 degrees S, 142 degrees E), low concentrations of dissolved iron (0.05-0.11 nM) and silicic acid (less than 1 micro-M) were measured throughout the upper water column, and our experimental results indicate that algal growth was limited by iron deficiency. These observations suggest that availability of dissolved iron is a primary factor limiting phytoplankton growth over much of the Subantarctic Southern Ocean in the late summer and autumn.

The importance of resource limitation in controlling bacterial growth in the high-nutrient, low-chlorophyll (HNLC) region of the Southern Ocean was experimentally determined during February and March 1998. Organic- and inorganic-nutrient enrichment experiments were performed between 42 degrees S and 55 degrees S along 141 degrees E.
Bacterial abundance, mean cell volume, and [3H]thymidine and [3H]leucine incorporation were measured during 4- to 5-day incubations. Bacterial biomass, production, and rates of growth all responded to organic enrichments in three of the four experiments. These results indicate that bacterial growth was constrained primarily by the availability of dissolved organic matter. Bacterial growth in the subtropical front, subantarctic zone, and subantarctic front responded most favourably to additions of dissolved free amino acids or glucose plus ammonium. Bacterial growth in these regions may be limited by input of both organic matter and reduced nitrogen. Unlike similar experimental results in other HNLC regions (subarctic and equatorial Pacific), growth stimulation of bacteria in the Southern Ocean resulted in significant biomass accumulation, apparently by stimulating bacterial growth in excess of removal processes. Bacterial growth was relatively unchanged by additions of iron alone; however, additions of glucose plus iron resulted in substantial increases in rates of bacterial growth and biomass accumulation. These results imply that bacterial growth efficiency and nitrogen utilisation may be partly constrained by iron availability in the HNLC Southern Ocean.

The download file also contains three excel spreadsheets of iron data from the project. The file Sedwick_A9706_Fe_data contains water-column dissolved Fe and total-dissolvable Fe data from cruise A9706, which is presented in Sedwick et al. (1999) and Sedwick et al. (2008).

The files Sedwick_A9706_ProcessStn1_Exp_data and Sedwick_A9706_ProcessStn2_Exp_data present data from shipboard experiments conducted during cruise A9706 at Process Stations 1 and 2, respectively, as reported in Sedwick et al. (1999).

Related URL

Link: GET DATA

Description: Download point for the data

Link: VIEW PROJECT HOME PAGE

Description: Public information for ASAC project 2256

Link: VIEW RELATED INFORMATION

Description: Download point for the referenced publication

Link: VIEW RELATED INFORMATION

Description: Citation reference for this metadata record and dataset

Geographic Coverage

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Spatial coordinates

N: -42.0

S: -55.0

E: 141.5

W: 141.5

Parent DIF

This data set description is a member of a collection. The collection is described in
ASAC_2256

Temporal Coverage

Start Date: 1997-09-01

Stop Date: 1998-03-31

Location Keywords

OCEAN > SOUTHERN OCEAN

GEOGRAPHIC REGION > POLAR

Science Keywords

OCEANS > OCEAN CHEMISTRY > NUTRIENTS

BIOLOGICAL CLASSIFICATION > BACTERIA/ARCHAEA

BIOLOGICAL CLASSIFICATION > BACTERIA/ARCHAEA > CYANOBACTERIA (BLUE-GREEN ALGAE)

BIOLOGICAL CLASSIFICATION > PLANTS > MICROALGAE

ISO Topic Category

OCEANS

Platform

R/V AA > R/V Aurora Australis
SHIPS

Quality See the referenced papers for more information.

Access Constraints Copies of the referenced publications are available for download from the provided URL to AAD staff only.

Use Constraints This data set conforms to the PICCCBY Attribution License
(http://creativecommons.org/licenses/by/3.0/).

Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_225... when using these data.

Ancillary Keywords

Iron

Algal Growth

Bacterial Growth

SAZ

Data Set Progress

COMPLETE

Data Center

Australian Antarctic Data Centre, Australia

Data Center URL: http://data.aad.gov.au

Data Center Personnel
Name: DATA OFFICER AADC Phone: +61 3 6232 3244 Fax: +61 3 6232 3351 Email: metadata at aad.gov.au Contact Address: Australian Antarctic Division 203 Channel Highway City: Kingston Province or State: Tasmania Postal Code: 7050 Country: Australia

Distribution

Distribution Media: HTTP

Distribution Size: 682 kb

Distribution Format: pdf

Fees: free

Distribution Media: HTTP

Distribution Size: 126 kb

Distribution Format: Excel, csv

Fees: Free

Personnel

PETER SEDWICK

Role: INVESTIGATOR

Role: TECHNICAL CONTACT

Phone: (757) 683-4936

Fax: (757) 683-5303

Email: psedwick at odu.edu

Contact Address:

4600 Elkhorn Ave

City: Norfolk

Province or State: VA

Postal Code: 23529

Country: USA

THOMAS WILLIAM TRULL

Role: INVESTIGATOR

Phone: +61 3 6226 2988

Fax: +61 3 6226 2973

Email: tom.trull at utas.edu.au

Contact Address:

GPO BOX 252-80

Antarctic CRC University of Tasmania

City: Hobart

Province or State: Tasmania

Postal Code: 7001

Country: Australia

DAVE CONNELL

Role: DIF AUTHOR

Phone: +61 3 6232 3244

Fax: +61 3 6232 3351

Email: dave.connell at aad.gov.au

Contact Address:

Australian Antarctic Division

203 Channel Highway

City: Kingston

Province or State: Tasmania

Postal Code: 7050

Country: Australia

Publications/References

Sedwick P.N., DiTullio G.R., Hutchins D.A., Boyd P.W., Griffiths F.B., Crossley A.C., Trull T.W., Queguiner B. (1999), Limitation of algal growth by iron deficiency in the Australian Subantarctic region, Geophysical Research Letters, 26, 2865

Creation and Review Dates

DIF Creation Date: 2012-01-17

Last DIF Revision Date: 2012-10-18

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