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Zooplankton distribution and abundance during the BROKE-West survey

Entry ID: BROKE-West_zooplankton

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Summary

Abstract: Samples were collected at trawl stations (approximately every second CTD station), as well as opportunistically when something interesting was spotted on the Echosounder. The samples were collected with an RMT-1 plankton net and preserved in Steedman's solution. Upon returning to Australia, the samples were passed onto Kerrie Swadling, who split them with a Folsom plankton splitter and counted ...

Related URL

Link: GET DATA

Description: Download point for the data - Excel Spreadsheets

Link: VIEW PROJECT HOME PAGE

Description: Public information for ASAC project 2655

Link: VIEW PROJECT HOME PAGE

Description: Public information for ASAC project 2679

Link: VIEW RELATED INFORMATION

Description: Citation reference for this metadata record and dataset

Geographic Coverage

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Spatial coordinates

	N: -61.66	S: -69.21	E: 80.02	W: 29.92

Min Depth: 0 M Max Depth: 200 M

Parent DIF

This data set description is a member of a collection. The collection is described in
BROKE-West

Temporal Coverage

Start Date: 2006-01-17

Stop Date: 2006-03-03

Location Keywords

OCEAN > SOUTHERN OCEAN

CONTINENT > ANTARCTICA

GEOGRAPHIC REGION > POLAR

Science Keywords

BIOLOGICAL CLASSIFICATION > ANIMALS/VERTEBRATES > FISH

BIOLOGICAL CLASSIFICATION > ANIMALS/INVERTEBRATES > ARTHROPODS > CRUSTACEANS

ISO Topic Category

BIOTA

OCEANS

Platform

R/V AA > R/V Aurora Australis
SHIPS

Instrument

PLANKTON NETS

TRAWL

ECHO SOUNDERS

Quality Krill/Zooplankton/Fish: Net Sampling
Regular trawl stations were laid out approximately every second CTD stations. Target trawls were undertaken whenever any target of interest were detected on the echosounder. Single opening-closing RMT 1+8 net (Baker et al., 1973) with CTD System installed was used for all of the tows (Regular and Target), Hard cod-ends were used for all the ... trawls. Flow meters were used to estimate the volume of water towed. Table 1 summarises the details of RMT stations. Ringnet deployments were undertaken at almost every CTD stations.

Regular Trawl
At each regular trawl station a quantitative standard double oblique tow was conducted from the surface down to 200 m (or to within 10 m of the bottom at stations shallower than 200 m). Such a depth range is considered to be the best compromise between the time available for sampling and the likely vertical depth range of krill. During the hauls, ship's speed was maintained constant at 2.5 plus or minus 0.5 knots. Wire speed of 0.7 to 0.8 m/s during paying out and of 0.3 m/sec during hauling(approx. 0.5 m/s and 0.2 m/s respectively at vertical depth change rate). The net mouth angle is remarkably constant during hauling within the speed ranges given above. When the net reaches maximum depth, the winch was stopped for about 30 seconds to allow the net to stabilise before retrieving. When hauling, the propeller thrust was turned off when the net reached depth of 15 to 20 m; this was to minimise the effects of the propeller action on the net operation and avoid damage of the samples.

Target Trawl
Whenever interesting targets were seen on the echo-sounder, or large amount of krill was required for any purpose, target trawls were performed. Once the position of the target was marked, the ship was turned and navigated to run over the target from direction required within navigation capacity. The ship speed was reduced to below 2.0 knots before hitting the target, so that the net could be lowered down to the desired depth when the net reached the target. Fine adjustments were made throughout the trawl by monitoring the echo-sounder in the aft control room. For live krill target trawl, ship speed was kept as slow as possible to avoid any damage to krill.

Laboratory Sampling and Processing

Sample processing for all regular trawl stations:
RMT-8
Measure the total sample volume (Drain water, then measure using water replacement; mandatory only for the regular hauls).
Sort out all Antarctic krill and count their number. If the sample mainly consists of krill and the volume is more than ~1L, a known portion of the whole sample was sub-sampled for the further processing.
Stage (TL, Carapace Length, Maturity) of all krill (or subsample), up to 50 to 150 individuals, and DG size (the longest axis) of up to 50 individuals were measured using digital calipers.
Other zooplankton groups were immediately sorted out from the catch and their numbers were recorded.

Preservation of RMT-8 samples
Krill (including those used for onboard demography measurements) were fixed in 10% formalin for their further analysis. Whenever excess amount of krill were caught, they were sampled and frozen for POP (persistent organic pollutant) measurements, preserved in 80% ethanol for genetic analysis, and frozen under -80C/ liquid nitrogen for chemical analysis. Fish were preserved in formalin, EtOH, or frozen. Squids were preserved in EtOH.

RMT-1
The whole sample was fixed with 10 % formalin.
If the sample volume was too large, then a known proportion of catch was randomly sub-sampled and fixed.

Access Constraints These data are publicly available from the provided URL.

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=BROKE-We... when using these data.

Ancillary Keywords

Zooplankton

Southern Ocean

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: 25 kb

Distribution Format: excel

Fees: free

Personnel

KERRIE SWADLING

Role: INVESTIGATOR

Role: TECHNICAL CONTACT

Phone: +61 3 6226 2522

Fax: +61 3 6226 2745

Email: k.swadling at utas.edu.au

Contact Address:

School of Zoology

University of Tasmania

GPO BOX 252-05

City: Hobart

Province or State: Tasmania

Postal Code: 7001

Country: Australia

SO KAWAGUCHI

Role: INVESTIGATOR

Role: TECHNICAL CONTACT

Phone: +61 3 6232 3216

Email: So.Kawaguchi at aad.gov.au

Contact Address:

Australian Antarctic Division,

Channel Highway

City: Kingston

Province or State: Tasmania

Postal Code: 7050

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

Creation and Review Dates

DIF Creation Date: 2007-01-29

Last DIF Revision Date: 2012-10-18

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