Krill swarms observed along transects 7 to 11 during the BROKE-West voyage

This is data describing acoustically observed krill swarms that was used in the Bestley et al. (2017) paper 'Predicting krill swarm characteristics important for marine predators foraging off East Antarctica' ( http://onlinelibrary.wiley.com/doi/10.1111/ecog.03080/full).

Abstract of the paper presented here:

Open ocean predator-prey interactions are often difficult to interpret because of a lack of information on prey fields at scales relevant to predator behaviour. Hence, there is strong interest in identifying the biological and physical factors influencing the distribution and abundance of prey species, which may be of broad predictive use for conservation planning and evaluating effects of environmental change. This study focuses on a key Southern Ocean prey species, Antarctic krill Euphausia superba, using acoustic observations of individual swarms (aggregations) from a large-scale survey off East Antarctica. We developed two sets of statistical models describing swarm characteristics, one set using underway survey data for the explanatory variables, and the other using their satellite remotely sensed analogues. While survey data are in situ and contemporaneous with the swarm data, remotely sensed data are all that is available for prediction and inference about prey distribution in other areas or at other times. The fitted models showed that the primary biophysical influences on krill swarm characteristics included daylight (solar elevation/radiation) and proximity to the Antarctic continental slope, but there were also complex relationships with current velocities and gradients. Overall model performance was similar regardless of whether underway or remotely sensed predictors were used. We applied the latter models to generate regional-scale spatial predictions using a 10-yr remotely-sensed time series. This retrospective modelling identified areas off east Antarctica where relatively dense krill swarms were consistently predicted during austral mid-summers, which may underpin key foraging areas for marine predators. Spatiotemporal predictions along Antarctic predator satellite tracks, from independent studies, illustrate the potential for uptake into further quantitative modelling of predator movements and foraging. The approach is widely applicable to other krill-dependent ecosystems, and our findings are relevant to similar efforts examining biophysical linkages elsewhere in the Southern Ocean and beyond.

This comma separated variable (CSV) file contains the krill swarm data used in:

Bestley, S., Raymond, B., Gales, N.J., Harcourt, R.G., Hindell, M.A., Jonsen, I.D., Nicol, S., Peron, C., Sumner, M.D., Weimerskirch, H. and Wotherspoon, S.J., Cox, M.J. (2017). Predicting krill swarm characteristics important for marine predators foraging off East Antarctica. Ecography.

The column descriptions are:

Depth_mean_m = (units m) mean depth of a krill swarm

Date = (YYYYMMDD) observation date (UTC)

Time = (HH:mm:ss.ss) observation time (UTC)

Lat = (dd.ddddd) latitude

Lon = (ddd.ddddd) longitude

transect = BROKE West transect number 7 to 11 (see Fig. 1, Bestley et al. 2017)

denVolgm3 = (units g wet mass m-3) internal krill swarm density in gram wet mass per cubic metre.

Identification info

Alternate title: Krill swarms observed along transects 7 to 11 during the BROKE-West voyage

Date (Publication): 2018-03-02

Edition: 1

Citation identifier

Dataset DOI

Title: Information and documentation - Digital object identifier system

Date (Publication): 2012-04-23

Citation identifier: ISO 26324:2012

Citation identifier: doi:10.4225/15/5a98a0fd53ded

Originator

Cox, M. and Kawaguchi, S.

Publisher

Australian Antarctic Data Centre

Principal investigator

COX, MARTIN

Australian Antarctic Division

203 Channel Highway

Kingston

Tasmania

7050

Australia

Principal investigator

KAWAGUCHI, SO

Australian Antarctic Division

203 Channel Highway

Kingston

Tasmania

7050

Australia

+61 3 6232 3216

Collaborator

COX, MARTIN

Australian Antarctic Division

203 Channel Highway

Kingston

Tasmania

7050

Australia

Collaborator

KAWAGUCHI, SO

Australian Antarctic Division

203 Channel Highway

Kingston

Tasmania

7050

Australia

+61 3 6232 3216

Name: CAASM Metadata

Website: https://data.aad.gov.au/metadata/records/AAS_4050_SWARM

Purpose: This data set can be used to describe the vertical distribution and internal densities of krill swarms observed along transects 7 to 11 of the 2006 BROKE-West voyage.

Status: Completed

Custodian

AU/AADC > Australian Antarctic Data Centre, Australia - AADC, DATA OFFICER (DATA CENTER CONTACT)

Australian Antarctic Division

203 Channel Highway

Kingston

Tasmania

7050

Australia

+61 3 6232 3244

+61 3 6232 3351 (facsimile)

Spatial resolution

Vertical sampling distance: 1

Spatial resolution

Spatial resolution: 20

Spatial resolution

Spatial resolution: 20

Temporal resolution: PT10S

Topic category

Biota
Oceans

Extent

Description: Temporal Coverage

Temporal extent

TimePeriod: 2006-02-08 2006-02-27

Extent

Description: Vertical Extent - Altitude

Vertical element

Minimum value: 0

Maximum value: 0

Identifier: urn:x-ogc:def:cs:EPSG:6499

Name: Vertical CS. Axis: height (H). Orientation: up. UoM: m.

Identifier: urn:x-ogc:def:axis:EPSG:114

Name: height

Title: Acoustic characterisation of the broad-scale distribution and abundance of Antarctic krill (Euphausia superba) off East Antarctica (30-80 E) in January-March 2006

Date (Publication): 2010

Citation identifier: 57

Author

Jarvis, T., Kelly, N., Kawaguchi, S., van Wijk, E., and Nicol, S.

Name: Deep Sea Research Part II: Topical Studies in Oceanography

Issue identification: 9-10

Page: 916-933

Title: Predicting krill swarm characteristics important for marine predators foraging off East Antarctica.

Date (Publication): 2017

Author

Bestley S, Raymond B, Gales NJ, Harcourt RG, Hindell MA, Jonsen ID, Nicol S, Peron C, Sumner MD, Weimerskirch H, Wotherspoon SJ, Cox M.J.

Name: Ecography