Dataset: EK80 Antarctic Krill Swarms

Name: Krill swarms detected with active acoustic EK80 onboard small boat surveys in Palmer Deep Canyon, Antarctica during January-March 2020
Published: 2025-01-30
Keywords: Antarctic krill, Palmer Deep, zooplankton, oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.949922.1

Spatial Extent: N:-64.79720121 E:-63.77062609 S:-64.9104786 W:-64.27354803

Palmer Deep Canyon, Antarctic

Temporal Extent: 2020-01-15 - 2020-03-10

Project:

Collaborative Research: Physical Mechanisms Driving Food Web Focusing in Antarctic Biological Hotspots (Project SWARM)

Co-Principal Investigator:

Kim S. Bernard (Oregon State University, OSU)

Student:

Ashley Hann (Oregon State University, OSU)

Jacquelyn Veatch (Rutgers University)

Contact:

Jacquelyn Veatch (Rutgers University)

BCO-DMO Data Manager:

Karen Soenen (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2025-01-30

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Krill swarms detected with active acoustic EK80 onboard small boat surveys in Palmer Deep Canyon, Antarctica during January-March 2020

Abstract:

These data include identified krill swarms observed by a hull-mounted SIMRAD EK80 single-beam, single frequency (120 kHz) echo sounder (Kongsberg Maritime) hereby referred to as “EK80”. Data were collected in Palmer Deep Canyon, Antarctica during January-March 2020. Small boat surveys were conducted twice weekly over known penguin foraging areas. EK80 data were processed using Echoview software and backscattering zooplankton were identified as krill when within a target strength of -70 dB to -30 dB. The EK80 survey was designed in concert with the ACROBAT, HFR and mooring observations to provide a wholistic view of the food web. Observing the distribution of krill swarms and their correlation with other ecosystem variables is important for understanding how the Palmer Deep ecosystem, and other coastal ecosystems globally, respond to complex coastal ocean currents and ways this system may be resilient to rapid warming. The collection and processing of these data was headed by Ashley Hann and Dr. Kim Bernard.

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Archival Copy

Version Date	Archive	Persistent Identifier (PID)	Date PID Issued
2025-01-30	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.949922.1	2025-01-30

Methods & Sampling

Day trip active acoustic surveys were conducted from Palmer Station Field Season aboard RHIB twice weekly from January-March 2020 using a hull-mounted SIMRAD EK80 single-beam, single frequency (120 kHz) echosounder (Kongsberg Maritime) along transects shown in Figure 1A (Veatch et al 2025).

The echosounder was configured with a 1 s ping rate, 512 µs pulse duration, and 24 µs sampling duration. Calibrations of the echosounder were performed in the vicinity of Palmer Deep Canyon using a tungsten sphere (diameter = 38.1 mm) during February, 2020. Acoustic data were processed in Myriax Echoview software version 11.1 following methods from (Tarling, Klevjer et al. 2009) and (Tarling, Thorpe et al. 2018). Raw data were processed to consider the echosounder calibration and in situ ocean acoustic conditions via incorporation of onboard CTD data, and to remove background noise and other interferences via the Background Noise Removal (De Robertis and Higginbottom 2007) and Impulse Noise Removal (Ryan, Downie et al. 2015) algorithms in Echoview. Krill were then detected using a target strength threshold of -70 dB to -30 dB(Tarling, Klevjer et al. 2009, Tarling, Thorpe et al. 2018) in Echoview following similar parameterization and protocols to (Nardelli, Cimino et al. 2021) and (Reiss, Cossio et al. 2021) (Figure 4, Veatch et al 2025).

Data Processing Description

All acoustically detected krill swarms were manually reviewed before exporting the acoustic data in NASC (Nautical Area Scattering Coefficient) values, a common proxy for organism presence in acoustic measurements. NASC values were calculated per detected swarm and exported along with depth, GPS position (longitude and latitude), swarm height, swarm length, and backscatter (Sv). These methods for acoustic surveys and processing of subsequent acoustic data follow those in (Hann, Bernard et al. 2023).

Data Files

File
949922_v1_ek80krill.csv (Comma Separated Values (.csv), 659.58 KB) MD5:cd207e24b097bfd1277bbc2cb0b5c6af Primary data file for dataset ID 949922, version 1

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Office of Polar Programs (formerly NSF PLR)	OPP-1744884
NSF Office of Polar Programs (formerly NSF PLR)	OPP-1745009
NSF Office of Polar Programs (formerly NSF PLR)	OPP-1745011
NSF Office of Polar Programs (formerly NSF PLR)	OPP-1745018
NSF Office of Polar Programs (formerly NSF PLR)	OPP-1745023
NSF Office of Polar Programs (formerly NSF PLR)	OPP-1745081

Deployments

None available yet

Instruments

Simrad EK80 echo sounder

Supplied Name: SIMRAD EK80

Supplied Description:

Hull-mounted SIMRAD EK80 single-beam, single frequency (120 kHz) echosounder (Kongsberg Maritime)

Instrument Type

Generic Name: Simrad EK80 echo sounder

Acronym: EK80

Generic Description:

A high precision scientific echo sounder, designed to simultaneously operate frequencies ranging from 10 to 500 kHz. EK80 is a modular echo sounder system, and can operate with a combination of split and single beam transducers facilitated by a built-in calibration application. This system was built in succession to the EK60 echo sounder.

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
Date_M	Day of observation in YYYMMDD format Format: %Y%m%d	unitless	date
Time_M	Time of observation, fraction of day	unitless	time
iso8601	Date and time of observation in ISO format: yyyy-MM-dd HH:mm:ss (GMT timezone) Format: %Y-%m-%d %H:%M:%S	unitless	ISO_DateTime_UTC
Lon_M	Longitude	decimal degrees	lon
Lat_M	Latitude	decimal degrees	lat
Depth_mean	Average depth of krill swarm measured from ocean surface	Meters (m)	depth
Sv_mean	Average Backscatter (dB)	dB	Acc_bksctr
NASC	Nautical Acoustic Scattering Coefficient	m²/nmi²	no_bcodmo_term
Height_mean	Vertical length of swarm	Meters (m)	length
Thickness_mean	Horizontal across-track length of swarm	Meters (m)	length
Length	Horizontal along-track length of swarm	Meters (m)	length
mld	Mixed layer depth as measured by ACROBAT (associated dataset)	Meters (m)	depth_mixed_layer
surface	Binary swarm above or below mld	Binary	behav_code

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Dataset: EK80 Antarctic Krill Swarms