<DATASET> bioacoustics

<STUDY> 0001pal

<DATE_RANGE> 13 Nov 2000 to 5 Jan 2001, and 30 Jan to 15 Mar 2001 on station;

acoustic transects from LMG: 10 Jan 2001

Continuous acoustic data was collected from two standard transects within the Palmer LTER nearshore study area.

A. An event_bld.list gives details of time and location for all acoustic transects, with links to the rest of the data collected through the event number. The ten variables in the event-bld.list are:

Event.number

Start.time (GMT)

End.time (GMT)

Start.Date (mmddyy GMT)

Flag

Grid(Palmer LTER grid location)

Start.Latitude (°S)

Start.Longitude (°W)

End.Latitude (°S)

End.Longitude (°W)

The transect distance is not the distance between the start and end latitudes and longitudes because the transects are slightly curved. Thus the end latitude has been estimated based on the actual distance of the transect. The actual distance is calculated from the sum of the distances between locations along the transect recorded at 10 min intervals. The Palmer LTER grid shows that on some days the entire transect was not completed due to ice or weather.

B. The calibration files give the calibration constants:

Variables are:

BeamPatternFactor

Rcvr1_G120logR

Rcvr1_G140logR

Rcvr2_G120logR

Rcvr2_G140logR

Rcvr3_G120logR

SrcLevel_at0dB

SrcLevel_at-3dB

SrcLevel_at-6dB

SrcLevel_at-10dB

SrcLevel_at-13dB

20/40CrossoverPt

<SAMPLING_FREQUENCY>

Twice weekly runs of the two Palmer nearshore transects (Pal J-F and Pal A-E) were planned from mid-November to mid-March, weather and ice conditions permitting, except during the annual cruise when transects were done from the research vessel (01janpal).

There were a total of 61 acoustic transects run from the zodiac for 0001pal, at weekly intervals from in the austral spring (n=34), and again after the cruise (n=27).

The two transects were also run at the beginning of the 01Jan cruise on the LMG (10 Jan).

The Palmer LTER uses Biosonics equipment and software to collect hydroacoustic data, and to do the preliminary processing on board during collection.

(1) collection of data

The acoustic system consists of a BioSonics Model 102 echo sounder connected to a downward looking 120 kHz transducer which was deployed with a tow body 1 (zodiac) or 2 (LMG) meters below the surface . The towbody was deployed from a Mark V zodiac or the research vessel. The sounder was operated with a 20 log R (R = range in m) time-varied-gain (TVG) function to compensate for one-way acoustic spreading loss.

(2) archival process

The analog voltage signals received by the echosounder are processed in the field through an interface tape unit that records a digitized version of each signal onto a digital audio tape (DAT) recorder. The DAT tapes can be replayed with the Biosonics Echo Signal Processing (ESP) software package for calculation of Sum Squared Voltage (SSV) data if a file is lost or if a different configuration file is desired.

(3) primary processing of data:

Echo integration of the returned acoustic energy (volts) was done with the BioSonics Model 221 Echo Signal Processor, and ESP version 3 on a Dec 486 computer on board. The system was configured to integrate voltage measurements over 2-m depth intervals and several pings. These integrated values were used to generate a two-dimensional (alongtrack, vertical) matrix of volume scattering data (VSD, m³ m^-3) for each acoustic transect, according to algorithms described in Apprendix C of BioSonics. When in deep water (>200 m) data was collected without a bottom algorithm. In shallow water, a bottom algorithm was used to automatically separate the bottom and biotic signal.

(4) calibration of the system was done by BioSonics ( Seattle, WA) in a tank at ambient temperature. The calibrations bracketing the use of the equipment were done on June 12, 2000 and June 19, 2001. There were only small differences in the calibrations. During 01Jan, the OldDeck/OldTow cable combination was used exclusively. During 0001pal, the 92Deck cable was used exclusively for the zodiac transects.

The Deck cables are 100' long, the Tow cables 218' long

- New Deck (S/N#141-94-870)

- New Tow (S/N#147-94-156)

- Old Deck (S/N#141-92-740)

- Old Tow (S/N#147-92-137)

<EXPERIMENTAL_DESIGN>

Acoustic transects on a weekly basis show seasonal trends in acoustic biomass, and in the size, distribution, depth and density of aggregations.

Antarctic krill are usually the dominant sound scatterer in the Palmer LTER region.

bioacoustics, antarctic krill, palmer lter

<FILE_FORMAT>

1) event_bld.list

ascii, space delimited

(number of columns)! 0001pal and identifying information

rows with column headers and the units of the parameter

data follow

2) calibration file

ascii, space delimited

3) VSD acoustic matrix for each event

binary file with results from echo integration of the voltage returning to the echo sounder. the data stored is mean voltage squared for each depth strata and ping.

<STORAGE_LOCATION>

The event_bld.list and calibration file are in:

~lter/data/0001pal/bioacoustics

Velella on the MSILTER Apple talk network

The VSD files are stored on a hard disk off line until room is available on line. They may be accessed by contacting Karen Baker, data manager for the Palmer LTER.

<FILE_NAMES>

(1) event_bld.list

There are two files, one for the zodiac operations (event.bld_list) and one for the transects from the research vessels (event.bld_list01janpal which is in the directory 01jan/bioacoustics/).

(2) files named: acoCalib.(date of calibration yymmdd)(old(92) deck cable only)

acoCalib.000612

acoCalib.010619

(3) rawdata/(event#).dat

the VSD acoustic matrix for each transect is named by the event.

<PRINCIPAL_INVESTIGATORS>

Robin M. Ross, Langdon B. Quetin

<ASSOCIATE_INVESTIGATORS>

none

<CONTACT_PERSON>

Robin M. Ross, Langdon B. Quetin

<SAMPLES_COLLECTED_BY>

D. Martin and S. A. Oakes 13Nov —18Dec

S.A. Oakes and C. C. Holmes 22 Dec — 5 Jan

J. T. Watson, R. M. Ross and S. A. Oakes 30 Jan — 15 Mar

On cruise: R. M. Ross and S. A. Oakes

<LAB_ANALYSIS_BY> J. Schneider

<DATA_ENTRY_BY>

RM Ross

<DATA_ANALYSIS_BY>

<SUBMITTED_BY>

RM Ross

<DATE_SUBMITTED>

rawdata in 4 Nov 2001, event_bld.list, acoCalib files and documentation 26 June, 2003

<DATES_UPDATED>

<SUPPORTING_DOCUMENTS>

BioSonics (1990) BioSonics Echo Signal Processor Operators Manual.

BioSonics, Inc., Seattle, WA, 373 pp.

Lascara (1996) Seasonal and mesoscale variability in the distribution

of Antarctic krill, Euphausia superba, west of the Antarctic Peninsula.

Ph. D. Thesis, Old Dominion University. 167 pp.

Greene, C. H., T. K. Stanton, P. H. Wiebe and S. McClatchie (1991)

Acoustic estimates of Antarctic krill. Nature 349: 110.

Nero, R. W. and J. J. Magnuson (1989) Characterization of patches

along transects using high resolution 70 kHz integrated acoustic data.

Canadian Journal of Fisheries and Aquatic Sciences 46: 2056-2064.

Wiebe, P. H., C. H. Greene, T. K. Stanton and J. Burczynski (1990)

Sound scattering by live zooplankton and micronekton: empirical

studies with a dual-beam acoustical system. Journal of Acoustical

Society of America 88: 2346-2360.

<QUALITY_ASSURANCE>

<DATA_REQUESTED_BY>

<FORM>

Datafile Form V1.2 for describing a data file.