Use of moored acoustic instruments to measure short‐term variability in abundance of Antarctic krill
Upward‐looking acoustic Doppler current profilers (ADCPs) (300 kHz) and echosounders (125 kHz) were deployed on moorings at South Georgia to measure abundance of Antarctic krill continuously over several months. Echoes from krill were identified using the theoretical difference in echo intensity at...
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crwiley:10.4319/lom.2006.4.18 2024-04-28T07:58:28+00:00 Use of moored acoustic instruments to measure short‐term variability in abundance of Antarctic krill Brierley, Andrew S. Saunders, Ryan A. Bone, Douglas G. Murphy, Eugene J. Enderlein, Peter Conti, Stéphane G. Demer, David A. 2006 http://dx.doi.org/10.4319/lom.2006.4.18 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.4319%2Flom.2006.4.18 https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lom.2006.4.18 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Limnology and Oceanography: Methods volume 4, issue 2, page 18-29 ISSN 1541-5856 1541-5856 Ocean Engineering journal-article 2006 crwiley https://doi.org/10.4319/lom.2006.4.18 2024-04-08T06:55:58Z Upward‐looking acoustic Doppler current profilers (ADCPs) (300 kHz) and echosounders (125 kHz) were deployed on moorings at South Georgia to measure abundance of Antarctic krill continuously over several months. Echoes from krill were identified using the theoretical difference in echo intensity at 300 and 125 kHz and scaled to krill density using target strengths appropriate for krill in the region: krill size was determined from diet samples from furseals and penguins foraging near the moorings. A method using water flow past the moorings was developed to convert time‐based acoustic observations of krill to area‐based abundance estimates. Flow past the stationary moorings was treated analogously to motion along‐track of a research vessel through a nominally stationary body of water during a conventional survey. The moorings thus provide a Eulerian view of variation in krill abundance. This is ecologically instructive for South Georgia, where krill are generally passive drifters on currents and where temporal fluctuations in abundance have significant consequences for krill‐dependent predators. Moorings were positioned on routine research vessel survey transects, and validity of the mooring method was assessed by comparison of mooring and vessel observations. Krill density estimates from the moorings were not statistically different from vessel estimates in adjacent time periods. A time series of krill density from a mooring revealed step‐changes that were not seen during short‐term vessel surveys. Moorings deliver data over time scales that cannot be achieved from research vessels and provide insight on environmental factors associated with variation in krill abundance at South Georgia. Mooring data may aid ecosystem‐based management. Article in Journal/Newspaper Antarc* Antarctic Antarctic Krill Wiley Online Library Limnology and Oceanography: Methods 4 2 18 29 |
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collection |
Wiley Online Library |
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crwiley |
language |
English |
topic |
Ocean Engineering |
spellingShingle |
Ocean Engineering Brierley, Andrew S. Saunders, Ryan A. Bone, Douglas G. Murphy, Eugene J. Enderlein, Peter Conti, Stéphane G. Demer, David A. Use of moored acoustic instruments to measure short‐term variability in abundance of Antarctic krill |
topic_facet |
Ocean Engineering |
description |
Upward‐looking acoustic Doppler current profilers (ADCPs) (300 kHz) and echosounders (125 kHz) were deployed on moorings at South Georgia to measure abundance of Antarctic krill continuously over several months. Echoes from krill were identified using the theoretical difference in echo intensity at 300 and 125 kHz and scaled to krill density using target strengths appropriate for krill in the region: krill size was determined from diet samples from furseals and penguins foraging near the moorings. A method using water flow past the moorings was developed to convert time‐based acoustic observations of krill to area‐based abundance estimates. Flow past the stationary moorings was treated analogously to motion along‐track of a research vessel through a nominally stationary body of water during a conventional survey. The moorings thus provide a Eulerian view of variation in krill abundance. This is ecologically instructive for South Georgia, where krill are generally passive drifters on currents and where temporal fluctuations in abundance have significant consequences for krill‐dependent predators. Moorings were positioned on routine research vessel survey transects, and validity of the mooring method was assessed by comparison of mooring and vessel observations. Krill density estimates from the moorings were not statistically different from vessel estimates in adjacent time periods. A time series of krill density from a mooring revealed step‐changes that were not seen during short‐term vessel surveys. Moorings deliver data over time scales that cannot be achieved from research vessels and provide insight on environmental factors associated with variation in krill abundance at South Georgia. Mooring data may aid ecosystem‐based management. |
format |
Article in Journal/Newspaper |
author |
Brierley, Andrew S. Saunders, Ryan A. Bone, Douglas G. Murphy, Eugene J. Enderlein, Peter Conti, Stéphane G. Demer, David A. |
author_facet |
Brierley, Andrew S. Saunders, Ryan A. Bone, Douglas G. Murphy, Eugene J. Enderlein, Peter Conti, Stéphane G. Demer, David A. |
author_sort |
Brierley, Andrew S. |
title |
Use of moored acoustic instruments to measure short‐term variability in abundance of Antarctic krill |
title_short |
Use of moored acoustic instruments to measure short‐term variability in abundance of Antarctic krill |
title_full |
Use of moored acoustic instruments to measure short‐term variability in abundance of Antarctic krill |
title_fullStr |
Use of moored acoustic instruments to measure short‐term variability in abundance of Antarctic krill |
title_full_unstemmed |
Use of moored acoustic instruments to measure short‐term variability in abundance of Antarctic krill |
title_sort |
use of moored acoustic instruments to measure short‐term variability in abundance of antarctic krill |
publisher |
Wiley |
publishDate |
2006 |
url |
http://dx.doi.org/10.4319/lom.2006.4.18 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.4319%2Flom.2006.4.18 https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lom.2006.4.18 |
genre |
Antarc* Antarctic Antarctic Krill |
genre_facet |
Antarc* Antarctic Antarctic Krill |
op_source |
Limnology and Oceanography: Methods volume 4, issue 2, page 18-29 ISSN 1541-5856 1541-5856 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.4319/lom.2006.4.18 |
container_title |
Limnology and Oceanography: Methods |
container_volume |
4 |
container_issue |
2 |
container_start_page |
18 |
op_container_end_page |
29 |
_version_ |
1797569728577798144 |