Measuring in situ krill tilt orientation by stereo photogrammetry: examples for Euphausia superba and Meganyctiphanes norvegica
The natural body orientation adopted by krill is a crucial parameter for understanding and estimating the acoustic backscattering from these animals. Published data are scarce and are usually acquired with single-camera systems that provide suboptimal control over the measurement accuracy. Here we d...
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Online Access: | http://hdl.handle.net/1956/10077 https://doi.org/10.1093/icesjms/fsv077 |
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ftunivbergen:oai:bora.uib.no:1956/10077 2023-05-15T16:08:27+02:00 Measuring in situ krill tilt orientation by stereo photogrammetry: examples for Euphausia superba and Meganyctiphanes norvegica Kubilius, Rokas Ona, Egil Calise, Lucio 2015-05-12 application/pdf http://hdl.handle.net/1956/10077 https://doi.org/10.1093/icesjms/fsv077 eng eng Oxford University Press Multi-frequency acoustic discrimination between gas bubble plumes and biological targets in the ocean urn:issn:1054-3139 http://hdl.handle.net/1956/10077 https://doi.org/10.1093/icesjms/fsv077 Copyright International Council for the Exploration of the Sea 2015. All rights reserved ICES Journal of Marine Science Euphausia superba krill Meganyctiphanes norvegica orientation stereo camera stereo photogrammetry tilt underwater photography Zooplankton zooplankton acoustics Journal article 2015 ftunivbergen https://doi.org/10.1093/icesjms/fsv077 2023-03-14T17:41:48Z The natural body orientation adopted by krill is a crucial parameter for understanding and estimating the acoustic backscattering from these animals. Published data are scarce and are usually acquired with single-camera systems that provide suboptimal control over the measurement accuracy. Here we describe a stereo-photo camera application for accurate krill measurements in situ, based upon several Euphausia superba and Meganyctiphanes norvegica datasets. Body-tilt orientation, body length and school volume density from scattered and schooling krill are presented. Some challenges to the practical implementation of the method are discussed, including practical limits on krill body yaw angles for obtaining useful measurement accuracy and how to account accurately for the true vertical. Calibration and measurement accuracy is discussed together with a practical definition of krill body orientation. Krill sizes determined from stereo-images are compared with those measured from trawl samples. The krill body-tilt measurements yielded mean estimates of positive (head-up) or negative tilt of 9-17° with rather large spread for scattered aggregations of M. norvegica (SD=30-37°) and about half of that for polarized schools of E. superba (SD=14-17°). The measured krill body orientation distributions were also used to calculate krill acoustic target strength as predicted by the stochastic distorted wave Born approximation (SDWBA) model. submittedVersion Article in Journal/Newspaper Euphausia superba Meganyctiphanes norvegica University of Bergen: Bergen Open Research Archive (BORA-UiB) ICES Journal of Marine Science 72 8 2494 2505 |
institution |
Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
topic |
Euphausia superba krill Meganyctiphanes norvegica orientation stereo camera stereo photogrammetry tilt underwater photography Zooplankton zooplankton acoustics |
spellingShingle |
Euphausia superba krill Meganyctiphanes norvegica orientation stereo camera stereo photogrammetry tilt underwater photography Zooplankton zooplankton acoustics Kubilius, Rokas Ona, Egil Calise, Lucio Measuring in situ krill tilt orientation by stereo photogrammetry: examples for Euphausia superba and Meganyctiphanes norvegica |
topic_facet |
Euphausia superba krill Meganyctiphanes norvegica orientation stereo camera stereo photogrammetry tilt underwater photography Zooplankton zooplankton acoustics |
description |
The natural body orientation adopted by krill is a crucial parameter for understanding and estimating the acoustic backscattering from these animals. Published data are scarce and are usually acquired with single-camera systems that provide suboptimal control over the measurement accuracy. Here we describe a stereo-photo camera application for accurate krill measurements in situ, based upon several Euphausia superba and Meganyctiphanes norvegica datasets. Body-tilt orientation, body length and school volume density from scattered and schooling krill are presented. Some challenges to the practical implementation of the method are discussed, including practical limits on krill body yaw angles for obtaining useful measurement accuracy and how to account accurately for the true vertical. Calibration and measurement accuracy is discussed together with a practical definition of krill body orientation. Krill sizes determined from stereo-images are compared with those measured from trawl samples. The krill body-tilt measurements yielded mean estimates of positive (head-up) or negative tilt of 9-17° with rather large spread for scattered aggregations of M. norvegica (SD=30-37°) and about half of that for polarized schools of E. superba (SD=14-17°). The measured krill body orientation distributions were also used to calculate krill acoustic target strength as predicted by the stochastic distorted wave Born approximation (SDWBA) model. submittedVersion |
format |
Article in Journal/Newspaper |
author |
Kubilius, Rokas Ona, Egil Calise, Lucio |
author_facet |
Kubilius, Rokas Ona, Egil Calise, Lucio |
author_sort |
Kubilius, Rokas |
title |
Measuring in situ krill tilt orientation by stereo photogrammetry: examples for Euphausia superba and Meganyctiphanes norvegica |
title_short |
Measuring in situ krill tilt orientation by stereo photogrammetry: examples for Euphausia superba and Meganyctiphanes norvegica |
title_full |
Measuring in situ krill tilt orientation by stereo photogrammetry: examples for Euphausia superba and Meganyctiphanes norvegica |
title_fullStr |
Measuring in situ krill tilt orientation by stereo photogrammetry: examples for Euphausia superba and Meganyctiphanes norvegica |
title_full_unstemmed |
Measuring in situ krill tilt orientation by stereo photogrammetry: examples for Euphausia superba and Meganyctiphanes norvegica |
title_sort |
measuring in situ krill tilt orientation by stereo photogrammetry: examples for euphausia superba and meganyctiphanes norvegica |
publisher |
Oxford University Press |
publishDate |
2015 |
url |
http://hdl.handle.net/1956/10077 https://doi.org/10.1093/icesjms/fsv077 |
genre |
Euphausia superba Meganyctiphanes norvegica |
genre_facet |
Euphausia superba Meganyctiphanes norvegica |
op_source |
ICES Journal of Marine Science |
op_relation |
Multi-frequency acoustic discrimination between gas bubble plumes and biological targets in the ocean urn:issn:1054-3139 http://hdl.handle.net/1956/10077 https://doi.org/10.1093/icesjms/fsv077 |
op_rights |
Copyright International Council for the Exploration of the Sea 2015. All rights reserved |
op_doi |
https://doi.org/10.1093/icesjms/fsv077 |
container_title |
ICES Journal of Marine Science |
container_volume |
72 |
container_issue |
8 |
container_start_page |
2494 |
op_container_end_page |
2505 |
_version_ |
1766404501739143168 |