Acoustic visualization of large scale macroplankton and micronekton distributions across the Norwegian shelf and slope of the Norwegian Sea.
We present results from acoustical (38 kHz split beam) surveys, biological sampling (trawling, zooplankton nets), and measurements of physical parameters (salinity, temperature, currents) across and along the shelf off Norway (62-70°N). Major recurrent structures were apparent both geographically an...
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ftimr:oai:imr.brage.unit.no:11250/105194 2023-05-15T15:48:04+02:00 Acoustic visualization of large scale macroplankton and micronekton distributions across the Norwegian shelf and slope of the Norwegian Sea. Melle, Webjørn Kaartvedt, Stein Knutsen, Tor Dalpadado, Padmini Skjoldal, Hein Rune 1993 application/pdf http://hdl.handle.net/11250/105194 eng eng ICES ICES CM Documents;1993/L:44 This report is not to be cited without prior reference to the authors http://hdl.handle.net/11250/105194 25 s. Norwegian Sea Norskehavet marine environment havmiljø distribution utbredelse plankton biomasse biomass VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 Working paper 1993 ftimr 2021-09-23T20:15:09Z We present results from acoustical (38 kHz split beam) surveys, biological sampling (trawling, zooplankton nets), and measurements of physical parameters (salinity, temperature, currents) across and along the shelf off Norway (62-70°N). Major recurrent structures were apparent both geographically and with time. Off the shelf, two deep scattering layers prevailed; one of 50-100 m thickness where the upper border by day fluctuated between 100 and 200 m depth, and one located deeper between 300-500 m. The upper layer was mainly composed of mesopelagic fish (Maurolicus muelleri) and krill (Meganyctiphanes norvegica), while the lower layer consisted of krill (Meganyctiphanes norvegica), mesopelagic fish (Maurolicus muelleri, Benthosema glaciale), shrimps (Sergestes arcticus, Pasiphaea multidenta), and jellyfish (Periphylla periphylla). During winter, these two layers roughly comprise 95% of the backscattering volume (biomass) in the upper 500 m. The shallow layer partly intrudes onto the continental shelf, where the bottom topography exerts strong impact on its distribution. In June/July an additional scattering layer was apparent in the upper 20-30 m throughout most of the study area, though integrated backscattering biomass varied by a factor of 50. In the south the layer was associated with water masses of salinity <35 (i.e. with coastal characteristics). Further north the layer was found off the shelf in water with stronger oceanic characteristics as well. Hydrographic features indicated that coastal water and biomass was transported off the shelf in connection with gyres over the banks. Trawl catches showed that this structure was composed of 0- group herring, fish (mainly seith), and krill. Backscattering volume was positively correlated with abundance of 0-group herring caught in trawl, but was not correlated with the meso-zooplankton biomass (mainly Calanus finmarchicus), or other components of the trawl catches. The lack of positive correlations between acoustic backscattering volume, and biomass from net and trawl samples probably reflected differences in selectivity of the sampling methods. Report Calanus finmarchicus Meganyctiphanes norvegica Norskehav* Norwegian Sea Zooplankton Institute for Marine Research: Brage IMR Norwegian Sea Norway |
institution |
Open Polar |
collection |
Institute for Marine Research: Brage IMR |
op_collection_id |
ftimr |
language |
English |
topic |
Norwegian Sea Norskehavet marine environment havmiljø distribution utbredelse plankton biomasse biomass VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 |
spellingShingle |
Norwegian Sea Norskehavet marine environment havmiljø distribution utbredelse plankton biomasse biomass VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 Melle, Webjørn Kaartvedt, Stein Knutsen, Tor Dalpadado, Padmini Skjoldal, Hein Rune Acoustic visualization of large scale macroplankton and micronekton distributions across the Norwegian shelf and slope of the Norwegian Sea. |
topic_facet |
Norwegian Sea Norskehavet marine environment havmiljø distribution utbredelse plankton biomasse biomass VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 |
description |
We present results from acoustical (38 kHz split beam) surveys, biological sampling (trawling, zooplankton nets), and measurements of physical parameters (salinity, temperature, currents) across and along the shelf off Norway (62-70°N). Major recurrent structures were apparent both geographically and with time. Off the shelf, two deep scattering layers prevailed; one of 50-100 m thickness where the upper border by day fluctuated between 100 and 200 m depth, and one located deeper between 300-500 m. The upper layer was mainly composed of mesopelagic fish (Maurolicus muelleri) and krill (Meganyctiphanes norvegica), while the lower layer consisted of krill (Meganyctiphanes norvegica), mesopelagic fish (Maurolicus muelleri, Benthosema glaciale), shrimps (Sergestes arcticus, Pasiphaea multidenta), and jellyfish (Periphylla periphylla). During winter, these two layers roughly comprise 95% of the backscattering volume (biomass) in the upper 500 m. The shallow layer partly intrudes onto the continental shelf, where the bottom topography exerts strong impact on its distribution. In June/July an additional scattering layer was apparent in the upper 20-30 m throughout most of the study area, though integrated backscattering biomass varied by a factor of 50. In the south the layer was associated with water masses of salinity <35 (i.e. with coastal characteristics). Further north the layer was found off the shelf in water with stronger oceanic characteristics as well. Hydrographic features indicated that coastal water and biomass was transported off the shelf in connection with gyres over the banks. Trawl catches showed that this structure was composed of 0- group herring, fish (mainly seith), and krill. Backscattering volume was positively correlated with abundance of 0-group herring caught in trawl, but was not correlated with the meso-zooplankton biomass (mainly Calanus finmarchicus), or other components of the trawl catches. The lack of positive correlations between acoustic backscattering volume, and biomass from net and trawl samples probably reflected differences in selectivity of the sampling methods. |
format |
Report |
author |
Melle, Webjørn Kaartvedt, Stein Knutsen, Tor Dalpadado, Padmini Skjoldal, Hein Rune |
author_facet |
Melle, Webjørn Kaartvedt, Stein Knutsen, Tor Dalpadado, Padmini Skjoldal, Hein Rune |
author_sort |
Melle, Webjørn |
title |
Acoustic visualization of large scale macroplankton and micronekton distributions across the Norwegian shelf and slope of the Norwegian Sea. |
title_short |
Acoustic visualization of large scale macroplankton and micronekton distributions across the Norwegian shelf and slope of the Norwegian Sea. |
title_full |
Acoustic visualization of large scale macroplankton and micronekton distributions across the Norwegian shelf and slope of the Norwegian Sea. |
title_fullStr |
Acoustic visualization of large scale macroplankton and micronekton distributions across the Norwegian shelf and slope of the Norwegian Sea. |
title_full_unstemmed |
Acoustic visualization of large scale macroplankton and micronekton distributions across the Norwegian shelf and slope of the Norwegian Sea. |
title_sort |
acoustic visualization of large scale macroplankton and micronekton distributions across the norwegian shelf and slope of the norwegian sea. |
publisher |
ICES |
publishDate |
1993 |
url |
http://hdl.handle.net/11250/105194 |
geographic |
Norwegian Sea Norway |
geographic_facet |
Norwegian Sea Norway |
genre |
Calanus finmarchicus Meganyctiphanes norvegica Norskehav* Norwegian Sea Zooplankton |
genre_facet |
Calanus finmarchicus Meganyctiphanes norvegica Norskehav* Norwegian Sea Zooplankton |
op_source |
25 s. |
op_relation |
ICES CM Documents;1993/L:44 This report is not to be cited without prior reference to the authors http://hdl.handle.net/11250/105194 |
_version_ |
1766383077248991232 |