High Latitude epipelagic and mesopelagic scattering layers—a reference for future Arctic ecosystem change
Ingvaldsen, Randi B.
MetadataShow full item record
Scattering structures, including deep (>200 m) scattering layers are common in most oceans, but have not previously been properly documented in the Arctic Ocean. In this work, we combine acoustic data for distribution and abundance estimation of zooplankton and fish with biological sampling from the region west and north of Svalbard, to examine high latitude meso- and epipelagic scattering layers and their biological constituents. Our results show that typically, there was strong patchy scattering in the upper part of the epipelagic zone (<50 m) throughout the area. It was mainly dominated by copepods, krill, and amphipods in addition to 0-group fish that were particularly abundant west of the Spitsbergen Archipelago. Off-shelf there was a distinct deep scattering layer (DSL) between 250 and 600 m containing a range of larger longer lived organisms (mesopelagic fish and macrozooplankton). In eastern Fram Strait, the DSL also included and was in fact dominated by larger fish close to the shelf/slope break that were associated with Warm Atlantic Water moving north toward the Arctic Ocean, but switched to dominance by species having weaker scattering signatures further offshore. The Weighted Mean Depths of the DSL were deeper (WMD > 440 m) in the Arctic habitat north of Svalbard compared to those south in the Fram Strait west of Svalbard (WMD ~400 m). The surface integrated backscatter [Nautical Area-Scattering Coefficient, NASC, sA (m2 nmi−2)] was considerably lower in the waters around Svalbard compared to the more southern regions (62–69°N). Also, the integrated DSL nautical area scattering coefficient was a factor of ~6–10 lower around Svalbard compared to the areas in the south-eastern part of the Norwegian Sea ~62°30′N. The documented patterns and structures, particularly the DSL and its constituents, will be key reference points for understanding and quantifying future changes in the pelagic ecosystem at the entrance to the Arctic Ocean.
© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Marine Science 4 (2017): 334, doi:10.3389/fmars.2017.00334.
Suggested CitationFrontiers in Marine Science 4 (2017): 334
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Klevjer, Thor A.; Torres, Daniel J.; Kaartvedt, Stein (Springer, 2012-06-13)The mesopelagic zone of the Red Sea represents an extreme environment due to low food concentrations, high temperatures and low oxygen waters. Nevertheless, a 38 kHz echosounder identified at least four distinct ...
Backus, Richard H.; Craddock, James E.; Haedrich, Richard L.; Shores, D. L.; Teal, John M.; Wing, A. S.; Mead, Giles W.; Clarke, William D. (Woods Hole Oceanographic Institution, 1968-10)A sound- scattering layer, composed of discrete hyperbolic echo-sequences and apparently restricted to the Slope Water region of the western North Atlantic, has been identified from the Deep Submergence Research Vehicle ...
Gjøsæter, Harald; Wiebe, Peter; Knutsen, Tor; Ingvaldsen, Randi B. (Frontiers Media, 2017-10-23)While sound scattering layers (SSLs) have been described previously from ice-covered waters in the Arctic, the existence of a viable mesopelagic community that also includes mesopelagic fishes in the Arctic has been ...