Unexpected fish and squid in the central Arctic deep scattering layer

Snoeijs, Pauline; Flores, Hauke; Sakınan, Serdar; Hildebrandt, Nicole; Svenson, Anders; Castellani, Giulia; Vane, Kim; Mark, Felix Christopher; Heuzé, Céline; Tippenhauer, Sandra; Niehoff, Barbara; Hjelm, Joakim; Hentati‐Sundberg, Jonas; Schaafsma, Fokje; Engelmann, Ronny

doi:10.1126/sciadv.abj7536

Cited by 22 publications

(18 citation statements)

References 63 publications

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“…Vertical zonation of mesozooplankton in the Eurasian Basin has also been characterized and synthesized over the past decades 11 , 12 . Some larger organisms, like armhook squid ( Gonatus fabricii ) and gelatinous zooplankton and nekton have been found 11 , 13 , as well as single individuals of Atlantic cod ( Gadus morhua ), glacier lanternfish ( Benthosema glaciale) and ice cod (Arctogadus glacialis) 13 . Faunal densities and biomass for the mapped Eurasian Basin water column are generally low in comparison to Arctic shelves and southern areas 11 , 12 , 14 due to overall low primary production and hence food availability 15 , 16 .…”

Section: Introductionmentioning

confidence: 99%

Under-ice observations by trawls and multi-frequency acoustics in the Central Arctic Ocean reveals abundance and composition of pelagic fauna

Ingvaldsen

Eriksen

Gjøsæter

et al. 2023

Sci Rep

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The rapid ongoing changes in the Central Arctic Ocean call for baseline information on the pelagic fauna. However, sampling for motile organisms which easily escape vertically towed nets is challenging. Here, we report the species composition and catch weight of pelagic fishes and larger zooplankton from 12 trawl hauls conducted in ice covered waters in the Central Arctic Ocean beyond the continental slopes in late summer. Combined trawl catches with acoustics data revealed low amounts of fish and zooplankton from the advective influenced slope region in the Nansen Basin in the south to the ice-covered deep Amundsen Basin in the north. Both arctic and subarctic-boreal species, including the ones considered as Atlantic expatriate species were found all the way to 87.5o N. We found three fish species (Boreogadus saida, Benthosema glaciale and Reinhardtius hippoglossoides), but the catch was limited to only seven individuals. Euphausiids, amphipods and gelatinous zooplankton dominated the catch weight in the Nansen Basin in the mesopelagic communities. Euphausiids were almost absent in the Amundsen Basin with copepods, amphipods, chaetognaths and gelatinous zooplankton dominating. We postulate asymmetric conditions in the pelagic ecosystems of the western and eastern Eurasian Basin caused by ice and ocean circulation regimes.

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Section: Introductionmentioning

confidence: 99%

Under-ice observations by trawls and multi-frequency acoustics in the Central Arctic Ocean reveals abundance and composition of pelagic fauna

Ingvaldsen

Eriksen

Gjøsæter

et al. 2023

Sci Rep

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“…The application of a fully autonomous bio-physical observatory enabled us to monitor animal behaviour under sea ice during its drift across the CAO, a task which has so far required immense logistic effort and therefore left considerable knowledge gaps regarding higher trophic levels in the Arctic ecosystem 49 . Similar technology will be important for understanding changes of the future Arctic ecosystem and its management, e.g.…”

Section: Discussionmentioning

confidence: 99%

Sea-ice decline makes zooplankton stay deeper for longer

Flores

Veyssière

Castellani

et al. 2023

Preprint

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As Arctic sea ice deteriorates, more light enters the Arctic Ocean, causing largely unknown effects on the ecosystem. A novel autonomous bio-physical observatory provided the first record of zooplankton vertical distribution under sea ice drifting across the Arctic Ocean from dusk to dawn of the polar night. Its measurements revealed that zooplankton ascend into the under-ice layer during autumn twilight, following an isolume of 5.5 10-4 W m-2. We applied this trigger isolume to IPCC models enabled to incorporate incoming radiation after sunset and before sunrise of the polar night. The models project that, in about three decades, the total time spent by zooplankton in the under-ice layer will be reduced by up to one month, depending on geographic region. This will impact zooplankton winter survival, the Arctic foodweb, carbon- and nutrient fluxes. These findings highlight the importance of processes in the twilight periods for predicting change in high-latitude ecosystems.

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“…In view of a warming Arctic, large environmental changes are expected as well as shifts in marine carbon cycling dynamics as a result of changes in the interplay between primary surface production and ice algae Wassmann et al, 2020). Species recognized from southern and lower latitudes appear in the Arctic region, which may cause a "borealization" of Arctic communities (Fossheim et al, 2015;Ingvaldsen et al, 2021;Snoeijs-Leijonmalm et al, 2022). One condition that determines if such new-coming species have the potential to establish viable populations in the Arctic will be the acquisition of available food resources.…”

Section: Closing Remarksmentioning

confidence: 99%

Chemosynthetic and photosynthetic trophic support from cold seeps in Arctic benthic communities

2022

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Benthic communities below the photic zone are largely reliant on the export of surface-water primary production and the flux of partially degraded organic matter to the seabed, i.e. pelagic−benthic coupling. Over the past decades, however, the role of chemosynthetically produced carbon in food webs has been recognized in various habitats. Cold seeps are now known to be widespread across circumpolar Arctic shelves where natural release of hydrocarbons occurs at the seabed. Here, we investigated to what extent chemosynthesis-based carbon (CBC) enters the food web in a high latitude shelf-system. Specifically, we estimated the contributions of chemosynthesis-based carbon to primarily benthic invertebrate taxa from seeps at both shallow and deeper shelves and comparative non-seep areas in the Svalbard-Barents Sea region using bulk stable isotope-analysis of carbon and nitrogen. Our results show low δ13C values (-51.3 to -32.7 ‰) in chemosymbiotic siboglinids and several species of benthic, higher-trophic level, invertebrates (mainly polychaetes and echinoderms; -35.0 to -26.1‰) collected at cold seeps, consistent with assimilation of chemosynthesis-based carbon into the Arctic benthic food web. Using a two-component mixing equation, we demonstrate that certain species could derive more than 50% of their carbon from chemosynthesis-based carbon. These findings show that autochthonous chemosynthetic energy sources can contribute to supporting distinct groups of ‘background’ benthic taxa at these Arctic seep-habitats beyond microbial associations and chemosymbiotic species. Furthermore, we found a higher degree of chemosynthesis-based carbon in benthos at the deeper Barents Sea shelf seeps (>330 m) compared to seeps at the Western Svalbard shelf (<150 m water-depth), and we suggest this result reflects the differences in depth range, surface production and pelagic-benthic coupling. We detected large intra-species variations in carbon signatures within and across geographical locations and, combined with isotopic niche-analysis, our results show that certain taxa that inhabits seeps, have wider trophic niches in comparison to taxa inhabiting non-seeps. The increasing number of discovered natural seeps in the Arctic suggests that chemosynthetic production from seeps could play a more critical role in Arctic trophic structure than previously thought. Seep-derived carbon should, hence, be accounted for as an additional carbon source and included in food-web and energy-flow models in future work.

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Unexpected fish and squid in the central Arctic deep scattering layer

Cited by 22 publications

References 63 publications

Under-ice observations by trawls and multi-frequency acoustics in the Central Arctic Ocean reveals abundance and composition of pelagic fauna

Under-ice observations by trawls and multi-frequency acoustics in the Central Arctic Ocean reveals abundance and composition of pelagic fauna

Sea-ice decline makes zooplankton stay deeper for longer

Chemosynthetic and photosynthetic trophic support from cold seeps in Arctic benthic communities

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