Multiple Trophic Markers Trace Dietary Carbon Sources in Barents Sea Zooplankton During Late Summer
No embargo required. <jats:p>We investigated diets of 24 Barents Sea zooplankton taxa to understand pelagic food-web processes during late summer, including the importance of sea ice algae-produced carbon. This was achieved by combining insights derived from multiple and complementary trophic...
| Published in: | Frontiers in Marine Science |
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| Main Authors: | , , , , , , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Frontiers Media SA
2021
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| Subjects: | |
| Online Access: | http://hdl.handle.net/10026.1/16807 https://doi.org/10.3389/fmars.2020.610248 |
| Summary: | No embargo required. <jats:p>We investigated diets of 24 Barents Sea zooplankton taxa to understand pelagic food-web processes during late summer, including the importance of sea ice algae-produced carbon. This was achieved by combining insights derived from multiple and complementary trophic marker approaches to construct individual aspects of feeding. Specifically, we determined proportions of algal-produced fatty acids (FAs) to reflect the reliance on diatom- versus dinoflagellate-derived carbon, highly branched isoprenoid (HBI) lipids that distinguish between ice-associated and pelagic carbon sources, and sterols to indicate the degree of carnivory. Copepods had the strongest diatom signal based on FAs, while a lack of sea ice algae-associated HBIs (IP<jats:sub>25</jats:sub>, IPSO<jats:sub>25</jats:sub>) suggested that they fed on pelagic rather than ice-associated diatoms. The amphipod <jats:italic>Themisto libellula</jats:italic> and the ctenophores <jats:italic>Beroë cucumis</jats:italic> and <jats:italic>Mertensia ovum</jats:italic> had a higher contribution of dinoflagellate-produced FAs. There was a high degree of carnivory in this food web, as indicated by the FA carnivory index 18:1(<jats:italic>n</jats:italic>−9)/18:1(<jats:italic>n</jats:italic>−7) (mean value < 1 only in the pteropod <jats:italic>Clione limacina</jats:italic>), the presence of copepod-associated FAs in most of the taxa, and the absence of algal-produced HBIs in small copepod taxa, such as <jats:italic>Oithona similis</jats:italic> and <jats:italic>Pseudocalanus</jats:italic> spp. The coherence between concentrations of HBIs and phytosterols within individuals suggested that phytosterols provide a good additional indication for algal ingestion. Sea ice algae-associated HBIs were detected in six zooplankton species (occurring in krill, amphipods, pteropods, and appendicularians), indicating an overall low to moderate contribution of ice-associated carbon from late-summer sea ice to pelagic consumption. The unexpected occurrence of ice-derived HBIs in pteropods and appendicularians, however, suggests an importance of sedimenting ice-derived material at least for filter feeders within the water column at this time of year.</jats:p> |
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