Although the small size-fraction of copepods (<1 mm) are important constituents of the Arctic food-web, their trophic interactions remain largely unexplored, partly due to methodological limitations. We here characterize the prey of the cyclopoid Oithona similis, harpacticoid Microsetella norvegica and calanoid Microcalanus spp. from the Arctic Barents Sea and Nansen Basin in March, April-May, August, and December using brute force prey metabarcoding of the 18S rRNA gene. Of the prey identified, chaetognaths were the most consistently identified taxa and composed 47% of all prey reads. Reads from diatoms (16%), dinoflagellates (11%) and urochordates (8%) were likewise abundant, but these taxa were more prevalent during specific seasons. Diatoms composed 43% of prey reads in April-May, dinoflagellates 15% in December and 17% in March, and urochordates 20% in August. Although some species differences were also discernible, we show that the dietary composition varied more among seasons than among species. This was observed despite the taxonomic and behavioural differences that distinguish the ambush-predator O. similis, chemosensoric particle-chaser M. norvegica and current-feeding Microcalanus spp. The results thus indicate that dietary plasticity is common in small Arctic copepods, regardless of their behaviours or strategies for finding food. We moreover hypothesize that such plasticity is an important adaptation in systems where prey availability is highly seasonal.

Primary Presenter: Snorre Flo, University Centre in Svalbard (UNIS) (snorreflo@gmail.com)

Authors:

Snorre Flo, Depatrtment of Arctic Biology, The University Centre in Svalbard, Svalbard, Norway. Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway  (snorref@unis.no)

Camilla Svensen, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway  (camilla.svensen@uit.no)

Kim Præbel, The Norwegian College of Fishery Science (NFH), UiT The Arctic University of Norway, Tromsø, Norway. Department of Forestry and Wildlife Management, Inland Norway University of Applied Sciences, Elverum, Norway.   (kim.praebel@uit.no)

Bodil Bluhm, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway  (bodil.bluhm@uit.no)

Anna Vader, Depatrtment of Arctic Biology, The University Centre in Svalbard, Svalbard, Norway.  (annav@unis.no)