The diet spectrum of fish in South Greenland waters: the role of gelatinous zooplankton as prey

• Main Authors: Throm, Julia Katharina, Dischereit, Annkathrin, Havermans, Charlotte
• Format: Conference Object
• Language: unknown
• Published: 2022
• Subjects: Gadus morhua; Greenland; greenlandic
• Online Access: https://epic.awi.de/id/eprint/57230/; https://hdl.handle.net/10013/epic.9beaac20-f7f1-4b3b-abf5-95b477ca14cd

Gelatinous zooplankton (GZ) or jellies, consisting of cnidarians, ctenophores and tunicates, can reach high biomasses, but so far, have been overlooked as a food source for higher trophic levels. Traditionally, GZ have been seen as trophic “dead-ends” in the food web, as they are rarely observed during visual inspections of predators’ stomach contents. This is particularly the case in fishery surveys, which conventionally rely on morphological stomach content analysis. However, high water content and fragility can result in quick digestion of gelatinous prey, meaning only those that were ingested shortly before sampling can be visually recorded. Modern molecular methods, which can detect the DNA of gelatinous species longer after ingestion, are increasingly showing that GZ are part of the diet of numerous animals, including various invertebrate groups, seabirds, turtles and fish. The evaluation of GZ as a potential food source for marine animals is particularly important in context of global warming, as the biomass of GZ is expected to further increase. This study uses DNA metabarcoding (18S and COI) to identify prey items in the stomachs of common Southern Greenlandic fish species, several of which are commercially exploited: Gadus morhua, Sebastes sp., Anarhichas sp., Argentina silus and Hippoglossoides platessoides. The analysis and comparison of the prey taxa detected with each of the two genes, should yield a comprehensive picture of the prey spectrum of the different fish species, including readily digested and fragile organisms like GZ. The selection of investigated fish species will allow a prey-spectrum assessment of different trophic groups across different habitats: East vs. West Greenland; pelagic vs. demersal fish; juvenile vs. adult.