Líffræðifélag Íslands
Líffræðiráðstefnan 2015
Erindi/veggspjald / Talk/poster V46
Cecilia E. K. Kvaavik (1,3,4), Guðmundur J. Óskarsson (1), Jonathan Grabowski (2), Hildur Pétursdóttir (1), Anna Kristín Daníelsdóttir (3) and Guðrún Marteinsdóttir (4)
1. Hafrannsóknastofnun, 2. Northeastern University, 3. Matís, 4. Háskóla Íslands
Kynnir / Presenter: Cecilia E. K. Kvaavik
Tengiliður / Corresponding author: Guðmundur J. Óskarsson, Jonathan Grabowski, Hildur Pétursdóttir, Anna Kristín Daníelsdóttir and Guðrún Marteinsdóttir (cecilia@hafro.is)
Warming of the world’s oceans has not only caused changes in the oceanic food webs, but it has also caused many pelagic marine species to shift their distribution - especially in a pole wards direction. Planktivorous fish populations can be very abundant and may have a great impact on the ecosystem by for example local depletion of zooplankton. Extensive numbers of pelagic planktivorous fish enter the Icelandic waters during summer to feed, this summer it was estimated that ~2.9 million mackerel (Scombrus Scomber) and ~ 3 million herring (Clupea harengus) were feeding within the Icelandic EEZ, which means that these stocks can exert significant top-down pressures on the food web. The mackerel are opportunistic feeders and feed on a variety of zooplankton and small fish, whilst herring are mainly filter feeders of zooplankton. Research into the diets of these two species suggests that the main zooplankton prey species in Icelandic waters are copepods (primarily Calanus finmarchicus), euphausiids, pteropods, amphipods and appendicularia. Mackerel also include fish prey such as larval sandeel (Ammodytes spp.), herring and capelin (Mallotus villosus). This study focuses on the differences between the diets of these two key pelagic species as well as the trophic links between them and their lower trophic level prey. This is done by analysing the stable isotope signatures (δ13C and δ15N) which will reflect biologically assimilated nutrients from the diet over a longer time period. The results of the isotope analysis coupled with stomach content data will show the diet composition and estimate the dietary impact of these two pelagic species on lower tropic level species.