1.5 Aim of study
Clione limacina is according to literature consideredto be a monophagous species, feeding
exclusively on L. helicina. Such a strategy is inconsistent with the current understanding of
Arctic marine zooplankton, where no other examples of monophagous species can be found.
As L. helicinaappears to be more or less absent from the water column in late autumn, winter
and early spring, C. limacina is faced with long periods of forced starvation. Although C.
limacinacan survive long periods offood scarcity, other zooplankton species are present in
the water when the abundance of L. helicina is low. Hence, alternative prey items could
potentially be consumed in periodsof either low availability of L. helicina or in seasons with
high density of other zooplankton species.
Based on this, I propose to testthe hypothesis of monophagy in Clione limacina:
H0: Clione limacinafeed exclusively on Limacina helicina in Arctic waters
H1: Clione limacina can consume other species of zooplankton
The main prediction from H1is that traces of prey items other than L. helicina will be detected
in the guts of C. limacina. The main method of investigating alternative prey items in C.
limacina was performed using molecular genetic tools. Group-specific primers targeting
potential prey species were used to amplify DNA extracted from C. limacinastomachs. The
group-specific primers gave qualitative data byindicating presence or absence of target
organism DNA. In addition, a few samples were sent for NGS-analyses without using
blocking-primers, to compare the results of the two molecular methods. Neither of these
techniques has been used to investigate prey-consumption in C. limacina previously. A
feeding experiment was attempted to investigate alternative prey consumption by direct
observations.