Alternative prey choice in the pteropod Clione limacina (Gastropoda) studied by DNA-based methods

Abstract

The gymnosome pteropod Clione limacina is regarded as a monophagous predator, feeding exclusively on the thecosome pteropod Limacina helicina in Arctic waters. C. limacina is adapted to survive periods of low food availability by long-term starvation. Although L. helicina is absent from the water, a number of other zooplankton species are present during this time. It may therefore seem surprising that C. limacina does not take advantage of these other food sources at times when their main prey is absent. DNA- based approaches have never been used to investigate C. limacina feeding habits previously. In this study, group-specific primers were used to analyse stomach content DNA in C. limacina. This is the first study to report that C. limacina feed on other types of prey than L. helicina. The traces of amphipod and calanoid DNA were positively identified by sequencing, suggesting that C. limacina is in fact a polyphagous predator. Predation on alternative prey may enable C. limacina to survive longer time periods of food scarcity. With L. helicina being susceptible to ocean acidification, utilising alternative prey may allow the continued existence of C. limacina if L. helicina populations decline.