Reliability of qPCR for quantitative gut content estimation in the circumglobally abundant pelagic tunicate Dolioletta gegenbauri (Tunicata, Thaliacea)

Gelatinous metazooplankton play a crucial role in marine planktonic food webs. In this study the authors report the development of a differential length amplification quantitative PCR (dla-qPCR) assay targeting the 18S rRNA gene to validate the use of qPCR-based approach to quantify consumption of specific plankton prey by the doliolid Dolioletta gegenbauri. Results indicate that prey DNA was not significantly digested during passage through the gut of D. gegenbauri. In the field, the centric diatom Thalassiosira spp. was detected in the gut of wild caught D. gegenbauri at very low abundance that was consistent with its relative rarity in the water column at the time of collection. Thus, both experimental and field investigations support the hypothesis that a qPCR approach will be useful for the quantitative investigation of the in situ diet of D. gegenbauri without introduced biases associated with cultivation.