A key question for understanding marine ecosystems is the competitive interactions between predators and their prey particle community. A particularly important trophic interaction is between benthic tunicates and prey, driving the benthopelagic energy transfer in many marine systems. In general, classical methods for characterizing diets of marine animals feeding on planktonic species in situ are not well adapted to identify species specific interactions. However, molecular gut content analyses tools have proven promising since small quantities of prey DNA is detected using polymerase chain reaction (PCR). In this study, the intestine of tunicate Ciona intestinalis collected from deployed growth structures at 3 different ages and 3 depths were amplified using PCR with universal primers targeting the 18S rDNA gene in combination with a C3 tunicate blocking probe. Clones libraries were further constructed and prey particles analyzed by Sanger sequencing. In addition, the general contribution of eukaryotes and prokaryotes in the Ciona instestine were investigated using real time quantitative PCR (qPCR). Our data indicated that the class Conoidasida was the most abundant species with dominant taxa being Heliospora cf. Longissima, Heliospora caprellae, Thiriotia pugettiae and Cephaloidophora cf. Communis. This group of organisms has been found as parasites of intestinal tracts in marine organisms. Furthermore qPCR analysis indicated a significant proportion of prokaryotes in the intestine, but that the eukaryote contribution was higher. Our data also indicated that there was a positive correlation between size and contents of both prokaryotes and eukaryotes prey, while depth alone did not affect growth or food uptake. To our knowledge, this is the first report of Ciona trophic interaction using molecular gut content techniques. Our study indicates a significant link between both the eukaryotic and prokaryotic community, and that C. intestinalis could be an important vector for the Conoidasida parasite group's life history.

Qualitative and quantitative analysis of Ciona intestinalis gut content using polymerase chain reaction (PCR) technique

247th National Meeting (2014)

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