Can Stomach Content and Microbiomes of Tuna Provide Near Real-Time Detection of Ecosystem Composition in the Pacific Ocean?

This preliminary study used DNA metabarcoding to test whether the stomach content and gut microbiome of tuna could be a viable near real-time monitoring tool for detecting composition change in oceanic ecosystems. The skipjack ( Katsuwonus pelamis , n=55) yellowfin Thunnus albacares n=46) captured Pacific Ocean during El Niño Southern Oscillation events (ENSO) between 2015-2017 were examined by high throughput sequencing complemented morphological assessments identify fishes, crustaceans cephalopods content. Gut was solely sequencing. Stomach compared species, ENSO capture location using generalised linear models. full model (tuna interaction with ENSO) best explained fish prey composition, while weakly cephalopods. Skipjack coastal areas (Longitude<170°W) showed greater diversity regions Pacific, much more diverse than K. (21 fish, eight six crustaceans). Fish La Niña higher Niño. Tuna species differences Phylum level, no Order or Family level. shows that T. albacares, assemblages