From April to August, a black-tailed gull (Larus crassirostris) is the most dominant species in Dokdo island located in East/japan Sea. This small island offers the optimal conditions for its breeding including the rocky cliffs with a high slope and the vegetation for the nesting material and shelter from the predator. It is also known that water around Dokdo island is ideal source for its breeding in which North Korea Cold Current and East Korean Warm Current a branch of Tsushima Warm Current collide each other creating a high productivity. However, feeding ecology of L. crassirostris inhabiting the island during the breeding season has not been made. The conventional diet study of avian species is usually conducted by a direct microscopic observation on the stomach contents by regurgitating or water-off-load technique. However, molecular analysis of fecal samples can be alternatively used as a non-invasive tool to study the feeding ecology of avian species. We adopted a metabarcoding analysis by MiSeq platform to identify potential prey items and clues involved in feeding behavior. In total, 60 fecal samples were collected from Dokdo island and NGS data generated by four different universal primer sets (16S rDNA, 23S rDNA, COI, and vertebrate) were analyzed.
Results/Conclusions
As a result of four different universal primer set, we identified that the major prey items of L. crassirostris were fish species including pacific saury (Cololabis saira), goldeye rockfish (Sebastes thompsoni), herring (Clupea pallasii), and sailfin sandfish (Arctoscopus japonicas). Microbial community analysis by the 16S rDNA showed L. crassirostris is carnivorous. Sargassum horneri from the fecal DNA was identified by 23S rDNA universal primer set. The floating masses of S. horneri is known as the spawning, a shelter, and a nursery place for the many fish species suggesting that L. crassirostris used to floating masses of S.horneri as the hunting sites. The NGS results generated by multiple universal primer sets turned out to be an effective method for the diet study of L. crassirostris, which provides a useful information related to its feeding ecology.