Meeting Abstract
Cownose rays, Rhinoptera bonasus, are highly migratory elasmobranchs native to the Western Atlantic and Gulf of Mexico. Cownose rays are known to feed predominantly on mollusks and crustaceans, but it is still unclear which species are most commonly consumed. Cownose rays are durophagous feeders, crushing their prey, making it difficult or impossible to identify stomach contents. Fieldwork conducted from 2010 to 2013 collected gut samples from cownose rays in Pamlico Sound, North Carolina, and Chesapeake Bay, Virginia (Bade 2013). Among these samples, 80% of stomach contents (by mass) could not be identified by visual inspection, and in spiral valves (intestines) the total unknown tissue was 95%. Even when prey items are crushed and anatomical identification is impossible, DNA in gut contents can be sequenced to establish connections between predators and prey. This study sequenced DNA from digestive tracts of the 33 cownose rays previously studied, as well as another 22 rays from Chesapeake Bay. The cytochrome oxidase I (COI) and 16S gene were targeted to better understand diet composition of cownose rays, even at different stages of digestion, and gut microbiome composition. Targeted amplification and high-throughput sequencing of barcoding genes holds the potential to transform our understanding of trophic connections in communities that are inaccessible and where traditional observations are costly or dangerous. A more thorough understanding of the feeding ecology of cownose rays will provide critical information for fisheries management and conservation.
