DNA metabarcoding of cloacal swabs provides insight into diets of highly migratory sharks in the Mid‐Atlantic Bight

Abstract

The abundances of migratory shark species observed throughout the Mid‐Atlantic Bight (MAB) during productive summer months suggest that this region provides critical habitat and prey resources to these taxa. However, the principal prey assemblages sustaining migratory shark biomass in this region are poorly defined. We applied high‐throughput DNA metabarcoding to shark feces derived from cloacal swabs across nine species of Carcharhinid and Lamnid sharks to (1) quantify the contribution of broad taxa (e.g., invertebrates, fishes) supporting shark biomass during seasonal residency in the MAB and (2) determine whether the species displayed distinct dietary preference indicative of resource partitioning. DNA metabarcoding resulted in high taxonomic (species‐level) resolution of shark diets with actinopterygian and elasmobranch fishes as the dominant prey categories across the species. DNA metabarcoding identified several key prey groups consistent across shark taxa that are likely integral for sustaining their biomass in this region, including Atlantic menhaden (Brevoortia tyrannus), Atlantic mackerel (Scomber scombrus), and benthic elasmobranchs, including skates. Our results are consistent with previously published stomach content data for the shark species of similar size range in the Northwest Atlantic Ocean, supporting the efficacy of cloacal swab DNA metabarcoding as a minimally invasive diet reconstruction technique. The high reliance of several shark species on Atlantic menhaden could imply wasp‐waist food‐web conditions during the summer months, whereby high abundances of forage fishes sustain a diverse suite of migratory sharks within a complex, seasonal food web.

Accumulation of Per- and Polyfluoroalkyl Substances (PFAS) in Coastal Sharks from Contrasting Marine Environments: The New York Bight and The Bahamas

“…The ∑PFAS concentrations (especially ultralong-chain PFAS) of common thresher sharks were notably higher than any other species from the NYB, which may be directly related to their feeding habits and trophic level. Common thresher sharks primarily feed on bony fish, exhibiting narrower dietary preferences in comparison with other shark species, , whereas shortfin mako sharks, sandbar sharks, and smooth dogfish feed across multiple trophic levels with diets comprising bony fish, mollusks, and crustaceans. ,− Nevertheless, common thresher sharks did not exhibit the highest δ 15 N values among the studied NYB species (Figure S2), suggesting that trophic position may not be the primary factor contributing to their high ∑PFAS concentrations in this study. Other factors, such as sexual maturity, thermoregulation, migration patterns, and habitat associations, may also drive variation in PFAS concentrations.…”

Analysis of winter diet in Guizhou golden monkey (Rhinopithecus brelichi) using DNA metabarcoding data

“…DNA metabarcoding, which combines high‐throughput sequencing (HTS) with DNA barcoding, allows for the processing of a greater number of samples and the recognition of multiple taxa in a shorter amount of time (Drake et al., 2023; Kuang et al., 2023). Because of its advantages, DNA metabarcoding has been used in dietary studies of a variety of animals, including sharks (Olin et al., 2023), Lutra lutra (Drake et al., 2023), birds (Schumm et al., 2023) and others. Accordingly, DNA metabarcoding of faecal samples has been used to characterize the plant diet of primates.…”

“…Because of its advantages, DNA metabarcoding has been used in dietary studies of a variety of animals, including sharks (Olin et al, 2023), Lutra lutra (Drake et al, 2023), birds (Schumm et al, 2023) and others. Accordingly, DNA metabarcoding of faecal samples has been used to characterize the plant diet of primates.…”