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Marine Ecology Progress Series

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MEPS 655:227-240 (2020)  -  DOI:

Utilizing next-generation sequencing to identify prey DNA in western North Atlantic grey seal Halichoerus grypus diet

Kelly R. Flanders1,3,*, Zachary H. Olson2, Kathryn A. Ono1

1University of New England, School of Marine Programs, Biddeford, Maine 04005, USA
2University of New England, Department of Psychology, Animal Behavior Program, Biddeford, Maine 04005, USA
3Present address: Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
*Corresponding author:

ABSTRACT: Increasing grey seal Halichoerus grypus abundance in coastal New England is leading to social, political, economic, and ecological controversies. Central to these issues is the foraging ecology and diet composition of the seals. We studied grey seal feeding habits through next-generation sequencing of prey DNA using 16S amplicons from seal scat (n = 74) collected from a breeding colony on Monomoy Island in Massachusetts, USA, and report frequency of occurrence and relative read abundance. We also assigned seal sex to scat samples using a revised PCR assay. In contrast to current understanding of grey seal diet from hard parts and fatty acid analysis, we found no significant difference between male and female diet measured by alpha and beta diversity. Overall, we detected 24 prey groups, 18 of which resolved to species. Sand lance Ammodytes spp. were the most frequently consumed prey group, with a frequency of occurrence (FO) of 97.3%, consistent with previous studies, but Atlantic menhaden Brevoortia tyrannus, the second most frequently consumed species (FO = 60.8%), has not previously been documented in US grey seal diet. Our results suggest that a metabarcoding approach to seal food habits can yield important new ecological insights, but that traditional hard parts analysis does not underestimate consumption of Atlantic cod Gadus morhua (FO = 6.7%, Gadidae spp.) and salmon Salmo salar (FO = 0%), 2 particularly valuable species of concern.

KEY WORDS: Foraging ecology · Prey DNA · Molecular scatology · Next-generation sequencing · Diet · Halichoerus grypus · Grey seal

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Cite this article as: Flanders KR, Olson ZH, Ono KA (2020) Utilizing next-generation sequencing to identify prey DNA in western North Atlantic grey seal Halichoerus grypus diet. Mar Ecol Prog Ser 655:227-240.

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