title: Stable isotopes confirm a coastal diet for critically endangered Mediterranean monk seals.
abstract: Understanding the ecology and behaviour of endangered species is essential for developing effective management and conservation strategies. We used stable isotope analysis to investigate the foraging behaviour of critically endangered Mediterranean monk seals (Monachus monachus) in Greece. We measured carbon and nitrogen isotope ratios (expressed as δ(13)C and δ(15)N values, respectively) derived from the hair of deceased adult and juvenile seals and the muscle of their known prey to quantify their diets. We tested the hypothesis that monk seals primarily foraged for prey that occupy coastal habitats in Greece. We compared isotope values from seal hair to their coastal and pelagic prey (after correcting all prey for isotopic discrimination) and used these isotopic data and a stable isotope mixing model to estimate the proportion of coastal and pelagic resources consumed by seals. As predicted, we found that seals had similar δ(13)C values as many coastal prey species and higher δ(13)C values than pelagic species; these results, in conjunction with mean dietary estimates (coastal=61 % vs. pelagic=39 %), suggest that seals have a diverse diet comprising prey from multiple trophic levels that primarily occupy the coast. Marine resource managers should consider using the results from this study to inform the future management of coastal habitats in Greece to protect Mediterranean monk seals.
authors.affiliation: a MOm/Hellenic Society for the Study and Protection of the Monk seal , Athens , Greece.
authors.forename: Alexandros A
authors.initials: AA
authors.lastname: Karamanlidis
authors.forename: P Jeff
authors.initials: PJ
authors.lastname: Curtis
authors.forename: Amy C
authors.initials: AC
authors.lastname: Hirons
authors.forename: Marianna
authors.initials: M
authors.lastname: Psaradellis
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Dendrinos
authors.forename: John B
authors.initials: JB
authors.lastname: Hopkins
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000378:metabolism; D049830:Cephalopoda / Q000378:metabolism; D033364:Decapoda / Q000378:metabolism; D004032:Diet; D056727:Endangered Species; D005260:Female; D005399:Fishes / Q000378:metabolism; D006115:Greece; D006197:Hair / Q000737:chemistry; D008297:Male; D008962:Models, Theoretical; D018482:Muscle, Skeletal / Q000737:chemistry; D009587:Nitrogen Isotopes / Q000378:metabolism; D046048:Seals, Earless / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes
keywords: Greece; Monachus monachus; carbon-13; diet; endangered species; food web; foraging; isotope ecology; nitrogen-15; seals