Open Access
feathers collected in the Pacific Northwest of North America
Reads0
Chats0
TLDR
The authors used stable isotope (δ(13)C, δ(15)N) analysis of feathers from glaucouswinged gulls (Larus glaucescens) in a heavily disturbed region of the northeast Pacific to ask whether diets of this generalist forager changed in response to shifts in food availability over 150 years, and whether any detected change might explain long-term trends in gull abundance.Abstract:
The world's oceans have undergone significant ecological changes following European colonial expansion and associated industrialization. Seabirds are useful indicators of marine food web structure and can be used to track multidecadal environmental change, potentially reflecting long-term human impacts. We used stable isotope (δ(13)C, δ(15)N) analysis of feathers from glaucous-winged gulls (Larus glaucescens) in a heavily disturbed region of the northeast Pacific to ask whether diets of this generalist forager changed in response to shifts in food availability over 150 years, and whether any detected change might explain long-term trends in gull abundance. Sampled feathers came from birds collected between 1860 and 2009 at nesting colonies in the Salish Sea, a transboundary marine system adjacent to Washington, USA and British Columbia, Canada. To determine whether temporal trends in stable isotope ratios might simply reflect changes to baseline environmental values, we also analysed muscle tissue from forage fishes collected in the same region over a multidecadal timeframe. Values of δ(13)C and δ(15)N declined since 1860 in both subadult and adult gulls (δ(13)C, ~ 2-6‰; δ(15)N, ~4-5‰), indicating that their diet has become less marine over time, and that birds now feed at a lower trophic level than previously. Conversely, forage fish δ(13)C and δ(15)N values showed no trends, supporting our conclusion that gull feather values were indicative of declines in marine food availability rather than of baseline environmental change. Gradual declines in feather isotope values are consistent with trends predicted had gulls consumed less fish over time, but were equivocal with respect to whether gulls had switched to a more garbage-based diet, or one comprising marine invertebrates. Nevertheless, our results suggest a long-term decrease in diet quality linked to declining fish abundance or other anthropogenic influences, and may help to explain regional population declines in this species and other piscivores.read more
Citations
More filters
Carbon and Nitrogen Stable Isotopes in Fastfood: Signatures of Corn and Confinement
H. Jahren,R. Kraft +1 more
TL;DR: Carbon and nitrogen stable isotopes were used to infer the source of feed to meat animals, the sources of fat within fries, and the extent of fertilization and confinement inherent to production within the U.S. diet.
Journal ArticleDOI
The gut of the finch: uniqueness of the gut microbiome of the Galápagos vampire finch.
Alice J. Michel,Lewis M. Ward,Shana K. Goffredi,Katherine S. Dawson,Katherine S. Dawson,Daniel T. Baldassarre,A. R. Brenner,Kiyoko M. Gotanda,John E. McCormack,Sean W. Mullin,Ariel O'Neill,Gabrielle S. Tender,J. Albert C. Uy,Kristie B. Yu,Victoria J. Orphan,Jaime A. Chaves +15 more
TL;DR: This study demonstrates the overall conservatism of the finch gut microbiome over short (< 1 Ma) divergence timescales, except in the most extreme case of dietary specialization, and elevates the evolutionary importance of seasonal shifts in driving not only species adaptation, but also gut microbiome composition.
Journal ArticleDOI
Land or sea? Foraging area choice during breeding by an omnivorous gull
TL;DR: High prevalence of terrestrial foraging during early breeding as well as support for dietary switching early in the breeding season are found, suggesting anthropogenic terrestrial food sources may play a role in the low breeding success of these gulls through either variation in quantity and/or quality.
Journal ArticleDOI
Stable Isotopes from Museum Specimens May Provide Evidence of Long-Term Change in the Trophic Ecology of a Migratory Aerial Insectivore
TL;DR: Results are consistent with the hypothesis that aerial insectivore populations are declining due to changes in abundance of higher trophic-level prey, but it is cautioned that museum-based stable isotope studies of terrestrial food chains will require new approaches to assessing baseline change.
Journal ArticleDOI
Origin of sulfur in diet drives spatial and temporal mercury trends in seabird eggs from Pacific Canada 1968-2015
Kyle H. Elliott,John E. Elliott +1 more
TL;DR: Variation in Hg in seabirds across space and time was associated with the origin of sulfur in the diet, and variation within and among seab birds near the top of the food web was associatedwith variation in δ34S at the base of theFood web more so than trophic position within the foodweb.
References
More filters
Journal ArticleDOI
A Global Map of Human Impact on Marine Ecosystems
Benjamin S. Halpern,Shaun Walbridge,Kimberly A. Selkoe,Kimberly A. Selkoe,Carrie V. Kappel,Fiorenza Micheli,Caterina D'Agrosa,Caterina D'Agrosa,John F. Bruno,Kenneth S. Casey,Colin M. Ebert,Helen E. Fox,Rod Fujita,Dennis Heinemann,Hunter S. Lenihan,Elizabeth M. P. Madin,Matthew T. Perry,Elizabeth R. Selig,Elizabeth R. Selig,Mark Spalding,Robert S. Steneck,Reg Watson +21 more
TL;DR: This article developed an ecosystem-specific, multiscale spatial model to synthesize 17 global data sets of anthropogenic drivers of ecological change for 20 marine ecosystems and found that no area is unaffected by human influence and that a large fraction (41%) is strongly affected by multiple drivers.
Journal ArticleDOI
Trophic Downgrading of Planet Earth
James A. Estes,John Terborgh,Justin S. Brashares,Mary E. Power,Joel Berger,William J. Bond,Stephen R. Carpenter,Timothy E. Essington,Robert D. Holt,Jeremy B. C. Jackson,Robert J. Marquis,Lauri Oksanen,Tarja Oksanen,Robert T. Paine,Ellen K. Pikitch,William J. Ripple,Stuart A. Sandin,Marten Scheffer,Thomas W. Schoener,Jonathan B. Shurin,Anthony R. E. Sinclair,Michael E. Soulé,Risto Virtanen,David A. Wardle +23 more
TL;DR: This empirical work supports long-standing theory about the role of top-down forcing in ecosystems but also highlights the unanticipated impacts of trophic cascades on processes as diverse as the dynamics of disease, wildfire, carbon sequestration, invasive species, and biogeochemical cycles.
Journal ArticleDOI
Getting to the fat of the matter: models, methods and assumptions for dealing with lipids in stable isotope analyses
David M. Post,Craig A. Layman,D. Albrey Arrington,Gaku Takimoto,John Quattrochi,Carman G Montaña +5 more
TL;DR: The results indicate that lipid extraction or normalization is most important when lipid content is variable among consumers of interest or between consumers and end members, and when differences in δ13C between end members is <10–12‰.
Journal ArticleDOI
Tracing origins and migration of wildlife using stable isotopes: a review
TL;DR: This paper reviews the use of stable isotope analyses to trace nutritional origin and migration in animals and concludes that this technique will be extremely useful in helping to track migration and movement of a wide range of animals from insects to birds and mammals.
Book
The Omnivore's Dilemma: A Natural History of Four Meals
TL;DR: The omnivor's dilemma: a natural history of four meals , The omnivore's dilemma): a naturalHistory of three meals, and more.