title: Broad-scale trophic shift in the pelagic North Pacific revealed by an oceanic seabird.
abstract: Human-induced ecological change in the open oceans appears to be accelerating. Fisheries, climate change and elevated nutrient inputs are variously blamed, at least in part, for altering oceanic ecosystems. Yet it is challenging to assess the extent of anthropogenic change in the open oceans, where historical records of ecological conditions are sparse, and the geographical scale is immense. We developed millennial-scale amino acid nitrogen isotope records preserved in ancient animal remains to understand changes in food web structure and nutrient regimes in the oceanic realm of the North Pacific Ocean (NPO). Our millennial-scale isotope records of amino acids in bone collagen in a wide-ranging oceanic seabird, the Hawaiian petrel (Pterodroma sandwichensis), showed that trophic level declined over time. The amino acid records do not support a broad-scale increase in nitrogen fixation in the North Pacific subtropical gyre, rejecting an earlier interpretation based on bulk and amino acid specificδ15N chronologies for Hawaiian deep-sea corals and bulkδ15N chronologies for the Hawaiian petrel. Rather, our work suggests that the food web structure in the NPO has shifted at a broad geographical scale, a phenomenon potentially related to industrial fishing.
authors.affiliation: Department of Integrative Biology and Ecology Evolutionary Biology and Behavior Program, Michigan State University, East Lansing, MI 48824, USA ostrom@msu.edu.
authors.forename: Peggy H
authors.identifier: http://orcid.org/0000-0002-9953-8809
authors.initials: PH
authors.lastname: Ostrom
authors.affiliation: Department of Biology, University of Akron, Akron, OH 44325, USA.
authors.forename: Anne E
authors.initials: AE
authors.lastname: Wiley
authors.affiliation: Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington DC 20013, USA.
authors.forename: Helen F
authors.initials: HF
authors.lastname: James
authors.affiliation: Department of Integrative Biology and Ecology Evolutionary Biology and Behavior Program, Michigan State University, East Lansing, MI 48824, USA.|Hubbs-Sea World Research Institute, 3830 S. Highway A1A no. 4-181, Melbourne Beach, FL 32951, USA.
authors.forename: Sam
authors.initials: S
authors.lastname: Rossman
authors.affiliation: Marine Mammal Laboratory, Alaska Fisheries Science Center, NOAA, Seattle, WA 98115, USA.
authors.forename: William A
authors.initials: WA
authors.lastname: Walker
authors.affiliation: Department of Integrative Biology and Ecology Evolutionary Biology and Behavior Program, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Elise F
authors.initials: EF
authors.lastname: Zipkin
authors.affiliation: Department of Biogeochemistry, Japan Agency for Marine Science & Technology, Yokosuka 237-0061, Japan.|Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo 060-0819, Japan.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Chikaraishi
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000737:chemistry; D001717:Birds; D057231:Climate Change; D003094:Collagen / Q000737:chemistry; D020387:Food Chain; D006254:Hawaii; D009587:Nitrogen Isotopes / Q000032:analysis; D009792:Oceans and Seas; D010140:Pacific Ocean
chemical_list: D009587:Nitrogen Isotopes; D003094:Collagen
keywords: anthropogenic impact; oceanography; seabird ecology; stable isotope biogeochemistry