Millennial-scale isotope records from a wide-ranging predator show evidence of recent human impact to oceanic food webs
Year: 2013
Type: article
Abstract: Human exploitation of marine ecosystems is more recent in oceanic than near shore regions, yet our understanding of human impacts on oceanic food webs is comparatively poor. Few records of species that live beyond the continental shelves date back more than 60 y, and the sheer size of oceanic regions makes their food webs difficult to study, even in modern times. Here, we use stable carbon and nitrogen isotopes to study the foraging history of a generalist, oceanic predator, the Hawaiian petrel (Pterodroma sandwichensis), which ranges broadly in the Pacific from the equator to near the Aleutian Islands. Our isotope records from modern and ancient, radiocarbon-dated bones provide evidence of over 3,000 y of dietary stasis followed by a decline of ca. 1.8‰ in δ(15)N over the past 100 y. Fishery-induced trophic decline is the most likely explanation for this sudden shift, which occurs in genetically distinct populations with disparate foraging locations. Our isotope records also show that coincident with the apparent decline in trophic level, foraging segregation among petrel populations decreased markedly. Because variation in the diet of generalist predators can reflect changing availability of their prey, a foraging shift in wide-ranging Hawaiian petrel populations suggests a relatively rapid change in the composition of oceanic food webs in the Northeast Pacific. Understanding and mitigating widespread shifts in prey availability may be a critical step in the conservation of endangered marine predators such as the Hawaiian petrel.
Institutions: Smithsonian Institution, National Museum of Natural History, Michigan State University, Smithsonian Conservation Biology Institute, National Zoological Park, University at Buffalo, State University of New York, University of Maryland, College Park, University of California, Irvine, Aarhus University, Natural History Museum of Denmark, University of Hawaiʻi at Mānoa, University of Hawaii System, National Park Service, Department of Land and Natural Resources
Language: English
Topic: Isotope Analysis in Ecology
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDG: Life below water
Open Access status: green
OpenAlex ID: W2015278463