title: Differing foraging strategies influence mercury (Hg) exposure in an Antarctic penguin community.
abstract: Seabirds are ideal model organisms to track mercury (Hg) through marine food webs as they are long-lived, broadly distributed, and are susceptible to biomagnification due to foraging at relatively high trophic levels. However, using these species as biomonitors requires a solid understanding of the degree of species, sexual and age-specific variation in foraging behaviors which act to mediate their dietary exposure to Hg. We combined stomach content analysis along with Hg and stable isotope analyses of blood, feathers and common prey items to help explain inter and intra-specific patterns of dietary Hg exposure across three sympatric Pygoscelis penguin species commonly used as biomonitors of Hg availability in the Antarctic marine ecosystem. We found that penguin tissue Hg concentrations differed across species, between adults and juveniles, but not between sexes. While all three penguins species diets were dominated by Antarctic krill (Euphausia superba) and to a lesser extent fish, stable isotope based proxies of relative trophic level and krill consumption could not by itself sufficiently explain the observed patterns of inter and intra-specific variation in Hg. However, integrating isotopic approaches with stomach content analysis allowed us to identify the relatively higher risk of Hg exposure for penguins foraging on mesopelagic prey relative to congeners targeting epipelagic or benthic prey species. When possible, future seabird biomonitoring studies should seek to combine isotopic approaches with other, independent measures of foraging behavior to better account for the confounding effects of inter and intra-specific variation on dietary Hg exposure.
authors: Louisiana State University, Department of Oceanography and Coastal Sciences, Baton Rouge, LA, 70802, USA. Electronic address: mpolito@lsu.edu.
authors: Michael J
authors: MJ
authors: Polito
authors: Southeast Missouri State University, Department of Biology, One University Plaza, MS 6200, Cape Girardeau, MO, 63701, USA.
authors: Rebecka L
authors: RL
authors: Brasso
authors: National Marine Fisheries Service, Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, La Jolla, CA, 92037-1508, USA.
authors: Wayne Z
authors: WZ
authors: Trivelpiece
authors: Department of Biology, Pomona College, Claremont, CA, 91711, USA.
authors: Nina
authors: N
authors: Karnovsky
authors: University of Saskatchewan, Department of Geological Sciences, Saskatoon, Saskatchewan, S7N 5E2, Canada.
authors: William P
authors: WP
authors: Patterson
authors: University of North Carolina Wilmington, Department of Biology and Marine Biology, Wilmington, NC, 28403, USA.
authors: Steven D
authors: SD
authors: Emslie
mesh_terms: D000367:Age Factors; D000818:Animals; D000864:Antarctic Regions; D001070:Appetitive Behavior; D004784:Environmental Monitoring; D033201:Euphausiacea / Q000378:metabolism; D005241:Feathers / Q000737:chemistry; D005260:Female; D005399:Fishes / Q000378:metabolism; D020387:Food Chain; D005766:Gastrointestinal Contents / Q000737:chemistry*; D008297:Male; D008628:Mercury / Q000032:analysis* / Q000097:blood; D046429:Spheniscidae / Q000097:blood / Q000378:metabolism*
chemical_list: D008628:Mercury
keywords: Antarctica; Mercury; Pygoscelis penguins; Stable isotope analysis