Polar bears make little use of terrestrial food webs: evidence from stable-carbon isotope analysis

  title={Polar bears make little use of terrestrial food webs: evidence from stable-carbon isotope analysis},
  author={Malcolm A. Ramsay and Keith A. Hobson},
SummaryThe mean stable-carbon isotope ratios (δ13C) for polar bear (Ursus maritimus) tissues (bone collagen −15.7‰, muscle −17.7‰, fat −24.7‰) were close to those of the same tissues from ringed seals (Phoca hispida) (−16.2‰, −18.1‰, and −26.1‰, respectively), which feed exclusively from the marine food chain. The δ13C values for 4 species of fruits to which polar bears have access when on land in summer ranged from −27.8 to −26.2‰, typical of terrestrial plants in the Arctic. An animal's δ13C… Expand
Stable isotope food-web analysis and mercury biomagnification in polar bears (Ursus maritimus)
Mercury (Hg) biomagnification occurs in many ecosystems, resulting in a greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through differentExpand
Dietary variation in arctic foxes (Alopex lagopus)-an analysis of stable carbon isotopes
This is the first time that stable isotopes have been used to reveal individual dietary patterns in arctic fox diet, and indicated that isotopic values can be used on a global scale. Expand
Can polar bears use terrestrial foods to offset lost ice‐based hunting opportunities?
Increased land use by polar bears (Ursus maritimus) due to climate-change-induced reduction of their sea-ice habitat illustrates the impact of climate change on species distributions and theExpand
Analysis of the diets of 1738 individual polar bears sampled across the Canadian Arctic over a 30-year span indicates that polar bears are capable of opportunistically altering their foraging to take advantage of locally abundant prey, or to some degree compensating for a decline in a dominant prey species. Expand
Stable carbon isotope ratios in Asian elephant collagen: implications for dietary studies
Carbon isotope analyses of bones from a southern Indian population of Asian elephant, a long-lived mammal that alternates seasonally between a predominantly C3 (browse) and C4 (grass) plant diet, showed two patterns that have important implications for dietary interpretation based on isotopic studies. Expand
Carbon and nitrogen stable isotope turnover rates and diet–tissue discrimination in Florida manatees (Trichechus manatus latirostris)
Stable carbon and nitrogen stable isotope ratios were examined over a period of more than 1 year in the epidermis of rescued Florida manatees that were transitioning from a diet of aquatic forage to terrestrial forage (lettuce). Expand
Stable carbon isotope ratios as indicators of marine versus terrestrial inputs to the diets of wild and captive tuatara (Sphenodon punctatus)
Male tuatara were more enriched in 13C than were females or juveniles, suggesting that males prey more heavily on seabirds, and blood cells from four different groups of captive tu atara differed significantly in δ13C. Expand
Diet of female polar bears in the southern Beaufort Sea of Alaska: evidence for an emerging alternative foraging strategy in response to environmental change
It is concluded that these results offer emergent evidence of an alternative foraging strategy within this population: ‘coastal’ bears, which remain near to shore for much of the year and use bowhead whale bone piles when they are present, in contrast to ‘pelagic’ Bears, which follow a more typical strategy and forage widely on sea ice for seals. Expand
Trophic relationships in an Arctic marine foodweb and implications for trace element dynamics
Tissues of subsistence-harvested Arctic marine and terrestrial mammals and potential prey species were analyzed for isotopes of carbon and nitrogen and selected trace elements describing contaminantExpand
Isotopic homogeneity of breath CO2 from fasting and berry-eating polar bears : implications for tracing reliance on terrestrial foods in a changing Arctic
No difference was found in the bear breath δ13C values for bears known to have recently fed on berries and those that had not, which was counter to the simple isotopic discrimination model that predicted bears metabolizing adipose tissue derived from seals would have breath £12C values close to these values. Expand


Fractionation and turnover of stable carbon isotopes in animal tissues: Implications for δ13C analysis of diet
It is shown that tissues of the gerbil have different δ13C values when equilibrated on corn (C4) or wheat (C3) diets with constant 13C/12C contents, which has important implications for the use of δ 13C values as indicators of animal diet. Expand
Stable Carbon Isotopes in Terrestrial Ecosystem Research
It has been known for some time that terrestrial plants, the primary producers, possess δ13C values substantially lower (more negative, 13C-depleted) than that of ambient atmospheric CO2 (ca. -7.7%).Expand
Stable-Carbon Isotope Ratios as a Measure of Marine Versus Terrestrial Protein in Ancient Diets
The stable-carbon isotope ratios for the flesh of marine and terrestrial animals from Canada's Pacific coast differ by 7.9 � 0.4 per mil, reflecting the ∼ 7 per mil difference between oceanic andExpand
Marine and Terrestrial Protein in Prehistoric Diets on the British Columbia Coast
by BRIAN S. CHISHOLM, D. ERLE NELSON, and HENRY P. SCHWARCZ Department of Archaeology, Simon Fraser University, Burnaby, B.C., Canada V5A 1S6 (Chisholm and Nelson)/Department of Geology, McMasterExpand
Effects of diagenesis on strontium, carbon, nitrogen and oxygen concentration and isotopic composition of bone
Abstract Paleodietary analysis based on variations in the trace element and stable isotopic composition of inorganic and organic phases in fossil bone depends on the assumption that measured valuesExpand
Natural Carbon Isotope Tracers in Arctic Aquatic Food Webs
Natural isotope abundances, both stable and radioactive, have emerged as powerful means of tracing ecosystem energetics and estimating the dependence of organisms on specific habitats or ecosystemExpand
The significance of supplemental food to polar bears during the ice-free period of Hudson Bay
The data indicated that individual needs and learning were major factors determining which bears used the Churchill dump, and bears which fed in the dump were significantly heavier than those which did not. Expand
Reproductive biology and ecology of female polar bears (Ursus maritimus)
Although cubs in western Hudson Bay were weaned at a younger age and a lighter weight than their counterparts in more northern populations, cub mortality rates were similar and it is speculated that sea-ice conditions may be sufficiently different to allow weaned bears at a lighter body weight to hunt seals more successfully there than further north. Expand
The Food Habits of Polar Bears of James Bay and Southwest Hudson Bay in Summer and Autumn
A study of summer and autumn food habits of polar bears ( Ursus maritimus Phipps) on some islands of James Bay and the coastal mainland of southwest Hudson Bay was conducted in 1968 and 1969.Expand
Influence of Carbon Source, Oxygen Concentration, Light Intensity, and Temperature on 13C/12C Ratios in Plant Tissues
Xanthium populations from various worldwide localities and hybrids between the populations, compared for differences in response to variations in growth conditions, presented an isotopic response to temperature that was not linear. Expand