Trophic relationships in an Arctic marine foodweb and implications for trace element dynamics

2005 2005

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Abstract (summary)

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 contaminant pathways in the food web. Feeding habits of ice seals were characterized using stable isotopes and gastric contents analysis. Bearded seals (Erignathus barbatus ) relied on the benthic food chain. Zooplankton and fishes were significant prey for ringed seals (Phoca hispida), while fishes were the principal prey in spotted seals (Phoca largha). Gastric prey composition and isotope ratios varied with age and sex. Effects of age, trophic level, and prey prevalence on trace element concentrations in seal tissues were investigated. Most trace elements differed significantly in phocid tissues. Bearded seals had the highest cadmium (Cd) concentrations and spotted seals the lowest. This indicates a connection of Cd with invertebrate prey, while mercury (Hg), in particular the proportion of organic to total Hg (THg), accumulated in the piscivorous food web. Silver (Ag) showed possible association to benthic feeding habits. Altered trace element accumulation patterns were observed in compromised seals. Stable isotopes illustrated belugas ( Delphinapterus leucas) occupied a higher trophic level than bowheads (Balaena mysticetus) and gray whales (Eschrichtius robustus). Trace element concentrations also differed significantly among these cetaceans. Observed relationships with age or length in species analyzed were complex and nonlinear rather than previously reported continuous bioaccumulation with age. Cd was similar in belugas and bowheads but lowest in gray whales. THg was highest in belugas and near detection limit in mysticetes, supporting the connection of Hg with fish and Cd with invertebrates. The hepatic selenium (Se):THg ratio exceeded the frequently described equimolarity in all species. Se:THg molar ratios and tissue concentrations of zinc (Zn) may show promise as indicators of immune status and animal health. Polar bears (Ursus maritimus) feed on the highest trophic level, though Cd concentrations were either similar to, or significantly lower than those in belugas or ice seals. Conversely, THg increased significantly from seal to bear. Generally, trace elements in Alaska-harvested animals were lower than for other Arctic regions, and trace metal magnification in the Arctic food web was not significant.

Indexing (details)

0329: Ecology
0383: Toxicology
0472: Zoology
0416: Oceanography
Identifier / keyword
Health and environmental sciences; Biological sciences; Arctic Ocean; Balaena mysticetus; Delphinapterus leucas; Erignathus barbatus; Eschrichtius robustus; Marine food web; Mercury; Phoca hispida; Phoca largha; Trace element; Trophic; Ursus maritimus
Trophic relationships in an Arctic marine foodweb and implications for trace element dynamics
Dehn, Larissa-A.
Number of pages
Publication year
Degree date
School code
DAI-B 67/02, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
9780542556623, 0542556626
Follmann, Erich H.
University of Alaska Fairbanks
University location
United States -- Alaska
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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