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Why do organochlorine differences between arctic regions vary among trophic levels?
Katrine Borgå1, Geir Wing Gabrielsen, Janneche Utne Skaare
1Norwegian Polar Institute, N-9296 Tromsø, Norway. katrine.borga@npolar.no
Environmental Science & Technology
|July 29, 2005
Summary
Organochlorine contaminants (OCs) show regional differences in Arctic marine food webs. While lower trophic levels like zooplankton and Arctic cod have similar OC levels across regions, marine mammals and seabirds reflect historical contamination, especially in the European Arctic.
Area of Science:
- Environmental Science
- Ecotoxicology
- Arctic Marine Ecology
Background:
- Organochlorine contaminants (OCs) exhibit varying distribution patterns in Arctic marine ecosystems.
- Previous studies showed conflicting regional contamination levels for OCs in Arctic biota.
- Understanding contaminant dynamics across trophic levels is crucial for accurate risk assessment.
Purpose of the Study:
- To statistically analyze and compare organochlorine contaminant (OC) levels in marine food webs from the European Arctic (central Barents Sea) and Canadian Arctic (Northwater Polynya).
- To investigate inconsistencies in OC contamination data between different trophic levels and regions.
- To assess the influence of trophic transfer, maternal transfer, and proximity to sources on OC distribution.
Main Methods:
- Simultaneous statistical analysis of marine food web OC data (zooplankton, Arctic cod, seabirds, ringed seals).
- Comparison of OC concentrations between the central Barents Sea (CBS) and Northwater Polynya (NOW).
- Evaluation of regional differences across various trophic levels and specific OC compounds like HCH.
Main Results:
- Higher OC concentrations were generally found in top predators (seabirds, ringed seals) from the CBS compared to the NOW.
- OC levels in lower trophic levels (zooplankton, Arctic cod) were similar between the CBS and NOW, with HCH being an exception (higher in NOW).
- Regional differences in OC contamination have diminished in lower trophic levels but persist in long-lived marine mammals and seabirds due to historical exposure and biomagnification.
Conclusions:
- Regional differences in OC contamination have largely evened out at lower trophic levels in the Arctic.
- Higher contaminant levels in Arctic marine mammals and seabirds reflect past contamination, maternal transfer, and longer lifespans.
- Simultaneous statistical analysis of raw data is essential for accurate spatial trend assessment, avoiding biases from mean-based comparisons.
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