SETAC Globe - Environmental Quality Through Science
  21 January 2011
Volume 12 Issue 1

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Use of Contaminant Mixtures as Ecological Signatures for Wildlife Populations Session
Summary from the 2010 SETAC North America Annual Meeting

Jennifer Yordy [National Institute of Standards and Technology (NIST)], Lori Schwacke [National Oceanic and Atmospheric Administration (NOAA)]

Exposure to environmental contaminants is a cumulative function of an individual’s environment (habitat), ecology (habitat usage, population structure, feeding ecology), biology (age, sex, reproductive history) and physiology (dietary absorption, tissue distribution, metabolism and excretion). As a result, contaminant levels and patterns are individual―specific patterns can vary widely within wildlife populations as a result of differences in habitat, ranging patterns, diet and life history. Research aimed at understanding the relationships between ecology and contaminant levels and patterns addresses two important objectives. First, contaminant patterns are being used as tools to better understand the ecology of hard-to-study wildlife species. Secondly, an understanding of the ecological factors that contribute to contaminant exposures is essential for accurate risk assessment and management.

The purpose of this session was to gain an overview of current research linking wildlife contaminant patterns to aspects of their ecology and to assess the potential utility of contaminant mixtures for understanding the biology of wildlife populations. The presentations utilized a combination of tissue contaminant pattern data, field monitoring data and/ or molecular data (i.e., stable isotopes/genetics) to link contaminant exposure with ecology of wildlife populations.

The majority of the research presented suggested that contaminant patterns might be useful for inferring preferred habitat and population structure of wildlife species. Photo-identification and movement studies of coastal common bottlenose dolphins indicate that proximity to point sources of pollution (i.e., Superfund sites, industrialized areas) can contribute to variations in individual contaminant patterns. In addition, spatial trends in biota concentrations and patterns were also used as a means to assess population structure and habitat. Differences in contaminant patterns between geographically discrete populations of beluga whales and loggerhead sea turtles further emphasized the usefulness of contaminant patterns for understanding population ecology of marine species. Stable isotope data can also be used as a means to link contaminant patterns with foraging ecology and migration patterns; analysis of Antarctic fur seals, and resident and migratory Antarctic sea birds indicates that contaminant patterns may be used to discriminate when and where an individual’s lipid stores are acquired. These data may be especially important for assessing risk to species that migrate between pristine areas of low contamination and highly-polluted, industrialized locations.

Ecological factors are not the sole influence on contaminant exposure.  Biological factors, such as age and sex, have also been shown to influence contaminant patterns. An in-depth analysis of contaminant patterns within a resident bottlenose dolphin population indicates that exposure varies significantly with life history. Age-related changes in male dolphin contaminant patterns appear to be driven by congener-specific bioaccumulation/metabolism; alternatively, age-related changes in female dolphin contaminant patterns are driven by the selective offloading the least lipophilic contaminant congeners during the first reproductive event and their reaccumulation thereafter.

Temporal trends in contaminant exposure were also identified as an influence on contaminant patterns, highlighting the ability of environmental changes to affect contaminant exposure. Analysis of wildlife tissues collected over a ten-year span indicates that specific wildlife populations (i.e., beluga whales, loggerhead sea turtles) are experiencing a selective increase in current-use compounds (i.e., bromated flame retardants and perfluorochemicals) over time while concentrations of legacy contaminants remain stable. The observation that temporal changes in contaminant usage might affect exposure suggests this may be a confounding factor when attempting to utilize contaminant patterns as a tool for studying wildlife ecology.

In addition to data collected from free-ranging wildlife populations, controlled laboratory studies were utilized to investigate the influence of physiology and physiochemical properties on biotic contaminant patterns. Controlled dosing of larval Chinook salmon have shown that congener-specific differences in bioamplification and metabolism might contribute to variations in contaminant exposure with growth; further proof that variations in contaminant exposure are not purely related to differences in habitat and ecology.
Overall, the presentations within this session utilized a variety of field- and lab- based techniques to identify population- and individual-level factors that influence biotic contaminant patterns. Although several limitations were identified (i.e., temporal trends), the majority of the evidence presented within this session underscored the potential utility of contaminant mixtures as tracers of wildlife ecology and biology.

Authors’ contact information:,

Balmer B.C.; Schwacke L.H.; Wells R.S.; George R.C.; Hoguet J.; Kucklick J.R., et al., Relationship between persistent organic pollutants (POPs) and ranging patterns in common bottlenose dolphins (Tursiops truncatus) from coastal Georgia, USA. Sci. Total Environ. In review.

Litz, J. A.; Garrison, L. P.; Fieber, L. A.; Martinez, A.; Contillo, J. P.; Kucklick, J. R., Fine-scale spatial variation of persistent organic pollutants in bottlenose dolphins (Tursiops truncatus) in Biscayne Bay, FL. Environ. Sci. Technol. 2007, 41, 7222-7228.

O’Connell, S. G.; Arendt, M.; Segars, A.; Kimmel, T.; Braun-McNeill, J.; Avens, L.; Schroeder, B.; Ngai, L.; Kucklick, J. R.; Keller, J. M., Temporal and Spatial Trends of Perfluorinated Compounds in Juvenile Loggerhead Sea Turtles (Caretta caretta) along the East Coast of the United States. Environ. Sci. Technol. 2010, 44, (13), 5202-5209.

Yordy, J. E.; Wells, R. S.; Balmer, B. C.; Schwacke, L. H.; Rowles, T. K.; Kucklick, J. R., Life history as a source of variation for persistent organic pollutant (POP) patterns in a community of common bottlenose dolphins (Tursiops truncatus) resident to Sarasota Bay, FL. Sci. Total Environ. 2010, 408, 2163-2172.

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