Long term trends in mercury in seabird eggs from Pacific Canada: relationships with stable isotopes particularly sulfur
Presentation Abstract
Eggs of marine birds are used widely to monitor environmental mercury because they are relatively easy to collect and integrate a signal from the entire food web. Trends in mercury from seabird eggs, however, may represent variation in diet rather than variation in mercury availability; due to biomagnification, seabirds switching to feed at a higher trophic level will usually have higher mercury levels. We measured mercury concentrations in eggs from six seabird species in Pacific Canada during the period 1968-2012. In contrast to expectation, storm-petrels feeding partially on invertebrates had the highest mercury burden while herons feeding on large fish had the lowest mercury burden. Rather than correlating with trophic level (δ15N), mercury levels correlated with δ34S (R2 = 0.86). For cormorants, the only group showing a significant temporal mercury trend, both mercury and δ34S decreased over time. Sulfate-rich environments (high δ34S) are occupied by sulfate-reducing bacteria that produce methylmercury, and we hypothesize that variation in mercury within and among seabirds is associated with variation in methylmercury production by sulfate-reducing bacteria at the base of the food web. Variation in mercury levels in seabirds across space and time were associated with the origin of sulfur in the diet.
Session Title
General contaminant toxicology in aquatic and terrestrial species
Conference Track
Fate and Effects of Pollutants
Conference Name
Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)
Document Type
Event
Start Date
2016 12:00 AM
End Date
2016 12:00 AM
Location
2016SSEC
Type of Presentation
Oral
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Sea birds--Effect of pollution on--Northwest, Pacific; Sea birds--Eggs--Northwest, Pacific; Sea birds--Environmental aspects--Northwest, Pacific; Mercury--Toxicology
Geographic Coverage
Salish Sea (B.C. and Wash.); Northwest, Pacific
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Long term trends in mercury in seabird eggs from Pacific Canada: relationships with stable isotopes particularly sulfur
2016SSEC
Eggs of marine birds are used widely to monitor environmental mercury because they are relatively easy to collect and integrate a signal from the entire food web. Trends in mercury from seabird eggs, however, may represent variation in diet rather than variation in mercury availability; due to biomagnification, seabirds switching to feed at a higher trophic level will usually have higher mercury levels. We measured mercury concentrations in eggs from six seabird species in Pacific Canada during the period 1968-2012. In contrast to expectation, storm-petrels feeding partially on invertebrates had the highest mercury burden while herons feeding on large fish had the lowest mercury burden. Rather than correlating with trophic level (δ15N), mercury levels correlated with δ34S (R2 = 0.86). For cormorants, the only group showing a significant temporal mercury trend, both mercury and δ34S decreased over time. Sulfate-rich environments (high δ34S) are occupied by sulfate-reducing bacteria that produce methylmercury, and we hypothesize that variation in mercury within and among seabirds is associated with variation in methylmercury production by sulfate-reducing bacteria at the base of the food web. Variation in mercury levels in seabirds across space and time were associated with the origin of sulfur in the diet.
