Do songbirds in wetlands show higher mercury bioaccumulation relative to conspecifics in non-wetland habitats?
- PDF / 670,147 Bytes
- 12 Pages / 595.276 x 790.866 pts Page_size
- 69 Downloads / 215 Views
Do songbirds in wetlands show higher mercury bioaccumulation relative to conspecifics in non-wetland habitats? Rebecka Brasso
1
●
Katie Ann Rittenhouse2 Virginia L. Winder3 ●
1234567890();,:
1234567890();,:
Accepted: 3 January 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Environmental conditions in wetlands facilitate favorable biogeochemical conditions for the conversion of inorganic mercury into methylmercury. For this reason, wetlands are increasingly classified as mercury hotspots, places where biota exhibit elevated mercury concentrations. While it is clear that wetlands play an important role in methylmercury production, factors such as geographic variation in mercury deposition, wetland type, and trophic dynamics can cause variation in mercury dynamics and bioaccumulation in biota occupying wetlands or connected to wetland trophic systems. Here, we use songbirds as bioindicators in a two-pronged approach aimed at evaluating the state of our understanding of mercury bioaccumulation by songbirds in wetland ecosystems. First, we use a case study in southeast Missouri to compare blood mercury concentrations in tree swallows (Tachycineta bicolor) and eastern bluebirds (Sialia sialis) occupying wetland and non-wetland habitats to test the hypothesis that songbirds in wetlands will have higher mercury bioaccumulation than those in non-wetlands. Adult tree swallows in wetlands had significantly higher blood mercury concentrations than those in nonwetlands; however, no difference between ecosystems was detected in eastern bluebirds. Second, we present a review of the current literature on mercury in songbirds in wetland ecosystems across North America. Mercury concentrations in songbirds varied among wetland types and with geographic location, often in an unpredictable manner. Mercury concentrations in songbird blood varied 3–10 fold at locations separated only by ~10 to several hundred kilometers. This magnitude of difference in blood mercury concentrations among wetlands exceeds documented differences between wetland and nonwetland ecosystems. Therefore, we caution against the automatic assumption that songbirds occupying wetlands will have higher mercury bioaccumulation than conspecifics living in other habitats. Keywords Bioaccumulation Blood mercury Eastern bluebird Estuary Freshwater wetland Salt marsh ●
●
Introduction Mercury pollution is a widespread threat to ecosystems due to atmospheric deposition, frequent re-emission, and long distance transport via atmospheric movements (Schwartzendruber and Jaffe 2012; Driscoll et al. 2013). Most nonpoint source mercury pollution enters aquatic and terrestrial
* Rebecka Brasso [email protected] 1
Department of Zoology, Weber State University, Ogden, UT 84408, USA
2
Department of Biology, Southeast Missouri State University, Cape Girardeau, MO 63701, USA
3
Department of Biology, Benedictine College, Atchison, KS 66002, USA
●
●
●
ecosystems via atmospheric deposition of the inorganic form of the contaminant (Dris
Data Loading...
