Impacts of run-of-river hydropower on food web structure and mercury bioaccumulation in American dippers of coastal British Columbia
Presentation Abstract
Run-of-river (RoR) dams are an increasingly common alternate energy source on mountain streams. Despite reductions in dam size and greenhouse gas emissions compared to conventional impoundments, RoR hydro may have ecotoxicological impacts through disruption of the natural flow regime. The American Dipper (Cinclus mexicanus) is a high trophic level river bird that occupies mountain streams suitable for RoR dams year-round and are known indicators of stream health; thus, they are an ideal species to study potential impacts of run-of-river hydropower. The objectives of this study are to 1) characterize the food web upstream and downstream of regulated and unregulated streams using stable isotopes (δ13C, δ15N, δ34S); 2) evaluate the methylmercury biomagnification potential upstream and downstream of regulated streams and compare dipper methylmercury levels between regulated and unregulated streams; and 3) determine if in-stream and riparian habitat features important for river birds are altered by run-of-river dams. Food webs were sampled at regulated and unregulated streams using a paired design a) upstream and downstream of 7 regulated and 7 unregulated streams and b) between regulated and unregulated streams. Surveys have found dippers congregating immediately upstream and downstream of several RoR dams in coastal BC, particularly during autumn. This has led to the hypothesis that reduced flow associated with these small dams creates a novel habitat in which dippers may forage more efficiently. Analyses of the blood and invertebrate samples from 14 streams has revealed isotopic changes on regulated streams, specifically 34S-depleted dipper blood, suggesting microbial activity associated with the headponds. We are assessing whether this modified habitat reflects higher levels of methylmercury than upstream of the dam or nearby unregulated streams. This study is an opportunity to examine the effects of reduced and stabilized flow on lotic food webs and improve our understanding of methylmercury biomagnification in mountain streams.
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)
American Dipper--Monitoring--British Columbia; American Dipper--Effects of habitat modification on--British Columbia; Dams--Environmental aspects--British Columbia
Geographic Coverage
Salish Sea (B.C. and Wash.); British Columbia
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
Impacts of run-of-river hydropower on food web structure and mercury bioaccumulation in American dippers of coastal British Columbia
2016SSEC
Run-of-river (RoR) dams are an increasingly common alternate energy source on mountain streams. Despite reductions in dam size and greenhouse gas emissions compared to conventional impoundments, RoR hydro may have ecotoxicological impacts through disruption of the natural flow regime. The American Dipper (Cinclus mexicanus) is a high trophic level river bird that occupies mountain streams suitable for RoR dams year-round and are known indicators of stream health; thus, they are an ideal species to study potential impacts of run-of-river hydropower. The objectives of this study are to 1) characterize the food web upstream and downstream of regulated and unregulated streams using stable isotopes (δ13C, δ15N, δ34S); 2) evaluate the methylmercury biomagnification potential upstream and downstream of regulated streams and compare dipper methylmercury levels between regulated and unregulated streams; and 3) determine if in-stream and riparian habitat features important for river birds are altered by run-of-river dams. Food webs were sampled at regulated and unregulated streams using a paired design a) upstream and downstream of 7 regulated and 7 unregulated streams and b) between regulated and unregulated streams. Surveys have found dippers congregating immediately upstream and downstream of several RoR dams in coastal BC, particularly during autumn. This has led to the hypothesis that reduced flow associated with these small dams creates a novel habitat in which dippers may forage more efficiently. Analyses of the blood and invertebrate samples from 14 streams has revealed isotopic changes on regulated streams, specifically 34S-depleted dipper blood, suggesting microbial activity associated with the headponds. We are assessing whether this modified habitat reflects higher levels of methylmercury than upstream of the dam or nearby unregulated streams. This study is an opportunity to examine the effects of reduced and stabilized flow on lotic food webs and improve our understanding of methylmercury biomagnification in mountain streams.
