Adult coho salmon pre-spawn mortality is caused by urban runoff and prevented by bioremediation
Presentation Abstract
Urban streams in the greater Seattle area have been the focus of habitat restoration projects since the 1990s. Post-project effectiveness monitoring surveys revealed anomalous behaviors among adult coho salmon returning to spawn in these restored streams. Behaviors included erratic surface swimming, gaping, fin splaying, and loss of orientation and equilibrium. Affected fish died within hours, and female carcasses showed high rates (> 90%) of egg retention. This phenomenon was termed coho pre-spawn mortality (PSM). From 2002-2012, rates of coho PSM ranged from ~30-90% in monitored urban streams. The severity of PSM was closely associated with both the timing and amount of fall rains. Affected coho exhibited evidence of exposure to metals and petroleum hydrocarbons, both of which commonly originate from motor vehicles. The weight of evidence suggests that an as-yet unidentified toxic contaminant or contaminant mixture in urban stormwater runoff is killing coho spawners. Geospatial analyses point to urban land uses, impervious surfaces and specifically road density as being directly related to the levels of PSM across watersheds. During the autumns of 2012 and 2013 we exposed adult coho recently returned to freshwater to collected urban road runoff. Across multiple rainfall events, untreated stormwater produced the familiar PSM symptomology in all fish within 4 hours. These behavioral effects were eliminated when the runoff was filtered through a mix of sand and compost (60:40). These protective effects of simple bioremediation were also evident in coho exposed to treated runoff for longer durations (24 h). Our findings show that exposure to urban stormwater is sufficient to cause coho PSM. Moreover, although the causal chemical agent(s) have not yet been identified, conventional green stormwater infrastructure can effectively protect adult spawners from the acutely toxic effects of runoff.
Session Title
Session S-09B: Bioretention for Improving Water Quality
Conference Track
Stormwater
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
2-5-2014 10:30 AM
End Date
2-5-2014 12:00 PM
Location
Room 608-609
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)
Coho salmon--Effect of Pollution on--Washington (State)--Seattle; Runoff--Toxicology--Washington (State)--Seattle; Bioswales--Washington (State)--Seattle
Geographic Coverage
Salish Sea (B.C. and Wash.); Seattle (Wash.)
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
Adult coho salmon pre-spawn mortality is caused by urban runoff and prevented by bioremediation
Room 608-609
Urban streams in the greater Seattle area have been the focus of habitat restoration projects since the 1990s. Post-project effectiveness monitoring surveys revealed anomalous behaviors among adult coho salmon returning to spawn in these restored streams. Behaviors included erratic surface swimming, gaping, fin splaying, and loss of orientation and equilibrium. Affected fish died within hours, and female carcasses showed high rates (> 90%) of egg retention. This phenomenon was termed coho pre-spawn mortality (PSM). From 2002-2012, rates of coho PSM ranged from ~30-90% in monitored urban streams. The severity of PSM was closely associated with both the timing and amount of fall rains. Affected coho exhibited evidence of exposure to metals and petroleum hydrocarbons, both of which commonly originate from motor vehicles. The weight of evidence suggests that an as-yet unidentified toxic contaminant or contaminant mixture in urban stormwater runoff is killing coho spawners. Geospatial analyses point to urban land uses, impervious surfaces and specifically road density as being directly related to the levels of PSM across watersheds. During the autumns of 2012 and 2013 we exposed adult coho recently returned to freshwater to collected urban road runoff. Across multiple rainfall events, untreated stormwater produced the familiar PSM symptomology in all fish within 4 hours. These behavioral effects were eliminated when the runoff was filtered through a mix of sand and compost (60:40). These protective effects of simple bioremediation were also evident in coho exposed to treated runoff for longer durations (24 h). Our findings show that exposure to urban stormwater is sufficient to cause coho PSM. Moreover, although the causal chemical agent(s) have not yet been identified, conventional green stormwater infrastructure can effectively protect adult spawners from the acutely toxic effects of runoff.
