Biological effects of hyporheic zone restoration in an urban stream
Presentation Abstract
Urban stream restoration can be an important tool for managing stormwater runoff. Fluxes between stream surface waters and groundwater occur in the subterranean interface called the hyporheic zone. Furthermore, the hyporheic zone serves as habitat for essential food web components such as macroinvertebrates. In an innovative approach, the City of Seattle incorporated hyporheic design elements into multiple floodplain reconnections projects within the Thornton Creek watershed in 2014. To evaluate hyporheic biological response, we have conducted annual monitoring of invertebrate and microbial communities to compare restored reaches, unrestored reaches, and reference reaches in undisturbed forested sites. Hyporheic invertebrate density and taxa richness were higher at restored than at unrestored reaches, and were comparable to forested reference reaches. We found that taxonomic structures of both invertebrate and microbial hyporheic communities were significantly different between restored and unrestored reaches. Functional testing determined that microbial heterotrophic production in hyporheic water was higher in restored than in unrestored reaches. In addition to annual monitoring, we attempted to speed biological recovery during the first year post-restoration by seasonally seeding one restored reach with invertebrates and microbes from forested reference reaches. Although there were limited changes in invertebrate or microbial taxonomic structure, we identified four aquatic invertebrate taxa that may have established in Thornton Creek. Our observations represent early biological responses to restoration that will be expanded with further monitoring
Session Title
Biological Indicators of Stormwater Impacts and Mitigation Effectiveness in the Salish Sea
Conference Track
SSE3: Fate, Transport, and Toxicity of Chemicals
Conference Name
Salish Sea Ecosystem Conference (2018 : Seattle, Wash.)
Document Type
Event
SSEC Identifier
SSE3-363
Start Date
6-4-2018 9:15 AM
End Date
6-4-2018 9:30 AM
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)
Stream restoration--Salish Sea (B.C. and Wash.); Runoff--Salish Sea (B.C. and Wash.); Hyporheic zones--Salish Sea (B.C. and Wash.)
Geographic Coverage
Salish Sea (B.C. and 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
Biological effects of hyporheic zone restoration in an urban stream
Urban stream restoration can be an important tool for managing stormwater runoff. Fluxes between stream surface waters and groundwater occur in the subterranean interface called the hyporheic zone. Furthermore, the hyporheic zone serves as habitat for essential food web components such as macroinvertebrates. In an innovative approach, the City of Seattle incorporated hyporheic design elements into multiple floodplain reconnections projects within the Thornton Creek watershed in 2014. To evaluate hyporheic biological response, we have conducted annual monitoring of invertebrate and microbial communities to compare restored reaches, unrestored reaches, and reference reaches in undisturbed forested sites. Hyporheic invertebrate density and taxa richness were higher at restored than at unrestored reaches, and were comparable to forested reference reaches. We found that taxonomic structures of both invertebrate and microbial hyporheic communities were significantly different between restored and unrestored reaches. Functional testing determined that microbial heterotrophic production in hyporheic water was higher in restored than in unrestored reaches. In addition to annual monitoring, we attempted to speed biological recovery during the first year post-restoration by seasonally seeding one restored reach with invertebrates and microbes from forested reference reaches. Although there were limited changes in invertebrate or microbial taxonomic structure, we identified four aquatic invertebrate taxa that may have established in Thornton Creek. Our observations represent early biological responses to restoration that will be expanded with further monitoring
