Assessment of recent benthic invertebrate community health declines around a municipal wastewater outfall
Presentation Abstract
The Capital Regional District (CRD) regularly monitors the effects of the region’s eight municipal wastewater outfalls that discharge into the Salish Sea. Benthic invertebrate community health assessments have been a component of the Macaulay Point outfall monitoring program since the 1990s, with annual monitoring occurring from 2000 to 2012. Declines in benthic invertebrate community health were observed following detailed statistical analyses of the 2008 to 2010 Macaulay Point dataset relative to the 2002 to 2007 time period when generally stable or improving community health conditions were observed. Over the same time frame, no significant concurrent declines in sediment or wastewater chemistry were observed. These apparently contradictory trends led CRD staff to consult with various benthic invertebrate experts in the hopes of receiving guidance on how to investigate potential causes of the declines. One of the early hypothesized causes was increased volumes of Pacific Ocean waters containing low concentrations of dissolved oxygen entering the deep waters of the Salish Sea. To determine whether these low oxygen levels were impacting the Macaulay Point benthic invertebrate communities, the CRD entered into a collaborative study with Ocean Networks Canada to deploy fixed moorings with continuous dissolved oxygen sensors. In addition, detailed assessments of the 2011 data have led to some questions about field and laboratory procedures employed from year-to-year; methodological variations could be confounding the CRD’s interpretation of the benthic invertebrate community health declines. This presentation will provide an overview of findings to date of both the oxygen monitoring and the field and laboratory method validations.
Session Title
Session S-03A: Changes in Salish Sea Water Quality
Conference Track
Marine Water Quality
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
30-4-2014 3:30 PM
End Date
30-4-2014 5:00 PM
Location
Room 615-616-617
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)
Aquatic invertebrate populations--Juan de Fuca, Strait of (B.C. and Wash.); Benthic animals--Ecology--Juan de Fuca, Strait of (B.C. and Wash.); Ecosystem health--Juan de Fuca, Strait of (B.C. and Wash.); Sewage disposal plants--Environmental aspects--Juan de Fuca, Strait of (B.C. and Wash.)
Geographic Coverage
Juan de Fuca, Strait of (B.C. and Wash.); 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
Assessment of recent benthic invertebrate community health declines around a municipal wastewater outfall
Room 615-616-617
The Capital Regional District (CRD) regularly monitors the effects of the region’s eight municipal wastewater outfalls that discharge into the Salish Sea. Benthic invertebrate community health assessments have been a component of the Macaulay Point outfall monitoring program since the 1990s, with annual monitoring occurring from 2000 to 2012. Declines in benthic invertebrate community health were observed following detailed statistical analyses of the 2008 to 2010 Macaulay Point dataset relative to the 2002 to 2007 time period when generally stable or improving community health conditions were observed. Over the same time frame, no significant concurrent declines in sediment or wastewater chemistry were observed. These apparently contradictory trends led CRD staff to consult with various benthic invertebrate experts in the hopes of receiving guidance on how to investigate potential causes of the declines. One of the early hypothesized causes was increased volumes of Pacific Ocean waters containing low concentrations of dissolved oxygen entering the deep waters of the Salish Sea. To determine whether these low oxygen levels were impacting the Macaulay Point benthic invertebrate communities, the CRD entered into a collaborative study with Ocean Networks Canada to deploy fixed moorings with continuous dissolved oxygen sensors. In addition, detailed assessments of the 2011 data have led to some questions about field and laboratory procedures employed from year-to-year; methodological variations could be confounding the CRD’s interpretation of the benthic invertebrate community health declines. This presentation will provide an overview of findings to date of both the oxygen monitoring and the field and laboratory method validations.
