Presentation Abstract
A strong decline in phytoplankton productivity has been proposed as a principal cause of the decline in salmon survival in the Strait of Georgia over the last four decades. The best estimate of total annual primary productivity in the Strait in the 1970s was 280 gC m-2 yr-1 (Harrison et al., 1983). We tested whether or not primary productivity had declined since that time by calculating recent productivity from regional nitrogen budgets. We constructed the budgets using measurements (collected 2001-2011) of dissolved and particulate nitrogen and stable isotopes of nitrogen in seawater, river water, sinking particles, bottom sediments, atmospheric deposition, and effluents from pulp mills, aquaculture and municipal wastewater. The budgets indicated a total annual productivity of 280 ± 20 gC m-2 yr-1. The flux of marine-derived organic matter into sediment cores supports this observation. Primary productivity in the Strait of Georgia has neither increased nor decreased since the 1970s.
Session Title
The Salish Sea Marine Survival Project: Juvenile Salmonid Growth and Survival
Keywords
Phytoplankton, Nitrogen budget, Sediment cores, Stable isotopes
Conference Track
SSE11: Species and Food Webs
Conference Name
Salish Sea Ecosystem Conference (2018 : Seattle, Wash.)
Document Type
Event
SSEC Identifier
SSE11-617
Start Date
5-4-2018 11:15 AM
End Date
5-4-2018 11:30 AM
Type of Presentation
Oral
Genre/Form
presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Marine productivity--Georgia, Strait of (B.C. and Wash.); Seawater--Nitrogen content--Georgia, Strait of (B.C. and Wash.)
Geographic Coverage
Georgia, 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
Included in
Fresh Water Studies Commons, Marine Biology Commons, Natural Resources and Conservation Commons, Terrestrial and Aquatic Ecology Commons
Has primary productivity declined in the Strait of Georgia since the 1970s?
A strong decline in phytoplankton productivity has been proposed as a principal cause of the decline in salmon survival in the Strait of Georgia over the last four decades. The best estimate of total annual primary productivity in the Strait in the 1970s was 280 gC m-2 yr-1 (Harrison et al., 1983). We tested whether or not primary productivity had declined since that time by calculating recent productivity from regional nitrogen budgets. We constructed the budgets using measurements (collected 2001-2011) of dissolved and particulate nitrogen and stable isotopes of nitrogen in seawater, river water, sinking particles, bottom sediments, atmospheric deposition, and effluents from pulp mills, aquaculture and municipal wastewater. The budgets indicated a total annual productivity of 280 ± 20 gC m-2 yr-1. The flux of marine-derived organic matter into sediment cores supports this observation. Primary productivity in the Strait of Georgia has neither increased nor decreased since the 1970s.
