Event Title

Influence of environmental drivers on satellite-derived chlorophyll a in the Strait of Georgia from 2003-2016

Presentation Abstract

The Salish Sea is a dynamic region with substantial temporal and spatial variability at lower trophic levels. This variability, in turn, may directly impact resident and migratory fish populations that are of major economic importance. Here, we examine the relationships between environmental drivers (e.g. SST, wind, river input) and patterns of satellite-derived chlorophyll a (chl a) from 2003-2016 in the Northern and Central Strait of Georgia. Average spring bloom start date in the Salish Sea occured in late March. Strong positive chl a anomalies in spring 2005 and 2015 resulted in the early spring blooms (mid-February). Anomalously high chl a concentrations (>20 mg m-3) were also observed in autumn 2008 in the Central region, which was twice as high as the maximum values typically observed in autumn throughout our time series. In contrast, later than average (late April) spring blooms occurred in 2007 and 2008. Results from analysis of the environmental drivers showed positive SST anomalies predominated between 2003-2006 and 2013-2016, with the highest anomalies occurring in spring 2015. Strong positive anomalies in Fraser River discharge, coupled with strong negative wind anomalies, occurred in both spring 2005 and 2015. Chl a in the Northern region was most highly correlated with SST and PAR (r = 0.328, p<0.0001 and r = 0.347, p<0.0001, respectively), whereas chlorophyll a in the Central region was most highly correlated with Fraser River discharge (r = 0.264, p<0.0001). Similar analyses on anomaly data revealed that chl a anomalies in both the Northern and Central regions were highly correlated with SST and PAR anomalies. Ultimately, results from this study will be paired with zooplankton data to provide insight into how changes in the seasonal patterns of lower trophic levels may influence the growth, survival, and overall return strength of salmon populations in the region.

Session Title

The Salish Sea Marine Survival Project: Phytoplankton and Zooplankton

Conference Track

SSE11: Species and Food Webs

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE11-238

Start Date

5-4-2018 4:00 PM

End Date

5-4-2018 4:15 PM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

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

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Apr 5th, 4:00 PM Apr 5th, 4:15 PM

Influence of environmental drivers on satellite-derived chlorophyll a in the Strait of Georgia from 2003-2016

The Salish Sea is a dynamic region with substantial temporal and spatial variability at lower trophic levels. This variability, in turn, may directly impact resident and migratory fish populations that are of major economic importance. Here, we examine the relationships between environmental drivers (e.g. SST, wind, river input) and patterns of satellite-derived chlorophyll a (chl a) from 2003-2016 in the Northern and Central Strait of Georgia. Average spring bloom start date in the Salish Sea occured in late March. Strong positive chl a anomalies in spring 2005 and 2015 resulted in the early spring blooms (mid-February). Anomalously high chl a concentrations (>20 mg m-3) were also observed in autumn 2008 in the Central region, which was twice as high as the maximum values typically observed in autumn throughout our time series. In contrast, later than average (late April) spring blooms occurred in 2007 and 2008. Results from analysis of the environmental drivers showed positive SST anomalies predominated between 2003-2006 and 2013-2016, with the highest anomalies occurring in spring 2015. Strong positive anomalies in Fraser River discharge, coupled with strong negative wind anomalies, occurred in both spring 2005 and 2015. Chl a in the Northern region was most highly correlated with SST and PAR (r = 0.328, p<0.0001 and r = 0.347, p<0.0001, respectively), whereas chlorophyll a in the Central region was most highly correlated with Fraser River discharge (r = 0.264, p<0.0001). Similar analyses on anomaly data revealed that chl a anomalies in both the Northern and Central regions were highly correlated with SST and PAR anomalies. Ultimately, results from this study will be paired with zooplankton data to provide insight into how changes in the seasonal patterns of lower trophic levels may influence the growth, survival, and overall return strength of salmon populations in the region.