Presentation Abstract

Kelp forests are foundation species in the Salish Sea, and their dynamics are key to the fate of many other species. Research in other regions has shown that kelp abundance is driven in part by climate and can be impacted by human activities (for example, pollution and altered competition among species). While downward trends in kelp abundance have been of concern globally, trends are often locally distinct. We combined long term monitoring datasets and historical records to explore whether bull kelp (Nereocystis luetkeana) and giant kelp (Macrocystis pyrifera) dynamics in the Salish Sea region: 1) correlate with climate conditions, and 2) show temporal trends in abundance over a century scale. Along the Strait of Juan de Fuca and outer coast of Washington State, we compared our 26 year monitoring record to environmental data. Results show greater kelp abundance during cooler, nutrient-rich conditions (positive correlation with NPGO and negative correlation to the Pacific Decadal Oscillation and Oceanic Niño Index). We explored long term trends in two regions. Along the Strait of Juan de Fuca, we found that modern kelp abundance is similar to abundance in 1911-1912, with the exception of the easternmost beds. In South Puget Sound, we synthesized known surveys and found that the length of shoreline with floating kelp has decreased markedly along all shorelines where it occurred historically except the Tacoma Narrows. These findings suggest distinct trajectories may be occurring within the Salish Sea, with stable populations near to oceanic influence and losses in the extreme reaches (proximate to urban centers). Future research is needed to understand trends in kelp forest canopy abundance throughout the Salish Sea and to link observed changes to large-scale environmental drivers versus local anthropogenic stressors. Better understanding of anthropogenic stressors on kelp will be important to guide management actions.

Session Title

Long-term Changes in Salish Sea Kelp Forests and the Benthos: Evidence of Response to Chemical Contaminants, Nutrient Loading, and Climate Change Pressures

Keywords

Kelp, Climate, Monitoring, Long-term trends

Conference Track

SSE16: Long-Term Monitoring of Salish Sea Ecosystems

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE16-503

Start Date

6-4-2018 10:30 AM

End Date

6-4-2018 10:45 AM

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 6th, 10:30 AM Apr 6th, 10:45 AM

Kelp forest dynamics: links to climate and long term trends

Kelp forests are foundation species in the Salish Sea, and their dynamics are key to the fate of many other species. Research in other regions has shown that kelp abundance is driven in part by climate and can be impacted by human activities (for example, pollution and altered competition among species). While downward trends in kelp abundance have been of concern globally, trends are often locally distinct. We combined long term monitoring datasets and historical records to explore whether bull kelp (Nereocystis luetkeana) and giant kelp (Macrocystis pyrifera) dynamics in the Salish Sea region: 1) correlate with climate conditions, and 2) show temporal trends in abundance over a century scale. Along the Strait of Juan de Fuca and outer coast of Washington State, we compared our 26 year monitoring record to environmental data. Results show greater kelp abundance during cooler, nutrient-rich conditions (positive correlation with NPGO and negative correlation to the Pacific Decadal Oscillation and Oceanic Niño Index). We explored long term trends in two regions. Along the Strait of Juan de Fuca, we found that modern kelp abundance is similar to abundance in 1911-1912, with the exception of the easternmost beds. In South Puget Sound, we synthesized known surveys and found that the length of shoreline with floating kelp has decreased markedly along all shorelines where it occurred historically except the Tacoma Narrows. These findings suggest distinct trajectories may be occurring within the Salish Sea, with stable populations near to oceanic influence and losses in the extreme reaches (proximate to urban centers). Future research is needed to understand trends in kelp forest canopy abundance throughout the Salish Sea and to link observed changes to large-scale environmental drivers versus local anthropogenic stressors. Better understanding of anthropogenic stressors on kelp will be important to guide management actions.