Presentation Abstract

Infectious disease has the potential to cause devastating damage to valuable marine organisms and habitats. Eelgrass wasting disease (EGWD), caused by the pathogenic protist Labyrinthula zosterae (LZ), has caused mass die-offs in Zostera marina at regional and global scales. Despite this, little is known about the host-pathogen interaction or disease drivers in the Salish Sea. To determine the regional impact of EGWD, we measured summer prevalence and severity in the San Juan Islands, Padilla Bay, Hood Canal, South Puget Sound, and Willapa Bay. We used cultures and quantitative PCR to verify results, measuring LZ load in lesioned tissue from multiple sites. EGWD was present at all 16 sites surveyed, with prevalence ranging from 80% disease prevalence. Recent data suggest water temperature increases the virulence of LZ, indicating possible climate sensitivity. At our sites, water temperatures influenced both EGWD prevalence and severity, suggesting environmental conditions and climate change could impact the eelgrass-LZ relationship and lead to increased virulence. We ran a three-week controlled experiment to examine the impact of LZ infection on eelgrass shoots over time. We exposed half the eelgrass shoots to LZ infection and sampled shoots at seven time points. All exposed shoots showed signs of infection. EGWD severity and lesion number increased through time, corresponding with a measurable decrease in leaf and root growth and increased phenols. Our results show EGWD is widespread in Washington state eelgrass beds and suggests that EGWD severity is positively correlated with water temperature. Furthermore, EGWD has a detrimental effect on eelgrass health, potentially contributing to decreased density and meadow declines. While levels of EGWD in the field are variable, we identified four sites that are experiencing high prevalence. Further research is needed to understand the conditions leading to EGWD outbreaks.

Session Title

Seagrass Cross-Border Connections: Stressors and Disturbance

Keywords

Eelgrass, Z. marina, Eelgrass wasting disease, Temperature

Conference Track

SSE4: Ecosystem Management, Policy, and Protection

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE4-296

Start Date

5-4-2018 2:15 PM

End Date

5-4-2018 2:30 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, 2:15 PM Apr 5th, 2:30 PM

Tipping the balance: the impact of eelgrass wasting disease in a changing ocean

Infectious disease has the potential to cause devastating damage to valuable marine organisms and habitats. Eelgrass wasting disease (EGWD), caused by the pathogenic protist Labyrinthula zosterae (LZ), has caused mass die-offs in Zostera marina at regional and global scales. Despite this, little is known about the host-pathogen interaction or disease drivers in the Salish Sea. To determine the regional impact of EGWD, we measured summer prevalence and severity in the San Juan Islands, Padilla Bay, Hood Canal, South Puget Sound, and Willapa Bay. We used cultures and quantitative PCR to verify results, measuring LZ load in lesioned tissue from multiple sites. EGWD was present at all 16 sites surveyed, with prevalence ranging from 80% disease prevalence. Recent data suggest water temperature increases the virulence of LZ, indicating possible climate sensitivity. At our sites, water temperatures influenced both EGWD prevalence and severity, suggesting environmental conditions and climate change could impact the eelgrass-LZ relationship and lead to increased virulence. We ran a three-week controlled experiment to examine the impact of LZ infection on eelgrass shoots over time. We exposed half the eelgrass shoots to LZ infection and sampled shoots at seven time points. All exposed shoots showed signs of infection. EGWD severity and lesion number increased through time, corresponding with a measurable decrease in leaf and root growth and increased phenols. Our results show EGWD is widespread in Washington state eelgrass beds and suggests that EGWD severity is positively correlated with water temperature. Furthermore, EGWD has a detrimental effect on eelgrass health, potentially contributing to decreased density and meadow declines. While levels of EGWD in the field are variable, we identified four sites that are experiencing high prevalence. Further research is needed to understand the conditions leading to EGWD outbreaks.