Presentation Abstract

Padilla Bay, WA has over 3300 hectares of eelgrass with vast areas of intermixed beds of the native Zostera marina and non-native Zostera japonica. Water temperature is thought to be one of the primary influences on eelgrass distribution, and long term monitoring shows that temperatures in Padilla Bay have increased substantially (mean increase >2°C) from 2011 through 2016. We were interested to see if changes in eelgrass distribution were correlated with the changes we observed in water temperature in Padilla Bay, however, our long term temperature monitoring station is located in a shallow channel within the eelgrass beds. Because of this sensor placement, we first needed to determine if these data were representative of temperatures experienced by eelgrass on the vegetated flats. To test this, we deployed 45 temperature loggers throughout the intertidal and subtidal distribution of Z. marina and Z. japonica. We found that temperatures recorded at our long term monitoring site greatly underestimated the high temperatures experienced by the intertidal eelgrass. In Padilla Bay, Zostera marina was exposed to temperatures above 8°C, the optimal temperature reported for Z. marina growth in the PNW, for over 90% of the time during the peak growing season (March – Sept.). Furthermore, Z. marina experienced extended periods of time above 15°C, temperatures thought to cause stress to local plants. Despite these elevated temperatures, Z. marina remain robust, suggesting that Z. marina in Padilla Bay may have a higher tolerance for warmer water temperatures than other beds in the PNW or may be living near the upper limits of tolerance for PNW plants. This study characterizes – on a fine spatial scale – the duration and intensity of temperatures extremes that eelgrass experience in shallow systems and ultimately provides insight into the health and performance of eelgrass in a warmer future ocean.

Session Title

Seagrass Cross-Border Connections: Stressors and Disturbance

Keywords

Eelgress, Padilla Bay

Conference Track

SSE4: Ecosystem Management, Policy, and Protection

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE4-538

Start Date

5-4-2018 1:30 PM

End Date

5-4-2018 1:45 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, 1:30 PM Apr 5th, 1:45 PM

Warm water temperature regimes in eelgrass beds (Z. marina and Z. japonica) of Padilla Bay, WA

Padilla Bay, WA has over 3300 hectares of eelgrass with vast areas of intermixed beds of the native Zostera marina and non-native Zostera japonica. Water temperature is thought to be one of the primary influences on eelgrass distribution, and long term monitoring shows that temperatures in Padilla Bay have increased substantially (mean increase >2°C) from 2011 through 2016. We were interested to see if changes in eelgrass distribution were correlated with the changes we observed in water temperature in Padilla Bay, however, our long term temperature monitoring station is located in a shallow channel within the eelgrass beds. Because of this sensor placement, we first needed to determine if these data were representative of temperatures experienced by eelgrass on the vegetated flats. To test this, we deployed 45 temperature loggers throughout the intertidal and subtidal distribution of Z. marina and Z. japonica. We found that temperatures recorded at our long term monitoring site greatly underestimated the high temperatures experienced by the intertidal eelgrass. In Padilla Bay, Zostera marina was exposed to temperatures above 8°C, the optimal temperature reported for Z. marina growth in the PNW, for over 90% of the time during the peak growing season (March – Sept.). Furthermore, Z. marina experienced extended periods of time above 15°C, temperatures thought to cause stress to local plants. Despite these elevated temperatures, Z. marina remain robust, suggesting that Z. marina in Padilla Bay may have a higher tolerance for warmer water temperatures than other beds in the PNW or may be living near the upper limits of tolerance for PNW plants. This study characterizes – on a fine spatial scale – the duration and intensity of temperatures extremes that eelgrass experience in shallow systems and ultimately provides insight into the health and performance of eelgrass in a warmer future ocean.