Type of Presentation

Poster

Session Title

The Role of Eelgrass Ecosystems in the Salish Sea

Description

SeagrassNet is a global seagrass monitoring program that is now established in 33 countries with 132 monitoring sites world-wide. Standardized protocols for scientific monitoring have been developed and are successfully implemented by trained teams of local scientists and managers. Quarterly fixed-transect sampling is carried out at sites for seagrass species composition including: cover, density, biomass, and canopy height, as well as temperature, salinity, and light. A monitoring team at each site sends data via the internet to an online database and archive at www.SeagrassNet.org.

In 2008, the Washington State Department of Natural Resources’ Nearshore Habitat Program established a SeagrassNet site at Dumas Bay. Eight years of sampling show, cumulatively, seagrass is declining at the site and particularly at transects located at the highest and lowest tidal elevations (+1 m and -1.6 m, respectively). Causal factors of decline have not been explicitly identified but we hypothesize change is related to environmental stressors such as temperature and reduced water clarity. Light data collected across the site varied consistently by season over time and data confirm there is adequate light to support eelgrass growth at all transect elevations monitored (>3 mol/day). Temperature measurements and ambient mean daily PAR were above seasonal averages throughout 2013. Z. marina responded differently than expected to increased light, with no clear response in plant morphology detected in subsequent sample events. Meanwhile, increased shoot density and canopy height in the non-native seagrass, Z. japonica was observed at the highest transect elevation. Above average light conditions were not observed at depth in 2013, indicating reduced light availability. Though not directly measured, reduced water clarity due to algal blooms noted could be a major driver of observed seagrass decline at the site.

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Linking seasonal trends of light and temperature conditions to eelgrass plant performance at Dumas Bay, Washington.

2016SSEC

SeagrassNet is a global seagrass monitoring program that is now established in 33 countries with 132 monitoring sites world-wide. Standardized protocols for scientific monitoring have been developed and are successfully implemented by trained teams of local scientists and managers. Quarterly fixed-transect sampling is carried out at sites for seagrass species composition including: cover, density, biomass, and canopy height, as well as temperature, salinity, and light. A monitoring team at each site sends data via the internet to an online database and archive at www.SeagrassNet.org.

In 2008, the Washington State Department of Natural Resources’ Nearshore Habitat Program established a SeagrassNet site at Dumas Bay. Eight years of sampling show, cumulatively, seagrass is declining at the site and particularly at transects located at the highest and lowest tidal elevations (+1 m and -1.6 m, respectively). Causal factors of decline have not been explicitly identified but we hypothesize change is related to environmental stressors such as temperature and reduced water clarity. Light data collected across the site varied consistently by season over time and data confirm there is adequate light to support eelgrass growth at all transect elevations monitored (>3 mol/day). Temperature measurements and ambient mean daily PAR were above seasonal averages throughout 2013. Z. marina responded differently than expected to increased light, with no clear response in plant morphology detected in subsequent sample events. Meanwhile, increased shoot density and canopy height in the non-native seagrass, Z. japonica was observed at the highest transect elevation. Above average light conditions were not observed at depth in 2013, indicating reduced light availability. Though not directly measured, reduced water clarity due to algal blooms noted could be a major driver of observed seagrass decline at the site.