Abstract Title

Session S-07E: Aquatic Vegetation

Keywords

Habitat

Start Date

1-5-2014 3:30 PM

End Date

1-5-2014 5:00 PM

Description

Hart Crowser is working with the Washington Department of Ecology, Toxic Cleanup Program to explore capping alternatives to remediate existing eelgrass habitat for low/intermediate levels of dioxin/furan contamination at Custom Plywood, a Model Toxic Control Act (MTCA) clean-up site in Fidalgo Bay, Anacortes, Washington. Eelgrass (Zostera marina) is a highly productive, submerged habitat in Puget Sound serving as refuge/nursery habitat for juvenile salmonids and forage fish. Remediation of legacy contamination in these habitats presents a unique problem where traditional capping may adversely affect or eliminate the habitat. Here, we examine the effects of various cap thicknesses and amendments on eelgrass survival and health in seven test plots. During 2013, sand caps of 4″ and 8″ (sand only and amended with activated carbon) were applied to these seven plots, and eelgrass metrics (density, biomass, blade length/width, etc.) were surveyed and compared to control and reference plots. Preliminary results suggest that eelgrass will not tolerate a cap thickness of 8″ (near 100% mortality), but will tolerate a 4″ cap. When compared to control plots, the 4″ plots exhibited a distinct reduction in eelgrass density and biomass followed by a recovery phase. Eelgrass did not seem to react differently to the carbon amendment in the 8″ plots, but there was some peripheral evidence suggesting the recovery phase was enhanced by the presence of activated carbon in the 4″ plots. Plots may be resurveyed in 2014 to determine long-term recovery trends. These findings can potentially provide design alternatives for remediating legacy contamination within existing productive eelgrass habitats.

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May 1st, 3:30 PM May 1st, 5:00 PM

Tolerance of Eelgrass to Capping in Fidalgo Bay (Preliminary Results): Investigation of Remediation Alternatives for Intermediate Levels of Contamination, Anacortes, Washington

Room 613-614

Hart Crowser is working with the Washington Department of Ecology, Toxic Cleanup Program to explore capping alternatives to remediate existing eelgrass habitat for low/intermediate levels of dioxin/furan contamination at Custom Plywood, a Model Toxic Control Act (MTCA) clean-up site in Fidalgo Bay, Anacortes, Washington. Eelgrass (Zostera marina) is a highly productive, submerged habitat in Puget Sound serving as refuge/nursery habitat for juvenile salmonids and forage fish. Remediation of legacy contamination in these habitats presents a unique problem where traditional capping may adversely affect or eliminate the habitat. Here, we examine the effects of various cap thicknesses and amendments on eelgrass survival and health in seven test plots. During 2013, sand caps of 4″ and 8″ (sand only and amended with activated carbon) were applied to these seven plots, and eelgrass metrics (density, biomass, blade length/width, etc.) were surveyed and compared to control and reference plots. Preliminary results suggest that eelgrass will not tolerate a cap thickness of 8″ (near 100% mortality), but will tolerate a 4″ cap. When compared to control plots, the 4″ plots exhibited a distinct reduction in eelgrass density and biomass followed by a recovery phase. Eelgrass did not seem to react differently to the carbon amendment in the 8″ plots, but there was some peripheral evidence suggesting the recovery phase was enhanced by the presence of activated carbon in the 4″ plots. Plots may be resurveyed in 2014 to determine long-term recovery trends. These findings can potentially provide design alternatives for remediating legacy contamination within existing productive eelgrass habitats.