Demonstration Dock Designed to Benefit Eelgrass Habitat Restoration (Washington)
The derelict Thomas Oil Dock on state tidelands in Port Townsend, Washington, was redesigned for the Northwest Maritime Center by a committee including marine scientists, architects, engineers, educators, regulators, and user groups. The committee's objectives were to create a ''demonstration dock'' using the best-available technologies and design features to restore nearshore habitat functions, particularly for threatened fisheries resources, while accommodating the unique requirements of the educational facility to house vessels ranging from historic tall ships to sea kayaks. A key nearshore habitat restoration goal was to reduce fragmentation of eelgrass where shade from the existing dock inhibited growth, by improving conditions with a new dock design and transplanting eelgrass to connect existing patches. Ecological conditions were evaluated through diver surveys; mapping existing eelgrass, macroalgae, and substrates; and review of controlling factors. Data on the attenuation an d diffusion of photosynthetically-active radiation (PAR) was collected and evaluated relative to eelgrass light requirements. Potential shade impacts of existing and alternative dock designs and materials were modeled. Key design features to improve habitat functions included the installation of reflective material under the dock to increase the incidence of PAR at the substrate level, reduction in the number of piles and associated shade impacts through the use of steel piles instead of wood, increase in the length of the trestle to 286 to move the greatest area of overwater structure beyond the range of eelgrass, and the use of grating in strategic locations to reduce the potential of a light/dark barrier to fish passage.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 15010599
- Report Number(s):
- PNWD-SA-6315
- Journal Information:
- Ecological Restoration, 22(2):140-141, Journal Name: Ecological Restoration, 22(2):140-141
- Country of Publication:
- United States
- Language:
- English
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