Subtidal eelgrass/macroalgae surveys for the proposed breakwaters at the US Coast Guard Station at Ediz Hook, Washington, March 1993

Technical Report · Sat May 01 00:00:00 EDT 1993

DOI:https://doi.org/10.2172/10168834· OSTI ID:10168834

Shreffler, D K ^[1]

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1. Battelle/Marine Sciences Lab., Sequim, WA (US)

In 1993, the US Coast Guard proposed to construct two breakwaters and a debris boom to protect its existing pier and moored vessels inside Ediz Hook in Port Angeles Harbor, Washington. To assist the US Army Corps of Engineers -- Seattle District in determining the potential environmental impacts of the proposed breakwaters, Battelle/Marine Sciences Laboratory performed subtidal SCUBA surveys as specified in the Washington Department of Fisheries intermediate eelgrass/macroalgae habitat survey guidelines. The objectives of the subtidal surveys were to (1) quantify the shoot densities of eelgrass; (2) provide percent cover estimates for non-eelgrass macroalgae species; (3) develop a site map indicating the qualitative distribution of eelgrass/macroalgae species, substrate characterization, approximate depth contours, and the approximate location of the proposed project features; and (4) document the time and date of the surveys, turbidity/visibility, presence of invertebrate/vertebrate species, and anecdotal observations pertinent to habitat characterization of the project site. A total of 14 dives along 12 transects (T1--T12) were successfully completed between March 15 and March 17, 1993. Eelgrass was observed on all of the transects except T7 and T8 at the western debris barrier and T12 along the waterward margin of the existing T-pier. The vicinity of the proposed east breakwater had the highest eelgrass shoot densities (up to 89 shoots/m{sup 2}) observed by the divers. Macroalgae and invertebrate species diversity were also highest at the east breakwater site. The low eelgrass densities observed at the west debris barrier site (0 to 14 shoots/m{sup 2}) can be attributed mostly to the lack of suitable substrate. The existing layer of wood debris armoring the bottom at the west project site currently limits, and in the areas of heaviest deposition probably precludes, the growth of eelgrass. As was expected, no eelgrass was observed at the south breakwater site.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: Department of Defense, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 10168834
• Report Number(s): PNL-8656; ON: DE93016831; TRN: 93:001977
• Resource Relation: Other Information: PBD: May 1993
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
59 BASIC BIOLOGICAL SCIENCES
DAMS
ENVIRONMENTAL IMPACTS
AQUATIC ORGANISMS
HABITAT
DISTRIBUTION
AQUATIC ECOSYSTEMS
SURVEYS
US COAST GUARD
WASHINGTON
DEPTH
TURBIDITY
VISIBILITY
SPECIES DIVERSITY
RECOMMENDATIONS
DESIGN
SHORES
COASTAL WATERS
SEAWEEDS
SITE CHARACTERIZATION
540350
550000
SITE RESOURCE AND USE STUDIES
BIOMEDICAL SCIENCES
BASIC STUDIES