Subtidal Benthic Video and Benthic Infauna Survey and Intertidal Cable Crossing Survey

Report

Title: Subtidal Benthic Video and Benthic Infauna Survey and Intertidal Cable Crossing Survey
Publication Date:
January 30, 2012
Pages: 128
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Attachment: Access File
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Citation

MER Assessment Corporation (2012). Subtidal Benthic Video and Benthic Infauna Survey and Intertidal Cable Crossing Survey. Report by Ocean Renewable Power Company (ORPC). pp 128.
Abstract: 

Ocean Renewable Power Company LLC (ORPC) is proposing to deploy its TidGen™ Power System in a section of Cobscook Bay (CB) in the vicinity of Grove (Gove) Point, North Lubec, Maine in an area shown in Figures 1 and 2. MER Assessment Corporation (MER) was requested to assist with habitat characterizations of the deployment areas and the subsea cable routes.

 

The full project deployment and subsea cable route area baseline survey and habitat characterization effort includes both subtidal and intertidal habitats. MER conducted the subtidal habitats portion of the survey in collaboration with Pepperell Cove Marine (PCM), Portsmouth, New Hampshire (photo below), on July 14 and 15, 2011, during a period of three daylight hours slack-tides (two low tides and one high tide) and moderate to large amplitude tides of 4.5m to 5.5m (18.6 ft. to 20.2 ft.). The intertidal habitat characterization was completed on July 15, 2011. This report summarizes the results of the subtidal video and benthic infauna survey and the intertidal sampling along the intertidal cable crossing area.

 

Cobscook Bay is characterized by large amplitude tides and very strong tidal currents. The selected deployment area is subject to some of the strongest tidal currents in the region. These strong currents present constraints on both the timing and duration of survey events (extremely short slack water period). Video recording of the bottom and grab sampling using remote equipment was considered difficult, if not impossible, throughout most of the area, particularly along the cross-current transect leading from the deployment area to the intertidal crossing area. Furthermore, use of SCUBA was considered impractical and unsafe due to the extremely strong currents. Consequently, tethered, surface-supply air divers were used to record video and collect benthic samples.

 

Video recording was accomplished using diver helmet-mounted cameras and lights with the divers following stainless steel cables attached to 4,000 lb mooring stones pre-set by CPM Contractors (CPM), Freeport, Maine. Benthic sampling was conducted in situ by the divers. The transects layout and benthic sampling stations for the CB deployment area and subsea cable route are shown in Figures 1-3.

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