Station and data summary for data collected on Stellwagen Bank on U.S. Geological Survey field activity 2015-062-FA, aboard the R/V Auk, Oct. 21 and 22 and Nov. 3 and 4 2015 (geographic, WGS84)

Sediment sampling methods:
As a part of the process of mapping the sea floor, the USGS developed the SEABed Observation and Sampling System (SEABOSS) to collect samples and video and photographic images of the seabed to aid in the interpretation of seabed sonar imagery. A modified Van Veen sediment grab sampler is mounted in the center of the SEABOSS frame, which ensures the sampler is properly oriented on the seabed when a sample is collected. Before deployment, the sampler bucket's jaws are opened by collapsing the extended arms to a near-horizontal position and locking them in place with two catches. The sampler operates passively to sample the seabed; it is not spring loaded.
To collect a sediment sample, the SEABOSS frame was lowered gently onto the seabed, reducing tension on the cable, which caused the two locking catches to be automatically released by gravity. As the cable was retrieved, the grab sampler's arms were pulled upward, closing the bucket around the sediment, and the SEABOSS was lifted off the seabed.
The SEABOSS was retrieved and set upon a wooden platform that kept the sampler bucket and camera systems above the deck. The sampler's arms were held in the upright position manually or by tension on the cable, the two doors on the upper side of the bucket were opened, and the sediment was removed. For this project, the upper 2 cm of sediment, representing the surface of the seabed, were removed with a rectangular shovel 2-cm deep and stored in a plastic bag for grain-size analysis. The remaining sediment was dumped into a tray on the deck below the sampler and discarded, after which the sampler was washed in preparation for sampling at the next site. Further information on the SEABOSS can be found in Valentine and others (2000).
Grain-size analyses of the sediment samples were performed at the USGS Woods Hole Coastal and Marine Science Center in Woods Hole, Massachusetts, by using a standard suite of analytical methods (Poppe and others, 2014). This laboratory has been in operation since 1963 and has analyzed many thousands of sediment samples collected by the USGS in New England.

Video methods and data availability:
Seabed video images were collected using a battery-operated, high-definition (1920 x 1080 pixels) GoPro digital video camera mounted on the USGS SEABed Observation and Sampling System (SEABOSS). The SEABOSS system actually had two GoPro cameras attached to it - with the second camera mounted a little higher on the frame which only shows a partial view of the seabed. This second camera was used only to observe obstacles, like gill nets and lobster gear, in order to avoid entanglement. Or, in the case of station 4382, provide a backup system if the primary camera failed.
As the SEABOSS drifted over the seabed, the forward-looking camera imaged the seabed at a rate of 60 frames per second from an altitude of ~1 meter. Lighting was provided by two, battery-operated Keldan LED video lights. Each light provided a light flux of up to 9000 lumens at a correlated color temperature of 5000 kelvins. Two parallel red lasers mounted 20 centimeters apart provided a scale in the video images.
Video imagery includes the launch and recovery of the SEABOSS, transit through the water column, and the drift over the seabed. The duration of individual video files ranges from 4 to 12 minutes. Video files are archived in .MP4 format and range in size from 0.9 to 2.6 gigabytes. These video files are not part of this data release.
The position (lat/lon) of the start of the video drift was recorded (from the navigation receiver) in the log book at the time of the deployment of the SEABOSS. Video was recorded during the descent through the water column (1-2 minutes), during the drift over the seabed, and during the ascent to the surface. The position (lat/lon) of the end of the video drift was recorded at the beginning of the ascent through the water column. The corresponding times are also recorded.

Photos:
No still photos were acquired during this field activity. However, frame-grabs of the video were taken to provide seabed images. These images are available from the Larger Work citation.

The station position (lat/lon) represents the location of the sediment sample (if collected). If a sediment sample was not collected, the station position represents the end of the video drift.

Water depth was determined using a Simrad ES60, 120 kHz, single beam echosounder using a 120-25 transducer, which detects the seabed to a depth of 800 m. Depth values (from the echo sounder monitor) and position (lat/lon) values (from the navigation receiver) were recorded in a log book at the time of deployment of the SEABOSS. Depth values were rounded to the nearest meter to account for ship motion.

This information was entered into an Excel spreadsheet, with a column for each piece of information as described in the entity and attribute section of the metadata.

The spreadsheet was opened in Excel (2010). A row was inserted (the third row) to have column headings that are compatible with importing the data into a GIS. Then the first two rows of the file were deleted and the spreadsheet was exported as an MS-DOS CSV file. This step and subsequent steps (unless otherwise noted) were performed by the same person - VeeAnn A. Cross.

Using ArcGIS 10.3.1, the CSV file was converted to a shapefile within ArcMap using File - Add Data - Add XY data. The CSV file was selected, with the x-coordinate set to STA_LON and the y-coordinate set to STA_LAT. The coordinate system of the input coordinates was set to the geographic coordinate system GCS_WGS_1984. Once the event theme was added to ArcMap, the data were then converted to a shapefile by right-clicking on the event theme - Data - Export Data. All of the features were exported using the layer's source data for the coordinate system. The output shapefile was set to 2015-062-FA_station_data_summary.shp.

Added keywords section with USGS persistent identifier as theme keyword.