Field Data Collection

The locations of vibracore sites were chosen based on analysis of high-resolution seismic reflection profiles collected by the USGS throughout the bay (Andrews and others, 2015b). A total of 18 marine vibracores were collected from Barnegat Bay in water depths greater than 1.5 m between May and August of 2014 from the NRCS Research Vessel (R/V) Doerner (fig. 2). A vessel-mounted tripod system was used to position, deploy, and recover the vibracores. At two additional target sites, coring efforts failed to recover sediment. A 5 ½-horsepower Briggs and Stratton motor attached to a concrete vibrator head with a 3-m shaft was used to vibrate 7.62-centimeter (cm) diameter aluminum core barrels into the estuarine seafloor to refusal. After recovery, the cores were capped, sealed, and labeled. Measurements of compaction were recorded for each core based on a comparison of the external riser height and the depth of the sediment-water interface inside the barrel. Date, time, site location (latitude and longitude), water depth, tidal period, total extracted core length, and estimated compaction were recorded for each core. All vibracores were stored in a refrigerator at the NRCS Plant Materials Center (PMC) in Cape May, N.J., until they were transported from the NRCS PMC to the USGS St. Petersburg Coastal and Marine Science Center (SPCMSC) in early September for description and textural analysis.

Figure 2. (A) Natural Resources Conservation Service (NRCS) personnel collecting a vibracore in Barnegat Bay from (B) the Research Vessel (R/V) Doerner. Photographs provided by Rob Tunstead (NRCS). [Click to enlarge]