Sampling was conducted along the Pacific Continental Shelf of Oregon and Washington (44.34 N to 46.99 N, depth 42 to 88 meters) during the following cruises (dates are provided in YYYY-MM-DD format):
COP2021 (2021-10-19) on R/V Pacific Storm,
COP2022A (2022-04-07) on R/V Pacific Storm,
COP2022B (2022-07-07 to 2022-07-10) on R/V Pacific Storm,
COP2022C, cruise IDs SP2215 and RS2215 (2022-07-22 to 2022-07-23) on R/V Gordon Sproul,
COP2022D, cruise ID SP2219 (2022-09-13 to 2022-09-19) on R/V Gordon Sproul,
COP2022E (2022-09-21 to 2022-09-22) on R/V Pacific Storm.
At each box core station, samples were collected with a modified Grey-O'Hara 0.1 square meter (m²) box core. One box core sample was taken at each station. Depth was recorded from the vessel's echosounder at the time the box corer hit the bottom. Only samples with a penetration depth of at least 4 centimeters (cm) were accepted for processing. Approximately 80 milliliters (mL) of sediment were collected from the undisturbed surface layer for later grain size analysis. Any organisms noticed in the sediment subsample at the time of collection were removed and placed in the organism sample jar. Surface sediment samples were then stored in the ship's refrigerator. The remainder of the collected core was sieved onboard through a 1.0 millimeter (mm) mesh screen, and all organisms except the target shrimp Neotrypaea (both infauna living in the sediment and small epifauna which may have been on the surface, hereafter collectively called "macrofauna") as well as debris retained on the screen were preserved in 70% EtOH. Neotrypaea in good condition were placed in a cooler with collected sediment and battery-operated bubblers to keep for experiments at the Hatfield Marine Science Center. Neotrypaea deemed not suitable for experimental work were preserved in 95% EtOH and placed in the freezer.
At approximately every third station, vertical water-column profiles of conductivity, temperature, dissolved oxygen, pH, and fluorescence were obtained with a Sea-Bird Electronics CTD (conductivity, temperature, depth) unit equipped with additional sensors. At approximately every third station on COP2022B, a camera lander with two downward-facing video cameras was dropped and left on the seafloor for one minute and then retrieved. Those videos will be later analyzed for the presence of burrows holes attributable to the Neotrypaea and to be used to check for false negatives (places where the shrimp are present but not collected in the box core).
At each camera lander station, a camera lander with two downward-facing video cameras and a set of lights for each camera was dropped and left on the seafloor for one minute and then retrieved. The field of view of each camera is ~0.4 m². Burrows holes attributable to Neotrypaea were quantified on each video. In addition to quantification, these were used to check for false negatives (places where the shrimp are present but not collected in the box core).
The EC lander deployments yield high-resolution time-series measurements of near-bed velocities and dissolved oxygen from which benthic fluxes of oxygen have been derived for each 15-minute sampling interval.
The BBL lander is a platform that supports a Nortek Aquadopp velocity profiler and a triggered sampling device that collects water samples at discrete heights (1 to 100 cm ) above the seabed. In cases where the near-bed gradients can be resolved, these data may be modeled to yield benthic fluxes.
The slow corer refers to a coring device that takes sediment cores (10.5 cm diameter) that typically have intact sediment water-interfaces and sediment column lengths of 50-60 cm. After collection, these are immediately moved to the cold van. These cores are utilized for core incubations made at sea to yield ex-situ benthic fluxes, and these cores are sectioned for post-cruise analyses of porosity, bulk density, grain size, total C and N, and inorganic C.
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