Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

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.

BCO-DMO Processing:
- renamed fields to comply with BCO-DMO naming conventions;
- replaced blanks with "No" in the VideoDive column (to distinguish from "no data");
- added date-time field in ISO8601 format;
- converted PDT dates to format YYYY-MM-DD;
- replaced blanks with "nd" (no data).

NSF Award Abstract:
Highly productive US West Coast fishery species and marine mammals rely on benthic invertebrate communities for food. However, these communities are changing. This project addresses the potential ecological consequences of a new member to these benthic communities, the ghost shrimp Neotrypaea. In estuaries, Neotrypaea continuously rework the sediment via their burrowing activities. The combination of high shrimp abundances and the effects of burrowing mitigate the impacts of nutrient run-off (natural and human-induced) that can exacerbate low oxygen conditions. However, Neotrypaea are also considered threats to the oyster industry because of their sediment-excavating activities. An expansion of their distribution beyond estuaries may have additional unforeseen consequences for the Dungeness crab fishery (regionally valued at $33-74M/y) as Neotrypaea are both competitors with juveniles and prey for larger Dungeness crab. Thus, new data are needed to determine how offshore benthic communities are being altered by the recruitment of Neotrypaea into new habitats. This study is comparing communities with high and low shrimp abundances to understand their impact on offshore benthic communities. The shrimp’s contributions to oxygen and carbon cycling are being estimated through field measurements. Benthic community assessments are quantifying changes to food resources on the seafloor caused by the presence of these relatively large shrimp. The coastal waters along the Oregon-Washington shelf are commercially valuable, yet they are also subject to growing human-related impacts. Sustainable management requires optimizing extractive, cultural, and recreational activities. The broader impacts of this research include key data for managers, commercial fisheries’ stakeholders and oyster growers that inform decisions regarding ocean-use planning and management of burrowing shrimp. This project is providing research training for three graduate students and two summer undergraduate students. Curriculum development for elementary school students is focused on the ecology of soft-bottom benthos. The ocean sandy/muddy benthos are often unknown to K-12 students on the West Coast who are usually more familiar with intertidal and kelp forest systems.

Changing environmental conditions in shelf waters along the Oregon and Washington coasts and elsewhere have included increasingly frequent and severe hypoxia events, ocean acidification, and warming. These changes have affected biological communities and altered species distributions. An abundant mid-shelf population of the burrowing ghost shrimp, Neotrypaea sp. was documented in shelf waters following the Marine Heat Wave of 2015. Neotrypaea are ecosystem engineers that were previously known to be abundant in intertidal estuary mudflats with an insignificant presence in the open ocean. In estuaries Neotrypaea continuously rework the sediment via their burrowing activities. The shrimp can increase oxygen cycling due to burrow irrigation and reduce impacts of nutrient loading such as low-oxygen conditions. However, enhanced benthic oxygen consumption linked to Neotrypaea sp. beds could have the opposite effect on the shelf by intensifying regional hypoxia. This study is characterizing the environmental conditions associated with the expanded distribution of Neotrypaea using a habitat-suitability modeling approach. Model predictions are being validated through extensive field sampling via box coring and video lander observations. In addition, the benthic samples are documenting changes in the benthic invertebrate communities within the Neotrypaea beds and how this is potentially affecting biological interactions. Analyses of aquatic eddy covariance and of core incubations in shelf areas with and without abundant shrimp are providing estimates of the shrimp’s contribution to benthic oxygen fluxes and organic carbon cycling. These data are being used to quantify the shrimp’s and their burrows’ effects on the overall productivity of the mid-shelf benthos relative to reference areas. How Neotrypaea alter seafloor structure and biogeochemistry need to be characterized to predict the impact of these ecosystem engineers on the food supply for higher trophic levels and fisheries.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.