Award: OCE-2126112

Burrowing shrimp influence the sediment properties, animal populations, and ecological processes of the seafloor where they live through the construction and maintenance of their burrows. The burrowing ghost shrimp Neotrypaea sp. are commonly found in U.S. west coast estuaries (bays), sometimes occupying >80% of the intertidal area. In 2022, a large population of ghost shrimp was documented for the first time offshore central Oregon in waters 40-70 m (< 200 ft) deep where environmental conditions are substantially different from estuaries. In this project, we conducted morphological and genetic analyses and found that the offshore population is comprised of individuals genetically the same as the rarer estuarine species, Neotrypaea gigas, but with shorter eyestalks and larger eyespot area. Individuals collected offshore when introduced into sediments in the laboratory constructed shallower and simpler burrows than the dominant estuarine species, Neotrypaea californiensis; however total burrow volumes were similar. Shrimp from each population spent different amounts of time doing various feeding and burrowing behaviors, suggesting contrasting feeding strategies and potential for different physical and chemical impacts to sediments. Comparisons of the microbial communities near and far from ghost shrimp burrows both in the estuary and offshore indicated some microbial groups in higher abundance near burrows across habitats. Specifically, a bacterial genus previously documented to cue the settlement of mussel and oyster larvae was more abundant in areas with shrimp burrows in both habitats. Habitat suitability modeling suggested the potential for additional offshore populations on the Oregon and Washington shelves, and ground-truthing found that the Oregon shelf locations predicted to be >30% suitable did have dense offshore populations of ghost shrimp while the Washington shelf areas did not. Box core sampling across 11 offshore sites indicated that bivalve (clam), worm, and crustacean abundances generally were higher in areas with ghost shrimp while gastropods (snails) were lower than in reference areas. Some of the more abundant bivalves have previously been demonstrated to have positive associations with oxygenated sediment generated by other burrowing organisms. In situ benthic flux, measurements by the eddy covariance method, and shipboard sediment core incubations at a subset of the shelf sites showed highest oxygen and nitrate uptake rates at sites where shrimp burrows were abundant. Across sites, the eddy covariance oxygen fluxes (assumed to fully represent seabed respiration) correlated with water flow and were greater than rates of dissolved oxygen uptake by sediment cores from the same locations. These findings illustrate how natural physical processes (seabed waves, currents, and swell) can relieve the stress of low oxygen exposure on the seafloor and that the presence of burrowing ghost shrimp may further increase sediment oxygenation, facilitating other sediment-dwelling organisms. Collectively this work has advanced our understanding of seabed chemical and organismal ecology on the northeastern Pacific shelf. The findings will serve as a benchmark to assess any future changes of the seabed associated with shifting organismal distributions, offshore development, or with climate change.

This project has directly supported five graduate students, six research associates, and seven undergraduate students at Oregon State University, building the STEM workforce by providing training, stipend, and opportunity for project development for those already in STEM higher education. We collaborated with Oregon Sea Grant, the Oregon STEM Hub, and Oregon’s Oceangoing Research Program to develop curricula for Oregon educators using data from this project and to provide more than ten vessel days at sea, allowing over 100 Oregon high students to participate in real ocean-going scientific research. To further build knowledge of and appreciation for soft sediment habitats on the Oregon shelf among K-12 students and the public, we developed an exhibit for the annual Marine Science Day at Oregon State University’s Hatfield Marine Science Center. This exhibit includes a poster of the seafloor showing Neotrypaea burrow holes, a sandbox from which kids sieve out snail and bivalve shells as we do from box core collections, and “ant farm” tanks holding live borrowing shrimp in which oxygenated areas of the sediment can be seen. Engaging with so many K-12 students and other citizens about our research helps increase public understanding of the science happening in their community as well as the scientific process itself.

Last Modified: 12/04/2025
Modified by: Sarah K Henkel