Utilizing U/Ca Ratios to Determine Best Management Practices for Shell Planting and Oyster Culture to Mitigate Ocean Acidification Impacts (2016-18)

Alyssa Shiel
College of Earth, Ocean, and Atmospheric Sciences
Oregon State University
104 CEOAS Admin Bldg
Corvallis, OR 97331
Phone: 541-737-5209

Co-PIs: Adam Kent, OSU; George Waldbusser, OSU

The Pacific Northwest and Oregon’s estuaries have supported shellfish harvesting and aquaculture for well over 100 years. Although the industry has faced challenges over that period of time, in the past decade ocean acidification has emerged as a serious new threat. As a result, the very reason for the highly productive coastal waters — upwelling of deep, old nutrient rich water — has now become the number one threat to sustainability of the oyster industry in Oregon and the broader Pacific Northwest. Models of the California Current, the source waters for the oceanic end member of Oregon’s estuaries, predict that the magnitude, duration, and frequency of acidification events will increase rapidly in the coming decades.

It has been previously argued that shells may play a critical role in buffering CO2 or other metabolic acids in temperate ecosystems that lack extensive carbonate sands. The Washington State Blue Ribbon Panel on Ocean Acidification noted shell planting as a possible adaptation/remediation strategy by providing a buffering effect. The ecological importance of shells to shellfish beds and aquaculture is well documented, however optimizing their use to best-offset acidification impacts is poorly documented. Dr. Shiel and her research team believe a simpler approach may be utilized by employing state-of-the-art geochemical techniques to document the exposure history of oysters in different possible shell planting configurations.

The objectives of the research are to (1) calibrate the uranium to calcium (U/Ca) ratio in oyster shells as a geochemical tool to assess the individual exposure to carbonate chemistry of oyster juveniles and young adults, (2) use this tool to determine optimal shell planting practices in oyster aquaculture to mitigate ocean acidification impacts, and (3) develop and disseminate a best management practices guide for shell use for aquaculture. This study will inform management practice of shell planting in response to ocean acidification and give the industry a tool to document individual oyster experiences. Development and demonstration of this tool in the field will support future efforts to evaluate variability in oyster experiences over larger areas and over time as ocean acidification increases in response to higher atmospheric CO2 levels.

Strategic Plan Focus Areas: Sustainable Fisheries and Aquaculture, Resilient Communities and Economies, Environmental Literacy and Workforce

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