Environmental Controls of the Abundance, Growth and Toxicity of the Known Shellfish Pathogen Vibrio tubiashii

EPA Grant Number: F13E20903
Title: Environmental Controls of the Abundance, Growth and Toxicity of the Known Shellfish Pathogen Vibrio tubiashii
Investigators: Gradoville, Mary Rose
Institution: Oregon State University
EPA Project Officer: Packard, Benjamin H
Project Period: September 29, 2014 through September 29, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Fellowship - Oceanography , Academic Fellowships


Vibriosis outbreaks in recent years have been devastating to Northwest oyster stocks and hatchery success. This research aims to investigate the biogeochemical and oceanic conditions controlling the abundance, growth and pathogenicity of the bacterium V. tubiashii.


The environmental controls of V. tubiashii growth and toxicity will be examined using a combination of observational fieldwork and laboratory experiments. In the laboratory, optimal conditions for growth and toxicity will be characterized by monitoring V. tubiashii isolates subjected to treatments of varying temperature, CO2 and O2 regimes. In the field,

the abundance and toxicity of V. tubiashii in local Oregon estuaries and coastal waters will be measured. Field sampling will focus on Netarts Bay,Yaquina Bay and transects off the Oregon coast; sampling will target the coastal upwelling season, with time points across the tidal cycle. Through all of these experiments, the abundance of V. tubiashii will be determined through quantitative polymerase chain reaction as well as traditional plating methods, and toxicity will be determined through oyster larvae toxicity assays. Data generated from laboratory and field experiments will relate the abundance and toxicity of V. tubiashii to biogeochemical regimes and local physics.

Expected Results:

The study will use multiple approaches to determine the environmental regulation of V. tubiashii growth and virulence. Preliminary environmental sampling and manipulative experiments suggest that V. tubiashii abundances in the Northwest may be linked to climatic conditions within the California Current upwelling regime; however, the scarcity of existing data make this suggestion speculative. This research will use controlled experiments to test how seawater chemistry affects V. tubiashii, then correlate V. tubiashii abundance and toxicity with environmental conditions in Oregon estuaries and coastal habitats. It is hypothesized that high V. tubiashii abundances are associated with specific oceanic conditions, such as strong upwelling followed by positive temperature anomaly, and that V. tubiashii and environmental conditions (such as ocean acidification) synergistically induce larval mortality.

Potential to Further Environmental/Human Health Protection

Vibriosis outbreaks in recent years have been devastating to oyster stocks and hatchery success in the Northwest, and these events have been sporadic and unpredictable. The knowledge gained from this research could be used by hatcheries to predict the risk of vibriosis from a combination of current ocean conditions and easily monitored parameters of incoming seawater (e.g., pCO2, temperature). More broadly, a mechanistic understanding of the forcing of V. tubiashii and the synergistic impact of ocean acidification and vibriosis on larval development would be valuable to nascent oyster restoration projects ongoing on the West coast.

Supplemental Keywords:

ocean acidification,Oregon estuaries,V. tubiashii

Progress and Final Reports:

  • 2015
  • Final