Northwest Fisheries Science Center

Ecotoxicology Research Areas


Dr. Nat Scholz
Program Manager
Staff Directory

Multiple stressors and disease

A properly functioning immune system is an important fitness trait that is critical for survival of the individual as well as the population. An altered immune system due to contaminants, either in conjunction with other stressors or alone, can result in an increase in disease susceptibility, which can lead to potential population level effects.

The Ecotoxicology Program in Newport, Oregon conducts research on a number of contaminants and stressors to determine their effect on immune function and disease susceptibility in endangered species. Recent work has focused on the impacts of pesticides and temperature stress, contaminants of emerging concern, PAHs, and fire retardants on juvenile salmon health. Environmentally relevant laboratory exposure studies are conducted based on prior field monitoring studies.

Program Contact

Mary Arkoosh

Project Staff

Joseph Dietrich, Lyndal Johnson, Nat Scholz

NWFSC Co-Investigators

Gina Ylitalo


Army Corps of Engineers, The next link/button will exit from NWFSC web site Walla Walla and The next link/button will exit from NWFSC web site Portland Districts
NOAA Office of Protected Resources
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Oregon Department of Fish & Wildlife, Corvallis Research Lab
The next link/button will exit from NWFSC web site Oregon State University, Coastal Oregon Marine Experimental Station
The next link/button will exit from NWFSC web site U.S. Environmental Protection Agency, Region 10
The next link/button will exit from NWFSC web site U.S. Department of Agriculture-Forest Service Wildland Fire Chemical Systems Program
The next link/button will exit from NWFSC web site U.S. Geological Survey-CERC


Dietrich, J.P., K. Eder, D.E. Thompson, R.A. Buchanan, J.R. Skalski, G.A. McMichael, D.S. Fryer, F.J. Loge. 2016. Survival and travel times of in-river and transported yearling Chinook salmon in the lower Columbia River and estuary. Fisheries Research, 183:435-446.

Arkoosh, M.R., J.P. Dietrich. 2015. Pathogenicity of members of the Vibrionaceae family to cultured juvenile sablefish. Journal of Aquatic Animal Health, 27(2):96-103.

Dietrich, J.P., S.A. Strickland, G.P. Hutchinson, A.L. Van Gaest, A.B. Krupkin, G.M. Ylitalo, M.R. Arkoosh. 2015. Assimilation efficiency of PBDE congeners in Chinook salmon. Environmental Science & Technology, 49:3878-3886.

Arkoosh, M.R., Van Gaest, A.L., Strickland, S.A., Hutchinson, G.P., Krupkin, A.B., and Dietrich, J.P. 2015. Dietary exposure to individual polybrominated diphenyl ether congeners BDE-47 and BDE-49 alters innate immunity and disease susceptibility in juvenile Chinook salmon. Environmental Science and Technology, 49:6974-6981.

Dietrich, J. P., Van Gaest, A. L., Strickland, S. A., and Arkoosh, M.R. 2014. The Impact of temperature stress and pesticide exposure on mortality and disease susceptibility of endangered pacific salmon. Chemosphere, 108:353-359.

Dietrich, J. P., Van Gaest, A. L., Strickland, S. A., Hutchinson, G. P., Krupkin, A. B., and Arkoosh, M.R. 2014. Toxicity of PHOS-CHEK LC-95A and 259F fire retardants to ocean and stream-type Chinook salmon and their potential to recover before seawater entry. Science of the Total Environment, 490:610-621.

Dietrich, J. P., M. S. Myers, S. A. Strickland, A. Van Gaest, and M. R. Arkoosh. 2013. Toxicity of forest fire retardant chemicals to stream-type Chinook salmon undergoing parr-smolt transformation. Environmental Toxicology and Chemistry 32 (1): 236-247.

Arkoosh, M.R., S.A. Strickland, A.L. Van Gaest, G.M. Ylitalo, L.L. Johnson, G.K. Yanagida, T.K. Collier, J.P. Dietrich. 2011. Trends in Organic Pollutants in Juvenile Snake River Spring Chinook Salmon with Different Outmigrating Histories through the Lower Snake and Middle Columbia Rivers. Science of the Total Environment, 409:5086-5100.

Curtis, L. R., C. B. Garzon, M. R. Arkoosh, T. K. Collier, M. S. Myers, J. Buzitis, J. Morrow, M. E. Hahn. 2011. Reduced Cytochrome P4501A Activity and Recovery from Oxidative Stress During Subchronic Benzo[a]pyrene and Benzo[e]pyrene Treatment of Rainbow Trout. Toxicology and Applied Pharmacology.

Van Gaest, A. L., J. P. Dietrich, D. E. Thompson, D. Boylen, S. A. Strickland, T. K. Collier, F. J. Loge, M. R. Arkoosh. 2011. Survey of Pathogens in Hatchery Chinook Salmon with Different Outmigration Histories through the Snake and Columbia Rivers. Journal of Aquatic Animal Health, 23(2):62-77. doi:10.1080/00028487.2011.572023

Arkoosh, M. R., D. Boylen, J. P. Dietrich, B. F. Anulacion, G. M. Ylitalo, C. F. Bravo, L. L. Johnson, F. Loge, T. K. Collier. 2010. Disease Susceptibility Of Salmon Exposed To Polybrominated Diphenyl Ethers (PBDEs). Aquatic Toxicology.

Dietrich, J. P., D. Boylen, D. E. Thompson, D. K. Spangenberg, C. F. Bravo, E. J. Loboschefsky, G. M. Ylitalo, D. S. Fryer, T. K. Collier, M. R. Arkoosh, F. Loge. 2011. An Evaluation of the Influence of Stock Origin and Out-migration History on the Disease Susceptibility and Survival of Juvenile Chinook Salmon. Journal of Aquatic Animal Health, 23(1):35-47. doi:10.1080/08997659.2011.568859

Bravo, C. F., L. R. Curtis, M. S. Myers, J. P. Meador, L. L. Johnson, J. Buzitis, T. K. Collier, J. D. Morrow, C. A. Laetz, F. Loge, M. R. Arkoosh. 2011. Biomarker response and disease susceptibility in juvenile rainbow trout Oncorhynchus mykiss fed a high molecular weight polycyclic aromatic hydrocarbon (PAH) mixture. Environmental Toxicology and Chemistry, 30(3):704-714. doi:10.1002/etc.439