University of California, Riverside

Environmental Sciences

Daniel Schlenk

Daniel Schlenk

Daniel Schlenk Photograph

Professor of Aquatic Ecotoxicology

Academic Degrees:

  • Ph.D. Oregon State University, 1989
  • B.S. Northeast Louisiana University, 1984


  • His research focuses on understanding the biochemical factors that influence susceptibility to environmental and natural chemicals. Four specific projects involve the impact of climate change on environmental factors that influence detoxification strategies in aquatic organisms; mechanistic investigations of the effects of salinity on pesticide toxicity in fish; the role of biotransformation as a mechanism of tolerance to natural and man-made toxic agents; impacts of endocrine disrupting chemicals on aquatic organisms.

Research Group:

    Representative Publications:

    • R. Lavado, R. Aparicio-Fabre, and D.Schlenk (2013) Effects of salinity acclimation on the pesticide metabolizing enzyme flavin-containing monooxygenase (FMO) in rainbow trout (Oncorhynchus mykiss). Comparative Biochemistry and Physiology Part C 157:9-15.
    • J.E. Drewes, P. Anderson, N. Denslow, A. Olivieri, D.Schlenk, S.A. Snyder, and K.A. Maruya (2013) Designing monitoring programs for chemicals of emerging concern in potable reuse- what to include and what not to include? Water Science and Technology 67:433-439.
    • K.L. Forsgren, N. Riar, D.Schlenk (2013) The effects of the pyrethroid insecticide, bifenthrin, on steroid hormone and gonadal development of steelhead (Oncorhynchus mykiss) under hypersaline conditions. General and Comparative Endocrinology 186:101-107.
    • Edward P. Kolodziej, Shen Qu, Kristy L. Forsgren, Sarah A Long, James B.Gloer; Gerrad D.Jones; Daniel Schlenk, Jonas Baltrusaitis, David M. Cwiertny (2013) Identification and Environmental Implications of Photo-Transformation Products of Trenbolone Acetate Metabolites. Environmental Science and Technology 47:5031-5041.
    • Lian-Jun Bao, Fang Jia, Jordan Crago, Eddy Y. Zeng, Daniel Schlenk, Jay Gan (2013) Assessing Bioavailability of DDT and Metabolites in Marine Sediments Using Solid Phase Microextraction with Performance Reference Compounds. Environmental Toxicology and Chemistry 32:1946-1953.
    • Doris E. Vidal-Dorsch, Steven M. Bay, Cataldo Ribecco, L. James Sprague, Mila Angert, Colleen Ludka, Oliana Carnevali, Darrin J. Greenstein, Daniel Schlenk, Kevin M. Kelley, Jesus A. Reyes, Shane Snyder, Brett Vanderford, Lan C. Wiborg, Dawn Petschauer, Roman Sasik, Michael Baker, Gary Hardiman (2013) Genomic and phenotypic response of hornyhead turbot exposed to municipal wastewater effluents. Aquatic Toxciology 140-141:174-184.
    • Brant Jorgenson, Erica Fleishman, Kate MacNeale, Daniel Schlenk, Nathaniel Scholz, Julann Spromberg, Inge Werner, Donald A. Weston, Qingfu Xiao, Thomas Young, Minghua Zhang (2013) Predicted Transport Of Pyrethroid Insecticides From An Urban Landscape To Surface Water. Environmental Toxicology and Chemistry 32:2469-2477.
    • Michael E. Baker, Doris E. Vidal-Dorsch,, Cataldo Ribecco, L. James Sprague, Mila Angert, Narimene Lekmine, Colleen Ludka, Andrea Martella, Eugenia Ricciardelli, Steven M. Bay, Joseph R. Gully, Kevin M. Kelley, Daniel Schlenk, Oliana Carnevali, Roman Šášik , Gary Hardiman (2013) Molecular analysis of endocrine disruption in hornyhead turbot at wastewater outfalls in southern California using a second generation multi-species microarray. PLOS ONE 8(9) e75553 1-16.
    • Navneet Riar, Lindley Maryoung, and Daniel Schlenk (2013) Effects of salinity acclimation on the endocrine disruption and acute Toxicity of bifenthrin in freshwater and euryhaline strains of Oncorhynchus mykiss. Environmental Toxicology and Chemistry 32: 2779-2785.
    • Keith Maruya, Paul Anderson, Nancy Denslow, Jorg Drewes, Adam Olivieri, Geoff Scott, Shane Snyder, Daniel Schlenk (2013) An Adaptive, Comprehensive Monitoring Strategy for Chemicals of Emerging Concern (CECs) in California’s Aquatic Ecosystems. Integrated Environmental Assessment and Management 10:69-77.
    • Ramon Lavado, Roseaura Aparicio-Fabre, Daniel Schlenk (2014) Effects of salinity acclimation on the expression and activity of Phase I enzymes (CYP450 and FMOs) in coho salmon (Oncorhynchus kisutch). Fish Physiology and Biochemistry 40:267–278.
    • Doris E. Vidal-Dorsch, Steven M. Bay, Darin Greenstein, Michael Baker, Gary Hardiman, Jesus Reyes, Kevin Kelley, Dan Schlenk, (2014) Biological responses of marine flatfish exposed to municipal wastewater effluent. Environmental Toxicology and Chemistry 33:583-591.
    • Beate Escher, Mayumi Allinson, Rolf Altenburger, Peter Bain, Patrick Balaguer, Wibke Busch, Jordan Crago, Andrew R. Humpage, Nancy Denslow, Elke Dopp, Klara Hilscherova, Anupama Kumar, Marina Grimaldi, B. Sumith Jayasinghe, Barbora Jarosova, Ai Jia, Sergej Makarov, Keith Maruya, Alex Medvedev, Alvina Mehinto, Jamie Mendex, Anita Poulsen, Erik Prochazka, Jessica Richard, Andrea Schifferli, Daniel Schlenk, Stefan Scholz, Fujio Shiraishi, Shane Snyder, Guanyong Su, Janet Tang, Bart Van Der Burg, Sander van der Linden, Inge Werner, Sandy Westerheide, Chris Wong, Min Yang, Bonnie Yeung, Xiaowei Zhang, Frederic Leusch (2014) Benchmarking organic micropollutants in wastewater, recycled water and drinking water with in vitro bioassays. Environmental Science and Technology 48:1940-1956.
    • Varenka Lorenzi, Daniel Schlenk (2014) Impacts of Combined Salinity and Temperature Extremes on Different Strains and Species of Tilapia Inhabiting the Watershed of the Salton Sea. North American Journal of Aquaculture 76:211-221.
    • Ramon Lavado, Jiwen Li, Daniel Schlenk (2014) Evaluation of the stereoselective biotransformation of permethrin in human liver microsomes: Contributions of cytochrome P450 monooxygenases to the formation of estrogenic metabolites. Toxicology Letters 226:192-197.
    • Kady Lyons, Ramon Lavado, Daniel Schlenk, Christopher G. Lowe (2014) Bioaccumulation of organochlorine contaminants and EROD activity in southern California round stingrays (Urobatis halleri) exposed to planar aromatic compounds. Environmental Toxicology and Chemistry 33:1380-1390.
    • Kristy L. Forsgren, Shen Qu, Ramon Lavado, David Cwiertny, Daniel Schlenk (2014) Trenbolone acetate metabolites promote ovarian growth and development in adult Japanese medaka (Oryzias latipes). General and Comparative Endocrinology 202:1-7.
    • Lindley A. Maryoung, Ramon Lavado, Daniel Schlenk (2014) Impacts of hypersaline acclimation on the acute toxicity of the organophosphate chlorpyrifos to salmonids. Aquatic Toxicology 152:284-290.
    • Allison Kupsco and Daniel Schlenk (2014) Mechanisms of selenomethionine developmental toxicity and the impacts of combined hypersaline conditions on Japanese medaka (Oryzias latipes). Environmental Science and Technology 48:7062-7068.
    • Fang Jia, Lian-Jun Bao, Jordan Crago, Daniel Schlenk, Jay Gan (2014) Use of Isotope Dilution Method (IDM) to Predict Bioavailability of Organic Pollutants in Historically Contaminated Sediments. Environmental Science and Technology 48:7966-7973.
    • David M. Cwiertny, Shane A. Snyder, Daniel Schlenk, and Edward P. Kolodziej (2014) Environmental Designer Drugs: When Transformation May Not Eliminate Risk. Environmental Science and Technology 48: 11737-11745.
    • Woo-Keun Kim, Sung-Kyu Lee, June-Woo Park, Kyung ho Choi, Jordan Crago, Daniel Schlenk, Jinho Jung (2014) Integration of multi-level biomarker responses to cadmium and benzo[k]fluoranthene in the pale chub (Zacco platypus). Ecotoxicology and Environmental Safety 110:121-128.
    • Jordan Crago, Kelly Tran, Anthony Budicin, Benjamin Schreiber, Ramon Lavado, Daniel Schlenk (2014) Exploring the impacts of two separate mixtures of pesticide and surfactants on estrogenic activity in male Fathead minnows and rainbow trout. Archives of Environmental Contamination and Toxicology 68: 362-370.
    • Michael E. Baker, L. James Sprague, Cataldo Ribecco, Barbara Ruggeri, Narimene Lekmine, Colleen Ludka, Ivan Wick, Laura Soverchia, Massimo Ubaldi, Roman Šášik, Daniel Schlenk, Kevin M. Kelley, Jesus A. Reyes and Gary Hardiman (2014) Application of a targeted endocrine q-PCR panel to monitor the effects of pollution in southern California flatfish. Endocrine Disruptors, 2:1, e969598, DOI: 10.4161/23273739.2014.969598.
    • Daryl Bulloch, Eric Nelson, Steve Carr, Chris Wissman, Jeff Armstrong, Daniel Schlenk, and Cynthia Larive (2015) Occurrence of halogenated transformation products of selected pharmaceuticals and personal care products in secondary and tertiary treated wastewaters from Southern California. Environmental Science and Technology 49:2044-2051.
    • Varenka Lorenzi, Ree Choe, Daniel Schlenk (2015) Effects of environmental exposure to diazepam on the reproductive behavior of fathead minnow, Pimephales promelas. Environmental Toxicology (in press).
    • Donald P. Weston, Daniel Schlenk, Navneet Riar, Michael J. Lydy, Marjorie L. Brooks (2015) Effects of pyrethroid insecticides in urban runoff on Chinook salmon, steelhead trout, and their invertebrate prey. Environmental Toxicology and Chemistry 34:649-657.
    • Lindley A. Maryoung, Brian Blunt, Keith B. Tierney, and Daniel Schlenk (2015) Sublethal toxicity of chlorpyrifos to salmonid olfaction after hypersaline acclimation. Aquatic Toxicology 161:94-101.
    • Daniel Schlenk and David E. Williams (2015) In Memorium: Donald Raymond Buhler (1925-2014) Aquatic Toxicology (in press).
    • Andréia Arantes Felício, Thiago Estevam Martins Parente, Lucilene Regina Maschio, Lílian Nogueira, Larissa Paola Rodrigues Venancio, Mauro de Freitas Rebelo, Daniel Schlenk, Eduardo Alves de Almeida (2015) Biochemical responses, morphometric changes, genotoxic effects and CYP1A expression in the armored cat fish Pterygoplichthys anisitsi after 15 days of exposure to mineral diesel and biodiesel. Ecotoxicology and Environmental Safety 115:26-32.
    • Jordan Crago and Daniel Schlenk (2015) The effect of bifenthrin on the dopaminergic pathway in juvenile rainbow trout (Oncorhynchus mykiss) Aquatic Toxicology 162:66-72.

    Courses Taught:

    • ENTX 101 Fundamentals of Toxicology
    • ENTX 208/ ENSC 208 Ecotoxicology
    • ENTX 205 Biotransformation of Organic Chemicals
    • ENSC 001 Introduction to Natural Resources
    • ENSC 191 Seminar in Professional Development

    Graduate Program Affiliations and Research Focus Areas:

    Honors and Awards

    Dr. Schlenk is a Fellow of the American Association for the Advancement of Science since 2010, and from 2007-2014, he was a permanent member of the USEPA FIFRA Science Advisory Panel which he chaired from 2012-2014. From 2003-2006, he was a member of the Board of Directors for the North American Society of Environmental Toxicology and Chemistry. He was co-editor-in chief of Aquatic Toxicology from 2005-2011, and still serves on the editorial board of Aquatic Toxicology as well as Toxicological Sciences, and Marine Environmental Research. He has been a recipient of the Ray Lankester Investigatorship of the Marine Biological Association of the United Kingdom; a visiting Scholar of the Instituto Del Mare, Venice Italy; a visiting Scholar in the Department of Biochemistry, Chinese University of Hong Kong; a Visiting Scientist at the CSIRO Lucas Heights Laboratory, in Sydney Australia, a Distinguished Fellow of the State Key Laboratory for Marine Environmental Science of Xiamen University, China, and a Visiting Professor Fellow of the National Counsel of Technological and Scientific Development at the University of Sao Jose Rio Preto, Brazil . He has been an ad hoc member for the USEPA Science Advisory Board for Aquatic Life Criteria Guidelines from the Ecological Processes and Effects Committee, and has participated in proposal review panels for the NSF, USEPA, NOAA, and the National Institute of Environmental Health Sciences.


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    University of California, Riverside
    900 University Ave.
    Riverside, CA 92521
    Tel: (951) 827-1012

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    Environmental Sciences
    Geology 2258

    Tel: (951) 827-5116
    Fax: (951) 827-3993