Richard Connon

Richard Connon

Position Title
Associate Adjunct Professor

  • Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine
Room 3205, Vet Med 3B, 1089 Veterinary Medicine Drive, Davis, CA 95616

Profile Introduction

Dr. Connon's research focus is on the assessment of molecular responses to chemical insult, their links to higher levels of organization, and how these tools can best be used as tools for monitoring aquatic systems. His interest in water quality is both in terms of human consumption and environmental health, and currently utilizes fish models towards understanding the mechanism(s) of action of agricultural and urban contaminants. His particular interest in pesticides and pharmaceuticals in the aquatic environment, and how these can impact behavior and reproduction.

Grad Group Affiliations

  • Molecular, Cellular and Integrative Physiology

Specialties / Focus

  • Behavioral Physiology
  • Molecular Physiology

Professional Societies

  • Society for Environmental Toxicology and Chemistry (SETAC)
  • California InterAgency Ecological Program (IEP)
  • Coastal and Estuarine Research Federation (CERF)
  • California Estuarine Research Society (CAER)


  • 2003 PhD Toxicology University of Reading, UK



2017       Connon RE, Jeffries KM, Komoroske LM, Todgham AE, Fangue NA. The utility of transcriptomics in fish conservation. Journal of Experimental Biology. ** IN PRESS **.

2017       Brander SM, Biales A, Connon RE. The Role of Epigenomics in Aquatic Toxicology. Environmental Toxicology and Chemistry, 36(10): 2562-2573.

2017       Darr CR, Moraes LE, Connon RE, Love CC, Teague S, Varner DD, Meyers SA. The relationship between mitochondrial DNA copy number and stallion sperm function. Theriogenology, 94: 94-9.

2017       Frank DF, Hasenbein M, Eder K, Jeffries KM, Geist J, Fangue NA, Connon RE. Transcriptomic screening of the innate immune response in delta smelt during an Ichthyophthirius multifiliis infection. Aquaculture, 473: 80-8.

2017       Frank DF, Miller GW, Connon RE, Geist J, Lain PJ. Transcriptomic profiling of mTOR and ryanodine receptor signaling molecules in developing zebrafish in the absence and presence of PCB 95. PeerJ, 5(e4106): 10.7717/peerj.4106.

2017       Hasenbein S, Lawler SP, Connon RE. An assessment of direct and indirect effects of two herbicides on aquatic communities. Environ Toxicol Chem.

2017       Hasenbein S, Peralta J, Lawler SP, Connon RE. Environmentally relevant concentrations of herbicides impact non-target species at multiple sublethal endpoints. Science of the Total Environment, 607(608): 733-743.

2017       Hobbs J, Moyle P, Fangue N, Connon RE. Is extinction inevitable for Delta Smelt and Longfin Smelt? An opinion and recommendations for recovery. San Francisco Estuary and Watershed Science, 15(2).

2017       White JW, Cole BJ, Cherr GN, Connon RE, Brander SM. Scaling up endocrine disruption dffects from individuals to populations: Outcomes depend on how many males a population needs. Environ Sci Technol, 51(3): 1802–10.

2016       Brander SM, Gabler MK, Fowler NL, Connon RE, Schlenk D. Pyrethroid pesticides as endocrine disruptors: Molecular mechanisms in vertebrates with a focus on fishes. Environ Sci Technol, 50(17): 8977–92.

2016       Brander SM, Jeffries KM, Cole BJ, DeCourten BM, White JW, Hasenbein S, Fangue NA, Connon RE. Transcriptomic changes underlie altered egg protein production and reduced fecundity in an estuarine model fish exposed to bifenthrin. Aquat Toxicol, 174: 247-60.

2016       Brown LR, Komoroske LM, Wagner RW, Morgan-King T, Connon RE, May JT, Fangue NA. Coupled downscaled climate models and ecophysiological metrics forecast habitat compression for an endangered estuarine fish. PLoS One, 11(1): e0146724.

2016       Cole BJ, Brander SM, Jeffries KM, Hasenbein S, He G, Denison MS, Fangue NA, Connon RE. Changes in Menidia beryllina gene expression and In vitro hormone-receptor activation after exposure to estuarine waters near treated wastewater outfalls. Arch Environ Contam Toxicol, 71(2): 210-23.

2016       Fong S, Louie S, Werner I, Davis J, Connon RE. Contaminant effects on California Bay-Delta species and human health. San Francisco Estuary and Watershed Science, 14(4): 1-34.

2016       Hasenbein M, Fangue NA, Geist J, Komoroske LA, Connon RE. Physiological stress biomarkers reveal stocking density effects in late larval delta smelt (Hypomesus transpacificus). Aquaculture, 450: 108-15.

2016       Hasenbein M, Fangue NA, Geist J, Komoroske LM, Truong J, McPherson R, Connon RE. Assessments at multiple levels of biological organization allow for an integrative determination of physiological tolerances to turbidity in an endangered fish species. Conserv Physiol, 4(1): cow004.

2016       Hasenbein S, Lawler SP, Geist J, Connon RE. A long-term assessment of pesticide mixture effects on aquatic invertebrate communities. Environ Toxicol Chem, 35(1): 218–32.

2016       Hasenbein S, Lawler SP, Geist J, Connon RE. Risikobewertung von Pestizidmischungen - von standardisierten Einzelartentests zu Modell-Ökosystemen (Risk assessment of pesticide mixtures - from standardized single species tests to model ecosystems). Mitt Umweltchem Ökotox, 22(1): 8-12.

2016       Jeffries KM, Connon RE, Davis BE, Komoroske LM, Britton MT, Sommer T, Todgham AE, Fangue NA. Effects of high temperatures on threatened estuarine fishes during periods of extreme drought. J Exp Biol, 219(Pt 11): 1705-16.

2016       Komoroske LM, Connon RE, Jeffries KM, Dexter J, Hasenbein M, Verhill C, Lindberg J, Fangue NA. Sublethal salinity stress contributes to habitat limitation in an endangered estuarine fish. Evol Appl, 9(8): 963-81.

2015       Biales AD, Fritsch EB, Connon RE. In response: integration of 'omics to larger-scale watershed assessments: a mixed government/academic perspective. Environ Toxicol Chem, 34(4): 700-2.

2015       Fritsch EB, Stegeman JJ, Goldstone JV, Nacci DE, Champlin D, Jayaraman S, Connon RE, Pessah IN. Expression and function of ryanodine receptor related pathways in PCB tolerant Atlantic killifish (Fundulus heteroclitus) from New Bedford Harbor, MA, USA. Aquat Toxicol, 159: 156–66.

2015       Hasenbein S, Connon RE, Lawler SP, Geist J. A comparison of the sublethal and lethal toxicity of four pesticides in Hyalella azteca and Chironomus dilutus. Environ Sci Pollut Res Int, 22(15): 11327-39.

2015       Hasenbein S, Lawler SP, Geist J, Connon RE. The use of growth and behavioral endpoints to assess the effects of pesticide mixtures upon aquatic organisms. Ecotoxicology, 24(4): 746-59.

2015       Javidmehr A, Kass P, Deanovic LA, Connon RE, Werner I. 10-day survival of Hyalella azteca as a function of water quality parameters. Ecotoxicol Environ Saf, 115: 250-6.

2015       Jeffries KM, Brander SM, Britton MT, Fangue NA, Connon RE. Chronic exposures to low and high concentrations of Ibuprofen elicit different gene response patterns in a Euryhaline fish. Environ Sci Pollut Res Int, 22: 17397-413.

2015       Jeffries KM, Komoroske LM, Truong J, Werner I, Hasenbein M, Hasenbein S, Fangue NA, Connon RE. The transcriptome-wide effects of exposure to a pyrethroid pesticide on the critically endangered delta smelt (Hypomesus transpacificus). Endangered Species Research, 28: 43-60.

2015       Komoroske LM, Connon RE, Jeffries KM, Fangue NA. Linking transcriptional responses to organismal tolerance reveals mechanisms of thermal sensitivity in a mesothermal endangered fish. Mol Ecol, 24: 4960–81.

2014       Hasenbein M, Werner I, Deanovic LA, Geist J, Fritsch EB, Javidmehr A, Foe C, Fangue NA, Connon RE. Transcriptomic profiling permits the identification of pollutant sources and effects in ambient water samples. Sci Total Environ, 468-469: 688–98.

2014       Komoroske LM, Connon RE, Lindberg J, Cheng BS, Castillo G, Hasenbein M, Fangue NA. Ontogeny influences sensitivity to climate change stressors in an endangered fish. Conserv Physiol, 2(1): cou008.

2014       Wang G, Yang E, Smith KJ, Zeng Y, Ji G, Connon RE, Fangue NA, Cai, JJ. Gene expression responses of threespine stickleback to salinity: implications for salt-sensitive hypertension. Front Genet, 5: 312.

2013       Brander SM, Connon RE, He G, Hobbs JA, Smalling KL, Teh SJ, White JW, Werner I, Denison MS, Cherr GN. From ‘omics to otoliths: Responses of an estuarine fish to endocrine disrupting compounds across biological scales. PLoS ONE, 8(9): e74251.

2013       Fritsch EB, Connon RE, Werner I, Davies R, Beggel S, Feng W, Pessah IN. Triclosan impairs swimming behavior and alters expression of excitation-contraction coupling proteins in fathead minnow (Pimephales promelas). Environ Sci Technol, 47(4): 2008-17.

2013       Hasenbein M, Komoroske LM, Connon RE, Geist J, Fangue NA. Turbidity and salinity affect feeding performance and physiological stress in the endangered delta smelt. Integr Comp Biol, 53(4): 620-34.

2012       Beggel S, Werner I, Connon RE, Geist JP. Impacts of the phenylpyrazole insecticide fipronil on larval fish: time-series gene transcription responses in fathead minnow (Pimephales promelas) following short-term exposure. Sci Total Environ, 426: 160-5.

2012       Connon RE, D'Abronzo LS, Hostetter NJ, Javidmehr A, Roby DD, Evans AF, Loge FJ, Werner I. Transcription profiling in environmental diagnostics: health assessments in Columbia River basin steelhead (Oncorhynchus mykiss). Environ Sci Technol, 46(11): 6081-7.

2012       Connon RE, Geist J, Werner I. Effect-based tools for monitoring and predicting the ecotoxicological effects of chemicals in the aquatic environment. Sensors (Special Issue: Biosensors), 12(9): 12741-71.

2012       Durieux EDH, Connon RE, Werner I, D'Abronzo LS, Fitzgerald PS, Spearow JL, Ostrach DJ. Cytochrome P4501A mRNA and protein induction in striped bass (Morone saxatilis). Fish Physiol Biochem, 38(4): 1107-16.

2011       Beggel S, Connon RE, Werner I, Geist J. Changes in gene transcription and whole organism responses in larval fathead minnow (Pimephales promelas) following short-term exposure to the synthetic pyrethroid bifenthrin. Aquat Toxicol, 105: 180-8.

2011       Connon RE, Beggel S, D'Abronzo LS, Geist JP, Pfeiff J, Loguinov AV, Vulpe CD, Werner I. Linking molecular biomarkers with higher level condition indicators to identify effects of copper exposures on the endangered delta smelt (Hypomesus transpacificus). Environ Toxicol Chem, 30(2): 290-300.

2011       Connon RE, Deanovic LA, Fritsch EB, D'Abronzo LS, Werner I. Sublethal responses to ammonia exposure in the endangered delta smelt; Hypomesus transpacificus (Fam. Osmeridae). Aquat Toxicol, 105(3-4): 369-77.

2010       Beggel S, Werner I, Connon RE, Geist JP. Sublethal toxicity of commercial insecticide formulations and their active ingredients to larval fathead minnow (Pimephales promelas). Sci Total Environ, 408(16): 3169-75.

2009       Connon RE, Geist J, Pfeiff J, Loguinov AV, D'Abronzo LS, Wintz H, Vulpe CD, Werner I. Linking mechanistic and behavioral responses to sublethal esfenvalerate exposure in the endangered delta smelt; Hypomesus transpacificus (Fam. Osmeridae). BMC Genomics, 10: 608.

2008       Connon R, Hooper HL, Sibly RM, Lim FL, Heckmann LH, Moore DJ, Watanabe H, Soetaert A, Cook K, Maund SJ, Hutchinson TH, Moggs J, De Coen W, Iguchi T, Callaghan A. Linking molecular and population stress responses in Daphnia magna exposed to cadmium. Environ Sci Technol, 42(6): 2181-8.

2008       Heckmann LH, Sibly RM, Connon R, Hooper HL, Hutchinson TH, Maund SJ, Hill CJ, Bouetard A, Callaghan A. Systems biology meets stress ecology: linking molecular and organismal stress responses in Daphnia magna. Genome Biol, 9(2): R40.

2008       Hooper HL, Connon R, Callaghan A, Fryer G, Yarwood-Buchanan S, Biggs J, Maund SJ, Hutchinson TH, Sibly RM. The ecological niche of Daphnia magna characterized using population growth rate. Ecology, 89(4): 1015-22.

2007       Heckmann LH, Callaghan A, Hooper HL, Connon R, Hutchinson TH, Maund SJ, Sibly RM. Chronic toxicity of ibuprofen to Daphnia magna: Effects on life history traits and population dynamics. Toxicol Lett, 172(3): 137-45.

2006       Heckmann LH, Connon R, Hutchinson TH, Maund SJ, Sibly RM, Callaghan A. Expression of target and reference genes in Daphnia magna exposed to ibuprofen. BMC Genomics, 7: 175.

2006       Hooper HL, Connon R, Callaghan A, Maund SJ, Leiss M, Duquesne S, Hutchinson TH, Moggs J, Sibly RM. The use of image analysis to estimate population growth rate in Daphnia magna. J Appl Ecol, 43: 828-34.

2005       Dewhurst RE, Callaghan A, Connon R, Crane M, Mather JD, Wood R. Toxicity testing of groundwater quality. Water Environ J, 19: 17-24.

2003       Connon R, Dewhurst RE, Crane M, Callaghan A. Haem peroxidase activity in Daphnia magna: a biomarker for sub-lethal toxicity assessments of kerosene-contaminated groundwater. Ecotoxicology, 12(5): 387-95.

2003       Dewhurst RE, Wells NC, Crane M, Callaghan A, Connon R, Mather JD. Multivariate relationships between groundwater chemistry and toxicity in an urban aquifer. Environ Toxicol Chem, 22(11): 2813-21.

2003       Sheehan P, Dewhurst RE, James S, Callaghan A, Connon R, Crane M. Is there a relationship between soil and groundwater toxicity? Environ Geochem Health, 25(1): 9-16.

2000       Amoros I, Connon R, Garelick H, Alonso JL, Carrasco JM. An assessment of the toxicity of some pesticides and their metabolites affecting a natural aquatic environment using the Microtox system. Water Science & Technology, 42(1): 19-24.