Aquatic Health Program

Graduate Students

Photo: Krista Callinan, Ph.D. Candidate

Krista Callinan, Ph.D. Candidate

I am a PhD candidate in the graduate group of Pharmacology and Toxicology. My background is in Ecology and my current research is focused on the toxic effects and interactions of aquatic contaminants in mixtures. I am specifically interested in contaminants that are commonly found at toxic concentrations in water bodies throughout the Central Valley and Sacramento/San Joaquin Delta (and world-wide), including organophosphate and pyrethroid pesticides, copper and ammonia. I measure lethal, sub lethal and biochemical endpoints and employ multiple statistical methods including ANOVA, factorial ANOVA, model fitting and multiple logistic regressions. Results from this work will be used to inform water quality regulations in the Sacramento-San Joaquin Delta and its tributaries for the protection of resident species. I hope to further conduct research in this area by incorporating cross-species comparisons of contaminant interactions, further biochemical analysis to better understand the underlying mechanisms of interactions, and the analysis of other environmental factors, such as physical stressors, for effects on contaminant mixture toxicity.


Photo: Sarah Lesmeister, Ph.D. Candidate

Sarah Lesmeister, Ph.D. Candidate

My research focuses primarily on the non-target effects of pesticides on zooplankton communities in the San Francisco Estuary (SFE).  I am interested in species-specific differences in sensitivities to pyrethroid and organophosphorus pesticides to the calanoid copepods, Eurytemora affinis and Pseudodiaptomus forbesi. These copepod species are considered important prey items for threatened and endangered fish species in the SFE. In addition to determining the median lethal concentration of key pesticides on E. affinis and P. forbesi, I am testing the toxicity of ambient delta waters to determine which combinations of pesticides cause the most toxicity. My future research will determine how changes in abiotic factors, specifically temperature and pH, will effect the toxicity of pesticides to E. affinisand P. forbesi.


Curriculum Vitae (pdf)

Photo: Ida Flores, Ph.D. Candidate

Ida Flores, Ph.D. Candidate

I am a graduate student in both Pharmacology and Toxicology. My research involves investigating the effects of Triclocarban, TCC, an ingredient in pharmaceutical care products, on the fish model, Japanese medaka. I’m interested in using molecular biology and histopathological techniques to find biomarkers of toxicity after exposure to TCC.  Recently published data from my work and collaboration with the Dr. Bruce Hammock's lab, has indicated that medaka bioaccumulate TCC immediately to achieve a steady concentration within the body when exposed to 20 µg/L of TCC. My future goal is to determine endocrine disrupting effects on medaka by looking at developmental changes due to chronic exposure to TCC.


Photo: Wilson Ramirez Duarte, Ph.D. Candidate

Wilson Ramirez Duarte, Ph.D. Candidate

As a graduate student in the Pharmacology and Toxicology program my research focuses on how acidic and aluminium-rich water can influence the toxicity of certain oil components in freshwater fish using the medaka as a model. In Orinoquia Region in Colombia, where there is a lot of oil exploitations, wastewater from drilling oil wells containing NaCl, vanadium, nickel, arsenic, chromium, lead, mercury, toluene, xylene, phenol, naphthalene among other compounds is discharged on rivers, creeks and land. The land is mildly acidic and has high concentration of Aluminium. My research will contribute to establish safe levels of specific compounds found in wastewater from oil exploitations for aquatic ecosystems in the context of Orinoquia Region in Colombia.


Curriculum Vitae (pdf)

Photo: Kristen Guggenheim, Ph.D. Student

Kristen Guggenheim, Ph.D. Student

I am a first year graduate student in the Agricultural and Environmental Chemistry graduate group.  I received my bachelors of science in biology at Purdue University, focusing in biochemistry and endocrinology.  I am interested in studying the effects of fipronil on endocrine function in the fish species, Japanese Medaka. Fipronil is a pesticide used for crop treatment and can be found in various flea and tick pet medications.