Present research focuses on the characterization, development and application of sublethal indicators of pollutant and temperature effects to assess deleterious effects in fish (Chinook salmon, steelhead trout, medaka, Sacramento splittail) and invertebrates (clams, insect larvae, crustaceans). Field and laboratory investigations for my projects are designed to investigate the relationship of acute versus chronic effects of toxic compounds or temperature stress in aquatic organisms by measuring a combination of conventional toxicity test endpoints and cellular and biochemical responses. In addition, we study the bioavailability and toxicity of sediment and DOM bound contaminants.

One area of emphasis has been the investigation of stress proteins (hsp70, hsp60, hsp90) as indicators of exposure and/or effect in various fish, bivalve, insect and amphipod species. Stress proteins are involved in cellular protein synthesis, transport and repair, and play an important role in cellular receptor activation. Their cellular functions make them a good candidate as an indicator of cellular protein damage and receptor related disruptions, caused by the action of xenobiotic compounds or physical stressors such as pH or temperature changes. In addition, we have studied developmental aspects of stress protein expression in fish (medaka, Oryzias latipes) and their relationship to temperature tolerance. This research is important for the understanding of when a particular organism is most susceptible to physiological insult. Ultimately, such cellular endpoints will only be meaningful tools in aquatic toxicology if they can be linked to deleterious effect at the organism or population level. In the case of biomarkers, this means linking biological effects at the cellular level to tissue alterations, individual organism and population responses.

My work at UC Davis includes several collaborative projects with the UC Davis - Aquatic Toxicology Laboratory. The Aquatic Toxicology Laboratory performs standard bioassays to measure toxicity in ambient water samples. This work links my interest in applied research with the more fundamental questions posed in biomarker research. Components of this research include aquatic monitoring studies to assess impact and efficacy of alternative pest control methods in the Sacramento/San Joaquin watershed, MTBE toxicity to freshwater organisms, and the effect of urban stormwater runoff on aquatic life.

Other areas of interest are the influence of metabolic energy reserves on cellular stress responses, the effect of temperature change due to global warming on the distribution of temperature sensitive species, and the effect(s) of multiple stressors on aquatic organisms.