Johann Lopez

My doctoral research focuses on the potential of metal-containing aerosols deposited on the ocean surface to alter the structure and distribution of microscopic plant (microalgae) communities. These organisms account for large fractions of global carbon fixation, and their abundance is tightly regulated by environmental variables. By observing how these organisms respond to different ‘metal environments’ that can be simulated in the laboratory, it is my hope to be able to improve models describing microalgae distributions in the context of metal availability.


While most work involving phytoplankton and metal availability is framed from the perspective of metal-limitation, my work looks at the gradient from limitation to toxicity that can be realized under certain environmental conditions related to total metal content, water stratification, and temperature. Copper is the particular metal of interest because there exists abundant literature showing reduced growth of microalgae following natural and simulated copper deposition from atmospheric aerosols. This reduction in growth is caused by the copper-catalyzed production of hydroxyl radical, and different species show different toxicity thresholds. By closely controlling the chemical profile of the media used to grow a phytoplankter, it is possible to determine the threshold at which a metal nutrient, like copper, transitions from limiting, to saturating, to toxic levels. This information can then be used to determine which organisms might outcompete others in different environmental regimes, and how/where that competition for shared resources may determine their co-existence or dominance. My doctoral research is funded by a UCI Bridge to the Doctorate Fellowship and a Graduate Research Fellowship from the National Science Foundation.