The School of Earth and Atmospheric Sciences Presents Dr. Julia Diaz, Scripps Institution of Oceanography, University of California San Diego

Friend or Foe?  Interrogating the Ecophysiology of Reactive Oxygen Species (ROS) in Marine Systems

Reactive oxygen species (ROS) are ubiquitous in seawater due to widespread production by microbes and abiotic photochemical reactions.  ROS are often assumed to be toxic molecules, causing harm through oxidative stress.  However, growing evidence also shows that ROS play a range of beneficial signaling functions in diverse organisms.  For example, production of extracellular ROS by model marine phytoplankton has been implicated in growth, cellular redox homeostasis, as well as biological interactions such as grazing and allelopathy.  In these ways, ROS infochemistry has the potential to shape both bottom-up and top-down controls on marine productivity and carbon cycling.  In this talk, I will present recent work showing how biological ROS production supports the vitality of marine phytoplankton, and I will discuss implications for marine ecosystem health and functioning.