Please join us for the first GS/MCG seminar of the fall quarter, held at Hubbs 4500 from 1-2pm. Julia Diaz, who just joined SIO over the summer, will be giving a talk on "The biogeochemistry of phytoplankton stress: insights into marine ecosystem health and functioning". The abstract is as follows:
"Phytoplankton are vital components of the Earth system. Marine phytoplankton communities sustain half of the world’s primary productivity and oxygen supply, while contributing to the regulation of global climate through the uptake of the greenhouse gas carbon dioxide. These ecosystem services depend critically on the ability of phytoplankton to survive and thrive under challenging biogeochemical conditions that are pervasive across the surface ocean, especially nutrient limitation. Such challenges lead to phytoplankton stress responses that benefit the adaptability of these microorganisms, which in turn, further shape the biogeochemistry, health, and function of marine systems. In this talk, I will present my group’s recent work in two areas of phytoplankton stress biogeochemistry: acquisition of the essential nutrient phosphorus (P) and production of extracellular reactive oxygen species (ROS). P is present at limiting concentrations over vast areas of the surface ocean and is regarded as the ultimate limiting nutrient over geologic time, however phytoplankton strategies for coping with P scarcity are not completely understood. On the other hand, ROS are stress-response molecules that fundamentally shape biological interactions and the cycling of carbon and metals in aquatic systems. Yet even in the absence of any obvious stressor, phytoplankton generate abundant extracellular ROS, the function of which has remained mysterious. Our research on P and ROS pairs high-sensitivity geochemical measurements in model phytoplankton cultures and natural communities with targeted proteomics analysis to investigate underlying biogeochemical pathways. As I will demonstrate, this work is advancing a mechanistic understanding of ocean system health and function by defining baselines of phytoplankton stress biogeochemistry across elemental cycles and over a broad range of natural complexity, from enzymes to ecosystems."
Coffee will be provided!