PhD Proposal Defense: Carly Moreno

The PhD Proposal Defense of Carly Moreno is presented by the Department of Marine Sciences. The main location of this event will be in room 3204 on the 3rd floor of Murray/Venable Hall on UNC campus in Chapel Hill, NC. The defense will be streamed live to room 222 at IMS in Morehead City, NC. This event will be held on Monday, January 14th, at 10:00 AM.

Title:  Iron and light: Coupled physiology and transcriptomic analysis of iron and light limitation in Southern Ocean diatoms

Abstract: Diatoms are an ecologically important group of Southern Ocean phytoplankton forming the base of the polar marine food web and significantly contributing to carbon and silica export. Changes in their physiological status can alter their growth, productivity, and elemental stoichiometry, and consequently affect food web dynamics and the efficiency of the biological pump. Iron and light availability are predicted to be two abiotic factors that control diatom physiology and productivity. Previous research has shown differences in how diatoms from temperate and polar regions adapt to low iron bioavailability and low light levels. Therefore, a better understanding of the ecological importance of iron and light limitation on Southern Ocean diatom molecular physiology is needed to decipher the role of diatoms in polar ocean ecology and biogeochemistry. By coupling laboratory methods and transcriptomic techniques, my dissertation will shed light on the physiology, metabolism, and genes within ecologically relevant diatom isolates and natural diatom assemblages from the Western Antarctic Peninsula (WAP). The focus of the first two chapters of my dissertation are to investigate the molecular underpinnings of a Southern Ocean diatom, Fragilariopsis kerguelensis, to differing iron availability and irradiance levels, and to understand how the elemental and biochemical composition of four Southern Ocean diatom species changes in low iron conditions. The focus of the third chapter is to investigate the ecological importance of iron and light limitation on the physiology of natural diatom communities along the WAP and to create potential molecular indicators for iron and/or light limitation. I will use metatranscriptomics and nutrient manipulation experiments to determine diatoms community molecular physiology along a natural iron gradient and investigate the potential for iron and light-co-limitation within natural phytoplankton assemblages along the WAP. This research will provide new insights on the physiological response of WAP diatoms to variations in iron and light availability and their potential effects on ecosystem processes, krill abundance, and carbon export.