Heshani Pupulewatte, a graduate research assistant in the Department of Chemistry and Chemical Biology, has already accomplished so much. She’s revealing how iron deficiency is damaging photosynthesis in the ocean’s key algae. Pupulewatte, the lead author of a new study, spent up to a month researching on board a British research vessel. This ship will spend 37 days transiting the South Atlantic and Southern Ocean in late 2023 and early 2024. Her ongoing research reveals how critical iron availability is to commercial marine phytoplankton. These important organisms play a huge role in regulating global carbon cycling.
During her six weeks at sea, Pupulewatte took hands-on samples of the water, using a CTD to measure conductivity, temperature, and depth. These samples were crucial for her groundbreaking analysis of the effects of iron deficiency on photosynthetic processes. Utilizing custom fluorometers designed by Max Gorbunov from the Falkowski Lab, she tested the samples for fluorescence – a measure of energy re-released by phytoplankton during photosynthesis.
Research Journey and Methodology
Pupulewatte’s research adventure started in the Southern Atlantic Ocean. She took an exciting journey along a long line, going from a point on the South African coast to the marginal ice zone of the Weddell Gyre and back again. This strategy allowed her to gather critical information. Finally, it will improve our fundamental understanding of the drivers of oceanic photosynthesis and how these drivers are changing under global climate change.
Onboard the research vessel, Pupulewatte took great care in collecting these water samples at three different depths. Combined with the data she collected during her field study, this data furthered our understanding of how changes in iron concentrations can influence the photosynthetic efficiency of phytoplankton. She combined fluorometers that specified and quantified fluorescence to a high degree. This gave a more complete view of how these organisms use light energy.
So once again, her research uncovered an incredible finding. Iron deficiency can result in the uncoupling of up to a quarter of light-harvesting proteins from energy-generating centers within phytoplankton. This uncoupling reduces the overall efficiency of photosynthesis and underscores the important role that iron has in marine ecosystems.
Implications of Iron Deficiency Research
The real-world effects of Pupulewatte’s research go well beyond an element of scholarly interest. Knowledge of how iron deficiency affects photosynthesis is critical. It allows us to better understand how climate change may be affecting ocean circulation and deposition of iron. Phytoplankton make a valuable contribution as primary producers in marine ecosystems. Their capacity to perform photosynthesis at high rates makes them major players in global carbon cycling and climate regulation.
Pupulewatte’s research highlights the precarious equilibrium found in oceanic ecosystems and the potential impacts of nutrient scarcity. At the same time, climate change is increasing the acidity and temperature of the ocean. Her work has provided important contributions to understanding how these changes will affect marine organisms and thus help shape the planet’s global climate.
Her findings have been published in a study available at DOI: 10.1073/pnas.2511916122. The publication underscores the significance of her work in advancing scientific understanding of marine phytoplankton photosynthesis and its susceptibility to environmental changes.