Ms Jacqui Stuart1,3, Dr. Natalie Robinson1,2, Dr. Craig Stewart2, Dr. Kirsty Smith3, Dr. John Pearman3, Dr. Svenja Halfter2, Prof. Ken Ryan1
1Victoria University Of Wellington, Wellington, New Zealand, 2National Institute of Water and Atmospheric Research (NIWA), Wellington, New Zealand, 3Cawthron Institute, Nelson, New Zealand
Biography:
Jacqui is a Research Assistant and PhD student at the Cawthron Institute and Victoria University of Wellington. She specialises in exploring the ecological and molecular responses of microalgae to environmental stressors associated with climate change, with a particular focus on Antarctica. Utilizing environmental DNA (eDNA) and advanced molecular tools, Jacqui investigates the diversity and composition of sea and platelet ice communities and examines how these may shift with changing ice conditions. Her work aims to address the complex challenges posed by climate change and enhance our understanding of the crucial role marine microalgae play in the ecosystem. Jacqui is also passionate about science outreach and communication, striving to engage audiences beyond the scientific community and foster a deeper appreciation for the importance of microalgae in marine ecosystems.
Abstract:
Changes in microalgal community composition and biomass are increasingly observed in aquatic ecosystems due to climate change. In 2022, southerly storms in McMurdo Sound led to the formation of landfast sea ice in late August rather than the usual late March. This created a unique opportunity to study Antarctic eukaryotic microalgal community (EMC) composition, diversity, and biomass under unusual conditions: congelation sea ice of normal thickness (~2m) and newer, thinner ice (~1m). A substantial sub-ice platelet layer (SIPL) existed beneath both types of ice, measuring 2-3 m under normal ice and 0.5-1 m in thinner ice. Sea ice core samples and SIPL cores were collected using a coring drill and a novel platelet layer sampling system that preserved the platelet ice structure. EMCs were assessed through chlorophyll-a measurements, cell concentrations, and high-throughput sequencing metabarcoding of environmental DNA samples. Analysis showed that biomass was highest at the congelation ice/SIPL interface in normal ice, while peak biomass under thinner ice was found in the platelet layer about 0.25 m below this interface. Total integrated biomass across the ice/SIPL column was greatest in thin ice. Significant differences were observed in dominant microalgal species between new and normal congelation and SIPL environments, with polar centric diatoms prevalent in thick SIPL environments and pennate diatoms dominating in thinner ice. As climate change progresses, later sea ice formation and thinner ice are expected, impacting EMC biomass, community composition, and diversity, which will affect all organisms reliant on these primary producers.