Using Silicon Isotopes to Trace the Biogenic Silica in the Southern Ocean ...

• Main Author: Devi, Riteshma
• Format: Thesis
• Language: English
• Published: The Australian National University 2023
• Subjects: Southern Ocean
• Online Access: https://dx.doi.org/10.25911/s1g1-qj28; https://openresearch-repository.anu.edu.au/handle/1885/307334

The diatoms, a unique group of primary producers, are inextricably linked to the marine silicon (Si) and carbon (C) cycles. Diatoms are regarded as unicellular, eukaryotic organisms that form biogenic silica (bSi) frustules. The use of stable isotopes and physicochemical factors (temperature, light, and trace metal) provides a promising method for understanding how Si and C fluxes will change in response to future climate change. The Si cycle in the Southern Ocean was investigated using an isotopic approach in incubation experiments and the natural environment. This study provides new measurements of the Si isotope composition of biogenic silica in a natural phytoplankton community and for multiple species isolated from the Southern Ocean and grown within a laboratory setting. During the annual phytoplankton bloom in the austral spring of 2018, a field study was conducted. This study compared high productivity during an austral spring bloom in the East Australian Current (EAC) to low productivity in the ...