Coupling shell growth and geochemistry in giant clams to explore biomineralization pathways

This PhD looks to use an interdisciplinary approach to explore the fundamental controls of Tridacna shell growth and biomineralization by examining several shell specimens from diverse reef environments in Sabah. Reefs from Sabah are part of the Coral Triangle, the region with the highest marine biodiversity on Earth. Under the current global change scenario, it has been hypothesized that turbid reefs maybe more resilient to bleaching events, therefore they may act as refugia habitats that could potentially support the conservation of clear-water reefs in the long term. Besides coral biodiversity studies, it is fundamental to incorporate other key reefal taxa, such as giant clams, to better understand environmental responses of biota to temperature and light controls. This approach will use advancing imaging and mineralogical techniques such as Scanning Electron Microscopy (SEM), Confocal Laser Scanning Microscopy (CLSM), and Electron Backscatter Diffraction (EBSD) to examine shell growth, microstructure and mineralization pathways of giant clams from turbid and clear water environments in Borneo. Alongside this, the student will use isotope ratio mass spectrometry and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) analysis on recently living Tridacna shells to generate geochemical proxy records (d18O, Sr/Ca, , Ba/Ca) to reconstruct environmental changes in both turbid and clear-water environments. These reconstructions will aid in deciphering how environmental stressors impact marine sessile organism and their ability to calcify. In addition to exploring the modern shell collection, the student will also utilize the fossil collection to determine if similar biomineralization features persisted under different environmental conditions.