This PhD project at the University of Southampton investigates the mechanisms of biomineralisation in marine calcifying organisms, specifically foraminifera and coccolithophores, to understand their resilience to global environmental change. Calcifying marine organisms are crucial to the global carbon cycle, forming extensive calcium carbonate deposits on the ocean floor that serve as important geological and climate proxies. However, the cellular processes underlying calcification are not fully understood, limiting our ability to predict how these organisms will respond to future oceanic changes such as acidification and shifts in carbon availability. The research will employ advanced techniques to compare the calcification strategies of foraminifera and coccolithophores, focusing on differences in carbon allocation between photosynthesis and calcification, the impact of cell size on carbon acquisition, and the influence of microenvironmental pH on geochemical proxies like boron isotopes. The project is based at the Marine Biological Association in Plymouth and is part of the IGNITE Doctoral Landscape Award programme, which offers comprehensive training in culturing marine protists, physiological measurements, microelectrode techniques, and cryo-electron microscopy. Students will also develop transferable skills in programming, quantitative analysis, and science communication. The supervisory team brings together expertise in algal biology, paleobiology, and ocean biogeochemistry. The IGNITE programme provides a supportive, multidisciplinary environment with opportunities to engage with academic, research, and policy partners. Funding includes a 3.5-year tax-free stipend at the UKRI standard rate (£20,780 for 2025/26), full coverage of Home tuition fees, a waiver for the difference between Home and International fees, and a Research Training Support Grant of £2,200 per year. Applicants should have a UK bachelor’s degree with upper second-class honours or higher in a relevant subject, or an international equivalent. English language proficiency is required (IELTS 6.5 overall, minimum 6.0 in all components, or equivalent). Applications are open to both UK and international students, though international places are limited. The deadline for applications is 8 January 2026. Prospective candidates are encouraged to contact the lead supervisor to discuss their suitability and are advised to apply for one project to tailor their application. The IGNITE programme also offers a guaranteed interview scheme for qualifying UK applicants from racially minoritised backgrounds. For further details, see the University of Southampton’s entry requirements and language policies, and refer to the provided references for background reading on marine biomineralisation and geochemical proxies.