The role of marine plankton in the Earth's chemistry

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Project BackgroundIn 2014 the IPCC stated that "natural global climate change at rates slower than current anthropogenic climate change caused significant ecosystem shifts and species extinctions". There is growing concern what impact this rapid climate change has on marine ecosystems and the services these provide to humans.Marine calcifying plankton have an amazing fossil record of more than 100 million years. Interestingly, the composition of marine carbonates evolved from a coccolithophore dominated ooze to a balance between foraminiferal (marine protist) and coccolithophore. This project aims to assess 1) the link between oceanography and evolution in changing this carbonate factory; 2) modern drivers of carbonate production 3) and vulnerability of carbonate production in response to changing climate. You will use the geological record and an Earth system model to determine the environmental and ecological drivers behind this change and whether there is a tipping point beyond which marine plankton cannot deal with the impact of climate change.Project Aims and Methods.The aim of the project is to test the hypothesis that environmental change will reduce carbonate production by marine plankton in the future. Laboratory experiments are impossible to conduct which would consider timescales of adaptation and the complexity of plankton ecology and diversity. Therefore, this project will use a combination of the geological record of biotic response to several environmental perturbations and its impact on the carbon cycle with Earth System modelling. You will, jointly with the supervisors, identify the most promising events and generate size records across events. You will (1) determine the impact of abiotic versus biotic drivers on the long term composition of marine carbonates. You will (2) use a novel a size structure trait-based plankton model within an Earth system model of these historical time intervals to disentangle different drivers of change. You will (3) use the model to quantify how traits might change across the transitions (4) compare modelled changes in traits to evidence from geological record. You will consider environmental pressures under different futures and develop projections of how carbonate production might change in response. The labs in Bristol and Exeter have automated microscopes, flow cytometers, and SEMs for size analysis of coccoliths.