Contribute to our understanding of the ocean’s feedback mechanisms on atmospheric CO2 through application of molecular tools to investigate the genetic control of calcification in marine organisms.
Rapid climate change due to anthropogenic CO2 emissions is having a substantial impact on the marine system. This is particularly true for organisms which calcify, as ocean acidification (OA) progressively challenges their ability to produce their calcium carbonate shells. This biogenic production, surface fluxes to depth, and deep-sea burial of calcium carbonate are all key processes in the global marine carbonate cycle with a combination of the first two providing an important feedback to atmospheric CO2.
The impact and sensitivity to future climate change (ocean warming, acidification and de-oxygenation) varies between calcifying organisms1 (foraminifera, coccolithophores and pteropods) due to strong organismal (and hence genetic) control of calcification. This means that we urgently need a better understanding of the genetic response to climate change, and the likely shifts in relative contributions of marine calcifiers to production, export, and burial, if we are to understand how these different groups will feed back on atmospheric CO2 in the future.
This project will focus on a key calcifying taxon, foraminifera. Foraminifera calcify across all marine and coastal habitats, from pole to pole. They buffer ocean carbonate chemistry by shell dissolution at depth and can contribute over 40%2 of the carbonate buried at the seafloor.
Cellular mechanisms of calcification in foraminifera include seawater vacuolization, transmembrane ion transport, carbon-concentrating mechanisms, and nucleation-promoting organic templates. All are key to understanding foraminiferal calcification, and its evolution and adaptability to a changing climate. One of the few foraminiferal species whose calcification mechanisms have been intensively investigated is the intertidal sediment-inhabiting benthic foraminifer Ammonia sp. T63. This species is also easily accessible, abundant, and cultured in the lab, making it an ideal model system for the first investigation of the calcification genes in foraminifera.
The genome and transcriptome of Ammonia sp. T6, is currently being sequenced in the laboratory of Dr Clare Bird, and this PhD project will involve analysis of this genetic information and aims to identify key calcification genes and their transcriptional control using molecular tools for DNA and protein analyses.
The direction of this project is flexible, but it is anticipated that the genetic information gained in the benthic species can be applied to investigate calcification in planktonic foraminifera, with the opportunity to gain experience in marine sampling off the coast of Chile, or Oregon, USA.
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An SEM image of the benthic foraminifera Ammonia sp. T6.