Is evolution of calcareous phytoplankton related to shallow marine carbonate system dynamics?

IOPD Expedition 359, Sea Level, Currents, and Monsoon Evolution in the Indian Ocean will be investigating the Maldives Ridge which stretches southward through the Indian Ocean as a double chain of coral atolls. These atolls lie along a volcanic ridge which formed over a mantle hotspot as the Indian plate moved northwards. As the ridge cooled it subsided to be replaced at the surface by the string of atolls and between them deeper troughs.Within these troughs vast thicknesses of carbonate sediments derived from the ridge have built up intermixed with open ocean sediments.

These sediments provide a unique opportunity to examine the relationships between open ocean planktonic carbonates and shallow marine carbonates - which normally are difficult to compare. This project seeks to exploit this opportunity to see whether there are any consistent correlations between changes in the pelagic carbonate producing coccolithophores and the shallow marine carbonate system. If such correlations do occur it will provide strong evidence that abiotic factors such as temperature and sea water chemistry have strong influences on large scale evolution of these systems. Conversely if no such linkages can be observed it will cal into question the degree to which changes in for instance coccolithophore abundance or calcification are interpreted as being caused by abiotic factors.

The great thicknesses of the successions also mean that intervals of abrupt change in plankton assemblages can be studied at higher resolution than is normally possible. This will provide the opportunity to test if such changes are caused by environmental events. The project will specifically focus on size variation in the dominant group of coccolithophores the reiticulofenestrids. This group shows a long term size reduction but this is formed of series of abrupt size reduction events separated by extended intervals of size increase. This will be the first time the set of size reduction events from the middle Miocene to the recent have been studied systematically in one place as well as testing to see if they correlate with change in environmental proxies or changes in the shallow marine carbonate system.

The proposed research will test the hypothesis that large scale patterns in calcareous nannofossil evolution have been controlled by global environmental change by investigating whether they have any parallels in shallow marine carbonate systems. Clearly the results will be of immediate relevance to nannofossil specialists and we will publish the results in suitable specialist journals. They also, however, will be of interest to a broader community of scientists interested in global environmental change and the way it impacts the biosphere.
To maximise the impact for this broader group of beneficiaries we will prepare a review paper on secular changes in nannoplankton assemblages through the Neogene to modern interval. This will cover the various types of signal which have been observed or suggested to occur through the interval - decrease in diversity, decrease in size and degree of calcification, decrease in contribution to carbonate fluxes. For each of these the ways in which trends have been measured will be discussed as well as critical analysis of the putative trends. The suggested causes of such patterns will then be reviewed - including global cooling, change in CO2 levels and oceanic pH, change in calcium concentration, competition between phytoplankton groups. This review will provide a framework for informed assessment of the record of change of coccolithophores, complimenting our primary research on an aspect of it. We will also present talks on this at suitable meetings.

Public knowledge transfer activities - the IODP has a strong program of shipboard educational activities (http://www.iodp.org/how-you-can-participate). The researcher, Jeremy Young, has a strong interest in such activities - he edited blogs on previous cruises (e.g. http://www.antarcticoacruise.org.uk ) and has played a lead role in the Lyme Regis Fossil Festivals (http://fossilfestival.com/programme/home). He will actively work with the educators on ship and seek to develop some post cruise follow up activities. He will also give talks on the shipboard experience at the Lyme Regis Fossil Festival 2016, and as part of UCL's Grant Museum of Zoology's educational program.

Nannotax. Our major knowledge transfer project is Nannotax (http://ina.tmsoc.org/Nannotax3), which was funded by a previous NERC grant knowledge transfer grant. This provides web-based documentation of nannofossil taxonomy and biostratigraphy. Google analytics on the site has ca 1300 user sessions a week, of average duration 13 minutes which supports our anecdotal evidence that the site is extensively used by a range of end users - from highly experienced experts to students first learning nannofossils and non-palaeontologists. We will use results from the project to support the project - particularly through producing high quality light microscope images of Neogene nannofossil taxa. We will also use the cruise to test how well it meets the need of shipboard scientists and determine how it can be modified to better meet these needs.