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

Lead Research Organisation: University College London
Department Name: Earth Sciences

Abstract

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.

Planned Impact

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.

Publications

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Christian G. Betzler, Gregor P. Eberli, Carlos A. Alvarez Zarikian, And The Expedition 359 Scientists Including Young, J. (2016) Maldives Monsoon and Sea Level in International Ocean Discovery Program Preliminary Report

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Archontikis, O.A. (2020) Extant Ceratolithus cristatus life-cycle observations and taxonomic simplification in Journal of Nannoplankton Research

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L├╝dmann T (2018) Carbonate delta drift: A new sediment drift type in Marine Geology

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Young J (2021) Nannofossil palaeoecology of Lower Miocene sapropels from IODP Expedition 359, the Maldives in Palaeogeography, Palaeoclimatology, Palaeoecology

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Betzler, C., Eberli, G.P., Alvarez Zarikian, C.A., And The Expedition 359 Scientists Including Young, J. (2017) Maldives Monsoon and Sea Level in Proceedings of the International Ocean Discovery Program

 
Description The sediment record recovered from IODP expedition 359 to the Maldives has ben used to study and compare two key intervals of abrupt global change in dominant calcareous phytoplankton: the Late Miocene disappearance of large Reticulofenestra pseudoumbilicus and Early Pleistocene extinction of Gephyrocapsa lumina. The two events are shown to have multiple similarities in terms of pattern and timing of change and to have been major drivers of the longer term pattern of evolutionary change within the group. However, neither event can be correlated with an external environmental driver. This implies that internal red queen dynamics may have played a major role in long term change in calcareous phytoplankton, as opposed to or in addition to environmental drivers.
Exploitation Route The findings are primarily of interest for research on biosphere responses to environmental change. A major decrease in calcification by calcareous phytoplankton, primarily coccolithophores, occurs during the Neogene and Quaternary and this has attracted considerable interest in terms of its causes and consequences our findings will provide a new focus for this study.
A secondary application of the results is within the field of biostratigraphy (dating of rocks) as applied within the petroleum sector. Our results demonstrate the value of this style of event for biostratigraphy and the need for quantitative studies in order to identify them.
Sectors Energy,Environment

 
Description Palaeontological and stratigraphic data on calcareous nannofossils gathered during this award have been published in the literature and added to the open access online database Nannotax (https://www.mikrotax.org/Nannotax3/index.php?dir=Coccolithophores). Taxonomic and stratigraphic information of this kind is widely used in the applied biostratigraphy industry.
First Year Of Impact 2017
Sector Energy,Environment
Impact Types Economic

 
Description Lyme Regis Fossil Festival talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Public talk at Lyme Regis Fossil Festival in Spring 2015 with Tom Dunkley-Jones on the IODP programme and specifically on leg 359 which I participated on later in the year.
Year(s) Of Engagement Activity 2015
 
Description Shipboard presentations during IODP expedition 359 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact During IODP expedition 359 I regularly supported the education officers, Michelle Darrieu and Juliet Crowley in video link presentations to school groups, participating in about 15-20 presentations during the cruise. I also was lead scientist on a Reddit AMA (ask me anything) session.
Year(s) Of Engagement Activity 2015
URL https://www.reddit.com/r/science/comments/3ttqut/science_ama_series_scientists_are_on_board_the_rv/