Periodic Reporting for period 4 - ALKENoNE (Algal Lipids: the Key to Earth Now and aNcient Earth)
Berichtszeitraum: 2019-10-01 bis 2021-03-31
The first part of the ALKENoNE project focused on developing algal (alkenone, long-chain diols) and bacterial/archaeal (tetra ethers) as proxies for temperature and/or other environmental parameters in the Canadian Prairies. Through the work of one post-doctoral research associate and two PhD students, we have successfully related alkenones and diols to temperature change in the prairies and GDGTs to salinity and anoxia. In the final phase of the project we reconstructed past temperatures and hydrological changes over the last 8,000 years using lake sediments as archives of change. We collected 8 sediment cores across the Saskatchewan prairies from which we have developed accurate, high-resolution age models, validating our proxy calibrations and generating long-term data. These data provide the first long-term (2,000 to 8,000 year long) records of change from the region where traditional proxies are limited due to high evaporative regimes that prevent tree growth (no tree-ring records) and creates unusual lake chemistries (high concentrations of evaporite minerals) that stress organisms and/or overprint other environmental signals.
This work is the first to develop quantitative temperature and salinity records dating before human instrumental records. We determined the response and resilience of lake and catchment ecosystems to environmental change through periods of known extremes, such as the Dust Bowl Drought (1930's) and the Little Ice Age. This work can inform land managers about the potential severity of future droughts and temperature extremes and the ecosystem's ability to adapt to these changes.
We have addressed the knowledge gap of what temperature extremes the Northern Great Plains experienced in the past 8,000 years, and assessed how common rapid rates of change associated with modern climate change were in the past. We have isolated, cultured and developed temperature calibrations from haptophytes in the N Great Plains. We have applied these calibrations to new downcore reconstructions of climate. Our latest results PhD Thesis: Zwick (2021) Recording high-resolution changes in temperature and hydrology in the Canadian Prairies – proxy development and application (publication in preparation) shows that during the Holocene periods of transition exhibit high-resolution, variability (at annual time-scales) leading up to and following the transition. Periods of stabilisation and reductions in extreme events can take up to 150-years, which may have implications for modern climate change. In particular, this behaviour is seen across the mid-Holocene transition, where the standard deviation in temperature values, inferred from alkenone biomarkers that were analysed at ultra high-resolution (using MALDI-FTIR/TOF-MS) fluctuate with both warm and cold extremes (±6 degrees C from the norm) before stabilising.
This work is the first to develop quantitative temperature and salinity records dating before human instrumental records. We determined the response and resilience of lake and catchment ecosystems to environmental change through periods of known extremes, such as the Dust Bowl Drought (1930's) and the Little Ice Age. This work can inform land managers about the potential severity of future droughts and temperature extremes and the ecosystem's ability to adapt to these changes.
We have addressed the knowledge gap of what temperature extremes the Northern Great Plains experienced in the past 8,000 years, and assessed how common rapid rates of change associated with modern climate change were in the past. We have isolated, cultured and developed temperature calibrations from haptophytes in the N Great Plains. We have applied these calibrations to new downcore reconstructions of climate. Our latest results PhD Thesis: Zwick (2021) Recording high-resolution changes in temperature and hydrology in the Canadian Prairies – proxy development and application (publication in preparation) shows that during the Holocene periods of transition exhibit high-resolution, variability (at annual time-scales) leading up to and following the transition. Periods of stabilisation and reductions in extreme events can take up to 150-years, which may have implications for modern climate change. In particular, this behaviour is seen across the mid-Holocene transition, where the standard deviation in temperature values, inferred from alkenone biomarkers that were analysed at ultra high-resolution (using MALDI-FTIR/TOF-MS) fluctuate with both warm and cold extremes (±6 degrees C from the norm) before stabilising.
Since the beginning of the project, we have established a framework of environmental statistical analysis that can be applied not only to testing the correlation of alkenones, but any biomarkers, with the large, environmental meta-dataset that is a unique asset to this project (Plancq et al. 2018). We have for the first time, shown through generalised linear models which environmental parameters affect the presence and absence of the haptophyte algae that produce alkenones, creating a testable hypothesis that can now be applied more globally (Plancq et al. 2018). This analysis also shows which environmental parameters lead to the highest production of alkenones and may have algal biofuel implications that can be followed up in future work. We have genetically identified the haptophyte species present in the Northern Great Plains lakes, namely two Group II haptophytes and one Group I haptophyte, and identified appropriate existing calibrations that can be applied to downcore records. With our Japanese colleagues and Steering Group member, Professor Shiraiwa, we have isolated 6 new haptophyte algal strains, grown them in cultures and performed temperature experiments to develop bespoke temperature calibrations for not just known indices, but have also created new indices that are temperature sensitive using the full suite of alkenone homologues and associated molecules (Ariae et al. 2018). These new calibrations have been employed down core for Lake Success and Last Mountain Lake, and in particular, the newly developed UK38 calibration for the Lake Success haptophyte isolate provides a novel applied calibration for a site where validation of the traditional UK37 cannot be used. This work is in preparation for publication, but awaiting final radiocarbon dates. It is currently contained in PhD Thesis: Zwick (2021) Recording high-resolution changes in temperature and hydrology in the Canadian Prairies – proxy development & application. For the final period we are applying these proxies to reconstruct long-term changes. We have presented our work at a number of international conferences, including AGU 2016, 2017, 2018, 2019; Goldschmidt 2017, 2018, and EGU 2018. We also had the opportunity to give an invited seminar at the US-Japan Research Institute in Washington DC (Dec. 2018) that was aimed at using the networks that USJI has in DC to reach and facilitate discussions on timely research with politicians, government bodies and companies.
Several aspects of the work are beyond state of the art, including: (1) having in isolated cultures 6 strains of haptophyte algae that will be used for further culture studies for environmental and biofuel work in the final stage of funding and beyond; (2) in the final stage of the project, accurate and high-resolution chronologies are needed to constraint the timing of extreme and abrupt events, so we are developing the BECS laboratory as a site of compound-specific radiocarbon sample preparation in concert with the Scottish Universities Environmental Research Centre, which has the capability to measure these rare, small samples and has developed a new positive ion mass spectrometer that revolutionises the introduction (via gas instead of graphite target) and size of sample needed for radiocarbon measurement. We expect samples from our project to be the first environmental (non-pharmaceutical) samples to be analysed on this instrument. (3) The first environmental calibration of lacustrine long-chain diols with temperature and a novel GDGT-based salinity calibration with potential for global application. (4) Our work points to the feasibility of a universal calibration for Group II haptophytes that would allow for a more global application of alkenones in terrestrial lake records – on par with the marine system (Theroux et al., in review at EPSL & Plancq et al., in review Biogeosciences). (5) Our laminated, likely annually resolved, time series of environmental change from Lake Success takes advantage of MALDI-FTIR/TOF-MS biomarker analysis through collaboration with Professor Hinrichs at Bremen University to decipher biogeochemical and ecological responses to past extreme and abrupt warm events during the mid-Holocene. (6) As new biomarkers emerged during the project we have been able to collaborate with other European researchers, who will use archived materials from ALKENoNE to, for example, supporting the work of early career researcher Thorsten Bauersachs, Christian-Albrechts-University, Germany on heterocyst glycolipids produced by cyanobacteria and their relationship to temperature.