Plankton Adaptation rates

Duration:

1.2.2019-31.01.2022

Problem statement

Understanding the response of marine ecosystems to climate change requires knowledge of processes that operate over long time scales. Over the last decades, abundant data have been generated on the change in the composition of marine microplankton assemblages across the last deglaciation. These data were used to reconstruct various aspects of the ocean and climate system during this climatic upheaval; however, their potential to evaluate biotic response to climatic forcing has been rarely explored.

Project Description

Over the last 600 ka, Earth’s climate is dominated by changes in the orbital geometry (eccentricity) causing glacial-interglacial cycles with a frequency of approximately 100 ka. These cycles are asymmetrical meaning long glacial periods are followed by rapid warmings. During these transitions – also referred to as deglaciations – the global climate is rapidly changing on a multi-millennial-scale which makes these time periods ideal to study potential adaptation to environmental change.

Marine plankton are of fundamental importance when it comes to the understanding of the pace and impacts that climate change will have on this planet. There are not only several feedback mechanisms which highlight the ability of marine plankton to contribute to global climate, but marine plankton are also very good indicators for climate change itself. They often have short live cycles and show a high evolutionary divergence; thus, it appears that plankton dynamics may be tightly coupled to environmental change. Also, marine plankton – by its definition – is free floating, so environmental change might be recorded by plankton distribution changes and shifts in their geographical range.

A basic goal of the present PhD project is to benefit from the vast amount of plankton assemblage data that have been published in environmental data archives such as PANGAEA and NCEI and to utilize these data to better understand the variability in natural time scales. In particular, this PhD project aims to spatially and temporarily investigate the rates of adaptation of marine plankton to environmental change. For that, assemblage as well as morphological data extracted from the fossil record will be analysed.

Objective of first manuscript

Yasuhara et al. (2020) showed a compositional shift (latitudinal diversity gradient - LDG) in planktonic foraminifera from low to mid latitudes during the last deglaciation by analysing global census data (ForCenS, MARGO). Since they only looked at two time slices (LGM, pre-industrial), they were not able to analyse the timing of this shift in more detail. However, they assume that this shift probably started after the onset of the postglacial warming around 15 ka ago. Here, we use a data set of planktonic foraminifera records (see description below) to analyse the timing and the nature of this transition.

Is this compositional transition rapid or slow?
Is it in pace with climate forcing or not?
What is the pattern of community transformation?

Working Area

North Atlantic Ocean

Data set

We compiled records of plankton response to the last deglaciation covering the entire North Atlantic Ocean. The records comprise assemblage composition data of marine zooplankton (planktonic foraminifera; n = 25) and phytoplankton (coccolithophores and dinoflagellate cysts; n = 5 and 6, respectively) covering the last 24 ka with a resolution of at least 1 ka. The comparability of the data is ensured as follows: For all sites, which are included in the PALMOD 130k marine palaeoclimate data synthesis V1.0 (Jonkers et al., 2020), the provided revised age models are used. For all other sites, which are not included in this synthesis, the same approach was used to revise the published age models to ensure the comparability of all analysed sites.

References

Jonkers, L., Cartapanis, O., Langner, M., McKay, N., Mulitza, S., Strack, A., & Kucera, M. (2020). Integrating palaeoclimate time series with rich metadata for uncertainty modelling: strategy and documentation of the PalMod 130k marine palaeoclimate data synthesis. Earth System Science Data, 12(2), 1053–1081. doi:10.5194/essd-12-1053-2020

Yasuhara, M., Wei, C.-L., Kucera, M., Costello, M. J., Tittensor, D. P., Kiessling, W., … Kubota, Y. (2020). Past and future decline of tropical pelagic biodiversity. Proceedings of the National Academy of Sciences, 117(23), 12891–12896. doi:10.1073/pnas.1916923117