Prof. Daniela Schmidt, University of Bristol
Rui Ying, University of East Anglia
Abstract:
Marine plankton is fundamental in driving changes in the ocean, providing food for other organisms, and regulating the chemical cycles of the ocean and its underlying sediments.
Understanding how marine ecosystems react to environmental change, in the past and future, is challenging due to the complex interactions of species, the physical environment and extreme events from global warming to meteorite impacts. In this talk we will provide an insights into the role of modern plankton in the Earth systems, focussing on planktic foraminifer. We will show examples of how evolution and environment has changed in the last 66 Ma these taxa, show the impact plankton ecology has on carbon and nutrients in the ocean. Using a novel trait based ecosystem model we have developed, we will show links between plankton evolution and global ocean biogeochemistry. We will explore what limits species to adapt to the modern warming and what determines if they might go extinct.
Bio:
Daniela Schmidt is Professor in the School of Earth Sciences at the University of Bristol. Her research focuses on understanding the causes and effects of climate change on marine socio-ecological systems, coastal ecosystems and nature's contribution to people. She was coordinating lead author for the AR6 IPCC WGII chapter on Europe and during the 5th assessment cycle lead author on the ocean chapter. She exploits the breadth of new and novel techniques to generate a holistic understanding of the vulnerability of people and ecosystems, working with colleagues in the humanities, social science and law.
Rui Ying is a Senior Research Associate at the University of East Anglia, specialising in Earth system modelling and marine ecology. His research combines Earth system models with geological records of past environmental change to understand how the ocean and its plankton respond to climate change. He develops and applies global ocean biogeochemical and Earth system models, including cGENIE and NEMO-PlankTOM, to investigate how plankton ecology shapes the cycling of carbon and nutrients across the modern ocean, past climates, and deep time.
Summary:
Focus: health of ocean ecologies under climate change
Key risks: biodiversity loss°radation, climate-induced extinctions
Climate change:
Known: changes atmospheric CO2->lowers ocean pH
Unknown: Impacts on organisms and ecosystems, migrations, extinctions
Past dynamics of global climate are a guide for the challenge we’re facing
Many times in the past have been as warm as we’re heading towards
Changes were generally slower than today but there have been sudden shifts
Can observe geologic record of organisms and how they responded to climate shifts
Example: Planktic Foraminifers
Unicellular marine organisms that are globally distributed and well preserved
We have many samples so can observe their evolution over time
Biodiversity
Phenology, size and geographic distribution across species
Challenge: combining diverse datasets and developing multi-domain/modal models
Complex dynamics: in the ocean everything changes together all the time
Comparison of trends over time: Calcification, Extinction, Migration
Challenge: these changes happen at much faster rates than can be directly captured in the geological record
Approach: using climate models to inform ecological dynamics
cGenie: Earth System Models of Intermediate Complexity
Captures the key dynamics of atmosphere, ocean, idea, bio-geochemistry
Runs quickly, which makes it usable for
Deep-history runs (e.g. 500m years ago)
Analyzing impacts of transitions that take many thousands of years (e.g. continental drift, closing/opening of sea channels)
EcoGEM: a trait-based plankton model in cGENIE
Simulate richness across different plankton classes
Modeled dynamics of Planktic Foraminifers and compared it to the recorded fossil record
Categories: Symbiont-barren spinose, Symbiont-barren non-spinose, Symbiont-facultative non-spinose, Symbiont-obligate spinose
Interactions with Phytoplankton and Zooplankton
Food web dynamics of grazing
Competition dynamics
Multiple size classes of plankton (micrometer-millimeter)
Validation:
Past 60m years: pattern of spatial distribution of difference categories matches fossil record
Past 21k years (since last glacier maximum):
Relating temperature to abundance
Thermal acclimation captured by model
Symbiont-obligate ecogroup most different from the others
Impact of global warming on plankton
Limited thermal niche change under future warming
Massive changes to species distribution of plankton under all upcoming scenarios
Modeling the K-Pg plankton extinction (most recent mass extinction from 66m years ago)
Asteroid impact caused global darkness and food web collapse
Most planktic foraminifera and nanoplankton went extinct
But some species less impacted
Why?
Our observational records track the collapse dynamics
During K-Pg most diversity was lost with specimens becoming much smaller in size
Simulation of the transition
Rapid cooling and ocean surface mixing and acidification
Productivity collapse
Nutrient pulse due to mixing
Simulation reproduced key measurements
Extinctions mostly in high latitude
Only small plankton survived
All surface Planktic Foraminifera were all extinct according to simulation, so what must have happened is that deep ocean taxa survived and recolonized the ocean surface
Experiment: Darkness as driver of selective extinction during K-Pg
Sufficient to drive extinction
Ocean acidification not needed