Ocean Acidification in the past: implications for further work

Ocean Acidification in the past: implications for further work

John A RavenUniversity of Dundee at SCRI

Scottish Crop Research InstituteInvergowrie

Dundee DD2 5DAUK

Contents

• Learning from the past: what organisms have survived (or not) over the last few billion years?

• Learning from the past: why did it take so long for anthropogenic ocean acidification to become an important research issue?

• Further work: progress and plans in Europe

Learning from the past: what organisms have survived (or not) in past high-CO2 episodes?

• Look at the fossil record of calcified organisms – what happened in past high CO2 episodes?

• Variations in atmospheric CO2 and calculated ocean surface pH through the Phanerozoic

• Usually too coarse a time resolution to determine if rates of acidification (and species turnover) were as great as expected over next few decades – centuries

• No extinction of major clades of calcifiers known as a result of ocean acidification episodes uncomplicated by other major environmental changes

Temporal variations in atmospheric CO2 and surface seawater pH

Ridgewell & Zeebe 2005 Earth & Planetary Science Letters 234: 299-315

Lessons from the geological record

• Palaeocene-Eocene Thermal Maximum (PETM)

• About 55 Myr ago• Lasted about 170 kyr• Temperature increase of 5oC in less than

10 kyr• Caused by release of about 2000 PgC

from destabilized CH4 hydrates, subsequently oxidised to CO2?

Palaeocene – Eocene Thermal Maximum 55 million years ago

Learning from the geological record

• Rapid acidification at start of PETM – but possibly slower that what we expect in the next few decades

• CO2 addition could have occurred over a time interval similar to the ocean turnover time at the PETM, so the carbonate system in the ocean, supplied from deep-sea carbonates, and from silicate and carbonate weathering on land – slower acidification

• Zachos et al. (2005) Science 308: 1611-5• Pagani et al. (2006) Science 314: 1566-7

Learning from the geological record

• Regardless of the rate of acidification, what does the palaeontology of calcified fossils tell us during the PETM?

• Gibbs et al. 2006 Science 314: 1770-3• Increased rates of extinction and

origination of coccolithophore species during PETM

• Extinction of rare organisms living close to niche limits?

Specific rates of extinction and origination of coccolithophore species around the PETMGibbs et al. (2006) Science 314: 1770-3

Calciosolenia – C. aperta one of the extinctions in the PETM

“Body” 30 μm long

Survival of Coccolithophores during Ocean Acidification

• Significant variability in response of extant coccolithophore genotypes to acidification

• Summarised by Fabry (2008) Science 320: 1020-1022

• Since this publication, further data sets have become available using additional genotypes showing similar variability

• Danforth et al. (2008) AGU Fall Meeting 2008 Abstract #OS21A-1159

• Langer et al. (2009) Biogeosciences Discussions 6: 4361-4383

Responses

of 4 strains

of coccolithophore

to increased CO2

and decreased

CO3- and pH

(Fabry, 2008,

Science 320:

1020-1022)

Survival of some calcified clades as uncalcified (hence unfossilized) forms in

acidified oceans?• Some (not all) marine organisms that are

normally calcified can grow as uncalcified forms in seawater at low pH

• Some corals: work of Fine and Tchernov (2007) Science 315: 1811

• Corals maintained for a year in the uncalcified form recalcify upon return to ‘normal’ seawater

• Laboratory experiment lacked natural grazers

Fine & Tchernov 2007 Science 315: 1811Oculina patagonica control colony (A), sea-anemone-like polyps after

deacidification (B), recalcification in normal seawater after 12 months of deacidification (C)

Learning from the past: why did it take so long for anthropogenic ocean acidification to become an important research issue?

• 1810 – 1950: variable, often high, estimates of atmospheric carbon dioxide

• “Crude” methodology early on.

• Not a good basis for studies of ocean acidification

Fonselius et al. (1956) Tellus VIII: 176-183

History of Understanding of Ocean Acidification: Atmosphere• Tyndall 1859: experimental verification of

suggestions of Saussure, Fourier, Pouillet… about greenhouse effect of certain atmospheric gases

• Arrhenius (1886) suggested that a doubling of CO2 would increase Earth surface temperatures by 4-6 degrees C.

John Tyndall

Svante Arrhenius

History of Understanding of Ocean

Acidification: Ocean Chemistry • Henderson and Hasselbalch (1908)

commonly thought to have originated the equation relating pH to dissociation of acids and bases

• Mass action equation used to describe this relationship as part of the Mass Action law in 1879 by Guldberg and Waage

• Problems with measuring Ocean pH then which are still with us today

History of Understanding of Ocean Acidification: Biology

• Hensen (1887): first publication on role of phytoplankton in marine productivity; estimates of rates five-fold too high

• Blackman (1905) measured dependence of photosynthesis of aquatic plants on [CO2] and PAR

• Keeling (starting in the 1950s) produced (against significant bureaucratic odds!) high-resolution continuous measurements of atmospheric CO2

Charles Keeling

EPICA ice core: temperature and CO2 over 800,000 years

Further Work: Progress and Plans in Europe

• CARBOOCEAN

• European Framework 6, 2005-2009, 47 groups of scientists from Europe, Iceland, Morocco and USA

• Focus on Atlantic and Southern oceans

• -200 - +200 years from now

• 5 main themes

CARBOOCEAN

• North Atlantic and Southern Ocean air-sea exchange of CO2 on seasonal to interannual scale

• Detection of decadal to centennial Atlantic and Southern Ocean changes in carbon inventory

• Carbon uptake and release at European regional scale

• Biogeochemical feedbacks on the ocean carbon sink

• Future scenarios for marine carbon sources and sinks

EPOCA(European Project on OCean Acidification)

• European Framework 7, 2008-2012; Europe, including Iceland

• Aims

• Document changes in ocean chemistry and biogeography through space and time

• Determine the sensitivity of marine organisms, communities and ecosystems to ocean acidification

EPOCA(European Project on OCean Acidification)

• Integrate results on the impact of ocean acidification on marine ecosystems in biogeochemical, sediment and coupled ocean-climate models to better understand and predict the responses of the Earth system to ocean acidification

• Assess uncertainties, risk and thresholds (“tipping points”) related to ocean acidification at scales from subcellular to ecosystem and local to global

MEECE(Marine Ecosystem Evolution in a Changing Environment)

• European FP7 Integrated Project

• 21 Partners

• Aim is to increase the predictive capacity of ecosystem modelling

• Decision making tool to support the EC Marine Strategy, EC Maritime Policy, EC Common Fisheries Policy

CalMarO(CALcification by Marine Organisms)

• European Framework 7 Marie Curie Initial Training Network

• Aim to improve the career perspectives of early researchers

• Addresses calcareous structures as well as calcification processes

• Sensitivity to changes in environmental conditions at all scales – cell, organism, population, ecosystem, and regional to global

BIOACID

• Biological Impacts of Ocean ACIDification

• Research initiative of the German Federal Ministry of Education and Research

• Partnership of nineteen German Universities and Research Institutes

• Five themes

BIOACID

• Primary production, microbial processes and biogeochemical feedbacks

• Performance characters: reproduction, growth and behaviours in animal species

• Calcification –sensitivities across phyla and ecosystems

• Species interactions and community structure in a changing ocean

• Integrating assessment – sensitivities and uncertainties

DEFRA pH

• UK Department of Environment, Food and Rural Affairs

• 2008-2010• Aim to determine baseline for pH

variability in UK shelf waters• Collect water samples for preservation and

subsequent Total Alkalinity and Dissolved Inorganic Carbon measurements, and measure underway pCO2

CARBON-OPS

• UK Natural Environment Research Council (NERC) Knowledge transfer project

• Aim to undertake autonomous pCO2

observations from 5 UK research vessels and process them in near real time for operational use by the UK Meteorological Office and Defra

• Cannot use pCO2 alone to estimate the other three parameters of the carbonate system

• www.bodc.as.uk/carbon-ops

NERC UK + DEFRA UK Ocean Acidification Programme

• £ 12 million

• 2009 – 2014

• Focus on North-East Atlantic, including European shelf and slope, Antarctic and Arctic Oceans

• Aims to deliver seven main science outputs


• Improve estimates of ocean CO2 uptake and associated processes

• Evaluate the impact of acidification on ocean biogeochemical processes

• Identify and improve understanding of potential impacts and implications of acidification on key ecosystems, communities, habitats and species, focussing on the continental shelf and slope

• Improve the understanding of the potential population, community and ecosystem impacts and implications for commercially important species


• Provide evidence from the palaeo-record of past changes in ocean acidity and resultant changes in marine species composition and Earth System function

• Identify and understand the indirect impacts of decreasing pH on atmospheric chemistry and the climate system

• Improve the understanding of the cumulative or synergistic effects of Ocean Acidification on ecosystem structure and function with other global change pressures


• Key component is the provision of a high quality service for carbonate chemistry measurements

• Four parameters of the carbonate system can be measured: total dissolved inorganic carbon, alkalinity, pCO2 and pH

• Two degrees of freedom, so the whole carbonate system, including the saturation state of seawater with respect to aragonite and calcite, can be calculated from any two parameters, but not from just one

• Different parameter pairs give different accuracy for the remaining parameters


• Total dissolved inorganic carbon and alkalinity are the pair most commonly used

• Difficult and expensive to make measurements of this pair with the required accuracy and precision, but can be made on suitably preserved samples

• Central facility with specialist staff and equipment


• Very difficult to measure seawater pH at the accuracy required for ocean acidification studies

• Strong covariance of pH and pCO2 another reason for not using them

• Alas, only pH and pCO2 can be measured autonomously at the moment

MISSING?

• None of the European research programmes appear to highlight the experimental investigation of genetic adaptation to high CO2

• Work of Sinéad Collins and Graham Bell (2004, Nature 431: 566-569 on the non-marine alga Chlamydomonas reinhardtii

• 600 generations of linearly increasing CO2 from 400 ppm to 1050 ppm, 400 generations at the 1050 ppm CO2: examine phenotypes of the selected strains

MISSING?

• No “adaptation” in the sense of increased fitness (as growth rate) of any of the strains from the high CO2 treatment showing greater fitness than the control, unselected, strain

• Some similar work (fewer generations!) being done on marine microalgae outside the main programmes, e.g. Kate Crawfurd in Plymouth Marine Laboratory (supervised by Ian Joint and John Raven)

Sinéad Collins

Relation to New Zealand?

• With much caution……

• Look for what seems good (wide scope) and bad (bureauocracy) about the European programmes

• Possible synergies: habitat similarities, e.g. fjordic coasts in Europe and NZ

• Species, habitat differences

What will happen to Durvillea antarctica?(up to 20 m long)

What will

become

of bryozoan

reefs?

Conclusions

• Major clades of calcified marine organisms (e.g. coccolithophores, foraminifera, corals, bivalves) have survived past ocean acidification events

• The Mass Extinction events in the geological record may involve ocean acidification but other factors are involved

Conclusions

• Widespread appreciation of anthropogenic ocean acidification as a phenomenon with significant biological consequences is a phenomenon of the 21st century

• Theoretical understanding and techniques required to appreciate and measure ocean acidification and its biological impacts had been available for decades to more than a century earlier

Conclusions

• Several research programmes related to measurements of ocean carbonate parameters and the biological effects of ocean acidification were and are proceeding in Europe

• Some involve measurements in the Southern Ocean

• Still plenty for New Zealand to do!

Acknowledgements

• John Beardall, Ken Caldeira, Kate Crawfurd, Harry Elderfield, Kevin Flynn, Mario Giordano, Keith Hunter, Catriona Hurd, Debora Iglesias-Rodriguez, Ian Joint, Andy Johnston, Janet Kübler, Stephen Maberly, F Andrew Smith

• Natural Environment Research Council, UK

Documents

Ocean Acidification in the past: implications for further work