1. Chemical and Physical Oceanography
What will be the impact of ocean acidification relative to climate change effects on oceanic biota?
Philip Boyd
NIWA / Otago Centre of
Chemical and Physical Oceanography
OUTLINE
Phytoplankton 101
Climate change and altered ocean properties
Where and when?
Winners and losers?
How to quantify the change?

2. The take home message Altered productivity of the EEZ Altered foodwebs
OCEAN ACIDIFICATION will have a pronounced influence on the
New Zealand EEZ – but it is not the only game in town.
All environmental controls on phytoplankton will be altered by climate change
Phytoplankton are the base of coastal and offshore ecosystems and marine
living resources
Altered productivity of the EEZ
Altered foodwebs
Altered flows of energy
Altered marine resources
Doney Nature (2006)

3. ‘Phytoplankton 101’ They fix half of the carbon in the Biosphere
>
Rutger
They fix half of the carbon
in the Biosphere
They form the base of
marine foodwebs

4. Phytoplankton and Mixology 101
Temperature
Light
Nutrients
CO2
Trace metals

5. Plant nutrient gradients in our waters
Courtesy Scott Nodder (NIWA)

6. Climate change and the ocean
CO2 pH
TODAY
TOMORROW

7. Other factors will also change
The supply of nutrients from the atmosphere

8. Climate change - from global to regional impacts
Boyd et al. (2008)
Projected changes over the next 50 years
Boyd & Doney 2002

9. Where within the EEZ will climate change have the greatest impact?
Chlorophyll
4 million km2
Warm & cold currents
A range of water bodies
Different ecosystems
Nitrate

10. Projected ocean temperature trends over next 50 years
Increasing climate variability and change
Their impact differs between water masses of the EEZ
Climate variability
Climate change
Boyd/Doney (unpublished)

11. Different phytoplankton groups
dominate in different water masses &
support different ecosystems

12. Non-calcifying phytoplankton dominate stocks within the EEZ
However, rising oceanic CO2 levels
will also impact non-calcifying
phytoplankton.
Both directly and in concert with other
factors that will be altered by climate change

13. Synechococcus Photosynthesis versus Light interplay of temperature and CO2
Fu et al. 2006 13

14. pCO2 and Fe availability: interactive effects on N2 fixation rates
Fu et al. 2008 14

15. So if the sky is falling
Where and when will change happen?

16. Who is in each water mass
The winners vs. the losers?

17. How to quantify the change?

18. Experiments provide a means to rank the impacts of these different and
concurrent changes in ocean properties
a) Physiological-based ranking schemes
(From Boyd, Strezpek, Fu & Hutchins, submitted)
Temperature > Light > Iron > Silicate > Nutrients > CO2
S.Ocean
Diatoms
ultimate
proximate

19. Linking these three questions
Where and when?
How to quantify the change?
Winners and losers?

20. A Climate Change Atlas for the New Zealand EEZ is required
To assess both the impact of Ocean Acidification
but also of other climate change effects on the biota
CO2 pH

21. The take home message Altered productivity of the EEZ Altered foodwebs
OCEAN ACIDIFICATION will have a pronounced influence on the
New Zealand EEZ – but it is not the only game in town.
All environmental controls on phytoplankton will be altered by climate change
Phytoplankton are the base of coastal and offshore ecosystems and marine
living resources
Altered productivity of the EEZ
Altered foodwebs
Altered flows of energy
Altered marine resources
Doney Nature (2006)