OUTLINE Phytoplankton 101 Climate change and altered ocean properties Where and when?

What will be the impact of ocean acidification relative

to climate change effects on oceanic biota?

Philip BoydNIWA / Otago Centre of

Chemical and Physical Oceanography

OUTLINEa) Phytoplankton 101b) Climate change and altered ocean propertiesc) Where and when?d) Winners and losers?e) How to quantify the change?

Doney Nature (2006)

The take home message

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 EEZAltered foodwebsAltered flows of energyAltered marine resources

‘Phytoplankton 101’

Rutger

>

They fix half of the carbonin the Biosphere

They form the base of marine foodwebs

Phytoplankton and Mixology 101

TemperatureLightNutrientsCO2

Trace metals

Courtesy Scott Nodder (NIWA)

Plant nutrient gradients in our waters

Climate change and the ocean

TODAY TOMORROWCO2

pH

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

Boyd & Doney 2002

Boyd et al. (2008)

Climate change - from global to regional impacts

Projected changes over the next 50 years

Where within the EEZ will climatechange have the greatest impact?

4 million km2

Warm & cold currentsA range of water bodiesDifferent ecosystems Nitrate

Chlorophyll

Increasing climate variability and change

Their impact differs between water masses of the EEZ

Projected ocean temperature trends over next 50 years

Climate variability Climate change

Boyd/Doney (unpublished)

Different phytoplankton groupsdominate in different water masses &support different ecosystems

Non-calcifying phytoplankton dominate stocks within the EEZ

However, rising oceanic CO2 levelswill also impact non-calcifyingphytoplankton.

Both directly and in concert with otherfactors that will be altered by climate change

Synechococcus Photosynthesis versus Lightinterplay of temperature and CO2

A

Light intensity (mol m-2 s-1)0 100 200 300 400 500 600 700 800 900 1000

g C

g

Ch

l-1

h-1

0

2

4

6

8

10

12

ControlHigh CO2High TemGreenhouse

Fu et al. 2006

pCO2 and Fe availability: interactive effects on N2 fixation rates

Fe-replete

0

1e-8

2e-8

3e-8

Fe-limited

pCO2 (ppm)

190 380 750

N2 f

ixat

ion

(n

mo

l cel

l-1

ho

ur-

1 )

0

1e-8

2e-8

3e-8

N2 f

ixat

ion

(n

mo

l cel

l-1

ho

ur-

1 )

Fu et al. 2008

So if the sky is falling

Where and when will change happen?

Who is in each water massThe winners vs. the losers?

How to quantify the change?

A

Light intensity (mol m-2 s-1)0 100 200 300 400 500 600 700 800 900 1000

g C

g

Ch

l-1

h-1

0

2

4

6

8

10

12

ControlHigh CO2High TemGreenhouse

Fe-replete

0

1e-8

2e-8

3e-8

Fe-limited

pCO2 (ppm)

190 380 750N

2 fi

xati

on

(n

mo

l cel

l-1

ho

ur-

1 )

0

1e-8

2e-8

3e-8

N2

fixa

tio

n (

nm

ol c

ell-

1 h

ou

r-1 )

Experiments provide a means to rankthe impacts of these different and concurrent changes in ocean properties

ultimate proximate

Temperature > Light > Iron > Silicate > Nutrients > CO2

a) Physiological-based ranking schemes

(From Boyd, Strezpek, Fu & Hutchins, submitted)

S.OceanDiatoms

Linking these three questions

Winners and losers?

Where and when?

How to quantify the change?

A

Light intensity (mol m-2 s-1)0 100 200 300 400 500 600 700 800 900 1000

g C

g

Ch

l-1

h-1

0

2

4

6

8

10

12

ControlHigh CO2High TemGreenhouse

CO2

pH

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

Doney Nature (2006)

The take home message

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 EEZAltered foodwebsAltered flows of energyAltered marine resources