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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?
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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?
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 EEZ Altered foodwebs Altered flows of energy Altered marine resources Doney Nature (2006)
‘Phytoplankton 101’ > Rutger They fix half of the carbon in the Biosphere They form the base of marine foodwebs
Phytoplankton and Mixology 101 Temperature Light Nutrients CO2 Trace metals
Plant nutrient gradients in our waters Courtesy Scott Nodder (NIWA)
CO2 pH Climate change and the ocean TODAY TOMORROW
Other factors will also change The supply of nutrients from the atmosphere
Climate change - from global to regional impacts Boyd et al. (2008) Projected changes over the next 50 years Boyd & Doney 2002
Where within the EEZ will climatechange have the greatest impact? Chlorophyll 4 million km2 Warm & cold currents A range of water bodies Different ecosystems Nitrate
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and change Their impact differs between water masses of the EEZ Climate variability Climate change Boyd/Doney (unpublished)
Different phytoplankton groups dominate in different water masses & support different ecosystems
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
Synechococcus Photosynthesis versus Lightinterplay of temperature and CO2 Fu et al. 2006
pCO2 and Fe availability: interactive effects on N2 fixation rates Fu et al. 2008
So if the sky is falling Where and when will change happen?
Who is in each water mass The winners vs. the losers?
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
Linking these three questions Where and when? How to quantify the change? Winners and losers?
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
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 EEZ Altered foodwebs Altered flows of energy Altered marine resources Doney Nature (2006)