antarctica, climate change, and krill: dr. grace saba
TRANSCRIPT
Humans are Impacting the Ocean
Tem
per
ature
(°
C)
Year
13
14
15
16
17
18
1860 1880 1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 2100
Hadley Centre for Climate Prediction and Research
Increase in CO2 causes:
•Increased atmospheric temperature
Rising Temperature: The CO2 Problem
Tem
per
ature
(°
C)
Year
13
14
15
16
17
18
1860 1880 1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 2100
Hadley Centre for Climate Prediction and Research
Increase in CO2 causes:
•Increased atmospheric temperature
•Warming of ocean (Increase in heat content)
Rising Temperature: The CO2 Problem
Krill in Antarctic Food Webs
Phytoplankton
Krill Swarms
Phytoplankton
Antarctic Circumpolar Current (ACC)
The West
Antarctic
Peninsula (WAP)
is the location
where the ACC
is closest to the
continent
Recent warming in the WAP
Fastest winter warming location on Earth
Northern WAP perennial ice is gone
87% of glaciers in retreat
Sea ice duration decreased by ~90 days
Increase in ocean heat content
YEAR
1992 1994 1996 1998 2000 2002 2004 2006
10
9 jo
ule
s p
er m
2
3.2
3.3
3.4
3.5
3.6
3.7
3.8
Martinson et al. 2008
Qslo
pe
(x1
09
J m
-2)
°C Increase of 6°C in the past 50 years
50-year changes in winter air
temperature
Hea
t co
nte
nt
(x10
9J
m-2
)
Seawater heat
content
Warming World
The oceans are
changing in our
lifetime
Warming World
Warming World
Recent changes in WAP phytoplankton
• 12% decrease in chlorophyll
over past 30 years, particularly
northern WAP
1970s-1980s
1998-2006
Montes-Hugo et al. 2009
• Shift from large to small
phytoplankton
Recent changes in WAP Antarctic krill
• Decrease in Euphausiasuperbaof over twofold per decade since mid-
1970s
Line 600 (north)
Atkinson et al., 2004
Recent changes in Adélie Penguins
• Decrease in Adélie penguins, increases in subpolar species
(Gentoos, Chinstraps)
Line 600 (north)
Recent changes in Adélie Penguins
Line 600 (north)
Increase in CO2 absorption = Increase in ocean acidity
Ocean acidification: The “Other” CO2Problem
Increase in CO2 absorption = Increase in ocean acidity
Station Aloha
Year
The chemistry of OA:carbonate chemistry
Increase in seawater CO2:
•Increase in seawater carbonic acid, H2CO3
•Release of hydrogen, H+, ions into the seawater
•Decrease pH = increase ocean acidity
•Decrease in CO32-ions (buffering process)
•Decreased calcification in organisms
The chemistry of OA:carbonate chemistry
Increase in seawater CO2:
•Increase in seawater carbonic acid, H2CO3
•Release of hydrogen, H+, ions into the seawater
•Decrease pH = increase ocean acidity
•Decrease in CO32-ions (buffering process)
•Decreased calcification in organisms
The chemistry of OA:carbonate chemistry
Increase in seawater CO2:
•Increase in seawater carbonic acid, H2CO3
•Release of hydrogen, H+, ions into the seawater
•Decrease pH = increase ocean acidity
•Decrease in CO32-ions (buffering process)
•Decreased calcification in organisms
What potential impacts could
ocean acidification have on
marine organisms and why?
Calcification and the Saturation State
Ωa < 1: undersaturated = dissolution
Ω = potential for the mineral to form or dissolve
product of concentrations of reacting ions that form the mineral
Product of the concentrations of those ions when mineral is at equilibrium (Ksp)
Ωa > 1: supersaturation of carbonate ions = precipitation
Ω =
Antarctic benthic community
Photo: Steve Clabuesch, NSF
• Rich, diverse, and mostly endemic marine benthic fauna in Antarctica
• Many benthic calcifying fauna are prominent in nearshore communities and are economically and/or ecologically important (e.g., bivalves, such as mussels and oysters, sea urchins, limpets, brachiopods, cold water corals)
• Lack of shell-crushing predators: clawed crabs, lobsters, heavily jawed fish
Dissolution of multiple Antarctic benthic invertebrates
BIVALVE LIMPET BRACHIOPOD
(McClintock et al. 2009)
Control, pH = 8.2 Acidified, pH = 7.4
Bivalve Y. eightsishell
Shell mass7.4 – Shell mass8.2
King crab invasion of Antarctica
Photo: Sven Thatje
• Warming sea temperatures are allowing shell-crushing, deep water king crabs to invade the continental shelves surrounding Antarctica (Thatje et al. 2005)
• Any additional weakening of invertebrate shells owing to ocean acidification will render them even more vulnerable to these predators.
• Coupling of rising temperatures, ocean acidification, and predator invasion is expected to influence both planktonic and benthic marine communities of Antarctica
Doney et al. 2009
What potential impacts could ocean
acidification have on NON-
CALCIFYING marine organisms
and why?
• Change in community structure
Effects of ocean acidification on large diatoms
• Increased primary productivity
100 ppmv
380 ppmv
800 ppmv
Tortell et al. 2008
CO2 Scenarios: Effects on biogeochemistry and food webs
High CO2
Large cells
BiomassProductivity
Would diatoms ultimately become nutrient limited?
N, P, Si, Fe uptake
Small diatoms responded negatively
• Lower biomass & productivity in high CO2
treatment
• No increase in biomass over course of study
(Saba et al., in prep)
* p < 0.05
0
5
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25
30
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2.5
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1.0
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hlo
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hyll a
(µ
g L
-1)
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. P
rod
. (m
g C
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)
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Nan
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cells
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-1)
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Time (days)
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. P
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Effects on krill embryo development(Kawaguchi et al. 2010)
380 pCO2 (μatm) 2000 pCO2 (μatm)
How do you study metabolism?
Metabolic physiology:
Water breathers rely almost entirely on ion exchange mechanisms to
maintain acid-base balance
pH/pCO2 effects on metabolic physiology:
Water breathers rely almost entirely on ion exchange mechanisms to
maintain acid-base balance
Pörtneret al. 2004
pH effects on brittle star metabolism & growth
Wood et al. 2008
8.0 6.87.37.7pH
8.0 6.87.37.7pH
pH effects on brittle star metabolism & growth
Wood et al. 2008
8.0 6.87.37.7pH
8.0 6.87.37.7pH
pH = 6.8pH = 8.0MUSCLE
LOSS
OA effects on krill metabolism & growth(Saba et al., 2012)
FEEDING
• Euphausiasuperbaresponded to elevated CO2by:– Increasing ingestion rates
OA effects on krill metabolism & growth(Saba et al., 2012)
EXCRETION
• Euphausiasuperbaresponded to elevated CO2by:– Increasing ingestion rates
– Increasing nutrient release rates and metabolic activity
• Increased metabolism reflects enhanced energetic requirements of acid-base regulation
• Associated compensation costs included the catabolism of proteins
OA effects on krill metabolism & growth(Saba et al., 2012)
• Euphausiasuperbaresponded to elevated CO2by:– Increasing ingestion rates
– Increasing nutrient release rates and metabolic activity
• Increased metabolism reflects enhanced energetic requirements of acid-base regulation
• Associated compensation costs included the breakdown and loss of proteins
Major Findings/Future focus
• Many calcifying organisms will be negatively affected by increased ocean acidification
Major Findings/Future focus
• Many calcifying organisms will be negatively affected by increased ocean acidification
• Most detrimental responses of organisms to ocean acidification are in early developmental stages
– Potential long-term population declines
Major Findings/Future focus
• Many calcifying organisms will be negatively affected by increased ocean acidification
• Most detrimental responses of organisms to ocean acidification are in early developmental stages
– Potential long-term population declines
• Little information thus far on non-calcifying organisms and physiological processes (including krill)
Major Findings/Future focus
• Many calcifying organisms will be negatively affected by increased ocean acidification
• Most detrimental responses of organisms to ocean acidification are in early developmental stages
– Potential long-term population declines
• Little information thus far on non-calcifying organisms and physiological processes (including krill)
• Positive effect of ocean acidification on large diatoms– Nutrient limitation may be an eventual problem
– Differential responses of different diatoms
– Food webs may be altered in ways we do not yet understand
Major Findings/Future focus
• Many calcifying organisms will be negatively affected by increased ocean acidification
• Most detrimental responses of organisms to ocean acidification are in early developmental stages
– Potential long-term population declines
• Little information thus far on non-calcifying organisms and physiological processes (including krill)
• Positive effect of ocean acidification on large diatoms– Nutrient limitation may be an eventual problem
– Differential responses of different diatoms
– Food webs may be altered in ways we do not yet understand
• Multistressorsneed to be considered: CO2, temperature, light, nutrient limitation, oxygen
Adaptation of organisms to ocean acidification?
CO2 levels were high at times in the geological past without there being much evidence for significant deleterious effects on marine planktonic organisms. That may be because they were slow changes that enabled organisms to evolve to adapt to gradually rising CO2
levels.
Adaptation of organisms to ocean acidification?
CO2 levels were high at times in the geological past without there being much evidence for significant deleterious effects on marine planktonic organisms. That may be because they were slow changes that enabled organisms to evolve to adapt to gradually rising CO2
levels.
Today the rate of rise in CO2 and acidification is 10 times faster than anything experienced since the demise of the dinosaurs 65 million years ago and is closely tied to anthropogenic inputs.
Adaptation of organisms to ocean acidification?
CO2 levels were high at times in the geological past without there being much evidence for significant deleterious effects on marine planktonic organisms. That may be because they were slow changes that enabled organisms to evolve to adapt to gradually rising CO2
levels.
Today the rate of rise in CO2 and acidification is 10 times faster than anything experienced since the demise of the dinosaurs 65 million years ago and is closely tied to anthropogenic inputs.
Organisms with prolonged life histories and long generation times (krill, pteropods, fish) will have fewer opportunities for successful acclimation or adaptation to high CO2/low pH seawater.
Adaptation of organisms to ocean acidification?
CO2 levels were high at times in the geological past without there being much evidence for significant deleterious effects on marine planktonic organisms. That may be because they were slow changes that enabled organisms to evolve to adapt to gradually rising CO2
levels.
Today the rate of rise in CO2 and acidification is 10 times faster than anything experienced since the demise of the dinosaurs 65 million years ago and is closely tied to anthropogenic inputs.
Organisms with prolonged life histories and long generation times (krill, pteropods, fish) will have fewer opportunities for successful acclimation or adaptation to high CO2/low pH seawater.
There will be winners and there will be losers, and these changes will ripple through the food webs
Resources for Teachers
• WHOI OCB:
– http://www.whoi.edu/OCB-OA/
• European Project on Ocean Acidification, EPOCA:
– http://www.epoca-project.eu/
• Palmer Long Term Ecological Research datazoo:
– http://pal.lternet.edu/outreach/data_zoo.php
• Carbon Dioxide Information Analysis Center:
– http://cdiac.ornl.gov/
• Carbon Dioxide Research Group, LDEO:
– http://www.ldeo.columbia.edu/res/pi/CO2/
• RU COOL, Rutgers Coastal Ocean Observation Lab:
– rucool.marine.rutgers.edu
Calcification and the Saturation State
• Calcite • Aragonite
– More soluble
More vulnerable
Future Projections – CO2 Emissions
2007 IPCC WG1 AR-4; Projected for end of 21st century
Feeley et al.,
submitted
Feeley et al.,
submitted
Marine snails, Pteropods• Shelled pteropods can reach densities of 1000s to 10,000
individuals m-3 in high-latitude areas and comprise up to 25% of total zooplankton biomass in the Southern Ocean
• Important prey species for a variety of other zooplankton and fish
• Contain a soluble calcium carbonate shell
Marine snails, Pteropods
UNDERSATURATION SUPERSATURATION
• Shelled pteropods can reach densities of 1000s to 10,000 individuals m-3 in high-latitude areas and comprise up to 25% of total zooplankton biomass in the Southern Ocean
• Important prey species for a variety of other zooplankton and fish
• Contain a soluble calcium carbonate shell (aragonite)
Dissolution of Clio pyramidatashell (Orr et al. 2005)
Risk map for krill hatching rate
(Kawaguchi et al. 2013)
Future Projections – Temperature
Future Projections – Sea Level Rise
Future Projections – Weather EventsScientists predict an increase in
the INTENSITY of weather
events: hurricanes, precipitation,
droughts, coastal flooding
Future Projections – Ocean Acidity
Recent changes in WAP phytoplankton
• 12% decrease in chlorophyll
over past 30 years, particularly
northern WAP
1970s-1980s
1995-2005
Montes-Hugo et al. 2009
• Shift from large to small
phytoplankton
# observations
(recent – past)
# observations
(recent – past)