antarctica, climate change, and krill: dr. grace saba

Antarctica, Climate Change, and Krill

Grace K. SabaRutgers University

saba@marine.rutgers.edu

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

10

15

20

25

30

0 2 4 6 8 10 12 14

0.0

0.5

1.0

1.5

2.0

2.5

0 2 4 6 8 10 12 14

2.5

2.0

1.5

1.0

0.5 C

hlo

rop

hyll a

(µ

g L

-1)

2 4 6 8 10 12 14 Time (days)

0

0

25

20

15

10

5

0

30

* *

* *

* P

rim

. P

rod

. (m

g C

m-3

d-1

)

0

1500

3000

4500

6000

7500

0 2 4 6 8 10 12 14

0

500

1000

1500

2000

0 2 4 6 8 10 12 14

3000

1500

Nan

o (

cells

mL

-1)

0

7500

*

* * * -84%

2 4 6 8 10 12 14

Time (days)

0

1500

500

Pic

o (

cells

mL

-1)

2000

-51% 0 *

*

1000

4500

6000

0

5

10

15

20

25

30

0 2 4 6 8 10 12 14

0.0

0.5

1.0

1.5

2.0

2.5

0 2 4 6 8 10 12 14

2.5

2.0

1.5

1.0

0.5 C

hlo

rop

hyll a

(µ

g L

-1)

2 4 6 8 10 12 14 Time (days)

0

0

25

20

15

10

5

0

30

* *

* *

* P

rim

. P

rod

. (m

g C

m-3

d-1

)

0

1500

3000

4500

6000

7500

0 2 4 6 8 10 12 14

0

500

1000

1500

2000

0 2 4 6 8 10 12 14

3000

1500

Nan

o (

cells

mL

-1)

0

7500

*

* * * -84%

2 4 6 8 10 12 14

Time (days)

0

1500

500

Pic

o (

cells

mL

-1)

2000

-51% 0 *

*

1000

4500

6000

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

Thank you!!

Contact info: saba@marine.rutgers.edu

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)