ecoevo 3rd by urabe

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A little advanced Ecology

Ecological Stoichiometryand

Environmental Changes

6 Nov. 2012 Ecology and Evoliution3rd



Today’s outline

1. Ecological Stoichiometry

2. Light & Nutrient balance

Theory/lab & eld experiments

3. CO2 and herbivore growth

4. Function of algal diversity



6

Nutrients

Producers

Grazing food web

Detrital food web

Detritus

Light ! energy "

CO2

N, P



Environmental Disturbances

http://www.lbri.go.jp/omia/54/omia54-0.htm

http://www.city.sapporo.jp/kankyo/

gaikyo/taikiosen/taiki.htm

Changes in absolute ! rate " and relative

! ratio " inputs of energy and materials.

http://www.kankyo.metro.tokyo.jp/sgw/page2.html

Eutrophication (Nutrients)

Global warming (CO 2, Temperature)

Climate change (H 2O, Light, Seasonality)



Stoichiometry? Numerical relationship in elements between

substrates and products of chemical reactions

An example from chemistry:6CO 2 + 6H 2O→ C6H12 O6 + 6O 2

Each side has 6 Cs, 12 Hs and 18 Os

photosynthesis



Ecological

Stoichiometry?

Prey-predator interactions(CX,P Y)Predator + (C

A,P B)Prey

→ Q(C X,P

Y) Predator + (C a ,P b)Waste

Y+B=QY+b

It examines how balance of elements inorganisms shapes ecological processes

Sterner & Elser (202) Ecological Stoichiometry, Princeton Univ



https://reader010.{domain}/reader010/html5/0609/5b1b590f70281/5b1b591a



! Ribosome: organelles where Proteins are synthesized ! Cell with rich Ribosome high protein synthesis rate ! Thus, P-rich cells are high in activity for material production

! Heterotrophs with rich P is higher in their growth rate

http://www.hr-online.de/fs/schulfernsehen/genzeit.html



Comparison among various animals and bacteria

RNA and animal growth rate



Plant !Algae " Stoichiometry

C 6H 12O 6

6O2P, N

C 106N 16P 1

6CO2

6H2O C 6H 12O 6

6O2P, N

C 600N30P1

6CO2

6H2O C6H12O6

6O2 P, N

C 106N16P 1

Favorable

Nutrientdecient

Lightdecient

6CO2

6H2O

Redeld ratio

Redeld ratio

C-rich cells



Autotrophs

Heterotrophs

Homeostasis in elemental ratios



Homeostasis 100

10

1 1 10 100 0.0001 0.001 0.01 0.1 1

1

0.1

0.01

0.001

0.0001

0.01 0.1 1 10

10

1

0.1

0.01 1 10

10

1

N : P a l g a e

N:P medium

C:N substrate

C : N b a c t e r i a

N:C medium

N : C

F u n g u s

D a p h n

i a P %

Algal P%



Algae Herbivorous [ Daphnia ]

CP

C P P

PC

CP

Variable P:C organisms High P:C organisms

Algae !Herbivore Stoichiometry

29

C



TER is C to element ratio below which animal growth is limited by thecontent of that element (N, P, etc.) in food rather than food abundance (C).

P-net intake = [C-net intake] x Z P:C

In the case of P

I ingestion rate

" assimilation efficiency

# loss rate F

C : P food C:P ratio

Z

C : P animal C:P ratio

k gross growth efficiency

Minimal model (! P =1, " P =0 )

= F P :C

* = k C

Z P :C TER

For Daphnia

Z P:C ~0.03, k C ~0.3TER P:C~ 9 ! gP/mgC

Urabe, J., and Y. Watanabe. 1992. Possibility of N or P limitation for planktonic cladocerans: an experimental test. Limnol. Oceanogr 37 : 244-251. Hessen D. O. 1992. Nutrient element limitation of zooplankton production. Am. Nat., 140 : 799-814.

F P : C =

k C

Z P : C

" P

# $ P I C " P

( k C

=

I C " C

# $ C

I C

)

I C

F P : C " P

# $ P = ( I C " C # $ C ) Z

P : C (eq1)

(eq2)



Urabe and Watanabe (1992) Limnology and Oceanography, 37 : 244-251

Threshold elemental ratio (TER) below which animal growth is limited by nutrientcontent (P, N) in food rather than food abundance (C)

For Daphnia TER P:C ~ 8.6 µg P/mgC or C:P ~300 atomic ratio

TER = Body P:C ratiox Gross Growth Efciency for C

Threshold Elemental Ratio

30

In the case of P Minimum model (! P =1, b P =0 )



Light!Nutrient Balance andHerbivore growth



Light intensity received each ask

PP

A theory

A l g a l A b u n d a n c e

( m g C / L )

Al g al P

: Cr a t i o

I n g e s t i o n r a t e

( C a r b o n / d a y )

Gr o w

t h r a t e

P

Light intensity received each ask



P

P

10 µM (high nutrient)

1.6 µM (low nutrient)

Low light High light

Low light High light

Experiment



0

5

10

0

25

50

75

20

30

10

0

P10 µmmol/L

10 100

10 100

Light intensity ( µE/m 2/s)


( m g C / L )

Al g al P

: Cr a t i o

( µ gP / m gP )

G r o w t h r a t e

( µ g D W / i n d )

Results High Nutrients

TER

Urabe & Sterner (1996) PNAS, 93:8465-8469



0

5

10

0

25

50

75

20

30

10

0

10 100

10 100

Light intensity ( µE/m 2/s)


( m g C / L )

Al g al P

: Cr a t i o

( µ gP / m gP )

G r o w t h r a t e

( µ g D W / i n d )

TER

Results Low Nutrients

Urabe & Sterner (1996) PNAS, 93:8465-8469

P

1.6 µmmol/L



In general…….Stephen Elser



I like ne weather, but if this makes my

food bad….



Background

The atmospheric CO 2 level is

expected to double or treble

by 2100 years.(IPCC 4th assessment report, 2007)



1.5

2.0

2.5

3.0

3.5

4.0

4.5

.5.0

1.0

370ppm

0 1 20

Number of lakes

19 lakes

58 lakes

l o

C O

,

m140° 145°

45°

40°

35°

Most lakes are CO2saturated



CO 2

DOC

DOC

CO 2

CO 2

Elevation of atmospheric CO2likely rises pCO2 in aquatics

much more via terrestrial input



Stoichiometric impactsof rising pCO2 on aplankton herbivore



A b u n d a n c e

days

Steady statebiomass

Exponentialgrowth rate

Daphnia growthex eriment

Body mass changes for 5 days

pCO 2; 360 ppm or 2000 ppmSemi-continuous culture (30% dilution per 2 days: 20°C) Nutrients: 1.5 µM P, N:P=80; Light: 150 µmoles m -2 s-1

Algae Scenedesmus (green algae)

Cyclotella (diatom)Synechococcus ( cyanobacteria)

Algal culture experiments



Results

Green algae Diatoms

4

8

2

6

2

CO2

2

4

6

CO2

2

4

CO2

4

8

2

6

2

CO2

2

4

6

CO2

2

4

CO2

A l g a l b i o m a s s

( m g C / L )

A l g a l P : C r a t i o

( x 1 0 3 )

D a p h n

i a

G r o w t h r a t e

( / d )

CO 2 treatment (ppm)360 2000 360 2000

TER TER



Results

Cyanobacteria

4

8

2

6

2

CO2

2

4

6

CO2

2

4

CO2

4

8

2

6

2

CO2

2

4

6

CO2

2

4

CO2

4

8

2

6

2

CO2

2

4

6

CO2

2

4

CO2

2/6 0/6n.s

n.s

n.s


( m g C / L )


( x 1 0 3 )

D a p h n

i a

G r o w t h r a t e

( / d )

CO 2 treatment (ppm)360 2000 360 2000 360 2000

TER TER TER

Urabe et al (2003) GCB 9:818-825, Urabe & Waki (2009) GCB 15:523-531

Green algae Diatoms



A pitfall

Various algal species co-occur in nature.

Herbivore’s response may differ betweenfeeding on single algal species and

feeding on multiple algal species.



A b u n d a n c e

days

Steady statebiomass

Exponentialgrowth rate

Daphnia growthexperiment

Body mass changes for 5 days

pCO2; 360 ppm or 2000 ppm

Semi-continuous culture (30% dilution per 2 days: 20°C) Nutrients: 1.5 µM P, N:P=80; Light: 150 µmoles m -2 s-1

Algae Scenedesmus (green algae)

Cyclotella (diatom)Synechococcus ( cyanobacteria)

Mixed culture experiments

Mixed culture

48



Results: two species

51

CO 2 treatment (ppm)

4

8

12

16

2

CO2

2

4

6

CO2

2

4

CO2

Green algae +

Cyanobacteria


( m g C / L )


( x 1 0 3 )

D a p

h n

i a

G r o w t h r a t e

( / d )

360 2000

TER

Urabe & Waki (2009) Global Change Biology 15:523-531




51


4

8

12

16

2

CO2

2

4

6

CO2

2

4

CO2


( m g C / L )


( x 1 0 3 )

D a p

h n

i a

G r o w t h r a t e

( / d )

360 2000

TER

4

8

12

16

2

CO2

2

4

6

CO2

2

4

CO2

Diatoms +

Green algae

360 2000

TER


Green algae +

Cyanobacteria




51


4

8

12

16

2

CO2

2

4

6

CO2

2

4

CO2


( m g C / L )


( x 1 0 3 )

D a p

h n

i a

G r o w t h r a t e

( / d )

360 2000

TER

4

8

12

16

2

CO2

2

4

6

CO2

2

4

CO2

360 2000

TER

4

8

12

16

2

CO2

2

4

6

CO2

2

4

CO2

Cyanobacteria +

Diatoms

n.s

360 2000

TER


Green algae +

Cyanobacteria

Diatoms +

Green algae



Results: three species


4

8

12

16

2

CO2

2

4

6

CO2

2

4

CO2


( m g C / L )


( x 1 0 3 )

D a p h n

i a

G r o w t h r a t e

( / d )

360 2000

Green algae + Diatoms +

Cyanobacteria

Threshold P:C

n.s




Results: three species


4

8

12

16

2

CO2

2

4

6

CO2

2

4

CO2


( m g C / L )


( x 1 0 3 )

D a p h n

i a

G r o w t h r a t e

( / d )

360 2000

Green algae + Diatoms +

Cyanobacteria

Threshold P:C

n.s

Green algae

4

8

2

6

2

CO2

2

4

6

CO2

2

4

CO2


( m g C / L )


( x 1 0 3 )

D a p

h n

i a

G r o w t h r a t e

( / d )

Threshold P:C

360 2000CO 2 treatment (ppm)




!!!

□ Numerically minor algae play nutritionallyimportant roles.

□ Nutritionally unimportant food becomebenecial in high CO 2.

□ Algal diversity serves to mitigate theadverse effects of rising CO 2.

Adverse e # ects of rising CO 2 on herbivoreoccur in single food environments but notin multiple food environments.



Why does this occur?

4

8

12

16

2

CO2

2

4

6

CO2

2

4

CO2


( m g C / L )


( x 1 0 3 )

D a p

h n

i a

G r o w t h r a t e

( / d )

360 2000


Green algae +

Diatoms +Cyanobacteria

Threshold P:C

n.s

Green algae

4

8

2

6

2

CO2

2

4

6

CO2

2

4

CO2


( m g C / L )


( x 1 0 3 )

D a p h n

i a

G r o w t h r a t e

( / d )

Threshold P:C

360 2000




Feedingcompensation

Stimulate feedingactivities

Assimilationenhancement

Functionally increaseassimilation efciency

Why high growth is maintained at high CO2 when fed multple algae?

Nutritionalcomplementarity

Complement decient nutrientseach other, orameliorate someharmful substances.

54

Possible mechanisms




Lab Experimentagain



G rowth rate

Ingestion rate ( 32P)

Assimilation rate ( 32P)

Measurements forG.I.A. rates

Low CO 2

2-3 speciestreatment

1 speciestreatment

High CO 2

2-3 speciestreatment

1 speciestreatment

Food abundance 1mgC/L Food abundance 1mgC/L

360ppm 2000 ppm



0

0.1

0.2

0.3

0.4

G r o w

t h r a t

( / d )

0 2.5 5 7.5 10

Algal P (µgP/L) or P:C ratio (µgP/mgC)

r 2 = 0.109

Single algae

Dual algae

Treble algae

Growth rate vs Algal P:C ratioLow High CO 2 CO 2

Results



0

0.1

0.2

0.3

0.4

G r o w

t h r a t

( / d )

0 2.5 5 7.5 10

Algal P (µgP/L) or P:C ratio (µgP/mgC)

r 2 = 0.109

Single algae

Dual algae

Treble algae

Growth rate vs Algal P:C ratio

0

0.1

0.2

0.3

0.4

G r o w

t h r a t e

( / d )

0 5 10 15 20

Ingestion for P (ngP/h/ind)

r 2 = 0.444

Growth rate vs Ingested P

Low High CO 2 CO 2

Results

l l d d f d f



0.0

0.5

1.0

1.5

2.0

2-3

F e e d

i n g r a t e

( m l /

h / i n d

)

Algal diversity and feeding performance

l



Single algae

Dual algae

Treble algae

Low High CO 2 CO 2

Results

0

0.1

0.2

0.3

0.4

G r o w

t h r a t e

( / d )

0 5 10 15 20


r 2 = 0.444


R l



Single algae

Dual algae

Treble algae

Low High CO 2 CO 2

Results

0

0.1

0.2

0.3

0.4

G r o w

t h r a t e

( / d )

0 3 6 9 12

Assimilation rate for P (ngP/h/ind)

r 2 = 0.726

Growth rate vs Assimilated P

0

0.1

0.2

0.3

0.4

G r o w

t h r a t e

( / d )

0 5 10 15 20


r 2 = 0.444


Al l di i d di i f



0.5

0.6

0.7

0.8

2-3 A s s i m

i l a t i o n e f c i e n

c y f o r P

( % )

Algal diversity and digestive performance



Feedingcompensation

Stimulate feedingactivities

Assimilationenhancement

Functionally increaseassimilation efciency

Why high growth is maintained at high CO2 when fed multiple algae?

Nutritionalcomplementarity

Complement decient nutrientseach other, orameliorate someharmful substances.

54

Possible mechanisms



Summary $ I %

■ Ecological Stoichiometry (ES) examines thebalance of elements in ecological interactions.

■ It is useful to understand the responses ofecosystems to environmental changes (light/CO 2/

nutrients) via quantity and quality of plants.

□ Putative increase in pCO 2 likely increase plant

(algal) abundance but reduce the nutrient contents.

□ Thus, algal species beneficial at present may notbe beneficial for herbivore in future (high CO 2 world).



Summary $ II %

□ However, adverse effects of rising CO 2 onherbivores can be mitigated by algal diversity

□ Algal diversity is certainly important for

sustaining herbivores especially at high CO2environment in future.

□ Finally, we need to study more on assimilationactivities of herbivores to understand theirresponse to changes in food condition.

ecoevo 3rd by urabe

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