Announcements: Final exam: Tuesday, March 17, 8:00 ‐10:00 on … · 2020-03-12 · Announcements: Final exam:Tuesday, March 17, 8:00 ‐10:00 on Canvas Get to a site with ensured

Announcements:

Final exam: Tuesday, March 17, 8:00 ‐10:00 on CanvasGet to a site with ensured network connectivity!This is YOUR responsibility!

Let me know if you have issues with this.

Marine Ecology Field Lab this summer:First session: MW 9‐12:30 in CBB 115.Instructor: Josh Smith ([email protected])

TODAY

Lecture:

1. Environmental change – Ocean Acidification‐ how does OA happen?‐ where does it occur?

2. Physiology, behavior, & movement

3. Ecology‐ how do we study this?‐ effects on post‐settlement processes‐ effects on pre‐settlement processes

TODAY

Multiple effects of increased CO2

1. Warming • Stratification• Sea‐level rise• Storms• Deoxygenation

2. Acidification

Harley et al. 2006

Multiple effects of increased CO2

Ocean AcidificationThe historical perspective

• CO2 in the atmosphere has risen from 280 ppm in 1800 to about 380 ppm today—a 36% rise.

• Oceans may have absorbed about one‐half of this CO2; about one‐third of currently produced CO2 goes into the oceans.

• Average oceanic pH has fallen from ~8.16 to ~8.05during this 200 year period.

• Projected rates of decrease in pH are model‐dependent. But, even conservative models say a pH of 7.9 could occur by the end of this century.

Trends of atmospheric CO2 and ocean CO2 and pH

CO2

CO2(aq)+ H2O

CO2

CO2(aq)+ H2O H2CO3 HCO3‐ + H+

Carbonic acid Bicarbonate

CO2


pH


CO2


CaCO3 CO32‐ + Ca2+


Calcium carbonate Carbonate Calcium

CO2


CO32‐ + H+




pH = 10

pH = 4 pH = 6

CO2


CO32‐ + H+


HCO3‐



Bicarbonate

pH = 4 pH = 6

pH = 6

pH = 10

CO2


HCO3‐ CO3

2‐ + H+




Bicarbonate

pH = 4 pH = 6

pH = 6

pH = 10

Ocean acidification ‐ Projections

CC SM3‐modeled decadal mean pH at the sea surface

8.4

8.2

8.0

7.8

7.6

pHT

Feely et al. 2009

1875 1995

20952050

1

14

12

13

11

10

9

8

7

6

5

4

3

2

0

Neutral

Moreacidic

Morealkaline

Lemon juice

Seawater (8.1‐8.2)

Milk of magnesia

Vinegar

The pH scale

pH = ‐ log [H+]

1

14

12

13

11

10

9

8

7

6

5

4

3

2

0

Neutral

Moreacidic

Morealkaline

Lemon juice

Seawater (8.1‐8.2)

Milk of magnesia

Vinegar

H+ (moles/liter)1

0.01

0.0001

0.000001

0.00000001

0.000000000001

0.00000000000001

Predicted changes in pH state are not homogenous.

Tropical oceans are predicted to see the largest absolutedecrease.

Polar regions are expected to see the largest relative decrease.

Ocean acidificationProjections

Spatial patterns in absolute decrease in pH

Spatial patterns in percent decrease in pH

Pattern: Global models don’t predict the conditions organisms may experience

Recent monitoring revealed very low pH water (<7.8) associated with upwelling

Organisms may experience much more extreme and variable environments

Distribution of the depths of the undersaturated water (aragonite saturation < 1.0; pH < 7.75)

Aragonite saturation state is commonly used to track ocean acidification because it is a measure of carbonate ion concentration.

When aragonite saturation state falls below 3, these organisms become stressed.

When saturation state is less than 1, shells and other aragonite structures begin to dissolve.

Upwelling of very low pH waters on continental shelf

Feely et al. 2008 Science

Lecture:




TODAY

Physiology, behavior, & morphology

II. Ocean acidification

A. Calcification and dissolution

B. Bioenergetics

C. Photosynthesis

D. Behavior

Figure: Kleypas and Yates 2009

Data: Langdon et al. 2003

Experimental CO2 enrichment:Coral calcification decreases with increasing acidification

Acidification

Calcification and dissolution

Bioenergetics

OA changes the ‘cost of living’?

GrowthCost of Living

Reproduction

Normal

Reproduction

GrowthCost of Living

Stressed

EnergyBudget

Energy budgets – If the cost of living (e.g. calcification) increases,less energy is available for growth and reproduction.

Mytilus edulisPhoto: Seattle Aquarium

pCO2 ppmv

Net calcification

Gazeau et al. 2007

windwindwind

(Melzner et al. 2011)

Upwelling in fjords enriches surface waters with CO2

Pattern: Kiel Bay: a seasonally CO2 enriched habitat

Slide adapted from F. Melzner

Dominated by calcifying species!Blue mussel‐Mytilus edulis

Barnacle – Amphibalanus improvisusEchinoderm – Asterias rubens

more acidic

Highest recruitment

of invertebrate

species occurred at peak pCO2

pCO2 >100 Pa(>1000 µatm)

Thomsen et al.2010Biogeosciences

pCO2 >230 Pa(> 2300 µatm)

Pattern: dominance of calcifying macrobenthos

Slide adapted from F. Melzner

Seasonal variation in pCO2

Hypothesis: Increased food supply can buffer effects of acidification

Melzner et al. 2011

Low food

High food

The effects of OA will depend on food

availability

and other factors

PhotosynthesisPlants and algae use CO2!

Scent + Normal pH

Scent + Reduced pH

Munday et al. 2009 PNAS

Behavior

Pattern: Many reef fish use olfactory cues to locate suitable settlement habitat.

General hypothesis: OA might affect their ability to detect the olfactory cues

Control Unsuitable habitat

Suitable habitat

Unreliablecue

Suitable habitat

Results: Juvenile fish lost their “homing ability” – or their ability to find suitable habitat

Behavior

However: recent study has refuted these results

Lecture:




TODAY

Harley et al. 2006

3. Ecology

Post‐settlement processes

A. OA and competition

Pattern: At volcanic CO2 vents, calcifying algae are less abundant in more acidic conditions, where fleshy turf algae dominate.

No CO2 vents CO2 vents

Kroeker et al. 2012

OA and competition ‐ Kroeker et al. 2012

General hypothesis: Fleshy algae is outcompeting calcifying algae for space by overgrowing it.

Specific hypothesis: In areas of CO2 venting, crustose coralline algae will successfully recruit onto settlement tiles during early stages of succession but will be overgrown by turfy algae during the late stages of succession.

Test: Settlement tiles in 3 pH zones for 1.5 years


Hall‐Spencer et al. 2008

Castello, Ischia, Italy

Extreme Low

Seawater pH

LowAmbient

Calcified taxaResults: Calcified taxa overgrown by fleshy algae in low pH

Turf algae

0

0.2

0.4

0.6

0.8

-1 4 9 14

0

0.2

0.4

0.6

0.8

0 2 4 6 8 10 12 14

Months

80

60

40

20

80

60

40

20

Ambient

Low

Extreme low


0

20

40

60

80

current future0

20

40

60

80

current future

0

1

2

3

current future0

2

4

6

current future

0

10

20

30

current future0

10

20

30

current future

Turf algae

Pe

rcen

t cover

Turf algae

Growth (m

g/da

y)

Levels of CO2

Vents

Mesocosms

Lab experiments

Connell, Kroeker, et al. 2013 P Roy Soc B

Temperate TropicalOA and competition ‐ Kroeker et al. 2012

Lecture:




TODAY

Pre‐settlement processes

OA decreases larval survival + development

pH 8.1

pH 7.7

Ophiothrix fragilis

OA slows (skeletal) development


Ocean acidification and settlementDoropoulos et al. 2012

Acropora millepora

Newly settled larva

Planulalarva

Pattern: Many corals use coralline algae for settlement. Research suggests OA will decrease percent cover of coralline algae


Ocean acidification and settlement

General hypothesis: OA will affect coral recruitment through changes in benthic community composition.

Specific hypothesis 1: Settlement tiles cultured in high CO2 seawater will have a different community than those cultured in low CO2, and coral recruitment will be linked to crustose coralline algae cover.

Methods: “Cultured” settlement tiles on reef for 6 months, then in lab in high, medium or low CO2for 2 months.

Test 1: Settlement assay on tiles raised in low, medium, and high CO2 in ambient (control) seawater.

Doropoulos et al. 2012

OA and settlement ‐ Doropoulos et al. 2012

Coral settle

men

t

low med high

pCO2

Results 1: Fewer coral larvae settled on tiles cultured in medium CO2.

Coral larvaeSettlement tiles

Exposed to high CO2

Test 1 Yes No

No Yes

Yes No



General hypothesis: OA will affect coral recruitment through changes in larval settlement behavior

Specific hypothesis 2: larvae exposed to normal benthic communities in seawater of different CO2 levels will differ in their settlement rates

Methods: Exposed larvae to normal (ambient) benthic communities in waters of three different CO2 levels

Test 2: Settlement assay in low, medium, and high CO2 water.



Exposed to high CO2

Yes No

No Yes

Yes No

Test 2

Results 2: Fewer coral larvae settled on tiles in higher CO2 water.

Coral settle

men

t



General hypothesis: OA will affect coral recruitment through changes in larval settlement behavior

Specific hypothesis 3: larvae exposed to benthic communities cultured different levels of CO2 ANDexposed to seawater of different CO2 levels will differ in their settlement rates

Methods: Exposed larvae to benthic communities cultured at different levels of CO2 AND water of different levels of CO2.

Test 3: Settlement assays…

A. OA and settlement ‐ Doropoulos et al. 2012


Exposed to high CO2

Yes No

No Yes

Yes YesTest 3

Results 3: Fewer coral larvae settled on tiles cultured at higher CO2and higher CO2 water.

Coral settle

men

t


Results of all three experiments


Exposed to high CO2

Yes No

No Yes

Yes Yes

Test 1

Test 2

Test 3

low med highpCO2

Coral settle

men

t


Conclusions: Ocean acidification could affect settlement through both mechanisms…or it could affect the cues themselves?

Coral settle

men

t

low med highpCO2

Announcements:

Final exam: Tuesday, March 17, 8:00 ‐10:00 on CanvasGet to a site with ensured network connectivity!This is YOUR responsibility!

Let me know if you have issues with this.

Marine Ecology Field Lab this summer:First session: MW 9‐12:30 in CBB 115.Instructor: Josh Smith ([email protected])

Thank you! Have a nice break

TODAY

Documents

Announcements: Final exam: Tuesday, March 17, 8:00 ‐10:00 on … · 2020-03-12 · Announcements: Final exam:Tuesday, March 17, 8:00 ‐10:00 on Canvas Get to a site with ensured