Ocean Acidification

Question 1

What is the most extreme future forecast of ocean pH?

Answer 1

pH 7.8

Question 2

What is current ocean pH?

Answer 2

~ pH 8.1

Question 3

What is carbonic acid?

Answer 3

CO2 that has dissolved in the ocean and combined with H2O

Question 4

What are the consequences of increased atmospheric CO2 on the ocean?

Answer 4

Increased concentration of dissolved CO2
Increased concentration of H+
Increased concentration of bicarbonate ions
Increased concentration of carbonate ions
Decreased pH

Question 5

What do marine organisms build hard parts / shells out of?

Answer 5

Calcium carbonate (calcite, aragonite)

Question 6

What does saturation state do?

Answer 6

Influences the difficulty of production of hard parts.
>1 = supersaturation, shell building is hard
<1 = undersaturation, shell building is difficult

Question 7

How long have we been in a glacial ice house period for?

Answer 7

43 MY

Question 8

What impacts did the End-Permian mass extinction have on the ocean and when was it?

Answer 8

250 MYA
95% of marine species went extinct. Calcified organisms affected most

Question 9

What are the biological effects of ocean acidification?

Answer 9

Less calcification, decreased saturation state, decreased pH

Question 10

What are 3 examples of calcifying holoplankton?

Answer 10

• Coccolithophores: single celled phytoplankton with secrete calcite shells
• Foraminifera: single celled protists with calcite shells
• Pteropods: planktonic snails, with aragonite shells

Question 11

What is an example of calcifying benthos?

Answer 11

Bihalves: mussles and oysters. At projected pCO2 levels of 2100, oysters calcification rate declines 10%.

Question 12

What are the biological consequences of ocean acidification to sharks?

Answer 12

High CO2 levels acidify the blood and tissues. Sharks are osmoconformers = blood plasma has the same osmolarity as sea water, meaning sharks are at a higher risk.
Increased pCO2 impairs olfactory senses

Question 13

What can volcanic events mean for ocean acidification?

Answer 13

• Ejects CO2 into water, reducing pH
• Calcerous algae is absent at low pH
• Non calcerous algae thrives at low pH
• Sea urchins are absent at low pH
• Shell dissolution at low pH

Question 14

How can ocean acidification be reversed?

Answer 14

By deliberate alkalinisation, as a geoengineering solution.