Lecture 21 - Ocean Acidification & Coral Reefs

what is seawater made of?

• Na⁺ / Cl^- /Ca⁺ / Mg⁺ / K⁺

• CO₂ / O₂ / H₂O

where do these ion and gases originate

• organisms respiring will release CO₂

• atmosphere → CO₂

• hydrothermal vents → underwater volcanoes

composition of the atmosphere

• nitrogen gas (78%)

• oxygen gas (21%)

• argon gas (1%)

• minute concentrations of

  • carbon dioxide

  • methane

  • nitrous oxide

  • ozone

  • chlorofluorocarbons

where do greenhouse gas (GHG) emissions come from in Canada?

• energy production

• transportation

• industrial processes

• fugitive sources (methane lost during oil and gas extraction)

• agriculture

• waste

what was happening in the 1700/1800s

industrial revolution → CO₂ emissions increase

how much CO₂ is absorbed by the ocean

25-30%

increases CO₂ in atmosphere = _______

increased CO₂ in the ocean

pH of freshwater and saltwater

freshwater: 6.5-8

saltwater: 8.2

ocean acidification process

reactions can go either way depending on how much CO₂ is dissolved.

currently moving left → right bc of our actions

acidity ______, as pH decreases

increases

what is coral skeleton made of?

• calcium carbonate

• aragonite crystals

• calcium abundant in seawater

• carbonate can change depending on levels of dissolved CO₂

acidification alters ocean chemistry and…

calcification

what will happen to coral as ocean water becomes more acidic

can’t grow their skeletons/weaken bc of poor calcification

• decreased growth rates

• less dense → more fragile → increase bioerosion/storm damage

• may use more energy to keep growth rates up → limits energy for things like reproduction

how can we test coral

• lab experiments

• field experiments

• look to natural environments

• study coral biochemistry

Fill in the correct answer after examining Figure 1.

In the 1900s the primary contributor to global emissions was _____. This trend continued and by 1920 another major contributor emerged, _____. Emissions from _____ became the third contributor after the 1950’s. After 1950 the total amount of carbon dioxide emissions began to _____ to more rapidly. By 1970 the top contributor was clearly _____ with _____ as the second major source. ______ ___has steadily increased from 1940 to 2013. In contrast, there has been a sharp increase in the contributor, _____, since 2000.

In the 1900s the primary contributor to global emissions was coal. This trend continued and by 1920 another major contributor emerged, oil. Emissions from natural gas became the third contributor after the 1950’s. After 1950 the total amount of carbon dioxide emissions began to increase more rapidly. By 1970 the top contributor was clearly oil with coal as the second major source. Natural gas has steadily increased from 1940 to 2013. In contrast, there has been a sharp increase in the contributor, coal, since 2000.

Complete the paragraph to help explain how pH has changed over time.

The pH level of the ocean has _____ over time. Since atmospheric _______ is _____, the amount of CO2 that the water takes in _____ as well. When there is more CO2 in ocean water, this changes ocean chemistry. The ending chemical reaction in the ocean results in an increase in _____ ions, which will result in a pH decrease, thus causing the ocean to become more _____.

The pH level of the ocean has decreased over time. Since atmospheric carbon dioxide is increasing, the amount of CO2 that the water takes in increases as well. When there is more CO2 in ocean water, this changes ocean chemistry. The ending chemical reaction in the ocean results in an increase in hydrogen ions, which will result in a pH decrease, thus causing the ocean to become more acidic.

If human continue to emit CO₂ at the amount we do right now, what does that mean for the future? Summarize in your own words.

• pH decrease

  • organisms that rely of calcium carbonate will have trouble forming skeletons

• food sources of coral, such as plankton, may also decrease

What are some things that you can do to decrease your carbon footprint and help decrease the overall emission of CO₂?

• walk, bike, public transportation > cars

• eat locally, but also look at how the food is grown (ecologically grown)

  • move away from industrial farming

• eat less meat

• turn off unnecessaries lights and water

• more energy efficient homes

• turn to renewable sources of energy

• reduce materialistic consumption → buy secondhand