In this IBDP Biology blog post, we will be looking at how the ocean is impacted by the climate changes within the enviornment, let's go!
Threats to coral reefs from increasing concentration
Emissions of carbon dioxide have an effect on the oceans
- Over 500 billion tonnes of CO2 released by humans since the start of the Industrial Revolution have dissolved in the oceans
- This has caused the pH to drop this repersents 30% acidification
- Ocean acidification will become more severe if CO2 concentrations in the atmosphere continue to rise
- Reef-building corals that deposit calcium carbonate in their skeletons need to absorb carbonate ions from seawater
There is a low concentration of carbonate ions in the water and the dissolved carbon dioxide makes the concentration even lower
- Carbon dioxide reacts with carbonate to form carbonic acid which disassociates into hydrogen ions and hydrogen carbonate ions
- Hydrogen coverts carbonate into hydrogen carbonate
- Reduced carbonate concentrations in water prevent calcium carbonate from being created but the calcium carbonate within the coral reefs are dissolved
Ocean acidification - causes and effects
The ocean abosrbs about 25% of the CO2 emitted into the atmosphere
As atmospheric CO2 increases so do ocean levels
Since the 1800s the pH of seawater has fallen by 0.1 units this is a 30% increase in acidity
As more CO2 accumulates in the ocean, the pH of the ocean decreases
Estimates of future CO2 levels predict a further decrease of 0.5 units in pH which translates to 150% acidification
When CO2 dissolves in water it forms a variety of molecules:
- Carbonic acid [affects pH]
- Carbonate [releases hydrogen ions affecting pH]
- Bicarbonate [releases hydrogen ions affecting pH]
- Free Carbon Dioxide
Ocean acidification - risks and benefits
Species at risk are
- Marine calcifying species [oysters, sea urchins, sea corals, calcerous plankton]
Benefit: Photysynthetic algae and sea grasses
These species need to:
- Absorb carbonate ions from seawater to make calcium carbonate in skeletons
Benefit: Low CO2 is a limiting factor for photosynthesis
Shelled organisms are very important in aquatic food chains - put the whole food chain at risk
Example: Pteropod tiny sea creatures that are a main food source for North Pacific juvinile salmon
That's all!
References:
- https://www.google.com/url?sa=i&url=https%3A%2F%2Fgoinggreenrecyclingnigeria.org%2Fgreenhouse-pollution-and-the-dangers-of-ocean-acidification%2F&psig=AOvVaw0x1WNNwfY0NNyNrM3-hiaM&ust=1626287842878000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCJjwhL3Y4PECFQAAAAAdAAAAABAI
- https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.iucn.org%2Ftheme%2Fmarine-and-polar%2Four-work%2Fclimate-change-and-ocean%2Focean-acidification&psig=AOvVaw17TJQ3nInmYue9Con0qGXm&ust=1626287901608000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCJi1mtjY4PECFQAAAAAdAAAAABAD
Drafted by Venetia (Biology)