As most know, Earth contains around 71% water, most of which (96.5%) lie in the oceans andcoral reefs. Water is very important for all kinds of life on Earth so when something that important to living organisms changes it will have consequences. As mentioned in my previous post about the structure of water and its properties, Water is a buffer so is a good environment for many organisms. I covered why water is a buffer in my last post.
Why are the oceans acidic?
The oceans are acidic because they absorb CO2. CO2 is an acidic gas and dissolves in the water. As of the increasing levels of CO2 more of the gas has been dissolving into the ocean. Lowering the pH of the water. Of course, this will not be by a lot because of water’s buffering properties. However, even small changes in pH can affect the organism living in it
How CO2 casues the water to be acidic.
When water reacts with carbon dioxide it forms 2H+ ions and CO3 2- ions. the H+ cause the pH to lower in the water. This is reversible reaction as shown below:
H2CO3 dissociates in water
H2CO3 is an acid. A weak one at that but still will lower the pH of the oceans.
How does this affect the fish?
Low water pH increases the solubility of metals in the water. Reading my post on gas exchange in fish will help you understand this section. The types of metals that are more likely to dissolve are heavy metals. Heavy metals are atoms with a high atomic number (proton number); for example, mercury. As mentioned in previous posts, mercury is toxic to pretty much everything, so fish gulping water with nasty heavy metals is not the best thing. Gulping this water as some fish do will cause the fish to have a slower metabolism as well as the metals entering the bloodstream via diffusion. Luckily fish have some sense and usually move away from this area. Aldo depending on the type of fish (pond and river) acidic conditions can burn the fishes skin
This was a shorter post than normal but still feel free to leave a reply/comment below with feedback or questions 🙂