How are marine plants and animals affected by the acidity of their habitats?

Answer 1

Generally speaking, most marine plants and animals are affected by acid in their environment in a negative way. There are some that are not affected negatively but for those that are, they have an impact on the entire ecosystem in many cases. For instance, a marine predator that specializes in one type of prey item risks dying out if it's prey item dies out because of increased acidity in the environment. The predator may not be affected directly by the increased acidity initially, but if it's prey is directly affected, the predator faces a real problem. To take that a step further, if the predator is not an apex predator, meaning it is not at the top of the food chain, it's decreasing numbers will in turn have an affect on the predators that would normally feed on it.

In regards to plants, photosynthetic algae has a huge impact on the seas and life in general. They produce more of the world's photosynthetic output than all the terrestrial forests combined and many are not hardy so increased acidity would have a negative affect not only on marine life but also on terrestrial life as well. Many marine plants, which can of course also be negatively affected by increased acidity, act as nurseries and hiding places for young fish and other marine life. Without these hiding places the young of many marine fish would be more exposed to predators and thus the numbers that make it to adulthood would drop significantly.