As pH of water nears 5, certain fish populations begin to disappear
* **Below a pH of 5, many populations have disappeared**, the benthic zone is covered with undecayed material, and mosses dominate shorelines, choking out other vegetation.
* **Below a pH of 4.5, the water is essentially devoid of fish.**
* **Acid deposition will dissolve aluminum** from compounds in the soil.
* **Al disrupts salt, water, and oxygen regulating mechanisms in fish**
* The aluminum will **cover the gills of fish, causing asphyxiation**.
* **Mercury can also be released** into streams which **bioaccumulates and biomagnifies through food chains.**