Final answer:
Most aquatic life cannot survive in water with a pH less than 5, as this level of acidity is harmful to many organisms. Aquatic ecosystems usually support life within a pH range of 6.5 to 8.5.
Step-by-step explanation:
The pH of water is critical for the survival of aquatic life. Most aquatic life in lakes cannot survive in water with a pH of less than 5. This is because the pH scale, which ranges from 0 to 14, indicates that a pH less than 7 is acidic. Aquatic life generally thrives in a narrow pH range, typically between 6.5 to 8.5, with seawater organisms adapted to a range of pH 7.5 to 8.4. Water too acidic (below pH 7) can be harmful to aquatic organisms, just as extreme alkalinity (above pH 7) can also present challenges for life.