The Effects of Acidity on Aquatic Organisms

Effects on Reproduction

• An overly acidic environment can hinder the ability of aquatic creatures to reproduce. The increased acid can interrupt the creature's natural sex cycle, during which the animal produces eggs and sperm cells. If the egg and sperm cells are malformed, no offspring can be produced. The acidic water also can harm the fertilized eggs, resulting in failure to hatch or deformed offspring with little chance of survival. Water with a pH of 5 or below can kill any aquatic organism's eggs.

Effecting Food Sources

• Many aquatic organisms feed on algae (microscopic aquatic plants) or plankton (microscopic aquatic animals). Algae and plankton are especially vulnerable to changes in pH. When the pH in a body of water lowers, the algae and plankton that are sensitive to the change will die off. Aquatic animals require large amounts of algae and plankton to survive. When the food source is depleted, the larger animals eventually begin dying as well.

Effect on Skin and Gills

• Acidic water can effect an aquatic animal's skin, gills and other tissues. If the water has a pH of 4 or lower, the organism's skin can be irritated and could flake off. Also, the protective layer of mucus that covers some fish could be harmed, which could expose the fish to bacteria. Aquatic animals that have shells could experience shell deterioration in acidic conditions. Also, acidic conditions in water are usually brought on by runoff from farms or industrial facilities, which often brings other harmful particulates (such as aluminum) that can clog the animals gills and make breathing difficult.

Acid Effects on Particular Species

• Certain aquatic species have different tolerances for acidity. Clams, shrimp and snails generally cannot survive in water with a pH below 6. Crayfish and bass can tolerate a slightly lower pH of 5.5. In water with a pH of 4.5, salmon, carp and trout begin to die off. Perch can survive a somewhat lower pH right above 4.5. Frogs are extremely tolerant of acidic conditions and can survive in water with a pH as low as 4. Any body of water with a pH below 3 cannot sustain any aquatic organisms other than certain plants and invertebrates.