Acid rain causes decrease in fish biodiversity, especially in restricted water systems, such as river and lakes. High levels of acidity interferes specially with the respiration of small fish and fish embryos, causing gill damage. Acidic rain also causes reproductive failure in fish and other aquatic animals. During mating season, female fish living in acidic lakes can fail to release ova or their reproductive cells. Some fish also suffer bone decalcification, or lack of calcium, which can lead to skeletal deformities.
Frogs and salamanders often breed in temporary pools, which can concentrate rain acidity, causing damage to eggs and juveniles. However, adults frogs can tolerate acidic water better than salamanders. Normal rain pH is about 5.6, but acid rain can have pH levels lower than 4. While frogs cope with waters at pH levels of 4, salamanders cannot survive when acidity levels pass the pH threshold of 5.
Acid rain can also endanger nonaquatic, tree nesting birds, causing them to lay defective and porous eggs, which can also fail to hatch. Acid rains affect birds indirectly, through the food chain. Snails and insects are the food source of most birds. Snails are their main source of calcium, an essential mineral in the formation of egg shells. Snails depend on the soil for their calcium source, but in areas of acid rain, such mineral is leached away. Although birds are still able to feed on spiders and insects, such food sources are very poor in calcium, causing egg deformations, according to Elmhurst College.
Acid rain causes damage to terrestrial and aquatic plants alike. It causes slower growth of trees, leaf damage, as well as forest soil degradation. Acid rain dissolves the soil nutrients and washes them away, at the same time it releases aluminum and other toxic substances into the soil. Acid rain has been affecting the Appalachian Mountains from Maine to Georgia, which includes the Shenandoah and Great Smoky Mountain National Parks. Plants in the aquatic ecosystem also suffer the effects of acid rain. Some types of algae overgrow in acidic environments, posing a threat to other species by reducing the amount of available oxygen and space.
Crayfish and other crustaceans are not found in acidic waters with pH is lower than 5. Decreasing number of crayfish also threatens the existence of animals, such as most fish species, that feed on them. Most insects deposit their eggs in the water or on the surface of leaves, being very vulnerable to the negative effects of acid rain. Low pH levels can kill the embryos inside the eggs, as well as the newly-hatched larvae.