Most lakes and streams have a pH level between 6 and 8. Lakes and streams become acidic when this level goes down and the soil around it cannot buffer the acid rain enough to neutralize it. In these areas, the acid rain releases aluminum into the water. This aluminum is highly toxic to fish and other organisms living in or around the lakes and streams. At pH level 6, basic forms of food dies that the fish eats. At a pH level of 5.5, there are more deformed adult fish due to a lack of nutrients in the water. During this time, fish cannot reproduce and the young fish have difficulty staying alive, and the older fish will die of suffocation. At a pH level of 5, the whole fish population will die off. A pH level of 4.0 will cause all life forms in that area of the lake or stream to die off. Fish, being one of the most important members of the food chain, provides nourishment for other animals, including humans. Since acid rain is affecting the aquatic ecosystem, this makes it dangerous for humans to eat fish and other animals that come from this area. The reason why acid rain has such a large affect on the aquatic ecosystem is that there are so ways in which acidic chemicals can enter the water. Chemicals substances enter the water in different ways. Some enter the waterways as dry particles. Other ways chemicals get into the water is through rain, sleet, and snow. Another way that acids enter the water is called spring acid shock. This occurs when snow melts in the spring rapidly because of a sudden temperature change. The acids then flood the soil with high levels of acid. The melted snow then runs off to smaller water sources and then eventually makes its way into larger water bodies. This causes a sudden drastic change in the pH level of the water. The aquatic ecosystem has no time to adjust to the drastic change in levels. This happens during a time when many of the aquatic life forms are reproducing.