In a lake with excess levels of phosphates and nitrates in its water, the most likely result would be an increase in the growth of algae in the lake.
Explanation:
1. Phosphates and nitrates act as nutrients for algae. When these nutrients are present in excess amounts, it can lead to an overgrowth of algae in the lake. This phenomenon is known as eutrophication.
2. As algae populations increase, they form algal blooms on the surface of the water. These blooms can reduce sunlight penetration into the deeper parts of the lake, affecting the growth of other aquatic plants and organisms.
3. The decomposition of excessive algae consumes oxygen in the water, leading to a decrease in dissolved oxygen levels. This can harm fish and other aquatic organisms that rely on oxygen to survive.
Therefore, in a lake with high levels of phosphates and nitrates, the growth of algae is likely to increase, causing a range of ecological problems within the lake ecosystem.