What is often observed in the eutrophic stage of a lake?

In the eutrophic stage of a lake, low oxygen levels and high turbidity are commonly observed due to excessive nutrient enrichment, primarily from runoff containing fertilizers and organic waste. This nutrient overload leads to rapid growth of algae, a phenomenon known as algal bloom, which can significantly cloud the water and increase turbidity. As algae die and decompose, the decomposition process consumes dissolved oxygen in the water, leading to low oxygen levels, particularly in deeper areas of the lake, which can create conditions that are detrimental to fish and other aquatic life. This cycle of nutrient input, algal growth, and subsequent oxygen depletion is characteristic of eutrophication and distinguishes this stage from others where clear water and healthy oxygen levels might be found.