Final answer:
Conditions most likely to contribute to the development of an algal bloom occur during the nutrient enrichment stage of the water cycle. Excessive growth of algae can lead to reduced light penetration in water and impact the survival of photosynthetic plants.
Step-by-step explanation:
Conditions most likely to contribute to the development of an algal bloom occur during the nutrient enrichment stage of the water cycle. When there is a large input of nitrogen and phosphorus (from sewage and runoff from fertilized lawns and farms), the growth of algae skyrockets, resulting in a large accumulation of algae called an algal bloom. This excessive growth of algae can lead to reduced light penetration in water, which in turn causes the lake or pond to become aphotic, impacting the survival of photosynthetic plants.