Final answer:
Algal blooms can obstruct sunlight for other photosynthetic organisms and lead to oxygen depletion in water bodies, which harms aquatic life and creates dead zones. The pH changes further disrupt the ecosystem.
Step-by-step explanation:
When algae grow out of proportion, resulting in algal blooms, this can have several detrimental effects on the ecosystem. These blooms can obstruct sunlight, preventing other photosynthetic organisms from growing. The subsequent death of these algae leads to a depletion of oxygen levels in the water as decomposing microorganisms use up oxygen in breaking down the organic matter, creating 'dead zones' where aquatic life cannot survive. Additionally, the change in the pH of the water can negatively affect metabolic processes in aquatic organisms.