Which of the following can lead to oxygen depletion in water bodies?

Which of the following can lead to oxygen depletion in water bodies?

• A. Presence of macro plants
• B. Excessive algal growth
• C. Increase in water temperature
• D. Improved water mixing

Answer: (B)

Excessive algal growth, also known as algal blooms, can lead to significant oxygen depletion in water bodies. When algae proliferate, they can cover large surface areas of the water, blocking sunlight and disrupting the growth of underwater plants. During the night and in the decomposition phase of algal blooms, these algae consume dissolved oxygen for respiration, reducing the amount of oxygen available for fish and other aquatic organisms. When the algae die, they are broken down by bacteria, a process that further consumes oxygen, exacerbating the depletion and potentially leading to hypoxic conditions, which can harm or kill aquatic life. Other options may influence oxygen levels in different ways, but none do so by directly causing depletion through the processes that excessive algal growth does. For instance, the presence of macro plants can contribute positively to oxygen levels during photosynthesis. Increased water temperature can affect oxygen solubility, but it doesn't necessarily lead to depletion on its own. Improved water mixing could actually enhance oxygen dispersion throughout the water body, potentially increasing dissolved oxygen levels.

Excessive algal growth, also known as algal blooms, can lead to significant oxygen depletion in water bodies. When algae proliferate, they can cover large surface areas of the water, blocking sunlight and disrupting the growth of underwater plants. During the night and in the decomposition phase of algal blooms, these algae consume dissolved oxygen for respiration, reducing the amount of oxygen available for fish and other aquatic organisms. When the algae die, they are broken down by bacteria, a process that further consumes oxygen, exacerbating the depletion and potentially leading to hypoxic conditions, which can harm or kill aquatic life.

Other options may influence oxygen levels in different ways, but none do so by directly causing depletion through the processes that excessive algal growth does. For instance, the presence of macro plants can contribute positively to oxygen levels during photosynthesis. Increased water temperature can affect oxygen solubility, but it doesn't necessarily lead to depletion on its own. Improved water mixing could actually enhance oxygen dispersion throughout the water body, potentially increasing dissolved oxygen levels.