Question

The levels of dissolved oxygen in water bodies is usually inversely proportional to

• A. Light
• B. Salinity
• C. Nitrogen
• D. Temperature

Hint:

High water temperature is doubly dangerous for fish:
1. It reduces the solubility of Dissolved Oxygen (less oxygen available).
2. It increases the metabolic rate and oxygen demand of the fish.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The concentration of dissolved gases (like oxygen) in water is governed by physical laws of solubility.

Step 2: Detailed Explanation:
According to Henry's Law, the solubility of a gas in a liquid decreases as the temperature of the liquid increases.
Therefore, cold water can hold much more dissolved oxygen (DO) than warm water.
As water temperature rises, dissolved oxygen levels drop significantly, showing a strong inverse relationship.
While salinity also has an inverse effect on DO solubility, the temperature effect is the most dominant and biologically critical factor in aquaculture.

Step 3: Final Answer:
Dissolved oxygen levels are inversely proportional to temperature, which is option (D).