Question

With the rise in water temperature, dissolved oxygen
(a)Remains Unchanged
(b)Increases in the amount
(c)Decreases in the amount
(d)It is more available to the aquatic organisms

Answer 1

The relation between dissolved oxygen and water temperature is inversely proportional. The dissolved molecules of oxygen are the ones that are available to the organisms. With the rise in water temperature, the availability of oxygen decreases.

Complete answer:
The solubility of oxygen in water highly varies with the temperature of the water. There exists an inverse relationship between the two. The dissolved oxygen is more in cold waters and decreases with a rise in the temperature of the water. This is due to the fact that in higher temperatures the motion of the molecules is faster and has more kinetic energy, thereby allowing the oxygen to escape.

Additional Information: -Salinity also has an inverse relation with the dissolved oxygen, with increased salt content, the oxygen holding capacity of water decreases.
-The temperature also affects the metabolic rates of aquatic fauna, the aquatic life prefers normally moderate temperature and a lot of aquatic species have seen to be migrating towards the water with moderately normal temperatures.
-Like the aquatic fauna, aquatic flora prefer moderately high water temperatures and remain dormant below 21°C, in order for the plants to flourish, the temperature should be above it.
-With increased water temperature, the solubility of many other compounds increases can cause toxicity of certain compounds like heavy metals.
-Very high temperatures or very low temperatures of water are both considered to be harmful to aquatic life. But the higher extreme is more dangerous than the lower extremes of temperature.
-Cold temperatures will mostly affect growth, disease tolerance, and overall survival of the aquatic organisms. Warmer temperatures will affect the respiration of aquatic life causing stress on it because of the decreased oxygen content.
Thus, the correct option is ‘Decreases in amount'

Note: The migration of aquatic life is the movement of the fish and other aquatic animals to areas that are better for their survival owing to better oxygen availability, proper breeding grounds, suitable water temperatures, and other such factors.