The sun shining on a tidal pool during a hot day heats the water, causing some water to evaporate. Because the water has become warmer and saltier, .

The oxygen content of the water decreases

Explanation:

The sun shining on a tidal pool during a hot day heats the water, causing some water to evaporate. Because the water has become warmer and saltier, the oxygen content of the water decreases.

The temperature and the salt content of a body of water determines how much oxygen it can hold.

The oxygen content of warm water decreases because the temperature of the water causes the water molecules to move faster. This leads to the expulsion of oxygen from the water, making it contain less oxygen.

Also, salty water will lead to a decrease in oxygen because of the presence of sodium chloride ions.

Therefore, a warmer and saltier water will contain a less amount of oxygen.