What can reduce the solubility of oxygen in water?

Higher salinity can indeed reduce the solubility of oxygen in water. When the concentration of dissolved salts increases, it creates a challenging environment for gases, including oxygen, to dissolve effectively in the water. This phenomenon occurs because the presence of salts alters the water's chemical properties, making it less capable of holding dissolved gases.

In terms of the other options, increased pressure generally increases the solubility of gases in liquids, including oxygen. Lower temperatures typically enhance the solubility of oxygen; cold water can hold more dissolved oxygen than warmer water. Higher turbidity, while it may affect the water quality and biological processes, does not directly correlate with the solubility of oxygen in the way that salinity does. Therefore, focusing on salinity provides the clearest understanding of how it impacts oxygen solubility in aquatic environments.