Final answer:
Ocean water near the surface is less dense than bottom layer water due to the temperature dependence of water density. The surface water is generally warmer and more affected by solar heating, leading to a less dense layer floating above the cooler, denser bottom water.
Step-by-step explanation:
The ocean is a complex system with varying properties in different zones. The query focuses on the characteristics of ocean water near the surface compared to the water found at the bottom. From the information provided, we understand that water is densest at around 4°C, and as it cools below this temperature, it becomes less dense, which is why ice floats. This implies that in the case of a lake or an ocean in winter, the surface water below the ice layer is warmer and denser than the very top layer which is frozen.
The answer to the student's question is that ocean water near the surface is less dense than bottom layer water. This is consistent with the information that warmer water, which is found near the surface of the ocean due to solar heating, is less dense compared to the cooler water that sinks to the bottom. Nutrient-rich deep water may be brought to the surface through a process called upwelling, which also supports aquatic life. The surface water also generally has more dissolved oxygen because of contact with the air and possibly due to photosynthetic activities in the photic zone where sunlight penetrates.
Therefore, the answer should be, 'Ocean water that is near the surface is less dense than bottom layer water.' This is relevant to understanding aquatic biomes and environmental science, especially the principles of thermoclines and oxygen distribution in aquatic systems.