How does ocean temperature stratification affect marine life?

The correct choice highlights the impact of ocean temperature stratification on marine life by noting that it creates distinct layers that limit nutrient mixing. Stratification occurs when the ocean's water becomes layered due to differences in temperature and salinity, usually resulting in a warmer layer on top and cooler, denser water below.

This stratification affects marine ecosystems significantly. The upper layer, or epipelagic zone, is typically warmer and receives sunlight, allowing for photosynthesis to occur, which supports phytoplankton and other primary producers. However, because the warmer surface water is less dense, it does not mix easily with the colder, nutrient-rich water below. As a result, essential nutrients that are found in deeper waters do not reach the surface layer easily. This can lead to lower productivity in the upper layers of the ocean and can impact the entire food web, affecting not only phytoplankton but also the entire range of marine organisms dependent on them.

Understanding this dynamic is critical for appreciating how marine life is distributed and how certain species may thrive or struggle based on the availability of nutrients influenced by thermal stratification. This phenomenon plays a vital role in marine ecology, influencing biodiversity and the overall health of oceanic habitats.