What is thermal stratification in a lake?

1. What is thermal stratification in a lake?
A) The mixing of water
B) The layering of water based on temperature differences
C) The mixing of surface and deep water
D) The same temperature throughout the lake
2. How does thermal stratification typically affect oxygen levels in a lake during summer?
A) Oxygen levels are uniform throughout the lake
B) Oxygen is higher at the bottom and lower at the surface
C) Oxygen is higher at the surface and lower at the bottom
D) Oxygen levels constantly fluctuate up and down the water column
3. The graph right shows how temperature and dissolved oxygen change with depth in a stratified lake during summer. What does this reveal about lake ecosystems?
A) Temperature and oxygen are uniform throughout the lake
B) The thermocline creates distinct layers with different temperatures and oxygen levels
C) Oxygen increases with depth while temperature decreases
D) Only temperature changes significantly with depth