1. Which environment has the greater concentration of dissolved oxygen: salt water or fresh water?

2. Which environment has the greater concentration of dissolved oxygen: warm water (31°C) or cool water (18°C)?

3. Which environment has the greater concentration of dissolved oxygen: a clear pond or a pond with a heavy algal mat? Explain.

Before we learn how to measure dissolved oxygen, let's consider the concept of primary productivity.

Continue to Primary Productivity.