Marine biologists studied the relationship between water temperature and dissolved oxygen (DO) concentration at various depths in a coastal ocean environment. Dissolved oxygen is essential for the survival of marine organisms; most fish species require DO concentrations of at least 5.0 mg/L to thrive.
The researchers collected water samples at 5 different depths (0 m, 25 m, 50 m, 75 m, and 100 m) during summer (August) and winter (February). They measured both temperature (in °C) and dissolved oxygen concentration (in mg/L) at each depth.
Figure 1 shows the relationship between depth and water temperature for both seasons.
Figure 2 shows the relationship between depth and dissolved oxygen concentration for both seasons.
Figure 3 shows how dissolved oxygen concentration varies with temperature, combining data from both seasons and all depths.