What are tolerance limits?
Image Credit: Mackenzie Angell (Graphic Designer)
Tolerance limits are the ranges held by every organism, where they can tolerate a change in an internal factor. Organisms survive changes in a factor if it remains in their tolerance range; however, if a factor leaves its tolerance range, it is fatal for the organism.
Different tolerance ranges include:
Different levels of organic and inorganic materials
Tolerance Limits' Ranges
There are three ranges or 'zones' for an organism's tolerance limits.
Optimal Range: The narrow, middle-range within an organism's tolerance range for a factor at which the organism functions best
Zone of Physiological Stress: The zone outside the optimal range but inside the tolerance range; not optimal but survival is possible
Zone of Intolerance: The zone outside the tolerance range for an organism's survival (fatal).
Case Study: Aquatic life's tolerance limits
Dissolved oxygen in the ocean allows for aquatic animals like fish, oysters, crabs and others to survive, because they require sufficient levels of dissolved oxygen in the water. The amount of dissolved oxygen in an estuary's water is the major factor that determines the type and abundance of organisms that live there.
In zones of physiological stress, marine life like crabs and fish survive but are lethargic due to their decreased respiration rate.
When air and water temperature increases or there is an increased decomposition of algal blooms, this oxygen depletion may result; many animals and plants cannot survive when dissolved oxygen falls to such low levels.