Per. 3 Science

Study Notes on Bioaccumulation and Biomagnification  

Bioaccumulation

  • Gradual build-up of chemicals within an organism's body over time.

Biomagnification (Bioamplification)

  • The concentration of harmful substances increases at each level of the food chain.

  • Example: DDT (a man-made chemical) is non-degradable and accumulates in fat cells, persisting in food chains and causing harm to organisms.

Key Points

  • DDT and PCBs are persistent environmental contaminants.

  • High concentrations of these toxins have been found in the breast milk of Inuit mothers and polar bears, often exceeding levels in other regions.


Carrying Capacity

Definition:

  • The maximum population size of a species that an ecosystem can support.

Factors Leading to Carrying Capacity:

  1. Increased Competition: There is more competition for resources like food, water, shelter, and space.

  2. Increased Crowding: Leads to higher susceptibility to predation and disease.

Human Influence on Carrying Capacity:

  1. Adding/Removing Resources: For example, adding water and nutrient-rich soil can increase the carrying capacity of trees.

  2. Altering Species Presence: Example - Removing a predator like robins increases the carrying capacity of prey like worms.

  3. Limiting Factor: Refers to any environmental factor that restricts the size of a population or where it can live (habitats).

  4. Tolerance Range: Refers to the range of conditions within which a species can survive.

  5. Near the upper and lower limits of the tolerance range, individuals experience stress.

  6. Optimal Range: Refers to the range of conditions within the tolerance range where the species is most likely to survive.