8.8

• Bioaccumulation: absorption and concentration of compounds (especially fat soluble ones like POPs) in the cells and fat tissues of organisms

  • Because fat-soluble compounds like POPs/methylmercury don't dissolve easily in water, they don't enter blood easily and don't leave body through urine easily
  • Instead they build up in fat tissues
  • Leads to increasing concentrations in organisms overtime
• What is biomagnification?

  Increasing concentrations of fat-soluble compounds
• What compounds are primarily involved in biomagnification?

  Methylmercury and persistent organic pollutants (POPs)
• Where does biomagnification begin in an ecosystem?

  In sediments or plants
• How do primary consumers accumulate POPs?

  By eating producers
• What happens to POP levels in primary consumers?

  They cause bioaccumulation in their tissues
• How do secondary consumers acquire POPs?

  By eating primary consumers
• What is the 10% rule in ecology?

  Only 10% of energy is transferred to the next level
• How does the 10% rule affect POP levels in organisms?

  Higher biomass consumption leads to higher POP levels
• Which organisms have the highest levels of POPs and methylmercury?

  Large predators like salmon, dolphins, and whales
• DDT was banned in many developed countries but still persists in sediments of bodies of water

  • Taken in by bottom feeders and biomagnified at higher trophic levels
  • Causes thinning of eggshells in top predator birds
  • Prompted the passage of the Endangered Species Act.
• Biomagnification of methylmercury:

  • Mercury emitted from burning fossil fuels and by volcanoes
  • Carried by wind and deposited in water where bacteria converts it into toxic methylmercury
  • Taken in by photoplankton and biomagnified in predators and later humans: leads to nervous system damage in humans and fish.