BIOACCUMULATION + BIOMAGNIFICATION

Bioaccumulation & Biomagnification

Definitions

  • Bioaccumulation: The buildup of toxins in an organism over time.
  • Biomagnification: The increasing concentration of toxins as they move up the food chain.

Pollutant Sources

  • Pesticides (e.g., DDT)
  • Heavy metals (e.g., mercury, lead)
  • Industrial waste & microplastics

Bioaccumulation in an Organism

  • Pollutants do not break down easily and accumulate in tissues.
  • Example: Microplastics in fish.
    • Ingestion (fish mistake plastics for food plankton etc)
    • Gill uptake (breathing)
    • Absorption (through the skin) less common or on the skin of animals they consume

Biomagnification in the Food Chain

  • Pollutants increase as the trophic level increases.
  • Humans are at the top of all food webs and thus are susceptible to bioaccumulation!

Mercury in Fish – River Derwent, Tasmania

  • Industry has used the Derwent River near Hobart as a place to dump waste since early colonial times.
  • In 1824, the water was deemed undrinkable because of pollution.
  • Mercury bioaccumulates in fish, affecting many forms of wildlife.
  • Crayfish, bream, and many other aquatic life are deemed unsafe to consume due to heavy metals.
  • Since 2007, the government has developed a water quality plan focusing on heavy metals and nutrients.
  • Monitoring heavy metal inputs and existing levels and limiting their release into the river.
  • There has been a gradual reduction in metal levels in sediment; however, shellfish and certain fish species maintain an elevated level of mercury due to their position in the food web.

Impacts of Bioaccumulation

Microplastics

  • Inflammation and cell damage
  • Endocrine disruption (hormone regulation)
  • Gastrointestinal issues
  • Neurotoxicity

Mercury

  • Neurological damage
  • Developmental Issues (lower IQ, physiological development)
  • Kidney damage
  • Cardiovascular problems
  • Reproductive Issues.

Research Task

  • Find a graphic/chart detailing the bioaccumulation of heavy metals (mercury, ddt) in fish in an area outside of Australia.
  • Outline a government program designed to combat the issue.
  • Submit online on Canvas