1. Effects of Bioaccumulation on Ecosystems
Chapter 2.3

2. What do you know? Bioaccumulation Bio-magnification
Orcas and pollution
Pesticides and the environment
Persistent organic pollutant
Heavy metal

3. Background
Some organic compounds as well as some heavy metals remain in the environment for a long time
As lower orders on the food chain consume plant or animal materials containing these chemicals, the chemicals can accumulate in tissues
The chemicals become biomagnified, moving up the food chain
Some chemicals are toxic at very low levels, causing reproductive failure, organ malfunction, and death.

4. Bio-indicators help monitor the health of the environment

5. Amphibians are bio-indicators
Life cycle includes aquatic phase
Shell-less eggs are susceptible to environmental effects of run-off and other pollutants
Highly permeable skin, which they use to breathe, also makes them more sensitive to toxic substances
Scientists believe that the factors that are negatively affecting amphibians today are also harming other species
If the frogs are showing negative effects, what does that say about the environment and other species?

6. Some chemicals are toxic at very low levels!
Parts per
ppm = Parts per Million
1cent in $10,000
ppb = Parts per Billion
1 cent in $10,000,000
ppt = Parts per Trillion
1 cent in $10,000,000,000
Some chemicals are toxic at very low levels!

7. Keystone Species

8. Bioaccumulation
Bioaccumulation refers to the gradual buildup of chemicals in living organisms.
Many harmful chemicals
cannot be decomposed naturally
can be eaten or absorbed and sometimes cannot be removed from the body of the organism effectively.
A keystone species is a vital part of an ecosystem
If a keystone species suffers a chemical bioaccumulation,
it can affect every other organism in its far-reaching niches.
Organisms are sometimes exposed to toxic chemicals.
See page 94

9. Bioaccumulation
Biomagnification is the process by which chemicals become more concentrated at each trophic level.
At each level of the food pyramid, chemicals
that do not get broken down build up in organisms.
When a consumer in the next trophic level eats
organisms with a chemical accumulation,
it receives a huge dose of the chemical(s).
Organisms are sometimes exposed to toxic chemicals.
See page 94

10. Bioaccumulation (continued)
An example of bioaccumulation in British Columbia is the effect of PCBs on the Orca.
PCBs are chemicals that were used for many industrial and electrical applications in the mid-20th century.
Because PCBs do not degrade,
The whale actually consumes
4550 kg worth of accumulated
PCBs.
See page 95
The bioaccumulation of PCBs begins with the absorption of the chemicals by microscopic plants and algae.

11. Bioaccumulation (continued)
PCBs were banned in 1977 because of their environmental impact.
PCBs bioaccumulate and
have a long half-life
(they break down very slowly).
PCBs will affect the
reproductive cycles of orcas
until at least 2030.
The bioaccumulation of PCBs begins with the absorption of the chemicals by microscopic plants and algae.
See page 95

12. Bioaccumulation (continued)
Chemicals like PCBs and DDT are called persistent organic pollutants (POPs)
POPs contain carbon, like all organic compounds, and remain in water and soil for many years.
Spraying DDT, 1958
See page 96

13. Bioaccumulation (continued)
Many POPs are insecticides, used to control pest populations.
DDT was introduced in 1941 to control mosquito populations, and is still used in some places in the world.
Like PCBs, DDT also bioaccumulates
and has a long half-life.
Even at low levels (5 ppm), DDT in
animals can cause nervous, immune,
and reproductive system disorders.
ppm = parts per million
Spraying DDT, 1958
See page 96

14. Bioaccumulation (continued)
Heavy metals are metallic elements that are toxic to organisms.
Levels of lead in the soil have increased due to human activities.
not considered safe at any level.
Many electronics contain lead and must
be recycled carefully.
can cause anemia and nervous and
reproductive system damage.
Electronics Waste Contains Lead.
See page 97

15. Bioaccumulation (continued)
Cadmium is also found in low levels naturally.
used in the manufacture of plastics
and nickel-cadmium batteries.
toxic to earthworms and causes many health problems in fish.
In humans, the main source of cadmium is exposure to cigarette smoke.
Cadmium causes lung diseases, cancer,
and nervous and immune system damage.
Electronics Waste Contains Lead.
See page 97

16. Bioaccumulation (continued)
Mercury
also is found naturally
has entered ecosystems through the burning of fossil fuels, waste incineration, mining, and the manufacture of items like batteries.
Coal burning accounts for 40 percent of the mercury released into the atmosphere.
bioaccumulates in the brain, heart and kidneys of many animals.
bioaccumulate in fish, adding risk for any organisms eating fish.
Take the Section 2.3 Quiz
See pages

17. Bioaccumulation (continued)
Reducing the effects of chemical pollution = Bioremediation
the use of micro-organisms or plants to help clean up toxic chemicals.
Example: the oil industry uses bacteria to “eat” oil spills.
Also: trapping chemicals in the soil where they cannot enter the food chains as easily.
Take the Section 2.3 Quiz
See pages

18. POPs

19. Bioremediation

20. Mercury Poisoning

21. Reading check and Reflection
Read Page 94-99
Make some notes about what you learn
Do reading check questions P.96 and P.99
Write a half page reflection about:
The impact of bioaccumulation on ecosystems
Methods of reducing chemical pollution

22. Find out activity 2-3A - Page 93
Do not eat the Candies!
Tap the prey on the elbow only.
Answers to What Did You Find Out?
The pesticide affected all or almost all of the animals in the ecosystem
The pesticide would continue to affect animals in the ecosystem for the next 50 years. This would make the ecosystem unhealthy.