Effects of Bioaccumulation on EcosystemsChapter 2.3

What do you know?

▪ Bioaccumulation▪ Bio-magnification▪ Orcas and pollution▪ Pesticides and the environment▪ Persistent organic pollutant▪ Heavy metal

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.

Bio-indicators help monitor the health of the environment

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?

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!

Keystone Species

Bioaccumulation

▪ Bioaccumulation refers to the gradual buildup ofchemicals 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.

See page 94

Organisms are sometimes exposed to

toxic chemicals.

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).

See page 94

Organisms are sometimes exposed to

toxic chemicals.

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 consumes4550 kg worth of accumulatedPCBs.

See page 95The bioaccumulation of PCBs begins with the absorption of the chemicals by microscopic plants

and algae.

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.

See page 95The bioaccumulation of PCBs begins with the

absorption of the chemicals by microscopic plants and algae.

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.

See page 96Spraying DDT, 1958

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

See page 96Spraying DDT, 1958

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.

See page 97

Electronics Waste Contains Lead.

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. See page 97

Electronics Waste Contains Lead.

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.

See pages 98 - 99

Take the Section 2.3 Quiz

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.

See pages 98 - 99

Take the Section 2.3 Quiz

POPs

Bioremediation

Mercury Poisoning

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

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?1. The pesticide affected all or almost all of the animals in

the ecosystem2. The pesticide would continue to affect animals in the

ecosystem for the next 50 years. This would make the ecosystem unhealthy.