Activity: Effects of Bioaccumulation on Ecosystems
Take a moment to think and to consider...
- What effects would having an excess amount of chemicals (both organic & synthetic) have on the ecosystem?
- How would they, or could they, affect the biotic organisms living in there?
- If a primary consumer were to ingest/consume an excess amount of the chemicals, would the consumers at the secondary & tertiary trophic levels be affected?
- Below you will find a list of words that will be important to know. Take a moment to examine the list. What do you think the terms means individually? How do you think they relate to one and other?
|
|
Your thoughts on the above questions and terms should be recorded in your individual Google document, Sustaining Earth's Ecosystems – Effects of Bioaccumulation on Ecosystems.
Once you have finished your brainstorming you should move on to Time to Research portion of this activity. While you are reading the notes below and watching the videos, you should be making notes in your individual Google Document, Sustaining Earth's Ecosystems – Personal Notes, if you prefer you can record your "personal notes" on paper.
Once you have finished your brainstorming you should move on to Time to Research portion of this activity. While you are reading the notes below and watching the videos, you should be making notes in your individual Google Document, Sustaining Earth's Ecosystems – Personal Notes, if you prefer you can record your "personal notes" on paper.
Time to Research (Read, Watch, and Take Notes)
Amphibians live on both land and in the water.
- Amphibians are sensitive to chemical changes in the environment.
- They are therefore valuable indicators of environmental health.
- Since the 1980s, many of the world’s amphibian species have suffered declines in population.
- There also have been alarming increases in amphibian birth deformities.
- Many theories attempt to explain these changes, including drought, increased UV rays, pollution, habitat loss, parasites, and diseases.
How Pollutants Climb the Food Chain
Bioaccumulation refers to the gradual buildup of chemicals in living organisms.
- Many harmful chemicals cannot be decomposed naturally.
- These chemicals can be eaten or absorbed and sometimes cannot be removed from the body of the organism effectively.
- If a keystone species suffers a chemical bioaccumulation, it can affect every other organism in its far-reaching niches.
- A keystone species is a vital part of an ecosystem.
- An example of a keystone species in British Columbia is salmon.
- In the fall they are an important food source for bears, wolves, eagles, and otters.
- Salmon alter the ecosystem with their decaying bodies become rich with nutrients, such as nitrogen for trees.
- salmon can also retain harmful chemicals in their body fat and transfer these chemicals to other organisms when they are consumed.
- When a consumer in the next trophic level eats organisms with a chemical accumulation, it receives a huge dose of the chemical(s).
PCBs and the OrcaAn example of bioaccumulation in British Columbia is the effect of polychlorinated biphenyls (PCBs) on the Orca.
|
|
Persistent Organic Pollutants
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.
- Many POPs are insecticides, used to control pest populations.
- Dichlorodiphenyltrichloroethane (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
Heavy Metals
- Heavy metals are metallic elements that are toxic to organisms.
Lead
Levels of lead in the soil have increased due to human activities.
- Lead is not considered safe at any level.
- Many electronics contain lead and must be recycled carefully.
- Lead can cause anemia and nervous and reproductive system damage.
Cadmium
- Cadmium is also found in low levels naturally.
- Cadmium is used in the manufacture of plastics and nickel-cadmium batteries.
- It is 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.
Mercury
Mercury also is found naturally.
- Mercury 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.
- Mercury bioaccumulates in the brain, heart and kidneys of many animals.
- Mercury compounds bioaccumulate in fish, adding risk for any organisms eating fish.
Reducing the Effects of Chemical Pollution
Reducing the effects of chemical pollution
- Bioremediation is the use of micro-organisms or plants to help clean up toxic chemicals.
- Example: the oil industry uses bacteria to “eat” oil spills.
- By trapping chemicals in the soil, they cannot enter the food chains as easily
Videos
- PCB's in B.C.'s Killer Whales - by Craig Delahunt
- What is BIOACCUMULATION? What does BIOACCUMULATION mean? BIOACCUMULATION meaning & explanation - by The Audopedia
- How Does Mercury Get Into Fish? - by Seeker
- Future Conditional: The Grasshopper Effect: Toxic Pollution in the Arctic - by Journey to Planet Earth
- Biomagnification and the Trouble with Toxins - by Amoeba Sisters
Processing - To Be Completed Before Moving On
Let's have a check in. Take the time to answer the following questions; record your answers in Sustaining Earth's Ecosystems - Effects of Bioaccumulation on Ecosystems. (You should be able to answer the following questions without having to refer to your notes).
- What is bioaccumulation?
- What is biomagnification?
- How does a chemical bioaccumulate in an organism?
- What are keystone species? Why are they important to the ecosystem?
- What are PCBs? What is their full chemical name?
- What were PCBs used for in the 1970s?
- In North America PCBs were banned in 1977. Explain why they are still having an effect on organisms today.
- How do orcas survive when salmon stocks are low? What effect does this have on their survival?
Checking-In - To Be Completed Before Moving On
Check-In One:
Take the time to search and to identify other effects that bioaccumulation has on ecosystems.
Check-In Two:
Finally, take a moment to think about what we can do as humans to decrease the amount of bioaccumulation in ecosystems.
Take the time to search and to identify other effects that bioaccumulation has on ecosystems.
- Find a specific example and answer the following:
- What chemical causes it?
- What are the effects on producers, primary consumers, and secondary consumers?
- What are the effects on humans?
- Share your example on the Padlet Wall for this activity.
Check-In Two:
Finally, take a moment to think about what we can do as humans to decrease the amount of bioaccumulation in ecosystems.
- Share it on the second Padlet Wall.