1. 2.3 Effect of Bioaccumulation on Ecosystems
Amphibians live on both ___________ and in the _________.
Amphibians are sensitive to ___________________________in the environment.
They are therefore valuable indicators of environmental ______________.
Since the 1980s, many of the world’s amphibian species have suffered ____________________in population.
There also have been alarming increases in amphibian _____________________.
Many theories attempt to explain these changes, including drought, increased UV rays, ______________, habitat loss, parasites, and ________________.
Amphibians, like this frog, have exhibited drastic changes since the 1980s.
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2. Bioaccumulation
Bioaccumulation refers to the gradual buildup of _________________ in _______________________.
Many harmful chemicals cannot be _______________ naturally.
These chemicals can be__________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 _______________________in its far-reaching niches.
A keystone species is a ________________of an ecosystem.
Biomagnification is the process by which chemicals become more ____________________ at each _____________________.
At each level of the food pyramid, chemicals that do not get broken down __________________ in organisms.
When a consumer in the next trophic level eats organisms with a chemical accumulation, it receives a _____________________of the chemical(s).
Organisms are sometimes exposed to toxic chemicals.
See page 94
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3. Bioaccumulation (continued)
An example of bioaccumulation in British Columbia is the effect of PCBs on the ____________.
PCBs are chemicals that were used for many _______________ and ___________________applications in the mid-20th century.
PCBs were banned in 1977 because of their __________________________.
PCBs ____________________
and have a long ____________
(they break down very slowly).
PCBs will affect the
_________________________
of orcas until at least 2030.
See page 95
The bioaccumulation of PCBs begins with the absorption of the chemicals by microscopic plants and algae.
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4. Bioaccumulation (continued)
Chemicals like PCBs and DDT are called
_____________________________________________(POPs).
POPs contain carbon, like all organic compounds, and remain in _________ and__________________for many years.
Many POPs are ______________________, 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 __________________(5 ppm),
DDT in animals can cause nervous,
immune, and reproductive system
_____________________.
ppm = parts per million
Spraying DDT, 1958
See page 96
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5. Bioaccumulation (continued)
Heavy metals are _____________________that are toxic to organisms.
Levels of ____________ in the soil have increased due to human activities.
Lead is not considered safe at _______level.
Many electronics contain lead and must
be _______________________________.
Lead can cause ____________ and nervous and
reproductive system ______________.
Cadmium is also found in low levels naturally.
Cadmium is used in the manufacture of plastics
and __________________________ batteries.
It is toxic to _______________ and causes many health problems in________________.
In humans, the main source of cadmium is exposure to _________________________________.
Cadmium causes lung diseases, _______________,
and nervous and immune system damage.
Electronics Waste Contains Lead.
See page 97
(c) McGraw Hill Ryerson 2007

6. Bioaccumulation (continued)
___________________ also is found naturally.
Mercury has entered ecosystems through the burning of _____________________, waste incineration, mining, and the manufacture of items like __________________.
Coal burning accounts for ___________of the mercury released into the atmosphere.
Mercury bioaccumulates in the______, heart and kidneys of many animals.
Mercury compounds bioaccumulate in fish, adding risk for any organisms _______________________.
Reducing the effects of chemical pollution
________________________ is the use of micro-organisms or plants to help clean up toxic chemicals.
Example: the oil industry uses bacteria to “___________” oil spills.
By trapping chemicals in the soil, they cannot enter the food chains as easily.
See pages
(c) McGraw Hill Ryerson 2007