Bioaccumulation
The start of the problem
• Many chemicals we use in our daily lives
are toxic.
Toxic chemicals include:
1. pesticides,
2. engine products and
3. many household cleaners.
Most toxins are made by humans;
they do not occur naturally.
Some of these toxins are
persistent.
• Persistent toxins can cause the following problems:
1. Reproductive failure
2. Birth defects
3. Immune system disorders (cancers and weakness
to disease)
4. Behaviour and learning disorders
5. Death
• Persistent toxins are also known as Persistent
Organic Pollutants (POPs).
Persistent Organic Pollutants
(POPs).
Water is the lifeblood of our planet – so
how can it be polluted?
Waterways get polluted by:
1.
2.
3.
4.
Runoff from pesticides
Runoff from fertilisers
Stock effluent seepage and dispersal
Sedimentation from land
clearance/erosion
Traveling through food chains
• We (humans) may use toxins on land, but
they can travel through the soil in
groundwater into waterways and into
the ocean.
• All persistent toxins eventually end up
in ocean food chains.
Bioaccumulation vs
Biomagnification
• Bioaccumulation refers to the
accumulation of a toxic chemical in the
tissue of a particular organism.
• Biomagnification refers to the
increased concentration of a toxic
chemical the higher an animal is on the
food chain.
The Effect of the Pollutant
• Different organisms show varying
degrees of sensitivity to toxins. Even
within a species, sensitivity to a
particular toxin may depend on age, sex,
food availability, reproductive condition
• with DDT, the egg shells of large birds
were so weak that they would be
crushed by the weight of the adult
birds.
Egg shells of large birds
A little goes along Way
From the article: Blooms and Gloom
Dinoflagellates are microscopic and some
species can produce toxins – which can
harm an organism.
Question 2
• ??????
Answer 2
• Biomagnification refers to the
increased concentration of a toxic
chemical the higher an animal is on the
food chain.
• Own words????
Question 3
• ????
Answer 3: Western Port Bay
• a) Food chains:
Detrius  tube worm 
squirter worm  black bream  pelican
• b) DDT increases from 1.4 to 22.8 in
this food chain
Tern, Pelican, Cormorant are all
Question 4
• ????
Carnivores as they eat meat
• The Black swan is the only bird that is
a herbivore
Answer 4
Question 5
• ?????
Answer 5a:
DDT levels in various organisms
• a) Tern DDT level is less than the
Pelican or the cormorant because:
Tern is a 3rd order consumer
Pelican is a 4th order consumer
Cormorant can be a 4th order consumer
Answer 5b:
DDT levels in the Black Swan
• Black Swan feeds on eel grass and not
detritus, therefore the DDT levels are
lower in the swan compared to other
birds
Question 6
• ????
Answer 6:
DDT in detritus is very high
• decomposing organic matter is found in the
detritus – so any organism that had a high
DDT content in it and dies will leave this DDT
in the detritus
Question 7
• ????
Answer 7:
Which fish would you buy?
• Black Bream = 2.1
• Yellow-eye mullet =1.4
• King George whiting = 1.2
• Reason???
Question 8
• ????
Answer 8:
How does DDT find its way into
waterways???
1.
2.
3.
4.
Runoff from pesticides
Runoff from fertilisers
Stock effluent seepage and dispersal
Sedimentation from land
clearance/erosion
Question 9
• ????
Answer 9:
Non-degradable substances
• Summarize how they accumulate
• What we want instead is:
✔
Biochallenge answers page 468
Answer a
• Birds of prey are further up the food
chain than the seed-eating birds and
would be more affected by the
accumulation of DDT
Answer b
The average thickness of the shells over
time has been reduced. The majority of
the dots are 1.4 in mid 1970, compared
to 2.0 in 1890
Answer c
A range of thickness observed in egg
shells in the same year could indicate:
• Eggs were collected from different
regions
• Some birds may not have consumed as
much DDT as others through their
feeding
Answer d
Based on the graph the DDT was most
likely used extensively in Australia just
before 1950
Evidence for this can be seen in the
increase in dots at index 1.2 and 1.4
The idea is: DDT causes thinning
of the shells of eggs
Answer e
Observation 1 supports the idea that
DDT causes thinning of the eggshells
Observation 2 neither supports or
disproves this idea
Observation 3 neither supports or
disproves this idea
Answer f: DDT levels in breast milk from
urban and rural areas in 1971 & 1979
• In 1971 Urban and rural differences existed
because the DDT was entering the food chain via
agricultural use – treatment for termites in rural
areas
• The change from 1971-1979 was that urban
numbers decreased from 2300-1200, and rural
numbers decreased from 17,000 to 1200 – due to
the restrictions the government put on the way
to treat termites