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. Runoff from pesticides2. Runoff from fertilisers3. Stock effluent seepage and

dispersal4. 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 WayFrom the article: Blooms and Gloom

Dinoflagellates are microscopic and some species can produce toxins – which can harm an organism.

Question 2

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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

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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

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Carnivores as they eat meat• The Black swan is the only bird that

is a herbivore

Answer 4

Question 5

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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 consumerPelican is a 4th order consumerCormorant 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

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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

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Answer 7:Which fish would you buy?

• Black Bream = 2.1• Yellow-eye mullet =1.4• King George whiting = 1.2

• Reason???

Question 8

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Answer 8:How does DDT find its way into waterways???

1. Runoff from pesticides2. Runoff from fertilisers3. Stock effluent seepage and

dispersal4. Sedimentation from land

clearance/erosion

Question 9

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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 bThe 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 cA 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 dBased 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 eObservation 1 supports the idea that

DDT causes thinning of the eggshellsObservation 2 neither supports or

disproves this ideaObservation 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