Human effects on ecosystems Flashcards

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1
Q

biodiversity

A

variety of living organisms in an area

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2
Q

fish farming

A

growing one kind of fish in an area

the fish are fed and the waste they produce is removed from their tanks

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3
Q

Why does overfishing of wild fish happen?

A
  • people get most of their protein from fish

- the population is increasing leading to overfishing to meet demands

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4
Q

advantages of fish farming

A

reduces overfishing of wild fish

less predators

more space efficient

larger sizes

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5
Q

disadvantages of fish farming

A

the waste can pollute the local area, changing conditions so that some local species die out (e.g. birds)

diseases from the farmed fish (such as lice) can spread to the wild fish and kill them

parasites/diseases spread easily so have to be treated

lots of fish are kept in a small space, causing distress to the fish

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6
Q

non-indigenous species

A

organisms that are not found naturally in the area/occurring in an area outside its natural range

they may be introduced on purpose (as pest control, aesthetic reasons) or accidentally to a region

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7
Q

advantages of introducing non native species to an area

A

may provide food for native species

may reduce numbers of a pest

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8
Q

disadvantages of non native species

A

may reproduce rapidly as there are no natural predators in the new area

may out-compete native species for food or other resources

may eat other indigenous species in the area

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9
Q

definition of eutrophication

A

the addition of more nutrients to (water in) an ecosystem (through fertilisers) than it naturally has

the addition of phosphates and nitrates to water through fertilisers

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10
Q

stages of eutrophication (7)

A
  • fertiliser containing phosphates and nitrates is added to a field, then excess is washed away by rain
  • it isn’t all taken up by plants, and some ends up in water courses
  • extra nutrients causes water plants and algae to grow quicker
  • plants and algae cover water surface, block light to deeper water
  • deeper plants can’t get light/photosynthesise and die
  • bacteria decompose dying plants, increase in numbers quickly, and take more oxygen from the water
  • there is not enough oxygen left in the water for fish, so they suffocate and die
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11
Q

basic stages of eutrophication

A

addition of nitrates

growth of plants

death of plants

growth of bacteria

lack of oxygen

suffocation

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12
Q

What type of fertilisers can cause eutrophication?

A

both natural and artificial fertilisers

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13
Q

Explain how eutrophication can lead to a decrease in biodiversity [3]

A

(growth of surface plants) blocks light so plants die

increase in bacteria uses up oxygen

fish and other animals die

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