Human effects on ecosystems Flashcards
biodiversity
variety of living organisms in an area
fish farming
growing one kind of fish in an area
the fish are fed and the waste they produce is removed from their tanks
Why does overfishing of wild fish happen?
- people get most of their protein from fish
- the population is increasing leading to overfishing to meet demands
advantages of fish farming
reduces overfishing of wild fish
less predators
more space efficient
larger sizes
disadvantages of fish farming
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
non-indigenous species
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
advantages of introducing non native species to an area
may provide food for native species
may reduce numbers of a pest
disadvantages of non native species
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
definition of eutrophication
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
stages of eutrophication (7)
- 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
basic stages of eutrophication
addition of nitrates
growth of plants
death of plants
growth of bacteria
lack of oxygen
suffocation
What type of fertilisers can cause eutrophication?
both natural and artificial fertilisers
Explain how eutrophication can lead to a decrease in biodiversity [3]
(growth of surface plants) blocks light so plants die
increase in bacteria uses up oxygen
fish and other animals die
