What is eutrophication?
Nitrates from fertilised fields can be washed into rivers and lakes by rain.
The nitrates cause lots of algae to grow at the surface of the water which prevents light from reaching the plants and other algae below.
Eventually these organisms die because they cant photosynthesise. Bacteria decompose the dead material and use up oxygen.
This oxygen isnt replaced becuase photosynthesis is only taking place at the surface.
Animals that need oxygen from the water lower down e.g fish will suffocate.
What is bio-accumulation?
As you go up the food chain the amount of waste in an organism will increase or accumulate
What is biodiversity?
The amount of diverent species and habitats in a particular area
The number of different species on Earth
The range of different types of organisms
The genetic variation between organisms of the same species