First 126 words of the document:
Fertilisers that leach off fields and sewage enrich
water with nitrates and phosphates.
The sudden increase in availability of these minerals
causes algae to grow at a much faster rate.
Algae out-competes other plants, so these plants die.
Algae also grows faster than it can be consumed, so
there is also a lot of unconsumed dead algae.
This sudden increase in detritus causes saprobionts
to multiply quickly, these bacteria respire aerobically
and decrease the oxygen concentration in the water.
This decrease in oxygen concentration means that
aerobes such as fish can no longer survive in that
body of water.
Also, anaerobic bacteria multiply quickly and release