Describe how fertiliser run-off can cause damage to a lake's ecosystem.

Fertilisers are generally high in nitrogen, to replenish the nitrogen in the soil assimilated by the crop plants. When this is drained into lakes in run-off, it can cause dramatic consequences. Nitrogen availability is usually the limiting factor of surface algae growth. As the nitrogen concentration increases, it becomes an excess, and the algae reproduce uncontrollably. This forms an algal bloom at the surface of the lake. The thick layer of algae absorbs and reflects all light that hits the lake, so photosynthetic organisms below the algae are deprived of light and die. This wide spread death in the lake reduces the biodiversity and alters food chains dramatically, destroying any ecosystem stability. It also creates a large amount of detritus, which feeds the breeding of anaerobic, decomposing microorganisms. These respire anaerobically with toxic waste products, causing the water to be toxic and killing most of the organisms left in the lake. This process is known as eutrophication.

Answered by William D. Biology tutor

3818 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

What is ultrafiltration?


What is the bonding in a DNA double helix


Explain how pressure differences in the heart ensure sufficient pumping of blood into the arteries. (3)


Explain how an impulse is transmitted between nerve cells.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2024

Terms & Conditions|Privacy Policy
Cookie Preferences