Question: if plankton ceased to exist, what would happen?

Russell Arnott answered on 8 Mar 2019:

Great question!

First of all, plankton form the base of all marine food chains. Sunlight is absorbed by phytoplankton (the plants) which are eaten by zooplankton (tiny animals) which are eaten by fish which are eaten by sharks, seals, whales and us. So without plankton, not only would we have no fish to eat but the seas would have no life in them; the food chains would collapse.

Secondly, because phytoplankton are plants they generate oxygen. We know now that plankton make 80% of the oxygen that we breathe to keep us alive; more than all the plants and trees on land. So without plankton, there would be much less oxygen available for life on land – chances are animals would be fewer and smaller.

Thirdly, it would rain less. Plankton produce a chemical that helps water molecules stick together to form clouds. Without clouds, we would have less rain which means less rivers and streams which means less plant life on land. The Earth would have vast areas of desert.

But you didn’t realise plankton were so important!