Duckweed Lemna minor
Explain how a human activity can change the organisation of an ecosystem: the example of an imported plant that has become invasive
Structure and functioning of agro-systems
Ecosystems: dynamic interactions between living things and between them and their environment
A simple study of a species presents almost everywhere: duck weed.

Duck weed is present on all continents. When they overgrow, they can be a sign of eutrophication.
Each duck weed creates a new leaf that grows, then breaks off and forms a new plant. This vegetative multiplication therefore does not involve seeds or spores.
Pair the growth of this very simple species with fertilizer rates in river water to illustrate the impact of current agriculture on our hydrosystems.
Students will observe that the higher the fertilizer rate, the faster the duck weed develops.

Composition :

• 1 strain of Lemna minor duck weed
  
• 2 doses of non-toxic fertilizer (= pollutant)
  
• 1 box of culture
  Optional material required:
  
• Camera or digital camera
  
• Counting software