PREDATOR PLANTS - Eutrophication impact

Imagine, you are walking in the summer in the country with lots of water sources, rivers, lakes, ponds and rivulets. You may remember that the water did not look the same. Some water seemed to be quite clean, some was covered with oily spill, other with lots of plants or it seemed just green.

But not everything what is green, is good for nature. Water with lots of plant organisms, like algae, is possible threat for other organism. How is it possible and is the big amount of plants in water natural for water?

Bring samples of different water sources in science class and study the differences. Can you find out whether the water pollution is caused by inorganic or organic material?