Lakes!

Oligotrophic lakes have low dissolved nutrients. There is also not much algae growth and organisms. They are unproductive lakes. Very low in phosphorous.
Mesotrophic lakes have the highest diversity of plants and organisms. They are mainly found in the North and West.
Eutrophic lakes are very high in phosphorus. Eutrophic lakes have a lot of minerals and nutrients. Abundant plants and algae.
It is important to understand the type of lake you are studying because each lake is different. Eutrophic have very high phosphorus where as Oligotrophic has a low amount. If you understand the type of lake then you will know what to expect from the different organisms in each lake.