In the above picture the experimenters are attempting to answer questions about the nutrients that encourage the growth of phytoplankton. Phytoplankton are tiny plants that form the basis for the food web in most freshwater ponds and lakes. Krystle, the hardworking experimenter wants to know the answer to two questions:

1. What nutrients do phytoplankton actually need to grow? and

2. Has the amount of these nutrients changed since the 1970's?

To answer these questions she filled the tubes (pictured above) with filtered water and added compounds containing nitrogen, and phosphorus. A previous study conducted in 1973 by David Gerhart had concluded that only when both nitrogen and phosphorus were present did the algae living in the lake begin to thrive. Krystle's plan was to recreate the 1973 study.

Each morning before sunrise Krystle would add nitrogen (N) to some tubes, phosphorus (P) in others, and a combination of both N and P in the remaining tubes. In the end, Krystle concluded that only when both nitrogen and phosphorus were present did the phytoplankton living in Mirror Lake really begin to multiply. Her study also revealed that the nutrient enrichment of Mirror Lake has probably not changed much in 32 years, which is very good!

Taking the trees out made the soil loose and when it rained the soil would run into the lake. as told by Kassandra age 11

There is a lake in equatorial Africa called Lake Victoria. It is the second largest lake in the world. It was full of life with many species of fish, plants, trees and other land animals. Then in 1858, the British found this land and claimed it for themselves even though there were already people living there. They started to make it a good environment for themselves. They cut down trees to make room for crops like coffee, tea, and banana trees.

The British then looked to fishing for enjoyment. They fished for the ngege. They fished the ngege so much they actually led the species to extinction. To replace the ngege the British introduced the tilapia as well as the Nile Perch to Lake Victoria. The British only added the Nile perch to make it fun to fish. It was a huge fish. It weighed up to 300 pounds. Anybody would love to catch a 300 pound fish and have that much food afterwards. The Nile perch was so big and it ate so much that it put most of the other fish to extinction.

But they ran into a problem. These fish were so big they wouldn’t dry without rotting. Instead of drying in the sun the Nile perch needed to be roasted over fire. They never thought about the ecosystem. Many trees around the lake were cut to provide wood for the fire. The trees had been holding the soil together. Taking the trees out made the soil loose and when it rained the soil would run into the lake. This is called erosion.

The lake ended up getting too many nutrients and became nutrient rich. The nutrient-rich water made it easy for algae to grow. When the algae dies it sinks to the bottom of the lake and it rots. The rotting algae used the oxygen in the lake which the fish need to breathe. Many species of fish died and became extinct.

The water became polluted and carried many human diseases in it. Many humans around the lake had to suffer from the symptoms of the diseases.

So, think back to the beginning. The British only meant to change one thing but ended up changing almost everything. Once you take a part of an ecosystem away it changes the whole thing. This will never stop because people think they are making it better.