Photosynthesis is the process through which plants use sunlight and carbon dioxide to make food to sustain themselves. Cellular Respiration is when cells use oxygen and water to create a food source for the cell. The formula for photosynthesis is the same for cellular respiration except it's backwards. Hope this helps.
I think the best answer is plant growth. My evidence for this is that to hot or to cold would kill them but if warm andwet environment is perfect to grow
To try and help although thee aren't any answers i would say... if they were to literally conduct a field study such as this, much pollution would occur, Millions of fish would die as of plants also. And would over-all Lake Michigan would never be the same again.