science

OO I don't know, lets see. How does a fertilizer deplete anything by going into a nearby like?
Probably then, some excess fertilizer leaked into the lake and did something to the plants and animals of the lake. Think of it as a "web of nutrients and respiration"

Shiv might it be oxygen

http://www.thefreedictionary.com/eutrophication

the point is not to do the homework for the kids. Being a pushover for no-thinking answers is a crappy marquee for this damned site.

Too many as there are!! You're absolutely right.

True, Farm, they do get to be a nuisance. In tis case however when I Googled the topic I was somewhat unsuccessful, so concluded maybe he did have a good q after all

Shivangi: I hope you're not being so LAZY as to think all you have to do is google and your answer will be at your fingertips. There are many answers to this question. I hope to not be adding to your detriment by explaining the following:
Phosphorus pollution accelerates eutrophication , which accelerates biological death due to depleted bioavailability of oxygen. Having too much phosphorus in aquatic plants such as Algae, can make them grow out of control, and can lead to bio death of freshwater.