Rowly, My 6 year old Grandson tosses every cow chip he finds into the water to fertilize it. He figures that if we use it for the lawn, it has to be good for water.
Seriously, if it has increased the phytoplankton base, it would seem that it would have to help the overall food chain. On the other hand, I have heard of some very prolific clear water lakes in your part of the world. I would keep an eye on the situation. If you get too much assistance, you can overdo a good thing. I have a small 1/6 acre pond that I used for forage. I stocked a pound of fatheads and 50 small bluegills. They spawned like crazy and I seined it a couple of times to start a neighbors pond. Then I couldn't get anybody to pull on the other end of a seine. Before long the water turned too green and everything died. Nasty stuff.
