Question
Our Florida lake is filled with algae. I wish to know since bacteria causes algae what can algae cause in the surrounding area?

Answer
Hi Maggie, I checked around and this is what I found "Algae control can be accomplished by reducing plant nutrients (fertilizers). These include phosphorus and nitrogen, minor nutrients such as sulfur and various micronutrients such as iron, manganese, magnesium, zinc, molybdenum, cobalt, etc. This is why algae removal using algaecides often results in weed growth and weed control with herbicides often results in heavy algal blooms.

The nutrients must go somewhere. They will go either into weeds or algae. Algae shade the water so weeds cannot grow. If the problem is excessive weed growth, the weeds take up the plant nutrients in the water so the algae cannot grow. Lakes naturally shift every few years from weeds to algae or from algae to weeds.  It all depends on what becomes established first in the season.

As you know, algaecides algae removal, likewise, several references indicate that both excessive copper algaecides and alum can kill fish and other aquatic animals or interfere with reproduction in fish. Copper compounds can kill beneficial bacteria in the lakes that want to feed on bottom organic sediment. Alum can leave an aluminium hydroxide flocculent on the bottom that interferes with both fish reproduction and with beneficial bacteria and insects that feed on bottom organic sediment muck).  Copper compounds can destroy water quality. As the dead algae decompose they not only release phosphorus and nitrogen, they also consume oxygen. Lack of oxygen causes a release of massive amounts of phosphorus and nitrogen from the sediment into the water. Reducing. oxygen often causes fish kills. Algaecides do nothing to improve the health and growth of fish, nothing to reduce bottom organic sediment. Copper compounds also add a new toxic sediment to the bottom, copper carbonate, which also interferes with bacterial decomposition of sediments and interferes with fish reproduction.

If you remove all the algae in a lake without eliminating the cause, the plant nutrients are still in the water. The algae will quickly return, unless weeds quickly take up the nutrients before the algae grow again. Then you have a lake full of weeds."   kATHY