1. Eutrophication

2. Process of Eutrophication  natural process of the aging of a body of water  As more nutrients enter the water more organisms live and die and add their organic molecules to the decaying / recycling process  Bodies of water evolve from oligotrophic to eutrophic

3. Process continued  Eutrophication can be accelerated by human activities –Increasing levels of nitrates and phosphates  Detergents  Sewage  Fertilizers from agricultural runoff

4. “death” of Lake Erie, 1960’s  Large amounts of detergents and fertilizers dumped in to lake  Caused increase of algae growth –Algal bloom  The decomposition of dead algae uses tremendous amounts of oxygen causing death to fish and other organisms at higher trophic levels

5. “death” of Lake Erie, continued  Lake Erie declared “dead”  Prompted a ban on phosphates in detergents in the late 1960’s  Within a decade, Lake Erie rebounded –Still suffers from other forms of pollution

6. Impacts of eutrophication  As oxygen levels deplete from decomposers, other aerobic organisms suffer and die contributing to the decomposition process (Positive Feedback)  Can lead to “death” of a body of water –Decrease in species diversity –Stagnant putrid water