Good Riddance Eutrophication!

By: Myrna Castro

Eutrophication, the cause for a mysterious sudden bloom of algae that has been troubling freshwater ecosystems for decades may possibly come to an end. There has been a strong trend in the past few years that shows as human population and their overall impact increase; the sudden growth of algae is becoming more frequent. As the clusters of algae expand over freshwater systems, they shade underwater plants causing them to die. Without the plants, bacterial decomposition and respiration cause an overall depletion of oxygen in the water, thus resulting in the death of the ecosystem. The article described a collection of research that initially narrows down the possible limiting factors for the algae are Nitrogen (N), and Phosphorus (P).  They analyzed the different in results between a small scale bioassay experiment and a whole large lake scale experiment. It was shown that the smaller assays were found to be inaccurate due to the unknown curb of eutrophication. They continued with large-scale experiments on over thirty different lakes. Their evidence supported that with the removal of N had absolutely no reduction in algae and that the only limiting nutrient is Phosphorus.

                                      Figure 1: Limiting factor supporting phosphorus evidence vs. nitrogen evidence (Schindler 2016)

Reference

David W. Schindler, Stephen R. Carpenter, Steven C. Chapra, Robert E. Hecky, and Diane M. Orihel: 

Reducing Phosphorus to Curb Lake Eutrophication is a Success Environmental Science & Technology 2016 50 (17), 8923-8929 http://pubs.acs.org/doi/abs/10.1021/acs.est.6b02204