Assessing and addressing the re-eutrophication of Lake Erie: Central basin hypoxia

Journal of Great Lakes Research, Volume 40, Issue 2, June 2014, Pages 226–246
http://dx.doi.org/10.1016/j.jglr.2014.02.004
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Posted by Chris Mallon,

​Of all the Laurentian Great Lakes, Lake Erie is the most sensitive to eutrophication. Its sensitivity arises from its shallow depth, making the water warmer and more amenable to algae growth. Lake Erie also receives direct runoff from major cities and intensely-managed agricultural landscapes in Canada and the United States. Lake Erie has therefore been one focal point for the study of eutrophication in freshwater ecosystems.

This article focuses on phosphorus as the main causal factor of eutrophication in Lake Erie. The article covers the history of phosphorus loading, explains the difference between total phosphorus (TP) and dissolved reactive phosphorus (DRP), and explains the impacts these nutrients have on algal growth, dissolved oxygen, and ecosystem health. It also provides a summary of agricultural best management practices (BMPs) that influence the release of TP and DRP into the Lake Erie ecosystem. A summary of the implications of climate change is provided, explaining the impact of more extreme weather events on the phosphorus loading trends already noted. The article concludes with a section describing policy and management implications.

This article offers value in several ways. Firstly, it provides an effective summary from many different disciplines to explain the overall impacts that phosphorus loading is having on the Lake Erie basin. In doing so, it also functions as an annotated bibliography for anyone interested in discussing or learning about the impacts of phosphorus on freshwater ecosystems. Secondly, it provides rare clarity on the historical progression of phosphorus contributions to the Lake Erie ecosystem, synthesizing many different datasets. The context and difference between point source and non-point source pollution is explained, with the overall message being that eutrophication is recurring now because of an increase in non-point source pollution. Thirdly, it very clearly outlines the different sources, both spatially and by industry, of the P loading. This enables one to get a sense of both the volume and nature of the phosphorus entering Lake Erie. Finally, it explains the basic difference between DRP and other types of P in light of the management challenges. The reader can gain a clear understanding that the re-eutrophication of Lake Erie is occurring largely due to the increase in dissolved reactive phosphorus.

​In summary, this is a multi-disciplinary introduction to freshwater eutrophication in the Great Lakes as a result of phosphorus loading.