PPT Slide
In the early 1970’s, there was a debate as to whether nitrates or phosphates were the principal limiting resource in aquatic ecosystems. Robert Wetzel led a team of scientists which divided a Canadian lake, simply called “Lake 226” in two with a plastic sheet, and enriched one side with phosphates. By the following summer, there was an enormous algal bloom on the treated side. In its time, this photograph was extremely dramatic.