Changing Chlorophyll Levels Show Lake Mendota’s Fall Turnover In Action

A graduate student at the University of Wisconsin’s Center for Limnology has captured the fall turnover of Lake Mendota in action, according to a blog post from the school. The rearranging waters were captured using chlorophyll measurements.

In Lake Mendota, this fall turnover coincided with an algae bloom that affected most of the lake’s shoreline waters. And so it was clear that nutrients trapped in cooler thermoclines during the summer were making their way to the surface.

Lake Mendota. (Credit: Wikimedia Commons User Archbob via Creative Commons)

A multi-parameter sensor attached to a boat allowed for lake-wide measurements to be taken in mid-October. The turnover began around October 10, when low chlorophyll readings were recorded around most of the lake. About two weeks later, concentrations near shore were considerably higher.

Interestingly, a data buoy in the middle of the lake didn’t record much of a change in chlorophyll, which shows just how variable lake conditions can be.