Twin Cities Seminar

The Greening of our Inland Waters: Feedbacks of eutrophication on lake carbon cycling


Dr. Mindy Morales-Williams
Post Doc, College of Biological Sciences

March 31, 2017


Lakes process a disproportionally large fraction of carbon relative to their size and spatial extent, and so represent an important component of the global carbon cycle. Alterations to lake ecosystem functioning via eutrophication and harmful cyanobacteria blooms may alter the balance of greenhouse gas flux in these systems. Without eutrophication, lakes function as sources of CO 2 to the atmosphere resulting from terrestrial inputs of organic and inorganic carbon. In eutrophic lakes, this process can be reversed due to high primary producer demand for CO 2 during sustained bloom events. Using a combined approach of high-frequency sensor measurements, stable carbon isotopes, optical characterization of dissolved organic matter, and phytoplankton community characterization, we show that anthropogenic eutrophication and cyanobacteria dominance result in autochthonous carbon pools, altering biogeochemical processing and gas exchange from these systems. Ongoing work will investigate feedbacks of this simplified carbon pool on microbial community diversity and ecosystem function at regional and global scales.


Limnologist, biogeochemist, phycologist specializing in cyanobacteria bloom dynamics, microbial community ecology, and lake carbon cycling.